ACMT Toxicology Visual Pearl – Who Toad You to Lick It?
When people intentionally lick this toad, which toxin can they be exposed to?
- Bufodienolides
- Ciguatoxin
- Mescaline
- Psilocybin
[Image by Spencer B. via iNaturalist]
PEM POCUS Series: Pediatric Musculoskeletal Ultrasound
Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric musculoskeletal evaluation. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.
Module Goals
- List the indications for performing pediatric musculoskeletal (MSK) point-of-care ultrasound (POCUS)
- Describe the technique for performing specific pediatric MSK POCUS applications
- List anatomical landmarks for specific MSK POCUS applications
- Interpret signs of fracture, effusion, dislocation, and osteomyelitis with POCUS
- Describe the limitations of MSK POCUS
Case Introduction: Adolescent with Left Knee Swelling
A 13-year-old female with no past medical history presents to the emergency department with pain and swelling to her left knee. The pain started 3 days ago, with the pain worsening and swelling noted on the day prior to arrival. She can bear weight but has a limp. She has had no other current or past joint pain or swelling, no known trauma, no fever or other infectious symptoms, no recent travel, and no known insect or tick bites. She spent the summer at camp in the northeast United States. Her vaccines are up to date.
On arrival, her vital signs are:
| Vital Sign | Finding |
|---|---|
| Temperature | 37.3 C |
| Heart rate | 109 bpm |
| Blood pressure | 117/74 |
| Respiratory rate | 20 |
| Oxygen saturation (room air) | 99% |
On physical examination, she is well appearing and in no acute distress. Her exam is significant for left knee swelling and tenderness to palpation anteriorly with decreased knee flexion due to pain. She has no redness, warmth, or numbness around her knee. She has an antalgic gait but can bear weight.
Given her pain and swelling of her left knee, blood tests and X-rays are ordered, and orthopedics is consulted. You decide to perform a musculoskeletal point-of-care ultrasound (MSK POCUS) examination.
Musculoskeletal POCUS can be performed for a variety of indications including trauma, swelling, erythema, pain, decreased range of motion of a joint, and limp or inability to bear weight. It can assist in early diagnosis of fracture, effusion, dislocation, and osteomyelitis and allow for expedited treatment. Children and adolescents are ideal candidates for MSK POCUS as they generally have less subcutaneous tissue, making it easier to obtain ultrasound images to assess for pathology.
Note: This module focuses on diagnostic uses in musculoskeletal POCUS and not on procedural uses.
Musculoskeletal POCUS can be incorporated into the physical examination by scanning the area of injury, the point of maximal pain or tenderness, or a joint for effusion.
Probe Selection and Patient Comfort
Figure 1. Linear ultrasound probe.
- Use a high frequency linear probe (Figure 1) to obtain high resolution images of generally superficial structures in MSK POCUS.
- A curvilinear probe may be necessary for older children to examine structures with depth greater than 4-6 cm (e.g., hip).
- Patient comfort is the key to obtaining quality images.
- Place in a position of comfort on the bed, chair, or in a parent’s lap.
- Apply copious warm gel (Figure 2L).
- Rest the base of your scanning hand on a non-tender area to avoid putting excessive pressure on a painful area (Figure 2R).
- Provide pain control.
- Distract with a toy, book, or phone/tablet.
- Consult a child life specialist, if available, to help ease the child’s anxiety.
Figure 2. Linear probe with copious gel (L). The clinician floats the probe on the gel and rests the base of the scanning hand on an uninjured area to minimize pressure on the painful area (R).
Pro-Tips
- When performing MSK POCUS, it is helpful to scan the contralateral normal side first. This allows for identification of the child’s normal anatomy, including growth plates if present, and comparison when scanning the area of pain/injury. It also allows the child to understand the MSK POCUS exam before scanning the painful area.
- Match the probe footprint to the area being scanned: a wider, longer footprint for the hips or long bones; a smaller footprint for the small bones of the hands or feet.
Musculoskeletal POCUS is excellent at identifying fractures of long bones (e.g., radius and ulna); however, it is less reliable for identifying fractures at joints, epiphyses, and the small bones of the hands and feet, where curved, irregular contours make imaging with POCUS more difficult. Additionally, non-displaced physeal fractures (Salter-Harris I) may be missed by POCUS.
Technique
To evaluate for fracture, dislocation, or osteomyelitis, place a linear transducer over the desired area to identify changes to the bony contour or alignment.
- Look everywhere. Scan bones circumferentially as much as possible and in perpendicular planes (longitudinal and transverse axes) to avoid missing pathology. Fractures may escape detection if the transducer is placed parallel to the course of the fracture.
- Scan the contralateral side for comparison. This is especially crucial when the pathology involves or is adjacent to a physis.
- Use the water bath technique. Submerge the injured extremity in a basin of water to facilitate imaging of the small bones of the hands and feet (Figure 3). The probe does not need to be in contact with the injured area in a water bath, and the probe is submersible up to the point where the electrical cord exits the probe.
Figure 3. Water bath technique to image a phalanx dorsally (L) and ventrally (R), with the submerged probe floating just above but not touching the injured hand.
Figure 4. Normal finger phalanx imaged with the water bath technique, with the probe not touching the finger and approximately 1 cm of anechoic fluid between the probe and the finger. Air bubbles may be visible in the water.
Figure 5. Ultrasound clip of a normal finger phalanx using the water bath technique.
Normal Findings
Normal bone is seen as a hyperechoic line with posterior acoustic shadowing.
Normal physis:
- Longitudinal view (Figure 6): Appears as a V-shaped, hypoechoic, uniform band of cartilage between the metaphysis and epiphysis that is symmetric with the contralateral side.
- Transverse view (Figure 7): Appears as a regular but ragged area between the hyperechoic curvilinear metaphysis and epiphysis of the bone.
|
Figure 6L. Longitudinal view of a normal physis. The hypoechoic band of cartilage forms a smooth V-shape between the hyperechoic metaphysis and epiphysis (yellow arrows: physis above, bone below). Compare with the contralateral side to confirm symmetry. |
Figure 6R. Longitudinal scanning of a normal physis. |
|
Figure 7L. Transverse view of a normal physis. The cartilage band appears regular but ragged between the curvilinear hyperechoic metaphysis and epiphysis (yellow arrows: physis above, bone below). |
Figure 7R. Transverse scanning of a normal physis. |
Ultrasonography can reliably detect diaphyseal (long bone) fractures including the forearm, lower leg, and clavicle. It is also useful for detection of other fractures.
1. Long Bone Fracture
- Longitudinal view (Figure 8): A fracture is visualized as a disruption in the bony cortex with a discontinuity or step-off. There may be associated periosteal changes, periosteal fluid, or hematoma. Angulation and displacement of the fracture fragments may be measured.
- Transverse view (Figure 9): The fracture site is identified by an irregularity in the hyperechoic, curvilinear bony cortex and/or a “jump” in the location of the bone as the fracture site is crossed.
- Ultrasound can detect fractures as small as 1 mm [1].
