Anastomosis is the connection of two things that are normally diverging. In medicine, an anastomosis typically refers to a connection between blood vessels or between two loops of the intestine.

An anastomosis can occur naturally in the body, or it can be created surgically.

Natural anastomosis

Naturally occurring anastomosis refers to how structures are connected biologically in the body. For example, many veins and arteries are connected to each other. This helps us efficiently transport blood and nutrients throughout the body.

Surgical anastomosis

A surgical anastomosis is an artificial connection made by a surgeon. It may be done when an artery, vein, or part of the intestine is blocked off. It can also be done for a tumor in part of the intestine. A surgeon will remove the portion that’s blocked in a procedure called resection. The two remaining parts will then be anastomosed, or joined together, and sewn or stapled.

In the case of blood vessels, the blocked part is often not removed. Instead it’s bypassed by a natural or artificial conduit. An example of a natural conduit would be using the saphenous vein to bypass blocked arteries in the heart. An example of an artificial conduit would be using a Dacron tube to bypass arteries in the leg. In these cases, anastomosis refers to where the two structures are sutured together.

Many people with gastrointestinal disorders, such as Crohn’s disease or colorectal cancer, may need a surgical anastomosis to help treat complications of their conditions.

An ileocolic or ileocolonlic anastomosis is the joining together of the end of the ileum, or small intestine, to the first part of the large intestine, called the colon. It’s usually performed after a bowel resection in people with Crohn’s disease. This is because the disease often affects the small intestine and first part of the large intestine.

Why it’s done

An ileocolic anastomosis is usually done to rejoin the intestines after a bowel resection. A bowel resection is the removal of a damaged portion of the intestine. People with the following conditions may need a bowel resection:

  • colorectal cancer
  • Crohn’s disease
  • ulcerative colitis
  • regional enteritis
  • intestinal abscess
  • Meckel’s diverticulum, an abnormal sac of intestine present at birth
  • severe intestinal ulcers
  • blockage in the intestines
  • precancerous polyps
  • trauma, such as a gunshot wound

In most cases, anastomosis can be performed using laparoscopy. Laparoscopy means that the surgery is done through a small incision using a small instrument called a laparoscope. A laparoscope is a long, thin tube with a camera and light at the end of it. It helps doctors see inside your body while they perform surgery.

There are several techniques used by surgeons to perform an ileocolic anastomosis:

  • End-to-end (EEA). This technique connects the two open ends of the intestines together.
  • Side-to-side (SSA). This connects the sides of each part of the bowel together rather than the two ends. The ends are stapled or sewn closed. SSA anastomoses are at less risk of having narrowing complications in the future.
  • End-to-side (ESA). This technique connects the end of the intestine that’s smaller with the side of the larger one.

The technique that a surgeon chooses may depend on the difference in diameter of each portion of the intestine that needs to be joined together.

Staples vs. sutures

Surgeons can choose to join together the two parts of the intestine using either sewing (sutures) or staples. Sewing by hand has been used successfully for over 100 years. However, staples take less time to perform. Newer surgeons find it easier to learn as well.

An EEA can only be done with sutures. An SSA is usually done with staples.

As with any surgery, anastomosis carries some risks. These include:

  • blood clots
  • bleeding
  • scarring
  • blockage
  • stricture, or abnormal narrowing
  • damage to surrounding structures
  • infections, which can lead to sepsis
  • anastomotic leakage, or leaking where the intestine is reconnected

Other types of bowel anastomoses may be performed during the following medical procedures:

Gastric bypass surgery

Gastric bypass surgery is a type of bariatric surgery that’s usually done to help a person lose weight.

Two anastomoses are done during a gastric bypass surgery. First, the top of the stomach is turned into a small gastric pouch. A piece of the small intestine is cut and then connected to this new gastric pouch. This is the first anastomosis. The other end of the small intestine is then reconnected to the small intestine further down . This is the second anastomosis.

Removal of a tumor

An example would be for a pancreatic tumor. Once the tumor is removed, the organs will need to be rejoined. This can include the bile ducts, pancreas, gallbladder, and part of the stomach.

After a bowel resection, a doctor needs to address the two open ends of intestine. They may recommend either a colostomy or anastomosis. It depends on how much of the bowel was removed. Here the differences between the two:

  • In anastomosis, the surgeon will reattach the two ends of the intestine together with stitches or staples.
  • In colostomy, the surgeon will move one end of the intestine through an opening in the abdominal wall and connect it to a bag or pouch. This is done so that stools that would normally move through the intestine to the rectum instead pass through the opening in the abdomen into the pouch. The bag must be manually emptied out.

A colostomy is often only used as a short-term solution. It allows other parts of your intestine to rest while you recover from another surgery. Once you’re recovered, an anastomosis is then done to reattach the two ends of the intestine. Sometimes, there isn’t enough healthy bowel left to do an anastomosis. In this case, a colostomy is a permanent solution.

Vascular and circulatory anastomoses occur naturally in the body. For example, your body may create a new route for blood to flow if one route is blocked off. Naturally occurring circulatory anastomoses are also important for regulating body temperature.

Vascular anastomosis can also be done surgically. It’s often used to repair injured or damaged arteries and veins. Conditions and procedures that may require vascular anastomosis include:

  • damage to an artery due to an injury, such as a gunshot wound
  • coronary artery bypass surgery to treat a blockage to an artery that supplies the heart because of atherosclerosis
  • solid organ transplant to connect the new organ to the blood supply
  • hemodialysis

During a coronary bypass surgery, for example, a surgeon will use blood vessels taken from another area of your body to repair a damaged or blocked artery. Your surgeon will remove a healthy blood vessel from inside your chest wall or leg. One end of the blood vessel is joined above the blockage and the other end below.

In contrast to the intestines and stomach, vascular anastomoses are always sewn by the surgeon and never stapled.

An anastomotic leak is a rare but serious complication of anastomosis. As the name suggests, an anastomotic leak occurs when the newly created connection fails to heal and begins to leak.

It’s estimated to occur in roughly 3 to 6 percent of colorectal anastomoses, according to a . In a of 379 patients undergoing ileocolic anastomosis, only 1.1 percent of them experienced leakage as a complication of the procedure.

The signs of an anastomotic leak following anastomosis may include:

  • fever
  • abdominal pain
  • low urine output
  • ileus, or a lack of movement in the intestine
  • diarrhea
  • higher than normal white blood cell count
  • peritonitis

The risk of leakage is higher in people who are obese or on steroids. Smoking and excessive drinking can also increase the risk of anastomotic leakage.

Treating anastomotic leak

If the leak is small, it may be managed with antibiotics or a drain placed through the abdominal wall until the intestines heal. If the leak is larger, another surgery is needed.

In some cases, a colostomy will be required along with an abdominal washout. During a washout, a saltwater solution is used to wash the peritoneal cavity, including the intestines, stomach, and liver.

Anastomotic leak has a mortality rate of up to 39 percent, according to a . The earlier it’s diagnosed, the better the outcome.

Ileocolic anastomosis is considered a safe and effective procedure. However, as with any surgery, there are risks. These include infection and anastomotic leakage.

Most people who have a bowel resection with anastomosis make a full recovery. Some people may still need ongoing medical care if they have a chronic bowel condition, such as Crohn’s disease. An anastomosis won’t cure the condition. Modern advancement in surgical techniques have greatly improved outcomes and recovery time.