Acute Abdomen in the ICU

• ICU peritonitis is blunted; watch for fever, rising pressor needs, feeding intolerance, and lactate.
• Find the source with CT abdomen; a perforated viscus needs source control plus broad-spectrum antibiotics, while ischemic bowel (lactate, AF, pressors) goes to surgery.
• Sustained intra-abdominal pressure >20 mmHg associated with new organ dysfunction defines abdominal compartment syndrome; urgent decompression is indicated.
• Keep pancreatitis, cholecystitis (calculous vs acalculous), C. diff colitis, and Ogilvie in the differential.
• Measure intra-abdominal (bladder) pressure in ventilated patients with abdominal distension.

Diagnosing and Managing Acute Abdominal Pathology in the Intensive Care Unit

• Take history of chief complaint and evaluate patient
• Patient alert and communicative?
• Physical exam — specific: localized tenderness — epigastrium, periumbilical, right upper quadrant, left upper quadrant, right lower quadrant, left lower quadrant
• Labs: ↑ or ↓ WBC with differential · ↑ LFTs · ↑ amylase · ↑ lipase · ↑ lactate · ABG (acidosis, hypoxemia) · urine analysis (casts, cells, bacteria)
• Physical exam — nonspecific: feeding intolerance · ileus · Δ in bowel movements · Δ in wound drainage · Δ in drain output · abdominal distention · guarding · rebound · rectal bleeding
• Vitals: ↑ HR · temp ↑ or ↓ · ↓ BP · ↓ UOP · obtain the labs listed
• Order imaging studies based on physical exam and laboratory values
• THREE-VIEW PLAIN FILMS OF THE ABDOMEN — indications: feeding intolerance · abdominal distension · absent bowel movements (obstruction) — findings: free air (perforation) · air-fluid levels (ileus, obstruction) · pneumatosis (necrotic bowel)
• ULTRASOUND — indications: RUQ pain · ↑ LFTs · ↑ amylase, ↑ lipase — findings: distended gallbladder · gallbladder wall thickening · ductal dilatation · gallbladder stones/sludge · intra-abdominal blood/fluid — HIDA scan if acalculous cholecystitis is suspected
• CT SCAN — indications: ↓ hematocrit · ↑ or ↓ WBC with left shift · fever of unknown origin · recent surgery · absent bowel movements (obstruction) — findings: anastomotic leak (intestinal, biliary, pancreatic) · intra-abdominal abscesses (including pelvic, splenic, hepatic, retroperitoneal, etc.) · bowel or biliary pneumatosis (mesenteric ischemia and necrotic bowel) · devitalized organ tissue (i.e., necrotic pancreas) · hematoma or leaking aneurysm · transition point or closed loop obstruction