Anastomotic Leak

An anastomotic leak occurs when a surgical anastomosis fails and contents of a reconnected body channel leak from the surgical connection. It’s one of the most serious complications of bowel resection surgery.


An anastomotic leak occurs when a surgical anastomosis fails.
A new surgical connection or “anastomosis” can leak.

What is an anastomotic leak?

An anastomotic leak is a potentially dangerous complication of anastomosis, a surgical procedure. Anastomosis connects two ends of a channel (a tube or passageway) together. It’s usually done after part of the channel has been removed (resected). For example, if you have surgery to remove part of your intestines (bowel resection), the two severed ends of the intestine are reconnected. This connection is called an anastomosis.

An anastomotic leak is a potential complication of this procedure. It occurs when the two ends of a channel that have been connected together don’t seal completely, and contents from the inside leak out. It’s serious because the channels in our bodies are designed to carry substances that don’t belong in other parts. For example, digestive contents in your gastrointestinal tract contain bacteria that can infect the abdominal cavity if they leak out.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

What happens when a bowel resection leaks?

A bowel resection is just one type of operation that involves anastomosis and anastomotic leaks. But it is the most common one. When bowel contents leak into your abdominal cavity, they can cause infection and inflammation of the peritoneum, the tissue that lines your abdominal cavity (peritonitis). Infection in your abdomen can spread to other abdominal organs and can enter your bloodstream. Serious infection can lead to sepsis, a life-threatening physical reaction that can include shock, organ failure or death.

Another body channel that can leak into your abdominal cavity is your urine channel. Any operation that removes one of the organs connected to your ureter, such as a kidney transplant or a prostatectomy, requires anastomosis. If it leaks, urine can collect inside of your abdominal cavity (urinoma). Infection and sepsis are also risks outside of your abdominal cavity. For example, an anastomotic leak in your esophagus — which is part of your gastrointestinal tract — can infect your chest cavity.

When does an anastomotic leak occur?

A leak may be present at the time of surgery, though surgeons can screen for leaks at this time. It’s more likely to occur sometime during the healing process. Most leaks show up within the first week after surgery, but some may occur later. Healthcare providers keep watch for leaks in the weeks following surgery. Smaller, slower leaks may take longer to show their effects. A delayed anastomotic leak, occurring more than 30 days later, is uncommon.


How common are anastomotic leaks?

Anastomotic leaks are reported in about 5% of anastomosis surgeries. About 75% of anastomotic leaks are associated with colectomy, removal of some part of your colon. They’re most common when the resection is located toward the end of your large bowel (in your rectum or sigmoid colon). This part is narrower and more technically difficult to operate on, especially in men.

Who does anastomotic leak affect?

Technically, anyone who has had anastomosis surgery can suffer the complication of an anastomotic leak. But certain risk factors seem to increase the likelihood of having one.

Risk factors include:


Symptoms and Causes

What causes an anastomotic leak?

A leak in an anastomosis typically results from a failure in the healing process. There’s no one direct cause, but several factors might contribute. For example:

  • Too much tension at the surgical connection. This is the main thing surgeons try to avoid to prevent a leak. Tension could theoretically cause the connection to pull and stretch with movement. It’s more of a risk when the surgical site is in a narrower place that’s more difficult to access.
  • Preexisting infection in your body cavity. A preexisting infection will cause inflammation and swelling of your body tissues. Long-term inflammation can cause a loss of collagen. Surgeons try to control for infection by rinsing your body cavity with antiseptic and giving you antibiotics. But your tissues may already be weakened at the time of surgery.
  • Reduced blood flow (ischemia) in your body channel being connected. Ischemia can be a preexisting condition or it can be a reaction to surgery.
  • Compromised immunity, due to a health condition, smoking, low nutritional status or use of immunosuppressants. Radiation therapy also damages tissues and compromises immunity. Many people having anastomosis surgery are people who have cancer, too.

What are the symptoms of an anastomotic leak?

The first and most common symptoms are:

More advanced symptoms may include:

Diagnosis and Tests

How is an anastomotic leak diagnosed?

During your visits with your healthcare provider following surgery, your healthcare provider will assess your condition carefully. They’ll check your vital signs, bloodwork and bowel function on a regular basis. If you show any signs of infection, or if your bowels aren’t functioning right following colorectal surgery, your healthcare provider will consider the possibility of an anastomotic leak. They’ll use imaging tests to investigate — usually, a CT scan with contrast dye.

Management and Treatment

How is an anastomotic leak treated?