- In the forearm and lower leg, be sure to scan both bones at the site of injury to avoid missing a fracture.
|
Figure 8L. Forearm fracture in longitudinal view. An angulated, displaced distal radius fracture is shown, with the physis visible distal to the fracture site. |
Figure 8R. Longitudinal scanning of a distal radius fracture. |
|
Figure 9L. Forearm fracture in transverse view. The fracture site shows an irregular curvilinear bony surface with both edges of the fracture visible. |
Figure 9R. Transverse scanning of a distal radius fracture. |
2. Buckle Fracture
- A buckle fracture appears as a small “bump” in the linear bone cortex, usually without any discontinuity of the bone (Figure 10).
|
Figure 10L. Two examples of buckle fracture of the distal radius (arrows). Top: small “bump” in the bony cortex without discontinuity. Bottom: a second buckle fracture of the distal radius in longitudinal view. |
Figure 10R. Buckle fracture of the distal radius. |
3. Finger Phalanx Fracture
- The discontinuity of the cortex of a phalanx may be seen in longitudinal and transverse views (Figures 11 and 12).
- A fracture appears as a break in the hyperechoic cortex, in contrast to a joint, which is regular and similar to adjacent fingers or to the contralateral normal side.
Figure 11. Discontinuity of the bony cortex of the phalanx (arrow) in a water bath, consistent with fracture. The adjacent joint is regular and intact.
|
Figure 12L. Longitudinal scanning of a phalanx fracture. |
Figure 12R. Transverse scanning of a phalanx fracture. |
4. Metacarpal Fracture
- The discontinuity of the cortex of a metacarpal may be seen in longitudinal and transverse views (Figure 13).
|
Figure 13L. Cortical discontinuity (arrow) in a metacarpal fracture, with periosteal fluid (asterisk) adjacent to the fracture site. |
Figure 13R. Scanning of a metacarpal fracture. |
5. Nasal Fracture
- The nasal bones may be identified, with fractures appearing as a discontinuity of the bone (Figures 14, 15, and 16). Use copious gel to facilitate imaging in this superficial, highly curved area and to minimize pain to the affected area.
Figure 14. Linear probe positioning to evaluate for a nasal fracture.
Figure 15. Transverse view of a normal nasal bone (L) and a nasal fracture with cortical discontinuities (arrows, R).
Figure 16. Transverse scan of a nasal fracture.
6. Healing Fracture
- Healing fractures will have a discontinuity in the bone with varying degrees of periosteal thickening and callus formation (Figures 17 and 18). The callus will be hypoechoic initially and will become more hyperechoic over time.
|
Figure 17L. Healing distal radius fracture in longitudinal view, with periosteal thickening and callus formation. |
Figure 17R. Longitudinal scan of a healing distal radius fracture. |
|
Figure 18L. Healing distal radius fracture in transverse view, with periosteal thickening and callus formation. |
Figure 18R. Transverse scan of a healing distal radius fracture. |
For evaluation of a joint effusion, the linear or curvilinear transducer is used to identify anechoic or hypoechoic fluid in the joint space. POCUS identifies the effusion but cannot distinguish hemorrhagic, infectious, or inflammatory etiologies; labs and/or advanced imaging are needed for further work-up.
POCUS of the lower extremity can assess for hip, knee, or ankle effusions. Findings must be interpreted with the clinical presentation and physical examination. For hip effusions, the Kocher criteria may be used to evaluate for septic hip.
1. Hip
- See the ALiEM module on POCUS: Hip Effusion for more detail.
- Positioning and probe placement: With the child’s leg in slight external rotation, place the linear transducer on the anterior hip parallel to the long axis of the femoral neck. Point the probe marker toward the patient’s head (Figure 19L).
- Normal findings
- Identify the hyperechoic curvilinear femoral head (+/- physis), hyperechoic linear femoral neck, and the posterior surface of the iliopsoas muscle (Figure 19R).
- Look for fluid/effusion between the femoral neck and the posterior surface of the iliopsoas muscle. Normally a femoral fat pad sits in this space.
Figure 19. Linear probe positioning to evaluate for hip effusion (L) and normal hip anatomy (R). The arrow points to the femoral head physis.
Figure 20. Longitudinal scanning of a normal hip.
- Abnormal finding: Hip effusion
- Location: Anechoic or hypoechoic fluid located between the femoral neck and the iliopsoas muscle (Figure 21).
- Measurement: A convex fluid collection measuring >5 mm (or >2 mm difference from the contralateral normal side) is positive for a hip effusion.
- There is debate regarding measurement technique for hip effusion, with measurement of the hypoechoic fluid directly vs. measurement from the anterior surface of the femoral neck to the posterior surface of the iliopsoas muscle. However, clinically significant effusions will likely be positive (>5 mm) regardless of measurement technique, and asymmetry compared to the contralateral normal hip will usually be evident.
Figure 21. Hip effusion with anechoic fluid layering over the femoral neck measured to 5.7 mm. Also visible are the femoral head with an open physis (arrow) and the iliopsoas muscle (*).
Figure 22. Longitudinal scanning of the hip showing a hip effusion.
2. Knee
- Positioning and probe placement: Place the linear transducer longitudinally on the anterior distal femur, just superior to the patella, in the midline over the quadriceps tendon. Point the probe marker toward the patient’s head (Figure 23L). This single, longitudinal view of the suprapatellar bursa, which has direct communication with the knee joint, is the most sensitive for identifying a knee effusion (Figure 24). You may also fan the probe in longitudinal and transverse views to further evaluate the suprapatellar bursa for effusion.
- Place a towel roll under the knee to provide about 30 degrees of knee flexion, the optimal position for detecting a knee effusion.
- Avoid excessive pressure: pressure from the probe can compress the suprapatellar bursa and mask a small effusion.
- To avoid missing a small effusion, milk fluid downward, medially, and/or laterally toward the probe to push fluid into the suprapatellar bursa. Hold the probe lightly while doing this.
Figure 23. Linear probe positioning to evaluate for knee effusion. Note the towel under the knee for slight knee flexion (L). Normal knee anatomy showing the quadriceps tendon (arrows) and cartilage around the patella (asterisk) (R).
Figure 24. Normal bursae anatomy at the knee. The suprapatellar bursa is contiguous with the knee joint space [2].
Figure 25. Longitudinal scanning of a normal knee.
- Normal findings
- Identify the linear, hyperechoic distal femur (+/- physis), the patella, and the quadriceps tendon attaching to the patella (Figure 23R). There is a pre-femoral fat pad between the femur and the quadriceps tendon. Look for a fluid collection in this suprapatellar space.
- The patella ossifies at approximately 3-6 years of age, so younger children may still have a cartilaginous patella. The patella appears hypoechoic and may not have posterior acoustic shadowing. Do not confuse the cartilaginous patella with a joint effusion.
- Abnormal finding: Knee effusion
- Location: Anechoic or hypoechoic fluid sits in the suprapatellar bursa between the femur and the quadriceps tendon (Figure 26).
- Measurement: Fluid measuring >2 mm in height is positive for a knee effusion.
Figure 26. Two examples of a knee effusion with anechoic fluid (*) between the femur and the quadriceps tendon (L) and with measurement of effusion (R).
Figure 27. Longitudinal scanning of a knee effusion.
3. Ankle
- Positioning and probe placement: Place the linear transducer in the longitudinal axis anteriorly over the ankle joint in the midline. Point the probe marker toward the patient’s head (Figure 28L) to evaluate the tibiotalar joint. The tibiotalar joint is the area most likely to identify an effusion. Interrogate the entire joint by fanning the probe in longitudinal and transverse views to avoid missing an effusion.
- Normal findings
- Identify the curvilinear hyperechoic lines with posterior acoustic shadowing of the tibia and talus bones and the “V” shape of the joint (Figure 28R).
