Adhesions are bands of scar tissue that form between internal organs or between organs and the abdominal wall, causing surfaces that should move freely to stick together. The most common cause is surgery: roughly 90 to 93% of people who undergo open abdominal surgery develop adhesions afterward. But surgery isn’t the only trigger. Infections, chronic inflammatory diseases, radiation therapy, and conditions like endometriosis can all set the process in motion.
How Adhesions Form
Whenever tissue inside your body is damaged, your immune system launches a repair response. Part of that response involves laying down fibrin, a protein that acts like biological glue to seal wounds. Normally, your body breaks down excess fibrin once healing is complete. But when the damage is extensive, repeated, or occurs in an area with reduced blood flow, the fibrin doesn’t dissolve. Instead, it matures into tough, permanent bands of collagen that fuse neighboring tissues together.
These bands can connect loops of intestine to each other, bind the uterus to the bladder, or tether the liver to the abdominal wall. Because organs in the abdomen and pelvis normally slide past one another as you move, eat, and breathe, even a small adhesion can restrict motion and cause pain, pulling, or blockages.
Surgery Is the Leading Cause
Abdominal and pelvic operations are responsible for the vast majority of adhesions. Any time a surgeon cuts, cauterizes, or handles internal tissue, the body interprets it as an injury and begins the scarring process. Drying of exposed tissue during an operation, contact with surgical instruments, and even the presence of suture material or foreign particles can intensify the response.
Open surgery (laparotomy) carries the highest risk. Laparoscopic procedures, which use small incisions and a camera, produce significantly fewer adhesions. Data published in The Lancet found that laparoscopy reduced the risk of adhesion-related hospital readmissions by about 32% compared with open surgery. Still, adhesions remain a real concern even with minimally invasive techniques.
The consequences are not trivial. Peritoneal adhesions are the single most common cause of small bowel obstruction, a potentially life-threatening condition in which scar bands kink or compress the intestine and block the passage of food. About a third of patients who develop post-surgical adhesions are readmitted to the hospital at least once within ten years.
Infections and Inflammation
Any condition that causes prolonged inflammation inside the abdomen or pelvis can trigger adhesion formation, even without surgery. The National Institute of Diabetes and Digestive and Kidney Diseases lists several: Crohn’s disease, diverticular disease, pelvic inflammatory disease (PID), peritonitis (infection of the abdominal lining), and endometriosis.
PID, typically caused by sexually transmitted bacteria that spread to the uterus, fallopian tubes, or ovaries, is a particularly well-known culprit. The infection creates scar tissue both inside and outside the fallopian tubes, which can block them entirely and lead to infertility or ectopic pregnancy.
Crohn’s disease and diverticular disease create a similar dynamic in the intestines. Repeated flares of inflammation damage the surface layer of the bowel, prompting the same fibrin-and-collagen repair cycle that follows surgery. Over months or years, loops of intestine can become matted together.
Endometriosis and Pelvic Adhesions
Endometriosis deserves its own discussion because it is one of the most common non-surgical causes of pelvic adhesions in women. In endometriosis, tissue similar to the uterine lining grows outside the uterus, often on the ovaries, fallopian tubes, or the tissue lining the pelvis. These implants respond to hormonal cycles just like the uterine lining does, bleeding a small amount each month into the surrounding space.
That repeated bleeding triggers a local inflammatory reaction. The body attempts to wall off the irritation, and fibrous bands form between whatever structures happen to be nearby. A common result is adhesions that bind the ovaries to the pelvic sidewall, fuse the uterus to the bowel, or seal the fallopian tubes shut. Among women with endometriosis-related infertility, adhesions are frequently part of the picture, physically distorting the anatomy needed for conception.
Radiation Therapy
Radiation directed at the abdomen or pelvis, often for cancers of the colon, rectum, cervix, or uterus, can damage the outer lining of the intestines (the serosa). Animal studies have shown that this serosal breakdown is the primary driver of radiation-induced adhesions, with bands forming most often around the large intestine near the cecum. These adhesions tend to appear weeks to months after treatment and can cause partial bowel obstruction, which is one of the most serious late effects of abdominal irradiation. Submucosal scarring also occurs but plays a smaller role than the adhesions themselves in creating strictures.
Why Adhesions Are Hard to Diagnose
One of the most frustrating aspects of adhesions is that standard imaging cannot detect them. CT scans, X-rays, and ultrasounds show the consequences of adhesions, such as a blocked or dilated segment of bowel, but they cannot visualize the scar bands directly. A specialized X-ray called a hysterosalpingogram can reveal blockages in the uterus or fallopian tubes, which may suggest adhesions in those areas. Beyond that, surgery is the only way to confirm their presence with certainty.
This means diagnosis often relies on clinical reasoning. If you have chronic abdominal or pelvic pain, a history of surgery or one of the inflammatory conditions described above, and no other explanation on imaging, your doctor may suspect adhesions as the cause. Many people live with adhesions that never produce symptoms and are never discovered.
Reducing the Risk After Surgery
Surgeons use several strategies to limit adhesion formation during and after operations. Minimally invasive techniques reduce tissue handling and drying, which lowers the inflammatory trigger. Careful surgical technique, including gentle tissue handling, thorough irrigation, and minimizing the use of cautery, also helps.
Physical barrier products placed between tissues during surgery have shown meaningful results in clinical trials. Bioresorbable membranes made from hyaluronic acid and carboxymethylcellulose (sold under the brand name Seprafilm) significantly reduce the severity of adhesions and lower the rate of chronic abdominal complaints. One study found chronic symptoms in 35% of patients who received the barrier versus 78% of those who did not. Another type of barrier, a collagen-based membrane, showed strong reductions in both the extent and severity of adhesions compared with controls.
Liquid solutions are also used. Icodextrin, a sugar-based solution instilled into the abdomen at the end of surgery, keeps tissue surfaces separated during the critical first days of healing. In one trial, it cut the recurrence rate of adhesion-related small bowel obstruction from about 11% to just over 2%. Gel-based agents have shown some ability to reduce adhesion formation, though their effect on long-term outcomes like pain and fertility is less clear.
No barrier eliminates the risk entirely. The most effective prevention is avoiding unnecessary surgery when possible and choosing laparoscopic approaches when surgery is needed.