You’ll be treated immediately with antibiotics to control infection. After that, your treatment will depend on the extent of the leak and how advanced your condition is. It may include:

  • Drainage. Contaminated fluid and/or swelling from inflammation may need to be drained from your body. If possible, your healthcare provider will do this percutaneously — through a hollow needle inserted through your skin.
  • Bowel rest. If your leak is in your intestines, you’ll have to avoid eating and drinking by mouth during treatment. Your healthcare provider will give you intravenous fluids and, if necessary, feed you intravenously.
  • Repeat surgery. Your surgeon may need to revisit the anastomosis in a repeat surgery. When possible, they'll use a minimally invasive technique such as a laparoscopy, which examines your abdomen through a tiny camera inserted through a tiny incision. Your surgeon can also place tiny tools through the incision to drain an abscess or wash out your cavity with antiseptic. If this doesn’t work, they’ll have to reopen the body cavity to access the leak. The anastomosis may need to be reinforced, or it may need to be re-created at another place with healthier tissue. Sometimes, your body channel may need more time to heal before the anastomosis can be recreated. In the case of intestinal surgery, your surgeon may need to redirect part of your intestines to a temporary ostomy, a new opening that bypasses the anastomosis, to give it more time to heal.

How long is the recovery?

Hospital stays for anastomotic leaks can be upwards of four weeks.


Can anastomotic leaks be prevented?

Many variables contribute to anastomotic leaks, and many of them can’t be changed, including the health status of the people being treated, the difficulty of the particular operation and what happens during the healing process. However, surgeons can screen for leaks that may have occurred at the time of surgery.


Tests to screen for leaks following anastomosis include:

  • Air test. Fill your body cavity with saline and introduce air into your body channel. If bubbles appear in the fluid, there’s a leak in the connection. Usually, these leaks are addressed by either redoing the connection or sewing over the connection.
  • Fluid test. Introduce an antiseptic solution to your body channel to see if it leaks.
  • Contrast test. In the case of intestinal surgery, your surgeon can check for leaks using a CT scan with contrast dye. The contrast is injected into your rectum near the anastomosis to see if it leaks out of the connection.

Screening at the time of surgery won’t prevent all leaks, but it can reduce their number and can highlight people who may be more at risk of a recurring leak.

Preventative stoma

In the case of intestinal surgery, surgeons may be able to prevent the worst effects of a bowel leak by keeping poop out of your bowels during healing. They can do this by creating a temporary colostomy or ileostomy to divert your bowel contents away from the connection and into a bag. This won’t prevent an anastomotic leak, but it will prevent bowel contents from infecting your abdominal cavity if a leak occurs.

Ostomies create a new, artificial opening for poop to come out, called a stoma. This allows your bowels to rest and heal without the irritation of poop passing through. Surgeons create temporary, preventative ostomies under certain conditions. Temporary ostomy surgery is recommended as a preventative measure when people are at higher risk of an anastomotic leak.

Outlook / Prognosis

What’s the prognosis for people who suffer an anastomotic leak?

Leaks that are found can usually be repaired, but early diagnosis and intervention are important for managing infections and controlling sepsis. In general, people who suffer anastomotic leaks are more at risk of further health complications and mortality (death) down the road. It’s not clear how many of these outcomes result from the anastomotic leak, or whether the leak is a symptom of low health status in general.

Living With

When should I see my healthcare provider?

If you’re recovering from anastomosis surgery, stay close in touch with your healthcare provider and report any unexpected symptoms. Seek immediate medical attention for any signs of infection, such as:

What questions should I ask my doctor before anastomosis surgery?

If you need to have anastomosis surgery and you’re worried about anastomotic leaks, you can ask your healthcare provider about your personal risk factors, what preventative measures they might take and what kind of intervention they might recommend for you. For instance:

  • Is my surgery a higher-risk surgery for anastomotic leaks?
  • Am I personally at higher risk?
  • How do you control for anastomotic leaks?
  • Do you test for leaks at the time of surgery?
  • How will I be screened for leaks following surgery?
  • What will happen if I have a leak after surgery?

A note from Cleveland Clinic

If you need anastomosis surgery, it’s probably a life-saving intervention. Under these circumstances, it can be difficult to also consider the possibility of a life-threatening complication resulting from the surgery. As much as healthcare providers dread it, an anastomotic leak is always possible. In general, though, the risk is low, and with awareness and early intervention, most cases can be managed.

Medically Reviewed

Last reviewed on 02/03/2022.

Learn more about our editorial process.

Appointments 216.444.7000