Figure 28. Ankle POCUS: Linear probe positioning to evaluate for ankle effusion (L) and normal ankle anatomy with an arrow pointing to the tibiotalar joint space (R).
- Abnormal finding: Ankle effusion
- Anechoic or hypoechoic fluid is seen in the tibiotalar joint space (Figure 29).
Figure 29. Ankle POCUS of bilateral ankles showing an effusion (*) in the right tibiotalar joint compared with the normal left side.
Figure 30. Longitudinal scanning of an ankle effusion.
POCUS of the upper extremity can assess for elbow and shoulder effusions. When an elbow effusion is identified after trauma, radiography is typically needed to further characterize a fracture.
1. Elbow
- Positioning and probe placement: With the child’s elbow flexed to 90 degrees, place the linear transducer over the posterior distal humerus in longitudinal and transverse views to visualize the olecranon fossa and the elbow posterior fat pad (Figure 31).
Figure 31. Linear probe positioning for performing POCUS of the elbow to evaluate the elbow posterior fat pad in longitudinal (L) and transverse (R) views.
- Normal findings
- Identify the hyperechoic cortex of the distal humerus and the olecranon fossa.
- The normal posterior fat pad (PFP) sits in the olecranon fossa below the continuation of the distal humeral line in the longitudinal view and below the line connecting both edges of the olecranon fossa in the transverse view. The triceps muscle can be seen above the elbow joint (Figure 32).
Figure 32. Elbow POCUS: Normal elbow anatomy in longitudinal (L) and transverse (R) views with the posterior fat pad (PFP) located under the distal humeral line (dotted line).
Figure 33. Scanning of a normal elbow in longitudinal (L) and transverse (R) views.
- Abnormal finding: Elbow effusion
- Elbow US has high sensitivity and moderate specificity for fracture, so a negative scan makes fracture unlikely.
- Sonographic findings: The posterior fat pad is elevated above the distal humeral line in the longitudinal view, and above the line connecting both sides of the olecranon fossa in the transverse view (Figure 34). Lipohemarthrosis, i.e., blood and lipid material in the posterior fat pad, may appear as hypoechoic areas within the elevated fat pad (Figure 36).
- Clinical significance: An elevated posterior fat pad and/or lipohemarthrosis is a marker of intracapsular elbow fracture, because the posterior fat pad sits intracapsular but extra-synovial.
- Caution: The radial neck and medial epicondyle are extracapsular, so fractures at these sites may occur without an elevated posterior fat pad.
- Application to nursemaid elbow: Annular ligament displacement (nursemaid elbow) does not usually produce a significant effusion or lipohemarthrosis. When the diagnosis is in question, a POCUS showing a normal posterior fat pad and no lipohemarthrosis may help rule out fracture and support proceeding with closed reduction.
Figure 34. Elevated posterior fat pad in longitudinal view rising above the distal humeral line (L) and transverse view rising above the line connecting both edges of the olecranon fossa (R). In both views, the posterior fat pad pushes up on the triceps muscle.
Figure 35. Scanning of an elbow effusion with an elevated posterior fat pad in longitudinal (L) and transverse (R) views.
Figure 36. Elbow POCUS: Elevated posterior fat pad with lipohemarthrosis (*) in longitudinal (L) and transverse (R) views.
2. Shoulder
- Positioning and probe placement: Place the linear transducer in the transverse view over the posterior shoulder and point the probe marker laterally (Figure 37L).
- Normal findings
- Identify the hyperechoic curvilinear humeral head (+/- physis) and the hyperechoic glenoid (Figure 37R). The humeral head should be located in the glenoid fossa, with the humeral head and glenoid in the same horizontal plane.
- Abnormal finding: Shoulder effusion
- Anechoic fluid is seen around the humeral head within the glenohumeral joint (Figure 38).
Figure 37. Shoulder POCUS: Linear probe positioning to evaluate for shoulder effusion (L) and the corresponding ultrasound view with normal shoulder anatomy (R).
Figure 38. Shoulder POCUS: anechoic fluid (*) adjacent to the humeral head (L) and transverse scanning of the same effusion (R).
1. Shoulder Dislocation
- Evaluate the relative positions of the glenoid and humeral head.
- In a normal shoulder, the humeral head and glenoid should be in approximately the same horizontal plane (Figure 37R).
- Anterior shoulder dislocation: The humerus is farther from the transducer and thus deeper on the ultrasound screen (Figure 39).
- Posterior shoulder dislocation: The humerus is closer to the transducer and thus higher up on the ultrasound screen.
- POCUS can be used to confirm relocation of the humerus into the glenoid fossa after a shoulder reduction.
Figure 39. Transverse view of an anterior shoulder dislocation: humeral head dislocated anteriorly, or farther away from the probe (L) and corresponding transverse scanning (R).
2. Finger Dislocation
- In a finger dislocation, the bone malalignment at the interphalangeal joint can be seen (Figure 40).
Figure 40. Finger dislocation with probe positioned dorsally (L) and ventrally (R).
Figure 41. Scanning of a finger dislocation: dorsal view (L) and ventral view (R).
- Ultrasound findings of osteomyelitis may precede X-ray findings by several days.
- Sonographic findings: Disrupted or irregular bony cortex, periosteal elevation and/or abscess, and increased vascular flow (Figure 42).
Figure 42. Osteomyelitis of the distal femur with irregular bony cortex and periosteal abscess (*) (L) and increased vascular flow adjacent to the periosteal abscess (R).
Figure 43. Scanning of a distal femur with osteomyelitis: longitudinal view (L) and transverse view (R).
Figure 44. Longitudinal scanning of a distal femur with osteomyelitis showing increased vascularity on color Doppler.
Bony pathology that may be missed
MSK POCUS is excellent for long-bone fractures but is less reliable for fractures at joints, epiphyses, and the small bones of the hands and feet, whose curved, irregular contours are more difficult to image. Non-displaced physeal fractures (Salter-Harris I) and fractures <1 mm may also be missed. POCUS generally focuses on the area of injury and does not image the entire bone, so distant pathology can be missed.
Additionally, for elbow evaluation, radial neck and medial epicondyle fractures are extra-capsular and may occur without an associated effusion. A normal posterior fat pad on POCUS does not exclude these fractures. If a patient has tenderness at the radial neck or medial epicondyle, obtain further imaging.
Underlying pathology that cannot be characterized
POCUS can identify the presence of pathology such as a joint effusion or bone infection, but it cannot determine the etiology (e.g., hemorrhagic vs. infectious vs. inflammatory effusion). Further work-up, such as labs, joint aspiration, or advanced imaging, is needed to characterize the underlying process.
Image sharing across systems
Sharing POCUS clips within or between institutions can be cumbersome. Where feasible, archiving images to the medical record helps preserve diagnostic context for the broader healthcare team.
There have been several systematic reviews and meta-analyses on musculoskeletal POCUS applications.
| Study | Application | N | Sensitivity | Specificity | Comments |
|---|---|---|---|---|---|
| Morello et al, Eur J Pediatr 2024 [3] | Distal forearm fractures | 23 studies, 3,484 children | 92–100% | 85–100% | Scoping review |
| Hassankhani et al, Skeletal Radiol 2024 [4] | Clavicle fractures | 7 studies, 1,255 patients | 94% | 98% | Pediatric subset (4 studies, 863 children): Sn 96%, Sp 94% |
| Zhao et al, Medicine 2019 [5] | Hand fractures | 7 studies, 842 patients | 91% | 96% | Fracture prevalence 39% |
| Tokarski et al, J Pediatr 2018 [6] | Elbow fractures | 6 studies, 512 children | 96% | 81% | Fracture prevalence 48% |
| Gottlieb et al, Am J Emerg Med 2019 [7] | Shoulder dislocation | 7 studies, 739 patients | 99% | 99% | Dislocation prevalence 41%; associated fracture: Sn 98%, Sp 99.8% |
Table 1. Key systematic reviews and meta-analyses on musculoskeletal POCUS.
