Abdominal adhesions are bands of scar-like tissue that form between organs, between organs and the abdominal wall, or between loops of intestine. They develop in the vast majority of people who undergo abdominal or pelvic surgery and are a leading cause of small bowel obstruction, chronic pain, and infertility. Despite being extraordinarily common, adhesions remain frustratingly difficult to diagnose without surgery, and the options for treating them are limited. What makes adhesions especially tricky is that they can cause no symptoms at all for years, then suddenly trigger a life-threatening bowel blockage.
How Adhesions Form
When the peritoneum, the thin membrane lining the abdominal cavity, is injured by a surgical incision, infection, or inflammation, the body responds with an inflammatory cascade. Part of that response involves depositing fibrin, the same protein mesh that forms the scaffold of a blood clot, across the damaged surfaces. Normally, the body’s own clot-dissolving system, driven by enzymes called plasminogen activators, breaks down this fibrin within a few days. The tissue heals cleanly and the surfaces stay separate.
The problem arises when fibrinolytic activity is impaired. Researchers have found that decreased activity of tissue plasminogen activator (tPA) after surgery or chronic inflammation allows fibrin to persist between damaged surfaces, and that persistence is a major driver of adhesion formation.1PubMed. Role of plasminogen activators in peritoneal adhesion formation The mesothelial cells lining the peritoneum appear to play a central role in regulating this fibrin balance, meaning the health and recovery of that lining largely determines whether adhesions develop.2PubMed. The role of fibrinolysis in adhesion formation Instead of dissolving, the fibrin scaffold gets colonized by fibroblasts and blood vessels, maturing into permanent connective tissue bands that tether structures together.
Surgery Is the Leading Cause
By far the most common trigger for abdominal adhesions is surgery itself. Any procedure that opens the abdomen and handles internal organs creates the tissue trauma that kicks off the fibrin cascade. But the type of surgery matters enormously. In a study comparing patients who had only laparoscopic (keyhole) surgery with those who had only open surgery (laparotomy), adhesions were found in about 41% of the laparoscopy group versus roughly 89% of the laparotomy group.3Obstetrics & Gynecology. Laparoscopy Compared With Laparotomy as a Risk Factor for Intra-abdominal Adhesion Formation The open surgery group also had far more severe adhesions: dense, cohesive bands that required longer operating time to separate when surgeons went back in.
This dramatic difference comes down to the extent of tissue trauma. Open surgery involves a large incision through the abdominal wall, exposure of bowel and other organs to room air (which dries the peritoneum), and typically more manual handling of tissue. Laparoscopic surgery uses small incisions and a camera, so the peritoneum takes less of a beating. That said, even laparoscopic surgery carries some adhesion risk, and the gas used to inflate the abdomen during these procedures, usually carbon dioxide, creates a low-oxygen environment at the peritoneal surface that itself contributes to adhesion formation. In animal studies, adhesion severity increased with the duration and pressure of gas insufflation, and adding small amounts of oxygen to the gas significantly reduced adhesion development.4PubMed. Peritoneal mesothelial hypoxia during pneumoperitoneum is a cofactor in adhesion formation in a laparoscopic mouse model
Non-Surgical Causes
Surgery gets most of the blame, but adhesions also develop from other sources of peritoneal inflammation. Infections such as peritonitis or pelvic inflammatory disease can cause extensive adhesion formation. Endometriosis, which affects roughly one in ten women of reproductive age, is strongly associated with pelvic adhesions; the chronic inflammation from endometrial implants on the peritoneum triggers the same fibrin-mediated scarring process.5Human Reproduction Update. Endometriosis-related peritoneal adhesion formation: molecular mechanisms and clinical significance Whether adhesion formation in endometriosis involves disease-specific mechanisms beyond ordinary peritoneal injury is still an open question, but the clinical result is the same: bands of scar tissue binding pelvic organs together, often contributing to chronic pain, infertility, and surgical complications.
Radiation therapy to the abdomen or pelvis can similarly trigger adhesion formation, as can any condition that causes significant intra-abdominal bleeding. Even ruptured appendicitis, where infected material spills into the peritoneal cavity, can set the stage for adhesions that cause trouble years later.
What Adhesions Feel Like
Many people with abdominal adhesions have no symptoms whatsoever. Adhesions are frequently discovered incidentally during surgery for an unrelated condition. When they do cause problems, the symptoms tend to fall into a few categories.
