An adhesion is a band of scar-like tissue that forms between two internal surfaces that aren’t normally connected. These bands can range from a thin film of connective tissue to thick, fibrous bridges containing blood vessels and even nerve tissue. They most commonly develop inside the abdomen and pelvis after surgery, but they can form anywhere the body heals from injury, inflammation, or infection.
How Adhesions Form
When tissue inside your body is damaged, whether by a surgical incision, an infection, or inflammation, the body launches a repair process. Part of that process involves laying down a protein called fibrin, which acts like biological scaffolding to patch the injured area. Normally, your body breaks down this temporary scaffolding once healing is complete. But when that cleanup system is disrupted, the fibrin hardens into permanent scar tissue that can bind nearby organs or tissues together.
Three things drive this process. First, the body’s ability to dissolve that temporary fibrin scaffolding gets suppressed at the injury site. Second, inflammation floods the area with chemical signals that promote scarring. Third, reduced oxygen around the wound triggers the growth of new blood vessels into the developing scar tissue, which helps it mature and persist. Within the first three days after surgery, immune cells dominate the wound site. By days five through seven, the cells responsible for building scar tissue take over, and the adhesion solidifies.
Common Causes
Surgery is the leading trigger. Roughly 90% of patients who undergo abdominal surgery develop adhesions afterward. Any procedure that opens the abdomen or pelvis, from a cesarean section to gallbladder removal to appendectomy, can set the stage. The more surgeries you’ve had, the higher your risk.
Surgery isn’t the only cause. Several conditions that involve ongoing inflammation or infection in the abdomen can produce adhesions on their own. These include Crohn’s disease, diverticular disease, endometriosis, pelvic inflammatory disease, and peritonitis (an infection of the abdominal lining). Radiation therapy to the abdomen or pelvis can also trigger adhesion formation.
Symptoms and When They Cause Problems
Most adhesions never cause symptoms. Many people live their entire lives with adhesions and never know they have them. When adhesions do cause trouble, the symptoms depend on where they are and what structures they’re pulling on or compressing.
The most serious complication is small bowel obstruction, which happens when adhesions kink, twist, or compress a section of the intestine tightly enough to block the normal flow of food and gas. Postoperative adhesions are the leading cause of small bowel obstruction in developed countries, responsible for more than 75% of cases. About a third of patients who develop adhesions after abdominal surgery will be readmitted to the hospital at least once in the following ten years because of them.
A bowel obstruction typically causes cramping abdominal pain that comes in waves, vomiting (which may become greenish as the blockage worsens), visible bloating, and an inability to pass gas or stool. This is a medical emergency. Complete obstructions can cut off blood supply to the trapped intestine, which can become life-threatening without prompt treatment.
In the pelvis, adhesions from endometriosis, prior surgery, or past infections can cause chronic pelvic pain and may contribute to infertility by distorting or blocking the fallopian tubes. Adhesions around the shoulder joint capsule are a different condition entirely, commonly known as frozen shoulder, but the underlying principle is similar: abnormal scar tissue restricting normal movement.
Why Adhesions Are Hard to Diagnose
One of the most frustrating aspects of adhesions is that they rarely show up on standard imaging. CT scans, MRIs, and ultrasounds can detect the consequences of adhesions, like a bowel obstruction or fluid buildup, but they generally cannot see the adhesion bands themselves. This means doctors often suspect adhesions based on your surgical history and symptoms, but can only confirm them visually during surgery, typically through a minimally invasive camera procedure called laparoscopy. For many patients, this creates a difficult gap between experiencing symptoms and getting a definitive answer.
Treatment Options
There is no medication that dissolves existing adhesions. When adhesions cause significant problems like bowel obstruction or chronic pain, the primary treatment is a surgical procedure called adhesiolysis, where a surgeon carefully cuts the scar tissue bands to free the affected organs. This can be done through open surgery or laparoscopically through small incisions.
The catch is that surgery to remove adhesions can itself create new ones. In one study comparing outcomes, about 11.5% of patients who had laparoscopic adhesiolysis experienced recurrent symptoms, and those who had undergone three or more prior surgeries were over seven times more likely to have adhesions return. This creates a difficult cycle: the treatment for adhesions carries real risk of producing more adhesions.
For bowel obstructions caused by adhesions, doctors often try non-surgical management first, using IV fluids and a tube through the nose to decompress the intestine, hoping the blockage resolves on its own. Surgery becomes necessary when the obstruction is complete, when there are signs the intestine’s blood supply is compromised, or when conservative measures fail.
Prevention During Surgery
Because treating adhesions is so challenging, surgeons focus increasingly on preventing them from forming in the first place. Several barrier products are approved by the FDA specifically for this purpose. These are thin films, gels, or solutions placed between tissues during surgery to physically keep healing surfaces separated long enough for the body’s natural fibrin cleanup system to do its job.
The most widely used barriers have demonstrated a 32 to 55% reduction in adhesion formation in clinical trials. That’s a meaningful improvement, but it means adhesions still develop in many patients even with barriers in place. Minimally invasive surgery (laparoscopy) also helps reduce adhesion formation compared to traditional open surgery, because it involves smaller incisions and less tissue handling. Gentle surgical technique, keeping tissues moist during procedures, and minimizing the use of materials that provoke inflammation all contribute to lower risk as well.