Other notable studies focusing on musculoskeletal POCUS include the following.
Pediatric Distal Forearm Fracture
The BUCKLED multicenter, noninferiority, randomized trial by Snelling et al enrolled 262 children ages 5–15 years with clinically non-angulated distal forearm injuries [8]. Children were randomized to POCUS or radiography. Those in the POCUS group with a cortical break identified also received radiography and usual care; buckle fractures were managed with a splint.
Results: At 4 weeks, physical function of the affected arm was non-inferior in the POCUS group. The POCUS group also had fewer X-rays, shorter emergency department length of stay, and higher patient satisfaction. The authors emphasized that physical function at 4 weeks is an important, real-world clinical outcome.
Joint Effusions
Adhikari and Blaivas compared POCUS with physical examination for the diagnosis of joint effusions [9]. They enrolled 54 adult patients with joint pain, erythema, and swelling.
Results: POCUS was more sensitive and accurate than physical examination. POCUS altered emergency department management in 65% of patients, either by avoiding an unnecessary joint aspiration or by identifying a clinically occult effusion.
Pediatric Hip Effusion
Jones et al conducted a multicenter prospective diagnostic study in children <18 years requiring radiology-performed hip ultrasound, comparing hip POCUS with the radiology study as the reference standard [10]. 161 children were enrolled by 18 PEM physicians, with 3 high-volume operators contributing 62% of cases.
Results: POCUS had an overall sensitivity of 94% and specificity of 98%. Among high-volume operators, sensitivity was 98% (specificity 98%); among low-volume operators, sensitivity was 83% (specificity 97%).
Case Resolution
A musculoskeletal POCUS of the left knee with a linear, high-frequency probe demonstrated a joint effusion in the suprapatellar bursa with internal septations (Figures 45 and 46).
Figure 45. Left knee POCUS demonstrating a joint effusion in the suprapatellar bursa (L) and internal septations within the effusion (R).
Figure 46. Longitudinal scan of the left knee showing the joint effusion with internal septations.
Initial laboratory studies showed a white blood cell count of 10 × 109/L, ESR 69 mm/hr, and CRP 32 mg/L. Knee radiographs were negative for fracture. Orthopedics performed an arthrocentesis that yielded synovial fluid with 52,000 white blood cells/µL, raising concern for septic arthritis.
The patient was admitted, started on intravenous antibiotics, and taken to the operating room for incision, drainage, and washout. Joint fluid cultures returned negative, but Lyme serologies returned positive. She was transitioned to a 28-day course of doxycycline for Lyme arthritis.
Read more from this series → PEM POCUS Series
References
- Grechenig W, Clement HG, Fellinger M, Seggl W. Scope and limitations of ultrasonography in the documentation of fractures—an experimental study. Arch Orthop Trauma Surg. 1998;117(6-7):368-371. doi:10.1007/s004020050268. PMID: 9709853
- Wilson C. Suprapatellar bursitis: causes, symptoms, treatment & recovery. Knee Pain Explained. Published June 2, 2024. Accessed May 23, 2026. https://www.knee-pain-explained.com/suprapatellar-bursitis.html
- Morello R, Mariani F, Snelling PJ, Buonsenso D. Point-of-care ultrasound for the diagnosis of distal forearm fractures in children and adolescents: a scoping review. Eur J Pediatr. 2024;184(1):19. doi:10.1007/s00431-024-05877-w. PMID: 39548004
- Hassankhani A, Amoukhteh M, Jannatdoust P, Valizadeh P, Gholamrezanezhad A. A systematic review and meta-analysis on the diagnostic utility of ultrasound for clavicle fractures. Skeletal Radiol. 2024;53(2):307-318. doi:10.1007/s00256-023-04396-3. PMID: 37433884
- Zhao W, Wang G, Chen B, et al. The value of ultrasound for detecting hand fractures: a meta-analysis. Medicine (Baltimore). 2019;98(44):e17823. doi:10.1097/MD.0000000000017823. PMID: 31689869
- Tokarski J, Avner JR, Rabiner JE. Reduction of radiography with point-of-care elbow ultrasonography for elbow trauma in children. J Pediatr. 2018;198:214-219.e2. doi:10.1016/j.jpeds.2018.02.072. PMID: 29681446
- Gottlieb M, Holladay D, Peksa GD. Point-of-care ultrasound for the diagnosis of shoulder dislocation: a systematic review and meta-analysis. Am J Emerg Med. 2019;37(4):757-761. doi:10.1016/j.ajem.2019.02.024. PMID: 30797607
- Snelling PJ, Jones P, Bade D, et al; BUCKLED Trial Group. Ultrasonography or radiography for suspected pediatric distal forearm fractures. N Engl J Med. 2023;388(22):2049-2057. doi:10.1056/NEJMoa2213883. PMID: 37256975
- Adhikari S, Blaivas M. Utility of bedside sonography to distinguish soft tissue abnormalities from joint effusions in the emergency department. J Ultrasound Med. 2010;29(4):519-526. doi:10.7863/jum.2010.29.4.519. PMID: 20375371
- Jones RM, Malia L, Snelling PJ, et al. Diagnostic accuracy of point-of-care ultrasound for hip effusion: a multicenter diagnostic study. Ann Emerg Med. 2025;86(6):566-575. doi:10.1016/j.annemergmed.2025.04.033. PMID: 40481828
PEM POCUS Series: Pediatric First-Trimester Pregnancy
Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric first-trimester pregnancy evaluation. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.
Module Goals
- List the indications for performing an obstetric point-of-care ultrasound (POCUS)
- Identify the characteristic findings of an intrauterine pregnancy in the first-trimester
- Describe how to measure fetal heart rate (FHR) and methods of estimating gestational age using POCUS
- Identify findings concerning for ectopic pregnancy in the first-trimester of pregnancy
Case Introduction
A 17-year-old female with a past medical history of pelvic inflammatory disease, presents as a walk-in from triage with lower abdominal pain and vaginal bleeding that started this morning. She has soaked through three pads since this morning without the passage of clots. She reports mild nausea, and dizziness. She denies any fevers, chills, chest pain, shortness of breath, vomiting, or decreased appetite. She is currently sexually active with one male partner in a monogamous relationship and does not use protection. Her menstrual periods are irregular and she is unsure of her last menstrual period.
On arrival, her vital signs are:
| Vital Sign | Finding |
|---|---|
| Temperature | 37 C |
| Heart rate | 94 bpm |
| Blood pressure | 98/62 |
| Respiratory rate | 14 |
| Oxygen saturation (room air) | 99% |
Exam
The patient is in mild distress secondary to pain and is lying supine in the stretcher. She has mild tenderness in lower quadrants with some voluntary guarding. There is no evidence of abdominal distension, rebound, rigidity, or palpable masses. Bowel sounds are present. On the pelvic exam, she has some blood in the vaginal vault, but no clots. No abnormal discharge. There is mild tenderness on the bimanual exam. The cervical os is closed. There is no cervical motion tenderness.
