Adhesions and adhesive bowel obstruction
Adhesions are bands of fibrous tissue that form between surfaces inside the abdomen that should normally slide freely over one another. They are the near-inevitable consequence of abdominal surgery — present in the great majority of patients who have had an operation — and most cause no trouble whatever. But they are also the commonest cause of small bowel obstruction in the developed world, a significant cause of chronic abdominal pain and of infertility, and the reason repeat abdominal surgery is more difficult and more dangerous than the first operation. Adhesions are, in short, the price of abdominal surgery, and an honest account of them belongs in any discussion about having an operation.
How they form
The peritoneum is lined by mesothelial cells sitting on a basement membrane. When that lining is injured — by surgical handling, drying from air exposure, diathermy, foreign material such as sutures and glove powder, ischaemia from tight sutures, blood left in the cavity, or infection — a repair process begins:
- Inflammation and fibrin deposition. The injured surface exudes a fibrin-rich fluid, which forms sticky fibrin bridges between adjacent surfaces within hours.
- The critical fork. Normally, fibrinolysis — driven by tissue plasminogen activator produced by mesothelial cells — dissolves these bridges within about three to five days, and the surfaces separate, healing independently.
- Where fibrinolysis fails. Surgical injury, ischaemia and inflammation suppress tissue plasminogen activator and increase its inhibitor (PAI-1). The fibrin bridge persists beyond the critical window.
- Organisation. Fibroblasts migrate into the persisting fibrin, lay down collagen, and capillaries grow in. Within one to two weeks the temporary fibrin bridge has become a permanent, vascularised fibrous adhesion.
Two points follow. First, the peritoneum heals differently from skin — it re-epithelialises across the whole injured surface simultaneously from islands of mesothelial cells rather than from the edges inward, which is why a large defect heals as fast as a small one and why leaving peritoneum open is not in itself harmful. Second, the decisive event is the failure of fibrinolysis in the first few days, which is why anti-adhesion strategies are aimed at that window.
Ischaemia is the single most important surgical factor. Tissue deprived of blood cannot produce tissue plasminogen activator. This is why rough handling, crushing clamps, tight sutures and extensive diathermy all increase adhesion formation, and why gentle technique genuinely matters rather than being a platitude.
Non-surgical causes include peritonitis of any kind, endometriosis, radiotherapy, tuberculosis, and previous intraperitoneal chemotherapy. A minority of adhesions are congenital.
What they cause
Small bowel obstruction
The commonest serious consequence. Adhesions cause obstruction by kinking the bowel, by compressing it beneath a band, or by forming a closed loop when bowel herniates under a band and twists — a closed-loop obstruction, which is the dangerous form because the blood supply is compromised early and the bowel can infarct within hours.
Chronic abdominal pain
Adhesions are frequently blamed for chronic abdominal pain, and the honest position is that the relationship is uncertain. Many patients with extensive adhesions have no pain, and many with pain have few adhesions. Division of adhesions for pain alone produces inconsistent results and creates new adhesions in the process. This does not mean adhesion-related pain does not exist — it clearly does in some patients — but it does mean that surgery for it should be approached with caution and realistic expectations.
Infertility
Adhesions involving the fallopian tubes and ovaries impair ovum pick-up and tubal transport, and are a recognised cause of secondary infertility after pelvic surgery, appendicitis or pelvic infection.
Difficult reoperation
Repeat abdominal surgery in an adhesion-laden abdomen carries a substantially increased risk of inadvertent bowel injury — particularly at the point of entry — and of enterotomy during dissection, which is a serious complication. Operating time is longer and complications are commoner.
Symptoms of adhesive obstruction
- Colicky central abdominal pain, coming in waves
- Vomiting — early and profuse in proximal obstruction, later and faeculent in distal obstruction
- Abdominal distension — more marked the more distal the obstruction
- Absolute constipation — no stool and no flatus. In partial obstruction, some flatus continues to pass.
- previous abdominal or pelvic surgery, or previous peritonitis — the history that makes the diagnosis
- high-pitched, tinkling bowel sounds early; absent sounds later
Features suggesting strangulation, which change the situation from urgent to immediate: constant rather than colicky pain; localised tenderness, guarding or rebound; fever; tachycardia; a rising lactate; and failure to improve with conservative treatment. These mandate surgery rather than continued observation.
How the diagnosis is made
- CT of the abdomen and pelvis with contrast — the investigation of choice. It confirms obstruction, identifies the transition point, excludes other causes such as a hernia or tumour (adhesive obstruction is a diagnosis of exclusion), and — most importantly — identifies features of ischaemia: bowel wall thickening, reduced enhancement, mesenteric oedema, free fluid, and the whirl sign of a volvulus around a band.
- Plain abdominal X-ray — dilated small bowel loops with air-fluid levels; less informative than CT.
- Water-soluble contrast (Gastrografin) study — both diagnostic and therapeutic. Contrast given orally and followed by X-ray at twenty-four hours: if it reaches the colon, the obstruction will almost certainly resolve without surgery, and the hyperosmolar contrast itself draws fluid into the lumen and may relieve the obstruction. This is a genuinely useful protocol that reduces both the need for surgery and the length of stay.
- Blood tests including lactate and electrolytes.