Chronic abdominal or pelvic pain is one of the most common complaints. The pain can be diffuse and hard to localize, often worsening with movement, eating, or anything that stretches or tugs on the affected tissue. Because the adhesions physically tether organs that should glide freely against one another, even normal digestive movements can pull on sensitive structures. Adhesive disease has been described as “life-altering” in many patients, particularly when it goes unrecognized.6PubMed Central. Abdominal adhesions: A practical review of an often overlooked entity
Bowel-related symptoms are also common. Adhesions can kink, twist, or partially compress loops of intestine, causing intermittent bloating, cramping, nausea, and constipation. In severe cases, this progresses to a complete bowel obstruction, which is a medical emergency. Infertility is another significant consequence, as adhesions in the pelvis can distort the fallopian tubes or ovaries, blocking the egg’s path. One study found that previous appendectomy was associated with intra-abdominal adhesions that were in turn linked to tubal pathology, though not necessarily through direct tubal blockage, suggesting adhesions may affect fertility through indirect mechanisms as well.7PubMed Central. The Association of Appendectomy, Adhesions, Tubal Pathology, and Female Infertility
Why Diagnosis Is So Difficult
One of the most frustrating aspects of adhesions is that standard imaging usually cannot see them. A regular CT scan or X-ray will not show adhesion bands directly. This means that for decades, the only way to definitively diagnose adhesions was to go in surgically and look, which, ironically, creates more adhesions.
Newer imaging techniques have improved the situation somewhat. The “visceral slide” test uses ultrasound to watch whether organs glide normally against the abdominal wall during breathing. If a loop of bowel is stuck to the wall by an adhesion, it will not move. A systematic review and meta-analysis found that ultrasound visceral slide assessment had a sensitivity of about 96% and a negative predictive value over 99% for detecting adhesions at the periumbilical region, meaning it is especially good at confirming that adhesions are absent in a specific area.8PubMed. Ultrasound Visceral Slide Assessment to Evaluate for Intra-abdominal Adhesions in Patients Undergoing Abdominal Surgery This is particularly useful for surgeons planning laparoscopic entry, since they need to know where they can safely insert a trocar without piercing a stuck loop of bowel.
Cine MRI, a type of motion-capture MRI, offers another option. A study comparing abdominal ultrasound and cine MRI head to head found both had similarly high sensitivity and specificity for adhesions to the abdominal wall (around 90–91%), but cine MRI was better at detecting adhesions between internal organs rather than just organ-to-wall adhesions.9European Journal of Radiology. Assessment of the diagnostic efficacy of abdominal ultrasonography and cine magnetic resonance imaging in detecting abdominal adhesions Neither technique has replaced direct surgical visualization entirely, but they are steadily making non-invasive diagnosis more reliable.
Small Bowel Obstruction
The most dangerous complication of adhesions is small bowel obstruction. Adhesions are the leading cause of this condition, which occurs when scar bands compress or kink the intestine enough to block the passage of food and liquid.10PubMed Central. Adhesive Small Bowel Obstruction: A Review Symptoms include severe cramping pain, vomiting, abdominal distension, and inability to pass gas or stool. If the blood supply to the trapped bowel segment is cut off, the tissue can die, making emergency surgery critical.
In practice, most patients admitted with adhesive small bowel obstruction are initially managed without surgery, using bowel rest, IV fluids, and a nasogastric tube to decompress the stomach. A large retrospective study found that about 78% of patients were initially treated this way, though roughly a third of those ultimately needed surgery anyway when conservative measures failed.11PubMed Central. Management of adhesive small bowel obstruction: the results of a large retrospective study Among those who required delayed surgery, about 10% needed a portion of bowel removed, though only a small fraction of those had actual intestinal ischemia. The challenge for clinicians is timing: waiting too long risks bowel death, while operating too early subjects patients to surgical risks that might have been avoided.
Surgical Risks of Repeat Operations
Every time a surgeon re-enters an abdomen that already has adhesions, there is a real risk of accidentally cutting into the bowel while trying to separate the scar tissue. This complication, called inadvertent enterotomy, occurred in about 19% of reoperations in one series and was associated with significantly more postoperative complications, more ICU admissions, and longer hospital stays.12British Journal of Surgery. Morbidity and mortality of inadvertent enterotomy during adhesiotomy The risk climbs sharply with the number of prior operations: patients who had three or more previous laparotomies were at dramatically higher risk.13PubMed Central. Inadvertent enterotomy in minimally invasive abdominal surgery
This creates a vicious cycle. Surgery causes adhesions, adhesions cause problems, and reoperation to fix those problems causes more adhesions and carries the risk of bowel injury. It is one of the main reasons surgeons are cautious about recommending adhesiolysis (surgical separation of adhesions) unless there is a clear and compelling indication.
Does Surgery for Adhesion-Related Pain Actually Work?
This is where the evidence gets genuinely uncomfortable. Observational studies, where surgeons perform laparoscopic adhesiolysis and then follow patients over time, consistently report that about two-thirds to three-quarters of patients experience pain improvement.14Human Reproduction Update. Surgical treatment of adhesion-related chronic abdominal and pelvic pain after gynaecological and general surgery: a systematic review and meta-analysis That sounds promising, until you look at the randomized controlled trials.
