Anastomotic Leak

Anastomotic leaks are defined as ‘a leak of luminal contents from a surgical join between two hollow viscera‘. They are the most important complication to recognise following gastrointestinal surgery.

Early diagnosis, resuscitation and treatment of an anastomotic leak is key. Delay leads to prolonged contamination of the abdomen or chest by the luminal contents, leading to the development of severe sepsis and progression to multi organ failure and death.

In this article, we shall look at the risk factors, clinical features and management of an anastomotic leak.

Figure 1 – The anastomotic leak is an important complication of GI surgery to identify and manage early

Risk Factors

There are several factors that increase the risk of an anastomotic leak developing:

  • Emergency surgery or longer intra-operative time
  • Peritoneal contamination
  • Oesophageal-gastric or rectal anastomosis
  • Medication (see Table 1)
  • Smoking or alcohol excess
  • Diabetes or obesity / malnutrition
Medication Type Evidence & Recommendations
Corticosteroids Steroid Prolonged use may increase AL
Infliximab Anti-TNF∝ monoclonal antibody Slows wound monoclonal healing but no impact of AL rate
Mycophenolate mofetil, cyclosporin A, tacrolimus and everolimus Immunosuppressant Mycophenolate AL risk based in clinical observational study.

For other drugs, experimental evidence suggests increased AL risk

Azathioprine Purine analogue immunosuppressant Contradictory evidence
Bevacizumab VEGF inhibitor Bevacizumab Should be stopped and not restarted for at least 28 days either side of surgery

Table 1 – Medications that influence the rate of anastomotic leak (AL), adapted from ASGBI guidelines on prevention, diagnosis and management of colorectal anastomotic leakage

Clinical Features

The most common clinical features of an anastomotic leak are abdominal pain and fever. They usually present between five and seven days post-operatively.

On examination, patients may be pyrexial, tachycardic, with signs of peritonism or prolonged ileus*. It is important to check for feculent / purulent material or bile in the wound drain (or in the chest drain for oesophageal anastomoses)

*Any patient with systemic sepsis or is not improving as expected (“failing to progress”) after a GI resection should be considered to have an anastomotic leak until proven otherwise.


The most appropriate initial investigation for a suspected anastomotic leak is urgent blood tests, including FBC and CRP, U&Es, LFTs, and a clotting screen.

A venous blood gas will assess degree of tissue perfusion. A repeat Group and Save will be needed for possible surgery or radiological drainage.

The definitive diagnosis of anastomotic leak is made by an urgent CT scan with contrast of the abdomen and pelvis, which will show the presence of extraluminal contents.


Once an anastomotic leak has been diagnosed, the key immediate principles in management relate to the treatment of the potential contamination and resultant sepsis. Any suspected anastomotic leak requires urgent senior review.

Initial Management

Ensure the patient is nil by mouth (NBM) and start broad spectrum antibiotic cover (as per local guidelines). Start IV fluid therapy and insert a urinary catheter to enable monitoring of fluid balance.

Definitive Management

Any minor leaks may be managed through observation and bowel rest alone, with potential for percutaneous drainage if needed.

For a major leak, exploratory laparotomy is required, whereby subsequent surgical intervention may involve stoma formation or diversion / stenting, with an abdominal washout.

Fig 1 - Anastamosis of the sigmoid colon, following bowel resection secondary to diverticular disease.

Figure 2 – Anastomosis of the sigmoid colon, following bowel resection secondary to diverticular disease.

Key Points

  • Anastomotic leaks are defined as ‘a leak of luminal contents from a surgical join between two hollow viscera’
  • They can present with abdominal pain and fever, typically 5-7 days post-operatively
  • Definitive investigation is made via CT scanning with contrast
  • Management is with bowel rest, IV antibiotics, and potential surgical intervention if a major leak


Question 1 / 3
Which of the following is NOT a risk for developing an anastomotic leak?


Question 2 / 3
How long after surgery do anastomotic leaks usually present?


Question 3 / 3
A patient who has undergone a bowel resection on the ward is not clinically improving post-operatively as was expected. What post-operative complication needs to be suspected and assessed for, until proven otherwise


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