Anastomotic leak
Formal Definition
A serious surgical complication defined as a defect in the integrity of a surgical anastomosis (connection between two structures, most commonly bowel segments, but also vascular conduits or ureters) allowing luminal contents to escape into surrounding tissues or spaces; in colorectal surgery, the most common and feared complication with leak rates of 3-15% depending on location (higher for low rectal anastomoses), with mortality of 10-30% when septic; classically presents on postoperative days 5-8 with tachycardia, fever, abdominal pain, leukocytosis, and often oliguria or mental status changes.
How It's Used on the Ward
"The anastomosis blew" or "leaked" — the new connection the surgeon made (between two ends of bowel, or between bowel and another structure) has sprung a leak and bowel contents are now spilling into the abdomen, causing peritonitis and often sepsis; marked by new tachycardia and fever around POD 5-8; usually requires going back to the OR to take down or divert the anastomosis.
Example
""72-year-old male POD#6 from sigmoid colectomy with low colorectal anastomosis (4cm from anal verge). Was doing well — tolerating clears, ambulating, afebrile. Suddenly developed T 39.0°C, HR 124, BP 96/58, WBC 22.4 with left shift, abdominal distension, new confusion. CT abdomen/pelvis with rectal contrast: extravasation of contrast at the anastomosis, free fluid, free air. Diagnosis: anastomotic leak at low colorectal anastomosis. Emergent return to OR — diverting loop ileostomy created, abdominal washout, drains placed. ICU post-op.""
Clinical Context
Risk factors: low anastomosis (rectal), preop radiation, malnutrition/hypoalbuminemia, chronic steroids, smoking, anemia, prolonged operative time, poor tissue quality at anastomosis (inflammation, prior radiation injury), tension on anastomosis, inadequate blood supply to the ends. Prevention: preop smoking cessation, preop nutritional optimization, mechanical bowel prep + oral antibiotics for colon cases (ERAS protocol), ensure tension-free anastomosis with good blood supply, consider diverting loop ileostomy for high-risk low anastomoses. Diagnosis: CT abdomen/pelvis with water-soluble oral/rectal contrast (Gastrografin, NOT barium — barium peritonitis is worse than contrast leak peritonitis). Treatment: broad-spectrum IV antibiotics, source control (operative washout, take down or divert), percutaneous drainage if contained, supportive care. Mortality 10-30% with leak; significantly worse the later the diagnosis. International study group definitions for colorectal leaks: Grade A (contained, no intervention), Grade B (requires intervention but not surgery), Grade C (requires operative reintervention).