Diagnostics and Management
She is started on IV fluids and is given PO acetaminophen. Vitals improve to HR 85, BP 105/70, RR 12, 99% on RA. Basic labs, PT/PTT/INR, type and screen, and a urine pregnancy test are sent. While waiting for the results, you are concerned about an ectopic pregnancy and decide to perform a point-of-care (POCUS) obstetric ultrasound examination.
An obstetric POCUS can be performed using both the curvilinear (transabdominal approach) and endocavitary probes (transvaginal approach). Certain anatomical structures such as the ovaries and an early pregnancy can be visualized earlier and with greater detail using an endocavitary probe due to its closer proximity to the area of interest. While earlier pregnancies may be identified by the transvaginal approach, we recommend starting with the transabdominal probe because it is less invasive. The transabdominal examination is best performed with a full bladder and the endocavitary examination is best performed with an empty bladder. Longitudinal and transverse views of the uterus should be obtained when using either the transabdominal or endocavitary probe.
Figure 1. Different probes used for first-trimester pregnancy ultrasound
Figure 2. Positioning for transabdominal approach
- Position the ultrasound machine to the patient’s right with the screen facing you (figure 2).
Obtaining the transverse view
- Place the transabdominal probe with the probe marker toward the patient’s right, just above the pubic bone and identify the bladder and uterus. The fundus of the uterus may be visualized superior to the bladder if the uterus is anteverted and posterior to the bladder if retroverted.
- Once the uterus is identified, scan through the uterus in its entirety and identify the myometrium, and endometrium.
- An examination of the adnexa can also be attempted to identify the ovaries, potential masses, or surrounding free fluid. The ovaries typically measure 2-3 cm in diameter and appear less echogenic than the surrounding tissue.
Figure 3. Normal transverse view of the uterus and bladder using the transabdominal probe. Image courtesy of The Pocus Atlas and Drs. Lindsay Davis and Hannah Koplinski
Obtaining the longitudinal (sagittal) view
- Rotate the transabdominal probe clockwise 90 degrees so that the probe marker is facing the patient’s head.
- In this view, you should be able to identify the bladder, uterine fundus, uterine body, cervix, vaginal canal, posterior cul-de-sac, and rectum. The thin, hyperechoic line in the center of the uterus is the endometrial stripe.
- An examination of the adnexa may also be attempted to identify the ovaries, potential masses, or surrounding free fluid (especially in the retrouterine cul de sac) by fanning slowly left and right.
Figure 4. Normal longitudinal (sagittal) view of an anteverted uterus and bladder using the transabdominal probe. Image courtesy of The Pocus Atlas and Drs. Lindsay Davis and Hannah Koplinski
Not all institutions have access to an endocavitary probe. However, if your institution does, the transvaginal ultrasound examination can provide additional views of the uterus and surrounding structures.
- Position the ultrasound machine to the patient’s right with the screen facing you, similar to the transabdominal positioning.
- Position the patient in the dorsal lithotomy position (similar to a normal pelvic exam), drape the patient, and have a chaperone present in the room
- Place gel at the tip of the endocavitary probe and apply a sterile condom or cover over the endocavitary probe. Subsequently apply sterile gel to the tip of the covered probe.
Figure 5a. Positioning of endocavitary probe in transvaginal approach using a simulation model
Figure 5b. Indicator labeled on endocavitary probe
Obtaining the longitudinal view
- Hold the probe with the indicator at the 12 o’ clock position (figure 5b).
- Slowly insert the probe until the endometrial stripe is visualized
- Tilt/fan the probe to the left and right and identify the bladder, uterine fundus, endometrial stripe, myometrium, cervix, posterior cul-de-sac, and rectum
Obtaining the transverse view
- Rotate the probe counterclockwise so that the indicator is facing the patient’s right (9 o’ clock position).
- Tilt/fan the probe up and down to visualize the bladder, endometrium and myometrium.
- Obtain a view of the ovaries by looking at the adnexa (lateral and/or posterior to the uterus).
Key Point: To definitively diagnose an intrauterine pregnancy, either a yolk sac or fetal pole must be visualized within the gestation sac of the uterus.
There are many conflicting opinions about the upper limits of the discriminatory zone (B-hCG level at which an embryo is expected to be seen). In general, for a patient with a positive B-hCG with concern for an ectopic pregnancy, an ultrasound should be performed. Typically, a pregnancy should be visible by transvaginal ultrasound examination with a B-hCG of 1000-2000 mIU/mL and by transabdominal ultrasound examination at 6000-6500 mIU/mL [1, 2].
Figure 6. Double decidual sac sign in a normal intrauterine pregnancy
Figure 7. Fetal pole and yolk sac in a normal intrauterine pregnancy
In these sonographic images, there are several characteristic sonographic features of a normal first-trimester IUP. To definitively diagnose an intrauterine pregnancy, either a yolk sac or fetal pole must be visualized within the gestation sac of the uterus.
- Gestational sac – an intrauterine, fluid-filled (anechoic or black) structure surrounding the embryo. This is the first structure seen in pregnancy by ultrasound in the first trimester and is characterized as an anechoic circular cavity
- Double decidual sac sign – consists of the decidua parietalis (lining of the uterine cavity) and the decidua capsularis (lining of the gestational sac) which on ultrasound is visualized as two concentric rings surrounding an anechoic gestational sac. The presence of a double decidual sac sign is highly indicative of an early intrauterine pregnancy (figure 6) [3].
- Yolk sac – this is the first anatomic structure identified within the gestational sac in the first-trimester and is seen on ultrasound as a circular, thick-walled echogenic structure with an anechoic center within the gestational sac (figure 7).
- Fetal pole – the growing embryo appears as an echogenic thickened margin on the edge of the yolk sac (figure 7).
- Ensure the gestational sac is well seated within the fundus of the uterus and surrounded by at least 5 mm of myometrium on all sides.
Once the embryo is identified, a fetal heart rate (FHR) can be obtained as early as 6 weeks of gestation. The fetal heart movement may be visualized as a flicker of movement. Visualization can be performed using either the endocavitary or curvilinear probe and the M-mode function. In POCUS, we do not use Doppler as this has a theoretical risk to the fetus.
To calculate the FHR, follow the following steps:
- Identify the beating fetal heart.
- Enlarge and center: Use the zoom function on the machine to enlarge fetal heart image
- M-mode: Align the M-mode line over the fetal heart, record the M-mode, and freeze the image. Find the sine wave and measure either crest to crest, or trough to trough.
A normal FHR usually ranges from 110-160 beats per minute. It begins around 90–110 bpm and increases to 170 bpm by 9 weeks of estimated gestational age.
Figure 8. Fetal heart rate measurement (rate of 148 bpm) using M-mode
The most accurate time to estimate gestational age is during the first trimester. Accurate estimation of gestational age is crucial for guiding prenatal care, decision making in high-risk pregnancies, and establishing a reliable due date. This can be performed by either measuring mean sac diameter (MSD) or crown-rump length (CRL).
