Diagnostics

CBC: neutrophilic leukocytosis

BMP: ↑ BUN, ↑ creatinine

Blood gas analysis: lactic acidosis (in ischemic perforation)

Indications: Consider only for patients too unstable to safely undergo CT scanning.

X-ray abdomen [7]

• Findings: free intraperitoneal air (pneumoperitoneum) under the diaphragm and/or between liver and lateral abdominal wall

Point of care ultrasound (POCUS) for which characteristic findings include: [8][9]

• Enhanced peritoneal stripe sign: a hyperechogenic focal thickening of the peritoneum

• Horizontal reverberation artifacts: horizontal stripes resulting from the interface of free air and fascia

First line: CT abdomen and pelvis with IV contrast (most sensitive)

• Indications: acute nonlocalized abdominal pain

• Findings

  • Pneumoperitoneum: the presence of air in the peritoneal cavity

    • An abdominal x-ray showing radiolucent air under the diaphragm and/or the delineation of the bowel wall by radiolucent air is diagnostic.

    • Can occur after perforation of a hollow abdominal viscus (e.g., perforated peptic ulcer) or after surgery in which air is introduced into the abdominal cavity.

  • Signs of perforated bowel: loss of bowel wall continuity, localized mesenteric fat stranding

Alternative: formal ultrasound abdomen

• Indication: preferred in patients with contraindications to radiation exposure (e.g., pregnancy)

• Findings: pneumoperitoneum, localized fluid collection, localized thickening of a bowel segment.