PEM POCUS Series: Intussusception

PATIENT CASE

Johnny is a 2-year-old boy who comes into the emergency department for abdominal pain for the last day. His parents are concerned that he has been having intermittent abdominal pain and has seemed very tired all day. Parents deny bloody stool.

On arrival, his vital signs are:

He is tired appearing, and his abdominal exam is soft but diffusely tender. Given his intermittent abdominal pain, you decide to perform an intussusception point of care ultrasound (POCUS) exam.

ULTRASOUND TECHNIQUE

Intussusception is when one part of the bowel telescopes, or gets stuck, in another part of the bowel. Typically intussusception refers to ileocolic intussusception where the ileum becomes stuck in the colon. To perform the ultrasound, start in the right lower quadrant and trace the colon. See below for a step-by-step technique.

Technique

• The patient should be positioned supine.
• To aid in comforting the child, the child can be positioned supine in the parent’s lap while undergoing the scan. Having the parent or another provider offer a toy, book, or phone/tablet to distract the child during the scan can also help ease anxiety.
• Begin in the right lower quadrant (RLQ), using a high frequency linear probe with the probe marker to patient’s right.
• First, identify the anatomical landmarks in the RLQ (see ultrasound images below):
  • Psoas muscle (green) laterally
  • Right iliac vessels (blue)
  • Abdominal muscles (red)
  • Bladder (yellow) medially

Ultrasound image: Anterior Abdomen (RLQ) View

Ultrasound Image: Anterior Abdomen RLQ (More Medial) View

• Perform graded compression, with slow steady pressure to displace bowel gas
• Follow the colon from the RLQ to right upper quadrant (RUQ) until the liver (purple) and gallbladder are identified

Ultrasound Image: Anterior Abdomen (RUQ) View

• Rotate the probe marker to patient’s head and scan the entire length of the transverse colon.
• Rotate the probe marker back to patient’s right and scan the entire length of the descending colon, making sure to scan all four quadrants.
• Save representative video clips and still images of each quadrant.
• If an intussusception is found, measure its diameter in transverse view and note in which quadrant(s) it is found.
• At the end of scan, if you have found an intussusception, re-image the abdomen to make sure it was not transient.
• The provider should maintain awareness of the patient’s comfort throughout the scan.

INTUSSUSCEPTION CLASSIC FINDINGS

Normal (no intussusception)

Abnormal findings

• Look for findings of a sandwich sign (or pseudo-kidney sign) in the longitudinal view and target sign (or donut sign) in the transverse view.
• If visualized, measure the diameter of the intussusception in short axis (transverse) and note which in which quadrant(s) it is located.

Sandwich

Target Sign

Additional Anterior Abdominal Ultrasound Videos

Pro Tip
It can be difficult to distinguish intussusception of the small bowel-small bowel (i.e., when the ileum or part of the small bowel telescopes into itself) versus ileocolic (i.e., when the ileum becomes telescopes into the colon). The former often does not require a procedure for reduction, while the latter typically does. If the target sign diameter is <2 cm and transient, a small bowel-small bowel intussusception should be suspected. The length of the intussusception, or how many quadrants are involved, can also be measured for an idea of how much bowel is involved.

Small bowel-small bowel intussusception

Ileo-colic intussusception

FACTS and LITERATURE REVIEW

Mimickers of Intussusception

There are additional pathologies that can be mistaken for intussusception such as an intussuscepted appendix, appendicitis surrounded by abscess, and Meckel’s diverticulum, which are beyond the scope of this course. Any concerning finding for intussusception should be followed by a confirmatory study by the radiology department.

Benefits of intussusception POCUS scans

There have been several studies examining point-of-care ultrasonography (POCUS) for intussusception, which have shown excellent test characteristics and a decreased length of stay when using POCUS. POCUS also has no radiation exposure and may further help reduce morbidity by reducing delays in diagnosis of intussusception [1].

POCUS performed by PEM physicians has demonstrated a high level of accuracy in diagnostic agreement with radiologist-performed ultrasounds. For example, in a study by Arroyo et al., POCUS agreement with radiologist-performed ultrasounds occurred in 97 of 100 cases [1]. There is also research comparing positive ultrasound diagnosis (including POCUS and radiologist-performed ultrasound) of intussusception to confirmatory surgical or contrast enema, as exhibited by the table below.

Below is a table of test characteristics of POCUS for intussusception.

In terms of Emergency Department (ED) length of stay (LOS), Kim et al. (2020) reported that after the introduction of an intussusception POCUS scanning protocol for PEM physicians to implement in the ED, the LOS decreased by more than 200 minutes [10]. An additional study has shown that a POCUS-first pathway can be a way to expedite care for children with suspected intussusception in the ED, leading to reduced physician initial assessment to reduction time by an average of 69.9 min when compared to traditionally waiting for radiologist-performed ultrasound evaluation [11].