Measuring mean sac diameter (MSD)
The MSD is the earliest measurement that can be used to estimate gestational age. This measurement is, however, less accurate than using crown-rump length and is typically performed between 5-8 weeks of gestation using the following steps:
- Obtain a longitudinal view of the gestational sac
- Measure the height and the length of the gestational sac
- Rotate the probe 90 degrees to obtain a transverse view of the gestation sac
- Measure the width of the gestational sac
- Add the height, length, and width then divide by 3 to obtain the MSD
Most ultrasound machines should help you perform this calculation; however, the gestational age can be calculated manually using the following formula: [4]
Gestational Age (days) = MSD (mm) + 30
Measuring crown-rump length (CRL)
Once an embryo is present in the gestational sac, CRL can be measured. CRL is the most accurate single measurement and is typically used to estimate gestational age between 6-13 weeks of gestation [4]. This measurement can be performed using the following steps:
- Obtain a mid-sagittal view of the entire embryo
- Measure the cephalic pole to caudal rump
Most ultrasound machines should help you perform this calculation. There are also available calculators (e.g. perinatology.com CRL calculator).
Figure 9. Crown rump length measurement showing an estimated fetal age of 6 weeks and 3 days
An ectopic pregnancy is a pregnancy in which a fertilized egg implants and grows outside the uterine cavity. The most common site for an ectopic pregnancy is the ampulla of the fallopian tube. The primary goal of performing an obstetric ultrasound in a pregnant patient who presents with abdominal pain, pelvic pain, and vaginal bleeding is not to rule in an ectopic pregnancy, but rather to rule in an IUP.
Ruling in an IUP essentially rules out an ectopic pregnancy, given that the incidence of a heterotopic pregnancy – the simultaneous occurrence of an intrauterine and an ectopic pregnancy – is 1 in 30,000. The rate of heterotopic pregnancies, however, rises significantly in patients who have undergone in-vitro fertilization (IVF) to ranges from 1 in 100 to 1 in 500 pregnancies [5]. A history of pelvic inflammatory disease also increases concern for heterotopic and ectopic pregnancy.
Uterus Views
If an empty uterus is visualized on bedside ultrasound in a patient (as shown below) with a B-hCG level greater than the discriminatory zone, the next step is to examine the adnexa for sonographic signs of an ectopic pregnancy. However, the lack of a visualized IUP on POCUS in a pregnant patient is concerning for ectopic pregnancy, and it is not expected to be able to visualize the actual ectopic pregnancy.
Video 1. Coronal (transverse) view of uterus without an intrauterine pregnancy
Video 2. Sagittal (longitudinal) view of uterus without an intrauterine pregnancy
Adnexa Views
To examine the adnexa in the transabdominal view, ensure that the patient has a full bladder and identify the uterus in the sagittal and transverse views. Using the uterus as a landmark, sweep laterally and posteriorly at which point the ovaries may or may not be visualized. Use color Doppler to help distinguish the ovary (which has a vascular hilum) from surrounding structures. Sonographic signs of an ectopic pregnancy include:
1. Tubal ring sign
A thick hyperechoic ring around a hypoechoic tubal mass
Video 3. Coronal (transverse) view of uterus showing tubal ring sign
2. Ring of fire sign
A well-circumscribed hypoechoic structure surrounded by a hypervascular ring seen on color Doppler due to trophoblastic activity and neovascularization. Note that the ring of fire sign is also present in corpus luteum cysts, which are a type of functional ovarian cyst that forms after ovulation to support a possible pregnancy.
Figure 10. Ring of fire of the adnexa
Free Fluid Assessment
If there is high suspicion for an ectopic pregnancy, assess for free fluid in the pelvis and abdomen, especially in the posterior cul-de-sac (pouch of Douglas) and hepatorenal recess (Morison’s pouch). The hepatorenal view is key for detecting hemoperitoneum in the supine patient. Fluid will often collect in Morison’s pouch first. Sweep through the pelvis in both sagittal and transverse planes to look for anechoic or hypoechoic fluid. While trace fluid may be normal in patients, the presence of moderate to large amounts of free fluid, particularly if echogenic (suggesting hemoperitoneum), raises concern for ruptured ectopic pregnancy and warrants immediate intervention. Ultimately, if the bedside ultrasound is inconclusive in a patient with clinical concern for ectopic pregnancy, a radiology performed ultrasound and/or gynecology consult should be ordered urgently.
Figure 11. Free fluid collecting in the right upper quadrant hepatorenal recess (Morison’s pouch)
Uterine fibroids, also known as leiomyomas or myomas, are benign smooth muscle tumors of the uterus. On ultrasound, they typically appear as well-circumscribed, hypoechoic (relative to the myometrium) structures that can arise within the myometrium (intramural), along the outer surface of the uterus (subserosal), project into the endometrial cavity (submucosal), and can be attached by a stalk (pedunculated).
Figure 12. Uterine fibroids
A molar pregnancy, also called a hydatidiform mole, is a type of gestational trophoblastic disease that results from abnormal fertilization, leading to the growth of abnormal trophoblastic tissue rather than a normal embryo.
A complete mole, which occurs due to fertilization of an empty ovum by one (or two) sperm, typically has a “snowstorm” or “cluster of grapes” appearance. On ultrasound, the uterus may appear larger than expected for gestational age and may show a diffusely echogenic intrauterine mass with numerous cystic spaces.
Figure 13. Molar pregnancy
An ovarian cyst is a fluid-filled sac within or on the surface of the ovary. Most are benign and functional, especially in reproductive-age women, and often resolve spontaneously.
On ultrasound, simple ovarian cysts appear as a thin, smooth-walled anechoic structure. A corpus luteum cyst, which may have a “ring of fire” appearance on color Doppler, is more thick-walled in appearance. Hemorrhagic cysts tend to have mixed echogenicity with a lacy, reticular pattern.
Figure 14. Ovarian cysts
Ovarian torsion is often on the differential for female patients presenting with sudden onset lower abdominal pain. It is a gynecologic emergency where the ovary twists on its own vascular pedicle, compromising blood flow. Patients with large ovarian cysts or masses ≥5cm are at increased risk.
On ultrasound, an enlarged, edematous ovary with absent or decreased flow may suggest this diagnosis. The ovary also tends to have peripheralized follicles. A midline ovary can also be a concerning sign. Venous flow is typically lost prior to arterial flow; however, presence of flow does not rule out ovarian torsion. Lastly, a highly specific finding for ovarian torsion may be the presence of a whirlpool sign which is visualized as a targetoid, coiled structure on color Doppler.
Figure 15. Ovarian torsion with midline, edematous ovary
Integration of the obstetric POCUS into early pregnancy assessment can significantly accelerate diagnosis and initiation of treatment, particularly in urgent cases like an ectopic pregnancy. Faster timelines could translate into improved clinical outcomes and more efficient ED workflows.
Studies that helped shape the landscape for the utility of POCUS in early pregnancy in the emergency department setting include:
| Study | Study Type, Location (Time frame) | N, Ages | Notes |
|---|---|---|---|
| Doubilet et al., N Engl J Med. 2013 [6] | Review Article | N/A | This review establishes more stringent ultrasound criteria for diagnosing early pregnancy failure to minimize false-positive results:
These guidelines are designed to protect viable pregnancies from premature or inappropriate interventions. |
| Thamburaj et al. Pediatr Emerg Care. 2013 [7] | Retrospective case-cohort review, Single ED at Newark Beth Israel Medical Center (2007) | 330 Female patients aged 13-21
Bedside POCUS group (n = 244, ~74%; Radiology group (n = 86) |
Time-to-scan: 82 min vs. 149 min (POCUS vs. radiology), P < 0.001
LOS: 142 min vs. 230 min (P < 0.001) Despite similar demographics, chief complaints, diagnoses, and dispositions between groups, bedside ultrasound significantly reduced both scan time and overall ED stay. |
| McRae et al. CJEM. 2009 [8] | Systematic review, multiple EDs including international data | N/A | ED-targeted ultrasound is highly specific and reliably identifies IUP. The specificity for detecting IUP exceeded 98% in most studies, and sensitivity typically above 90%.