Treatment
Conservative management — the default
Unlike large bowel obstruction, adhesive small bowel obstruction settles without surgery in the majority of cases. Initial management is:
- nil by mouth
- nasogastric tube to decompress the stomach and relieve vomiting
- intravenous fluids with careful electrolyte correction — losses are large
- analgesia and antiemetics
- urinary catheter and fluid balance monitoring
- water-soluble contrast study at twenty-four hours
Conservative treatment is generally continued for up to three to five days, but not longer — prolonged non-operative management beyond that increases complications without improving the chance of resolution. And it is abandoned immediately at any sign of strangulation.
Surgery
Indicated for signs of strangulation or peritonitis, for failure of conservative treatment, and for obstruction in a "virgin abdomen" with no previous surgery, where another cause must be sought.
The operation is adhesiolysis — careful division of the adhesions — with resection of any non-viable bowel. Laparoscopic adhesiolysis is appropriate in selected patients, particularly those with a single band, few previous operations and no gross distension, and is associated with less subsequent adhesion formation. It requires care, since the risk of inadvertent bowel injury on entry is real.
An important caution: enterotomy during adhesiolysis is a serious complication, and recognising and repairing all injuries before closing is essential. This is one reason reoperation is undertaken deliberately rather than readily.
Prevention
This is where the meaningful gains lie.
- Minimally invasive surgery — laparoscopic surgery produces substantially fewer adhesions than open surgery, through less tissue handling, less drying, and smaller peritoneal injury. This is one of its most under-appreciated long-term benefits.
- Meticulous technique — gentle handling, avoiding unnecessary dissection and diathermy, avoiding ischaemia, minimising foreign material, careful haemostasis, avoiding drying by irrigation, and avoiding leaving blood in the cavity.
- Adhesion barriers — hyaluronic acid-carboxymethylcellulose membranes and icodextrin solution physically separate surfaces during the critical few days of fibrinolysis. They reduce the extent of adhesions, though whether they reduce clinically important outcomes such as obstruction is less firmly established. They are used selectively, particularly in high-risk cases.
- Avoiding unnecessary abdominal surgery in the first place.
Recovery
Conservatively managed obstruction typically settles within two to four days, with oral intake resumed gradually. Surgery for adhesive obstruction involves a hospital stay of five to ten days, longer if bowel has been resected, with a recovery of six to eight weeks. Return of bowel function is often slow after adhesiolysis.
Recurrent obstruction is common — a meaningful proportion of patients have a further episode — and surgery itself creates new adhesions, which is why the threshold for operating on recurrent obstruction that settles conservatively remains high.
When to seek help urgently
Colicky abdominal pain with vomiting and inability to pass wind, particularly after previous abdominal surgery, requires emergency assessment. Constant severe pain, fever, or feeling very unwell in that setting requires it immediately.
Common questions
Everyone tells me I have adhesions. What actually are they?
Bands of internal scar tissue joining surfaces inside the abdomen that should slide freely past one another. They form as part of healing after any operation, infection or inflammation. Most people who have had abdominal surgery have them, and most never know.
Can they be prevented?
Partly. Keyhole surgery produces considerably fewer than open surgery, and careful handling of tissue during any operation reduces them. Special barrier materials placed at the end of an operation separate surfaces during the few critical days when adhesions form, and reduce their extent. None of these eliminates them entirely.
Are my adhesions causing my chronic pain?
This is genuinely uncertain, and you deserve an honest answer rather than either a confident yes or a dismissal. Many people with extensive adhesions have no pain at all, and many with pain have few adhesions. Operating to divide them for pain alone gives inconsistent results and creates new adhesions in the process, so it is approached cautiously and with realistic expectations.
Can they be removed permanently?
No. They can be divided, but the act of dividing them causes new ones to form. This is the central frustration of the condition and the reason surgery is reserved for clear mechanical problems — principally obstruction — rather than performed as a general clearance.
Do I need an operation for this blockage?
Probably not. Most blockages caused by adhesions settle with rest of the bowel, a tube to empty the stomach and fluids through a drip, usually within a few days. A special contrast drink given on the first day both predicts whether it will settle and often helps it to. Surgery is needed where there are signs the bowel's blood supply is compromised, or where it does not settle within a few days.
Will it happen again?
It may. A significant proportion of people have a further episode at some point, and this is one reason surgery is avoided where the blockage settles on its own — operating creates new adhesions and does not prevent future episodes. Knowing the warning signs and seeking help early is the practical approach.
Why is a repeat operation more difficult?
Because the surfaces are stuck together, so entering the abdomen safely takes longer and carries a real risk of accidentally injuring bowel, and separating everything can take hours. This is a genuine factor that surgeons weigh when deciding whether a further operation is worthwhile.
Can adhesions affect fertility?
Yes. Adhesions involving the fallopian tubes and ovaries can interfere with the egg reaching the tube, and are a recognised cause of difficulty conceiving after pelvic surgery, appendicitis or pelvic infection. This is worth raising if you have had such surgery and are having trouble conceiving.
Related conditions
Other conditions of the peritoneal disease covered on this site:
- Peritoneal metastases
- Pseudomyxoma peritonei
- Peritoneal mesothelioma
- Primary peritoneal cancer
- Peritonitis
- Intra-abdominal abscess
This page provides general information and does not replace an individual medical consultation. Symptoms of bowel obstruction require emergency hospital assessment.