Nine percent of patients with negative CT for anterior abdominal stab wound (AASW) subsequently required therapeutic laparotomy. Negative CT for AASW was inadequate to consider patients safe for immediate discharge.
Why does this matter?
Imaging continues to improve, but there are some things even the mighty CT can't show. Hollow viscus injury is notoriously difficult to detect on CT, and this is a common injury with AASW. This matters because some will recommend you to send the patient home if the CT is negative, and that is bad advice.
It's just a flesh wound...or not
This was a systematic review of 7 studies with significant heterogeneity. The sensitivity of CT for detecting serious intraabdominal injury ranged from 50-100%. Of patients with negative CT, 9% subsequently needed therapeutic laparotomy. Half of the missed injuries were hollow viscus (mostly small bowel). Don't immediately discharge patients with AASW and negative CT. Observe them. Ideally, Trauma would admit for observation. EAST states that, "The vast majority of patients with penetrating abdominal trauma managed nonoperatively may be discharged after twenty-four hours of observation in the presence of a reliable abdominal examination and minimal to no abdominal tenderness (Level 3)." No one really knows the ideal period of observation, but we know this - immediately after negative CT is the wrong answer.
Accuracy of Computed Tomography in Diagnosis of Intra-abdominal Injuries in Stable Patients with Anterior Abdominal Stab Wounds: A Systematic Review and Meta-Analysis. Acad Emerg Med. 2018 Jan 25. doi: 10.1111/acem.13380. [Epub ahead of print]
There is a recent study showing 100% sensitivity and specificity for local wound exploration (LWE) of abdominal stab wounds. Just be careful. It is often done sloppily by sticking in a cotton swab or finger. That is not LWE. LWE requires local anesthetic and dissection with good lighting to see the deepest extent of the wound to assess for fascial penetration. Also LWE is limited if the patient is obese, very muscular, moving around, has multiple wounds, or not on the anterior abdomen. Best to admit if any doubt.
Peer reviewed by Thomas Davis, MD.