Bedside ultrasound reduced missed ectopic diagnosis, decreased time to surgical treatment for ectopic cases, shortened ED lengths of stay in normal pregnancies, and showed greater cost-effectiveness versus formal radiology ultrasound. |
| Durston et al. Am J Emerg Med. 2000 [9] | Retrospective cohort, single-center (1992-1998) | 120 patients diagnosed with ectopic pregnancy | Compared 3 different ultrasound availability models over sequential time periods:
Increasing ED ultrasound availability improved the quality of ectopic pregnancy detection. The combined approach of initial ED physician bedside ultrasound followed by formal imaging when indicated was the most cost-effective and efficient. |
| Mateer et al. Acad Emerg Med. 1995 [10] | Prospective cohort, single-center | 148 pregnant women at risk for ectopic pregnancy | Emergency physicians trained in bedside transvaginal ultrasound (TVUS) demonstrated a 93% agreement rate with gynecologists in interpreting scans. Most ectopic pregnancies were identified early, allowing prompt management.
Established feasibility and high accuracy of ED physician-performed POCUS for early pregnancy evaluation, promoting wider adoption in emergency care. |
| Beals et al. Am J Emerg Med. 2019 [11] | Systematic review, multi-center | 2,350 patients across 6 studies | Patients who received POCUS had a mean reduction in ED LOS of 73.8 minutes (95% CI: 49.1–98.6) compared to those who underwent comprehensive ultrasound.
All included studies reported decreased LOS with POCUS. |
Table 1. Key published studies on first-trimester obstetric POCUS
Case Resolution
You use a curvilinear abdominal probe (Figure 16) and endocavitary probe (Figure 17) and visualize the following:
Figure 16. Right adnexal view showing a “ring of fire” sign suggestive of an ectopic pregnancy
Figure 17. Sagittal view of uterus showing the absence of an intrauterine pregnancy
Given her initial low blood pressure and an obstetric ultrasound concerning for an ectopic pregnancy, you decide to perform a FAST exam, and you see free fluid in the hepatorenal recess.
Figure 18. Right upper quadrant abdominal view, showing free fluid in Morison’s pouch
ED Course
Serum labs show the following:
- hCG 8400 mIU/mL
- WBC 13.3 x 103/uL
- Hematocrit 25.1%
The obstetrics and gynecology team is consulted for a likely ectopic pregnancy, and the patient is taken to the OR for an emergent laparotomy.
References
- Hamza A, Meyberg-Solomayer G, Juhasz-Böss I, et al. Diagnostic Methods of Ectopic Pregnancy and Early Pregnancy Loss: a Review of the Literature. Geburtshilfe Frauenheilkd. 2016;76(4):377-382. doi:10.1055/s-0041-110204
- Kadar N, DeVore G, Romero R. Discriminatory hCG zone: its use in the sonographic evaluation for ectopic pregnancy. Obstet Gynecol. 1981;58(2):156-161. PMID: 7254727
- Rodgers SK, Chang C, DeBardeleben JT, Horrow MM. Normal and Abnormal US Findings in Early First-Trimester Pregnancy: Review of the Society of Radiologists in Ultrasound 2012 Consensus Panel Recommendations. Radiographics. 2015;35(7):2135-2148. doi:10.1148/rg.2015150092
- Weissleder R, Wittenberg J, Harisinghani MG, Chen JW. Primer of Diagnostic Imaging. 5th ed. Mosby/Elsevier; 2011. ISBN: 9780323065382
- Habana A, Dokras A, Giraldo JL, Jones EE. Cornual heterotopic pregnancy: contemporary management options. Am J Obstet Gynecol. 2000;182(5):1264-1270. doi:10.1067/mob.2000.103620. PMID: 10819869
- Doubilet PM, Benson CB, Bourne T, Blaivas M. Diagnostic Criteria for Nonviable Pregnancy Early in the First Trimester. N Engl J Med. 2013;369(15):1443-1451. doi:10.1056/NEJMra1302417
- Thamburaj R, Sivitz A. Does the use of bedside pelvic ultrasound decrease length of stay in the emergency department? Pediatr Emerg Care. 2013;29(1):67-70. doi:10.1097/PEC.0b013e31827b53f9. PMID: 23283267
- McRae A, Murray H, Edmonds M. Diagnostic accuracy and clinical utility of emergency department targeted ultrasonography in the evaluation of first-trimester pelvic pain and bleeding: a systematic review. CJEM. 2009;11(4):355-364. doi:10.1017/s1481803500011416. PMID: 19594975
- Durston WE, Carl ML, Guerra W, Eaton A, Ackerson LM. Ultrasound availability in the evaluation of ectopic pregnancy in the ED: comparison of quality and cost-effectiveness with different approaches. Am J Emerg Med. 2000;18(4):408-417. doi:10.1053/ajem.2000.7310. PMID: 10919529
- Mateer JR, Aiman EJ, Brown MH, Olson DW. Ultrasonographic examination by emergency physicians of patients at risk for ectopic pregnancy. Acad Emerg Med. 1995;2(10):867-873. doi:10.1111/j.1553-2712.1995.tb03099.x. PMID: 8542485
- Beals T, Naraghi L, Grossestreuer A, Schafer J, Balk D, Hoffmann B. Point of care ultrasound is associated with decreased ED length of stay for symptomatic early pregnancy. Am J Emerg Med. 2019;37(6):1165-1168. doi:10.1016/j.ajem.2019.03.025. PMID: 30948256
ACMT Toxicology Visual Pearl – Sauté Gone Sour
Ingestion of the pictured mushroom is most associated with which toxicity?
- Disulfiram-like reaction
- Hallucinations
- Liver failure
- Seizures
[Image credit to William Morris via Creative Commons]
(more…)
PRoMPT BOLUS: A Landmark PECARN Trial Defining Fluid Choice in Pediatric Sepsis
Article reviewed: Balamuth F, Weiss SL, Long E, et al; PRoMPT BOLUS Investigators of the PECARN, PERC, and PREDICT Networks. Balanced Fluid or 0.9% Saline in Children Treated for Septic Shock. N Engl J Med. Published online April 24, 2026
DOI: 10.1056/NEJMoa2601969 | PubMed: PMID 42028918
DOI: 10.1056/NEJMoa2601969 | PubMed: PMID 42028918
For years, clinicians and researchers have debated a fundamental question in pediatric emergency care: does the type of fluid used in pediatric sepsis resuscitation matter?
The PRoMPT BOLUS trial was designed to answer this question. Conducted across 47 international sites in 5 countries and enrolling more than 9,000 children, this large, pragmatic randomized trial compared 0.9% saline with balanced crystalloids in children treated for suspected septic shock.
The results have just been released. Across a wide range of clinically meaningful outcomes (including kidney injury, mortality, and recovery), there was no difference between fluid types.
Background
Sepsis remains a major global health concern, affecting approximately 50 million people each year, with children accounting for nearly half of these cases. Early fluid resuscitation is a cornerstone of treatment, making the choice of fluid a critical and historically debated decision.
