Abdominal compartment syndrome after AAA repair — FFICM MCQ

Correct answer: E — Measure intra-abdominal pressure via the bladder

The correct answer is E, measure intra-abdominal pressure via the bladder. This patient has a tense, distended abdomen with oliguria, rising creatinine, hypercapnic-metabolic acidosis (pH 7.30) and a borderline MAP after major abdominal aortic surgery, the classic triad suggesting intra-abdominal hypertension progressing to abdominal compartment syndrome. Bladder (intravesical) pressure measurement is the recognised bedside method for quantifying intra-abdominal pressure, as normal IAP in critically ill patients is around 5 to 7 mmHg, with sustained elevation above 20 mmHg plus new organ dysfunction defining abdominal compartment syndrome. Confirming raised IAP is essential before committing to definitive management (medical decompression or re-laparotomy), since treating the oliguria as a pure renal or fluid problem without recognising the mechanical cause will delay appropriate surgical referral and worsen outcome. Why the other options are wrong: B, Start furosemide infusion immediately: Diuretics do not address the mechanical compression of the renal veins and parenchyma caused by raised IAP and may cause further intravascular volume depletion and hypotension without improving renal perfusion. C, Commence renal replacement therapy as first test: RRT treats established renal failure but does not diagnose the underlying cause; instituting it first bypasses the reversible surgical diagnosis and delays decompression. D, Request urgent colonoscopy: Colonoscopy risks perforation in a distended, high-pressure abdomen and has no role in diagnosing compartment syndrome; it is contraindicated and unnecessary here. E, Increase enteral feed rate: Increasing feed volume worsens bowel distension and further raises intra-abdominal pressure, aggravating the underlying pathology rather than diagnosing it. Key point: Oliguria with a tense abdomen, rising creatinine and acidosis post-laparotomy mandates bladder pressure measurement to diagnose abdominal compartment syndrome before any other renal or GI intervention.

Reference: BJA Education (Royal College of Anaesthetists), 'Abdominal compartment syndrome', Continuing Education in Anaesthesia, Critical Care and Pain: https://www.bjaed.org/article/S1743-1816(17)30156-7/fulltext