Anastomotic Leak

What an anastomosis is

When a surgeon removes part of the bowel, for example for colorectal cancer, diverticulitis or Crohn's disease, the two healthy ends are joined with stitches or staples. This join is called an anastomosis. Similar joins are made in stomach, esophagus, pancreas and weight-loss operations.

For the join to heal, the bowel ends need a good blood supply, no tension and healthy tissue. If healing fails at any point, bowel contents leak out, causing infection and inflammation in the abdomen (peritonitis) or a localized collection of pus (abscess).

Symptoms of an anastomotic leak

Symptoms usually appear between days 3 and 7 after surgery, but can occur up to several weeks later. Early signs are often subtle:

• belly pain that is increasing rather than settling, or pain out of proportion to the operation
• fever or chills
• a fast heart rate (above about 100 beats per minute) or new irregular heartbeat
• feeling generally worse, restless or confused
• bloating, nausea and vomiting, and failure of bowel function to return (ileus)
• reduced urine output
• discolored or feculent fluid from a surgical drain or the wound
• after esophageal surgery: chest pain, breathlessness, fever

A large leak can cause sepsis and septic shock within hours. A small, contained leak may only cause a low-grade fever and slow recovery.

Risk factors

Surgeons reduce risk by optimizing nutrition and stopping smoking before surgery, checking blood supply during the operation, and sometimes creating a temporary protective stoma (diverting ileostomy) to keep stool away from a low rectal join while it heals.

Diagnosis

• Clinical monitoring: heart rate, temperature, pain and bowel function are watched closely after surgery.
• Blood tests: rising C-reactive protein (CRP), particularly on days 3 to 5, and white cell count. A falling CRP is reassuring.
• CT scan with contrast: the main test. It shows free fluid or air, abscesses, and contrast leaking through the join.
• Contrast enema or swallow study for rectal or esophageal joins.
• Endoscopy in some cases to see the join directly.

Treatment

Treatment depends on the size of the leak and how unwell the patient is.

Small, contained leaks

• IV antibiotics
• nil by mouth or a restricted diet for a short period
• nutritional support, sometimes through a vein (parenteral nutrition)
• CT-guided drainage of any abscess

Endoscopic treatment

Leaks from the esophagus, stomach or rectum may be treated endoscopically with covered stents, clips or endoluminal vacuum (sponge) therapy.

Surgery

Patients with generalized peritonitis or sepsis need urgent reoperation. The surgeon washes out the abdomen and usually takes down the join and brings the bowel out as a stoma (colostomy or ileostomy), or protects the join with an upstream stoma. Stomas may be reversed months later once the patient has recovered.

Supportive care

Intensive care, fluids, blood pressure support and treatment of organ failure in severe cases.

Complications and outlook

• longer hospital stay and recovery
• a permanent stoma in some people
• fistula formation (an abnormal channel to the skin or another organ); see enterocutaneous fistula
• narrowing of the join (stricture)
• poorer bowel function after low rectal surgery
• in cancer surgery, a possible increase in local recurrence

Mortality varies widely with the site and severity of the leak and how quickly it is treated. Most people survive with prompt treatment, but anastomotic leaks remain a leading cause of death after bowel surgery.

Frequently asked questions

What are the signs of an anastomotic leak?

Signs include worsening belly pain after surgery, fever, a fast heart rate, bloating, vomiting, not passing gas or stool, feeling increasingly unwell or confused, and unusual fluid from a drain or wound. They usually appear 3 to 7 days after surgery but can be later.

How common is an anastomotic leak?

It occurs in roughly 2 to 7% of colon operations and is more common after low rectal surgery, esophageal surgery and emergency operations. Smoking, obesity, malnutrition, diabetes, steroids and pelvic radiotherapy all increase the risk.

Can an anastomotic leak happen after leaving hospital?

Yes. Although most leaks are diagnosed in the first week, some occur after discharge, sometimes up to several weeks later. Return to hospital promptly if you develop fever, increasing belly pain, vomiting or feel unwell after bowel surgery.

How is an anastomotic leak treated?

Small contained leaks may be treated with antibiotics and drainage of any abscess. Larger leaks, or leaks causing peritonitis or sepsis, usually need further surgery, often with a temporary stoma. Endoscopic stents or vacuum therapy can treat some esophageal and rectal leaks.

Can an anastomotic leak be prevented?

The risk can be reduced but not eliminated. Stopping smoking, improving nutrition, controlling blood sugar and reducing steroids before surgery help. Surgeons check blood supply to the join and may create a temporary protective stoma for high-risk low rectal joins.