Two primary types of crystalloid fluids are used in practice:
- 0.9% saline, which contains a higher-than-physiologic chloride concentration
- Balanced fluids (such as lactated Ringer’s, Hartmann’s solution and PlasmaLyte), which more closely resemble plasma electrolyte composition
Prior research raised concerns that saline could contribute to metabolic acidosis and kidney injury, while balanced fluids were associated with improved outcomes in some adult and smaller pediatric studies. However, the pediatric literature remained inconsistent, with observational studies reaching conflicting conclusions. As a result, guidelines offered only weak recommendations favoring balanced fluids and called for more definitive trials.
PRoMPT BOLUS was designed to fill this gap.
Study Design
This trial used a pragmatic, randomized design (NS vs. balanced fluids), intentionally embedded into routine clinical care. Pragmatic trials evaluate clinical interventions within typical practice, rather than highly controlled clinical settings. By incorporating fluid randomization without modifying additional aspects of clinical practice, this approach allowed investigators to study fluid choice in real-world conditions across diverse healthcare systems. PRoMPT BOLUS was a collaborative effort across multiple networks including PECARN (Pediatric Emergency Care Applied Research Network), PERC (Pediatric Emergency Research Canada), and PREDICT (Paediatric Research in Emergency Departments International Collaborative).
Children ages 2 months to <18 years were eligible if clinicians suspected sepsis and were planning to treat with more than one fluid bolus for abnormal perfusion consistent with septic shock. They were randomized to receive either balanced fluids or 0.9% saline, with clinicians otherwise managing care as they normally would.
The primary outcome was MAKE30 (Major Adverse Kidney Events within 30 days), a composite that includes mortality, need for renal replacement therapy, or persistent kidney dysfunction at hospital discharge or 30 days, whichever came first.
This pragmatic approach was critical to the study’s success. It allowed for:
- High enrollment across multiple international sites
- Enrollment at the beginning of sepsis resuscitation so that most early fluid was as randomized
- Strong generalizability to everyday clinical practice
- Minimal disruption to clinical workflows
Results
Primary Outcome
The primary outcome, MAKE30, occurred at nearly identical rates in both groups:
- Balanced fluids: 3.4%
- Saline: 3.0%
This difference was neither statistically nor clinically significant. There were also no differences in any of the individual MAKE30 components between treatment groups.
Secondary and Safety Outcomes
Similarly, there were no meaningful differences in:
- Mortality
- Hospital length of stay
- Hospital-free days (median of 23 days in both groups)
- Safety events such as thrombosis or cerebral edema
Together, these findings strongly support the conclusion that both fluids are equally safe and effective.
Biochemical Differences
Although there were measurable and statistically significant biochemical differences between groups (such as higher rates of hyperchloremia and hypernatremia with saline and hyperlactatemia with balanced fluids), these changes did not translate into clinically meaningful outcomes.
Subgroup Analyses
Subgroup analyses across patient characteristics, illness severity, and total fluid volume showed no differences in outcomes. While there was a non-significant trend suggesting potential benefit of balanced fluids in the most severely ill patients, the study was not powered to confirm this finding.
Major Findings
The results of PRoMPT BOLUS can be distilled into several key conclusions:
- Both 0.9% saline and balanced fluids are safe and effective for treatment of children with suspected septic shock
- Fluid type does not influence major clinical outcomes, including mortality or kidney injury
- Biochemical differences exist between fluid choices, but did not translate to differences in clinical outcomes
Importantly, while the study cannot fully exclude a benefit of balanced fluids in the sickest patients, it provides strong evidence that for children presenting to the ED with suspected sepsis, either fluid is an appropriate choice.
Clinical Implications
These findings have immediate and meaningful implications for clinical practice.
First, they simplify decision-making. Clinicians can focus on timely recognition and treatment of children with suspected sepsis, and engage in fluid resuscitation with fluids that make sense for the clinical scenario.
Second, the results support flexibility in care. Fluid choice can now be guided by:
- Availability
- Medication compatibility
- Patient-specific factors (e.g., electrolyte abnormalities, underlying conditions)
Limitations
While the study is robust, several limitations should be considered.
The overall incidence of MAKE30 was lower than expected (~3% vs. an anticipated ~6%), which may reflect a less severely ill population than initially projected. This could limit the ability to detect small differences between groups.
Additionally, although subgroup analyses suggested a possible benefit of balanced fluids in more severely ill patients, the study was not powered to draw definitive conclusions in this population.
Bottom Line
The PRoMPT BOLUS trial provides the strongest evidence to date addressing fluid choice in children presenting to the ED with suspected sepsis. Both 0.9% saline and balanced crystalloids are safe and effective for resuscitation in children with suspected septic shock.
References
- Balamuth F, Weiss SL, Long E, et al; PRoMPT BOLUS Investigators of the PECARN, PERC, and PREDICT Networks. Balanced Fluid or 0.9% Saline in Children Treated for Septic Shock. N Engl J Med. Published online April 24, 2026. doi:10.1056/NEJMoa2601969
ACMT Toxicology Visual Pearl: Delayed Skin Burn
What type of burn may not develop findings shown until days to weeks after the exposure?
- Chemical
- Electrical
- Radiation
- Thermal
[Image generated via Google Gemini]
ALiEM AIR Series | Non-ACS Cardiology Module (2026)
Welcome to the AIR Non-ACS Cardiology Module! After carefully reviewing all relevant posts in the past 12 months from the top 50 sites of the Digital Impact Factor [1], the ALiEM AIR Team is proud to present the highest quality online content related to non-ACS cardiology emergencies in the Emergency Department. 9 blog posts met our standard of online excellence and were approved for residency training by the AIR Series Board. More specifically, we identified 6 AIR and 3 Honorable Mentions. We recommend programs give 5 hours of III credit for this module.
AIR Stamp of Approval and Honorable Mentions
In an effort to truly emphasize the highest quality posts, we have 2 subsets of recommended resources. The AIR stamp of approval is awarded only to posts scoring above a strict scoring cut-off of ≥30 points (out of 35 total), based on our scoring instrument. The other subset is for “Honorable Mention” posts. These posts have been flagged by and agreed upon by AIR Board members as worthwhile, accurate, unbiased, and appropriately referenced despite an average score.
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Take the AIR quiz at ALiEMU. Free, 1-time login required.
Highlighted Quality Posts: Non-ACS Cardiology 2025
| Site | Article | Author | Date | Label |
|---|---|---|---|---|
| EMCrit | Supraventricular Tachycardia | Dr. Josh Farkas | January 5, 2025 | AIR |
| EMCrit | Right Ventricular Failure | Dr. Josh Farkas | March 21, 2025 | AIR |
| EMCrit | Valvular Heart Disease | Dr. Josh Farkas | January 27, 2025 | AIR |
| EMCrit | Antiarrhythmics | Dr. Josh Farkas | January 8, 2025 | AIR |
| EM Cases | Acute heart failure risk stratification and disposition | Dr. Anton Helman | August 19, 2025 | AIR |
| EMCrit | SCAPE (sympathetic crashing acute pulmonary edema) | Dr. Josh Farkas | January 30, 2025 | AIR |
| RCEMlearning | Cardiogenic Pulmonary Oedema | Dr. Victoria Henson | May 30, 2025 | HM |
| EMCrit | Acute Pericarditis | Dr. Josh Farkas | September 20, 2025 | HM |
| EMCrit | Acute Myocarditis and evaluation of newly discovered HFrEF | Dr. Josh Farkas | October 1, 2024 | HM |
(AIR = Approved Instructional Resource; HM = Honorable Mention)
If you have any questions or comments on the AIR series, or this AIR module, please contact us!