Differentiating small bowel-small bowel from ileocolic intussusception

In general, true ileocolic intussusceptions are:

• Found on the right side of the abdomen
• >2 cm in diameter
• Have mesenteric fat (which is white) and lymph nodes in the center
• Do not self-resolve

There have been studies looking at distinguishing small bowel-small bowel intussusception (SB-SBI) from ileocolic intussusception (ICI). Most of these, however, have been radiology-based rather than POCUS studies, making generalizability to the ED setting challenging. Thus, if there is a concern for an intussusception, a radiology ultrasound should be ordered.

In a small study of 27 patients, Wiersma et al. (2006) [12] found that SB-SBI had smaller mean diameters and shorter lengths than ICI. Consistent with these findings, a more recent study reported similar findings, with all ICI cases in the study having lesion diameters greater than 2 cm [13]. This study also suggested a difference in age distribution between the two intussusception lesions studied: patients with SB-SBI tended to be older and exhibited a wider age range, whereas the ICI group consisted predominantly of infants younger than 1 year [13].

Lioubashevsky et al. (2013) [15] evaluated a larger cohort of 174 patients and reported similar findings. In addition to assessing the inner fat core-to-outer wall thickness ratio, the authors examined the presence or absence of lymph nodes within the intussusception. These findings were supported by Zhang et al. (2021) [16], who identified lymph nodes in only one case of SB-SBI, compared with 56 cases (93%) of ICI. Zhang et al. also found that the fat core was visible on ultrasound in all cases of ICI but was absent in 16% of SB-SBI cases [16]. Similarly, Goel et al. reported an inner fat core-to-outer wall thickness ratio > 1 in all cases of ICI and < 1 in all cases of SB-SBI, further supporting the diagnostic utility of this sonographic feature [14].

These differences may be explained by the underlying anatomical and physiological characteristics of the involved bowel segments [14,15]. The mesentery associated with the ileocolic region contains greater amounts of adipose tissue and lymph nodes than the mesentery involved in SB-SBI [14-16]. This could explain why ileocolic intussusceptions tend to demonstrate greater lymph node and fat involvement, appearing as hyperechoic structures on ultrasound [15-17]. The increased proportion of mesenteric fat and lymphatic tissue may also contribute to the larger diameter of ICI lesions [14,16,17]. In contrast, the shorter length of SB-SBI lesions reported in previous studies may be attributable to active bowel peristalsis and the greater likelihood of spontaneous resolution in these cases [16,17].

Subramaniam et al. (2022) [18] looked at POCUS differentiating SB-SBI from ICI. Similar to above, they noted the predominant location of SB-SBI in the periumbilical or left abdomen compared with the right-sided predominance of ICI; the larger diameter of ICI, typically greater than 2.5 cm; the greater length of ICI, typically exceeding 3 cm; the presence of lymph nodes within ICI; the presence of peristalsis within SB-SBI; and the larger core-to-wall index associated with ICI [18].

While beyond the scope of this module, there is some evidence that POCUS may facilitate the treatment of intussusception in addition to its diagnostic utility. Zymerman et al. (2026) [19] reported a case series of 9 reductions with an 88.9% success rate for POCUS-guided hydrostatic reduction of ICI performed at the bedside by a pediatric emergency medicine physician. Similarly, Atia et al. (2026) [20] reported a retrospective chart review with 24 of 28 ICI (86%) successfully reduced when ICI was diagnosed using POCUS and bedside ultrasound-guided hydrostatic reduction was performed by a pediatric radiologist. This study also reported a mean time from admission to reduction of 126 minutes and a mean hospital length of stay of 407 minutes [20]. Together, these findings suggest that POCUS may serve not only as a reliable diagnostic tool for differentiating ICI from SB-SBI but also as a means of facilitating timely and effective bedside therapeutic intervention.

Case Resolution

You place a linear, high-frequency probe on the right side of the patient’s abdomen. You perform a bedside ultrasound scan, viewing transversely and longitudinally through the upper and lower abdomen. You observe the following:

What is the diagnosis?

This is an intussusception!

The intussusceptum (red) is the part of the bowel that has telescoped into the intussuscipiens (blue). When ileum becomes trapped in the colon, this can lead to ischemia and necrosis over time. This is what causes the classic “currant jelly stools”, which are bloody stools.

Tip: The classic triad of colicky abdominal pain, palpable mass and bloody stool are present in less than 50% of patients, and intussusception should be suspected for patients with vomiting, abdominal pain, and/or lethargy.^​1​

Hospital course

Johnny underwent an air enema reduction in the Radiology department, which successfully reduced the ileocolic intussusception.

Reference

1. Daneman A, Alton D. Intussusception. Issues and controversies related to diagnosis and reduction. Radiol Clin North Am. 1996;34(4):743-756. PMID 8677307.

The PEM POCUS series was created by the UCSF Division of Pediatric Emergency Medicine to help advance pediatric care by the thoughtful use of bedside ultrasonography.

Learn more about bedside ultrasonography on the ALiEM Ultrasound for the Win series