Anastomosis in surgery connects two body channels together, such as blood vessels or parts of your intestines. Surgeons create a new anastomosis after removing or bypassing part of a channel, or after removing or replacing an organ that was connected to a channel.


What does anastomosis mean (definition)?

An anastomosis is a connection between two passageways. It may be where two river channels meet, or where plumbing pipes connect under the street. Your body also has many passageways with natural anastomoses. Two major examples of this are your blood vessels (arterial anastomosis) and your gastrointestinal tract, which is your esophagus connected to your stomach, connected to your intestines.


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 is an anastomosis in medicine?

Anastomosis is also an important surgical procedure. Surgeons have to connect body channels together all the time that were previously unconnected. If one of your channels is damaged, they might have to remove the damaged part and reconnect the ends to each other. If one of your body channels has a blockage, they might have to bypass the blockage by creating a new connection and a new pathway.

What is an anastomosis in the colon?

Intestinal anastomosis is one of the most common types of anastomosis procedures. Your colon is part of your large intestine or large bowel. You might need an anastomosis in your colon after having a colectomy — part of your colon removed. For example, an ileocolonic (or ileocolic) anastomosis reconnects your ileum, the end of your small intestine, to the remaining part of your colon.

Where in your body does surgical anastomosis happen?

Surgical anastomosis most often happens in your circulatory system and your digestive system, and sometimes in your genitourinary tract (your pee pathway). The most common types are vascular and intestinal. A vascular anastomosis joins two blood vessels (arteries or veins). An intestinal or bowel anastomosis reconnects a part of your bowels (your small and large intestines) with another part of your GI tract.

Procedure Details

An intestinal anastomosis can be end-to-end, end-to-side or side-to-side.
Anastomosis surgery connects your body channels together in one of three ways.

What types of surgical procedures involve anastomosis?

Some common examples include:

  • Bowel resection surgery. A large or small bowel resection removes a portion of your intestines. Afterward, your surgeon will have to re-establish the channel that your food will follow through the digestive process. When the remaining ends of your GI tract are in good condition, your surgeon can reconnect them together to restore continuity.
  • Ileal pouch surgery. If you have a total proctocolectomy (all of your colon and rectum removed) and your anus is in good condition, your surgeon may make you an internal ileal pouch (J-pouch) to replace your rectum and reconnect this pouch to your anus (ileal pouch-anal anastomosis). This usually requires multiple surgeries.
  • Gastric / intestinal bypass surgery. Surgeries that bypass part of your gastrointestinal tract, such as many weight loss procedures do, require a new anastomosis. Your surgeon will have to connect the upper portion of your GI tract with the part below the bypass.
  • Arterial bypass surgery. A peripheral or coronary artery bypass uses an anastomosis to connect one of your arteries to a new channel with better blood flow. The new channel is a graft of an artery or vein taken from somewhere else in your body. Taking it out also requires anastomosis.
  • Dialysis access surgery. Before you can begin hemodialysis treatment for kidney failure, you will have a small procedure to create easier access between the dialysis machine and your bloodstream. This involves an anastomosis between two of your blood vessels (arteriovenous fistula).
  • Organ transplantation surgery. Removing an organ and replacing it with a new one requires many anastomoses. The new organ has to be connected to all the vessels and organs that the previous organ was in order to do its job within your body system.


What are the three types of anastomoses?

Surgeons may reconnect your body channels in a few different ways. They may use these terms:

  • End-to-end anastomosis. Two open ends are connected together to form a seamless tube.
  • Side-to-side anastomosis. Two channels are connected side-by-side, and their ends are closed.
  • End-to-side anastomosis. One open end is connected to the side of the other channel, and the open end of that channel is closed.

When is an anastomosis not recommended?

If your tissues are inflamed due to an infection or disease, your surgeon will want to give them time to heal before attempting anastomosis surgery. This sometimes happens after a bowel resection. When your bowels can’t be reconnected during the same surgery, your surgeon creates an ostomy instead. That means they divert your bowels to a new opening in your abdomen with an ostomy bag attached.


Can I have an anastomosis surgery after my original procedure?

Some people need permanent ostomies, but others will only need temporary ones. These people may have anastomosis surgery at a later time. A temporary ileostomy may be simply reversed or converted to a permanent internal ileal pouch with an ileal pouch-anal anastomosis. A temporary colostomy can be converted to a permanent ileocolic anastomosis. With a successful anastomosis, your surgeon will close your ostomy.

Risks / Benefits

What are the possible risks or complications of anastomosis surgery?

All surgical procedures carry certain standard risks, including:

  • Bleeding.
  • Blood clots.
  • Inflection.
  • Injury to nearby organs or vessels.

Complications that are particular to an anastomosis include:

Anastomotic stricture (stenosis). An anastomotic stricture happens when scar tissue at the site of the anastomosis causes the passageway to narrow. Stenosis occurs in 5% of intestinal anastomoses, usually after a few weeks. A stricture can slow down or partially obstruct the passage of food through your GI tract. Stenosis can also occur in the neck of your bladder after prostate surgery, when your urethra is connected to your bladder neck. (This is called bladder neck contracture.) In both cases, healthcare providers can often treat the stricture by dilating it with a balloon, or with tubes. Dilation is a non-surgical procedure.

Anastomotic leak. An anastomotic leak happens when the two ends of your body channel that have been connected together don’t seal completely, and contents from the inside leak out. Anastomotic leaks are reported in about 5% of anastomosis surgeries. Most (75%) are associated with intestinal anastomosis, but they can also occur in vascular anastomosis. Leaks are 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 intestines contain bacteria that can infect the abdominal cavity if they leak out. A leak may require surgical repair.

A note from Cleveland Clinic

Creation of an anastomosis is an important part of many surgical procedures. It’s what makes many of these procedures possible. As a result, it’s also a cornerstone of surgical training. Surgeons have many tools and techniques at their disposal to make your anastomosis successful and to manage complications when they occur. Most succeed without complications. If you do have a leak, early intervention can control it and prevent further complications. If you develop a stricture, it can often be treated with non-surgical methods.

Medically Reviewed

Last reviewed on 08/09/2022.

Learn more about our editorial process.

Appointments 216.444.7000