A 28-year-old female with a stab wound to the left flank is brought to the emergency department. She is conscious, BP 92/60 mmHg, HR 115/min, and complaining of left-sided abdominal pain. Physical examination reveals a single stab wound with minimal external bleeding. The abdomen is soft with mild tenderness around the wound. Two units of O-negative blood are ordered. Which investigation is most appropriate to determine the need for exploratory laparotomy in this potentially penetrating abdominal trauma case?

Explanation

## Investigation of Choice for Penetrating Abdominal Trauma (Stab Wound) **High-Yield:** Local wound exploration (LWE) under adequate anesthesia remains the most appropriate **initial** investigation to determine peritoneal/fascial penetration in a hemodynamically borderline-stable patient with a stab wound to the flank. It directly visualizes whether the anterior fascia has been breached, which is the key decision point for operative intervention. **Key Point:** The goal of LWE is to determine **fascial penetration**: - If fascia is **intact** → observe, no laparotomy needed - If fascia is **breached** → further evaluation (DPL, CT, or laparotomy) or direct operative intervention **Clinical Pearl:** This patient has a BP of 92/60 mmHg and HR 115/min — consistent with Class II hemorrhagic shock (ATLS). She is conscious with a soft abdomen and minimal external bleeding, making her relatively stable for a brief, bedside/OR procedure. LWE takes only 5–10 minutes and avoids the time and radiation of CT, or the invasiveness of DPL. If she deteriorates at any point, proceed directly to exploratory laparotomy without delay. > **Why not CT (Option A)?** CT is excellent for anatomical delineation in truly stable patients (SBP >100), but this patient is borderline hypotensive. Sending her to the CT scanner risks deterioration in an unmonitored environment. CT is increasingly used at trauma centers for stable penetrating flank trauma, but LWE is the ATLS-recommended first step when stability is uncertain. > **Why not DPL (Option D)?** DPL is invasive, largely superseded by CT and FAST, and is more applicable to blunt trauma or when CT is unavailable. The supraumbilical approach is used when pelvic fracture is suspected; it is not the first-line investigation here. > **Why not serial clinical exam (Option B)?** Serial examination alone has poor sensitivity for early peritonitis and introduces unacceptable diagnostic delay in a patient already showing signs of hemodynamic compromise. ## ATLS Principle > *"In penetrating abdominal trauma, the question is not 'Is there injury?' but 'Does it require operative intervention?'"* — LWE answers this directly and rapidly. ## Comparison of Investigations in Penetrating Trauma | Investigation | Time | Stability Required | Diagnostic Role | |---|---|---|---| | **Local Wound Exploration** | 5–10 min | Borderline stable | Fascial penetration — **first-line** | | CT abdomen/pelvis | 15–30 min | Truly stable (SBP >100) | Solid organ/retroperitoneal injury | | DPL | 10–15 min | Any | Detects hemoperitoneum; invasive; less used | | Serial clinical exam | Ongoing | Any | Adjunct only; delays diagnosis | **Reference:** ATLS 10th Edition (American College of Surgeons); Bailey & Love's Short Practice of Surgery, 27th Ed., Chapter on Abdominal Trauma.