When researchers compared laparoscopic adhesiolysis to diagnostic laparoscopy alone (where the surgeon looks around but does not cut any adhesions), the results were essentially identical. A recent updated meta-analysis of four randomized trials found pain improvement in about 39% of those who had adhesiolysis versus about 36% of those who had the sham procedure, with no statistically significant difference.15PubMed Central. Laparoscopic adhesiolysis for adhesion-related chronic abdominal and pelvic pain after gynaecological and general surgery: an updated meta-analysis and systematic review The high improvement rates in observational studies likely reflect a combination of placebo effect, natural fluctuation in chronic pain, and the fact that the act of looking inside the abdomen and telling someone what was found can itself be therapeutic in terms of reassurance.
The picture is different, though, when the goal is preventing future bowel obstructions rather than treating pain. A study following patients for five years found that elective adhesiolysis reduced the rate of readmission for adhesive small bowel obstruction to about 7%, compared with roughly 27% in patients managed without surgery. In patients who had already had prior obstruction episodes, the contrast was even starker.16PubMed Central. Elective adhesiolysis for chronic abdominal pain reduces long-term risk of adhesive small bowel obstruction So while the evidence for cutting adhesions to relieve chronic pain is weak, the case for doing so to prevent recurrent obstruction is considerably stronger.
Prevention Strategies During Surgery
Because treating adhesions is so problematic, the real hope lies in preventing them from forming in the first place. The most straightforward approach is good surgical technique: minimizing tissue trauma, avoiding unnecessary drying of the peritoneum, controlling bleeding meticulously, and using laparoscopic rather than open approaches wherever feasible. But even with the best technique, adhesions still form in many patients, so researchers have developed physical barriers and liquid agents designed to keep healing surfaces separated during the critical first days after surgery.
Barrier materials are sheets or films placed over surgical sites before the abdomen is closed. A systematic review identified ten barrier products that reduced adhesion incidence in both animal and human studies.17PubMed Central. Barrier materials for prevention of surgical adhesions: systematic review One of the better studied is a bioresorbable membrane made from glycerol, hyaluronate, and carboxymethylcellulose. In a randomized trial, about a third of patients treated with this membrane were adhesion-free at second-look surgery, compared with only 10% in the control group, and both the extent and severity of adhesions were significantly reduced.18PubMed. Prevention of postoperative abdominal adhesions by a novel, glycerol/sodium hyaluronate/carboxymethylcellulose-based bioresorbable membrane In rat models, combining this membrane with a neurokinin-1 receptor antagonist reduced adhesions by about 86% compared with controls, suggesting that multi-targeted approaches may be even more effective.19PubMed. The efficacy of a hyaluronate-carboxymethylcellulose bioresorbable membrane that reduces postoperative adhesions is increased by the intra-operative co-administration of a neurokinin 1 receptor antagonist in a rat model
Liquid agents take a different approach, bathing the abdominal cavity in a solution that keeps surfaces apart by flotation. Icodextrin 4%, a glucose polymer solution, has been tested in a randomized controlled trial for patients undergoing surgery for adhesive small bowel obstruction. The recurrence rate of obstruction was about 2% with icodextrin versus 11% without it over a mean follow-up of about three and a half years.20Journal of Gastrointestinal Surgery. P.O.P.A. Study: Prevention of Postoperative Abdominal Adhesions by Icodextrin 4% Solution After Laparotomy for Adhesive Small Bowel Obstruction Registry data from a range of surgical procedures also suggest that icodextrin can be safely combined with good surgical technique across different types of operations.21PubMed Central. Use of icodextrin 4% solution in the prevention of adhesion formation following general surgery: from the multicentre ARIEL Registry
Neither barriers nor liquid agents eliminate adhesions entirely, and they are not used as often as the evidence might warrant. Part of the challenge is that surgeons vary widely in how seriously they take adhesion prevention, and the cost-effectiveness calculations are complicated. One analysis estimated that the direct healthcare costs of adhesion-related complications in the first five years after surgery are roughly $2,350 after open procedures and $970 after laparoscopy, with anti-adhesion barriers potentially saving several hundred dollars per patient in open cases.22PubMed. Epidemiology and Prevention of Postsurgical Adhesions Revisited
Manual Therapy and Conservative Approaches
For patients with adhesion-related symptoms who want to avoid another trip to the operating room, manual physical therapy has attracted growing interest. The idea is that sustained, directed pressure applied to the abdomen by a trained therapist can mechanically stretch and disrupt adhesion bands. A systematic review of the available studies found preliminary strong evidence for benefits of soft tissue mobilization on symptoms from acute post-surgical adhesions, and moderate evidence for chronic post-surgical adhesions, with improvements in pain, quality of life, scar mobility, and, in some cases, fertility.23PubMed. Effect of soft tissue mobilization techniques on adhesion-related pain and function in the abdomen: A systematic review
Animal research supports the biological plausibility. In a rat model, a modeled manual therapy technique significantly reduced adhesion size, with treated animals showing markedly fewer primary adhesions than untreated controls.24PLoS ONE. Attenuation of postoperative adhesions using a modeled manual therapy Case reports have also documented resolution of partial small bowel obstruction symptoms with manual therapy alone.25PubMed Central. Manual Physical Therapy for Non-Surgical Treatment of Adhesion-Related Small Bowel Obstructions: Two Case Reports The overall evidence base is still small and mostly made up of uncontrolled studies, so expectations should be calibrated accordingly. But for people dealing with chronic adhesion pain who are poor candidates for more surgery, it is a reasonable option to discuss with their care team.
