Adhesive Small Bowel Obstruction

What adhesions are

Adhesions are fibrous bands that form between loops of bowel, or between the bowel and the abdominal wall, as the body heals after surgery, infection or inflammation. They form after most open abdominal operations and after many keyhole operations. Most never cause problems. A band can kink, compress or twist a loop of small intestine, causing a blockage.

Common operations linked to adhesions include bowel and appendix surgery, cesarean section and hysterectomy, gallbladder surgery and hernia repair. Obstruction can occur weeks or decades after surgery. Pelvic infection, endometriosis and radiation therapy can also cause adhesions.

Symptoms

• cramping, colicky belly pain coming in waves, often around the belly button
• nausea and vomiting, which may be green (bile) and later brown
• a swollen, bloated belly (abdominal distention)
• not passing gas or stool, though stool already beyond the blockage may pass at first
• loud, high-pitched bowel sounds
• signs of dehydration: thirst, dry mouth, dark urine

Warning signs of strangulation

A closed loop or twisted bowel can lose its blood supply. This is called strangulation and causes the bowel to die within hours. Warning signs:

• pain that becomes constant and severe rather than cramping
• fever and a fast heart rate
• a tender, rigid belly
• low blood pressure or confusion

Diagnosis

1. History and examination: previous operations, timing and pattern of pain, hernia check.
2. Blood tests: blood count, electrolytes, kidney function and lactate, which rises with bowel ischemia.
3. CT scan of the abdomen and pelvis: the main test. It shows the level and severity of blockage, a transition point, and signs of strangulation such as poor bowel wall enhancement or free fluid.
4. Abdominal X-ray: may show dilated bowel loops with fluid levels but is less informative than CT.

Paralytic ileus, where the bowel stops moving without a physical block, and other causes of bowel obstruction, such as an inguinal hernia, tumor or Crohn's disease, need to be excluded.

Treatment

Non-operative management

Most adhesive obstructions without strangulation resolve without surgery, often within 72 hours.

• Nothing by mouth to rest the bowel.
• IV fluids and correction of potassium and other electrolytes.
• Nasogastric tube: a tube through the nose into the stomach drains fluid and gas, easing vomiting and distention.
• Water-soluble contrast: a drink of contrast dye (such as Gastrografin) followed by an X-ray. If the contrast reaches the colon within 24 hours, the obstruction is very likely to resolve. It may also help it resolve faster.
• Pain relief and anti-nausea medicine.

Surgery

Surgery is needed for signs of strangulation, perforation, peritonitis or a closed loop, and when there is no improvement after about 72 hours of non-operative treatment. The surgeon cuts the adhesive band (adhesiolysis) by keyhole or open surgery and removes any dead bowel. Keyhole surgery shortens recovery in selected patients.

Complications

• bowel ischemia and perforation
• sepsis
• dehydration and kidney injury
• aspiration of vomit into the lungs
• recurrence: adhesive obstruction comes back in a significant minority of people, whether treated with or without surgery

Outlook

The outlook is good for uncomplicated cases treated promptly. Death rates rise sharply when strangulation is missed or surgery is delayed. Each new operation can create new adhesions, so surgeons balance the benefits of operating against the risk of future obstruction.

Prevention

Complete prevention is not possible, but the risk is lowered by keyhole rather than open surgery where suitable, careful surgical technique, and, in some operations, adhesion barrier materials. If you have had abdominal surgery, know the warning signs and seek care early.

Frequently asked questions

What causes adhesive small bowel obstruction?

It is caused by adhesions, bands of scar tissue that form inside the abdomen after surgery, infection or inflammation. A band can kink, compress or twist the small intestine. It is the most common cause of small bowel obstruction in adults who have had abdominal surgery.

Can adhesive bowel obstruction resolve without surgery?

Yes. Most cases without signs of strangulation resolve with bowel rest, IV fluids and a nasogastric tube, often within 2 to 3 days. A water-soluble contrast study helps predict which patients will improve. Surgery is needed if it does not resolve or the bowel's blood supply is threatened.

How soon after surgery can adhesions cause a blockage?

Adhesions can cause obstruction within weeks of surgery, but many cases occur years or even decades later. The risk is highest after open bowel and pelvic surgery. Any combination of crampy pain, vomiting and no gas after past surgery should be assessed.

What are the signs that a bowel obstruction is an emergency?

Constant severe pain, fever, a fast heart rate, a rigid tender belly, vomiting feces-like material or feeling faint suggest strangulation or perforation. These need emergency surgery. Any suspected bowel obstruction should be assessed in an emergency department.

Will adhesions come back after surgery?

They can. Surgery to cut adhesions can itself create new ones, and adhesive obstruction recurs in a significant minority of patients. Keyhole techniques and surgical barriers may reduce new adhesions, but no method prevents them completely.