Scalp lacerations over hair-bearing areas require wound closure, usually with staples. An alternative technique is the Hair Apposition Technique, also known as the HAT trick [1, 2]. This technique provides a more cost-effective, faster, and less painful approach to scalp laceration repair. Imagine the scalp hairs as suture ties already embedded in the skin.

hair apposition technique

What are the steps for the HAT trick?

  • Perform wound irrigation and a meticulous examination.
  • Twist together 3-7 strands of hair on one side of the wound.
  • Do the same on the other side of the wound.
  • Interlock these two hair bundles in a 360-degree revolution. Do not tie a knot.
  • Secure the intertwined hair bundles by applying a few drops of a tissue adhesive.
  • Repeat as needed to close the length of the laceration.
  • The patient no longer needs to return for staple removal in 7-10 days. The hair will unravel on its own after a week.
Demo of intertwining the 2 hair bundles using a 360-degree revolution twist.
Example of the HAT trick in action.

Contraindications for using the HAT trick:

  • Scalp lacerations more than 10 cm
  • Grossly contaminated wounds
  • Active bleeding from the laceration
  • Significant wound tension
  • Hair strands less than 3 cm in length

1. Ong ME, Coyle D, Lim SH, Stiell I. Cost-effectiveness of hair apposition technique compared with standard suturing in scalp lacerations. Ann Emerg Med. 2005 Sep;46(3):237-42.

2. Hock MO, Ooi SB, Saw SM, Lim SH. A randomized controlled trial comparing the hair apposition technique with tissue glue to standard suturing in scalp lacerations (HAT study). Ann Emerg Med. 2002 Jul;40(1):19-26.


Michelle Lin, MD
ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg SF General. ALiEM Founder @aliemteam #PostitPearls at Bio:
Michelle Lin, MD