The Financial Toll
Adhesion-related problems impose a staggering economic burden. In the United States, adhesiolysis-related hospitalizations (both as the primary reason for admission and as a secondary procedure during other operations) have been estimated at over 350,000 per year, accounting for nearly a million inpatient days and roughly $2.3 billion in hospital expenditures alone.26PubMed Central. The inpatient burden of abdominal and gynecological adhesiolysis in the US When looking specifically at adhesive small bowel obstruction, a systematic review found that the national costs ranged into the billions of dollars, with patients managed surgically costing several times more than those treated conservatively.27The American Surgeon™. Financial and Inpatient Burden of Adhesion-Related Small Bowel Obstruction: A Systematic Review of the Literature The average hospital stay for surgical patients was nearly three times longer than for those managed without an operation.
Adhesions in Children
Adhesive complications are not limited to adults. Children who undergo abdominal surgery, especially neonatal procedures, develop adhesions at concerning rates. A study tracking pediatric patients found that those who had surgery on the small intestine faced the highest risk: about 9% were readmitted for adhesion-related problems within five years, and for children who had ileostomy creation or closure, the figure reached 25%.28PubMed. Adhesions after abdominal surgery in children Appendectomy, the most common pediatric abdominal surgery, carried a much lower but non-zero readmission rate of about 0.3%.
When adhesive small bowel obstruction does occur in children, the consequences tend to be severe. In a series of over 100 pediatric patients, most of whom had their original surgery during the neonatal period, roughly 87% required a laparotomy for their first obstruction episode because conservative management was not sufficient. Postoperative complications occurred in over half of cases, and the median cost of a single episode of acute adhesive small bowel obstruction was over $36,000.29Journal of Pediatric Surgery. Paediatric Adhesive Small Bowel Obstruction is Associated with a Substantial Economic Burden and High Frequency of Postoperative Complications The first obstruction episode often came within months of the original surgery, highlighting how quickly adhesions can become clinically significant in young patients.
A pilot study from the Philippines examining pediatric postoperative adhesions found that nearly two-thirds of cases occurred within the first year after surgery, with stoma creation during the original operation being a significant risk factor for both morbidity and mortality when adhesion-related complications developed.30BMJ Journals. Postoperative adhesions after abdominal surgery in children: a pilot study in the Philippines The limited availability of anti-adhesion products tested and approved specifically for pediatric use makes prevention in this population an unresolved challenge.
Emerging Pharmacological Approaches
Beyond barrier films and liquid agents, researchers are exploring drugs that might tip the fibrinolytic balance back in the body’s favor. One intriguing avenue involves statins, the cholesterol-lowering drugs used by millions of people. Statins appear to increase the activity of tissue plasminogen activator in mesothelial cells by inhibiting a signaling pathway called Rho-Rho kinase, which could boost the peritoneum’s ability to dissolve fibrin before adhesions take hold. Early data suggest that statin use in patients with signs of adhesion-related bowel obstruction was associated with fewer revision surgeries.31ScienceDirect / Asian Journal of Surgery. Current options for the prevention of postoperative intra-abdominal adhesions This is still preliminary, but the prospect of repurposing a widely available and well-tolerated drug class for adhesion prevention has generated genuine excitement in the field.
Other experimental approaches include agents that target specific inflammatory pathways involved in adhesion formation, gene therapy strategies aimed at boosting local fibrinolysis, and novel hydrogels that combine barrier function with drug delivery. None of these have reached routine clinical use, but they represent a shift in thinking from purely mechanical prevention (keeping surfaces apart) toward biological prevention (changing the biochemistry of healing). Whether any of them will dramatically reduce the burden of adhesive disease in the coming decades remains to be seen, but the direction of travel is encouraging for anyone who has experienced the real toll this condition can take.