Bowel obstruction: symptoms, treatment, and when to worry
Last updated September 3, 2026.
A bowel obstruction is a blockage that stops food, fluid, and gas moving through the intestines, and it is a medical emergency. The classic quartet is cramping abdominal pain that comes in waves, vomiting, a swollen tight abdomen, and inability to pass stool or gas. Anyone with that picture needs hospital care the same day.
What causes it?
In adults, the commonest causes are scar tissue from previous abdominal surgery (adhesions) and hernias trapping a loop of bowel, followed by tumors, inflammatory bowel disease strictures, and volvulus, where the bowel twists on itself. A related condition, ileus, is a temporary paralysis of the bowel after surgery or illness rather than a physical blockage, and it looks similar. The treatment differs by cause, which is why hospital assessment with scans comes first.
What actually helps?
- Hospital, today: obstruction is managed with admission, no food or drink by mouth, IV fluids, and often a tube through the nose to drain the stomach and rest the bowel.
- Many settle without surgery: partial obstructions and ileus often resolve with that rest-and-drain approach under close observation.
- Surgery when needed: complete blockages, twisted or strangled bowel, and obstructions that fail to settle need an operation to relieve the blockage and remove any damaged bowel.
- Do not eat and wait at home: eating into an obstruction worsens vomiting and risk. Nothing by mouth, and get assessed.
- Know your risk if you have had surgery: previous abdominal operations mean adhesions, and the same symptom picture after past surgery deserves a low threshold for hospital.
When is it an emergency?
Bowel obstruction is itself the emergency. Call 911 or get to an emergency department now for severe cramping abdominal pain with persistent vomiting, a swollen hard abdomen, and no passage of stool or gas, or for abdominal pain with fever, a racing heart, faintness, or confusion, which suggest the bowel's blood supply is compromised. Do not eat, drink, or take laxatives while you wait. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
What does a bowel obstruction feel like?
Cramping abdominal pain arriving in waves, a belly that swells and tightens, vomiting that can progress to foul or feculent material, and the telling sign: no stool and eventually no gas passing either. Partial obstructions may still leak some liquid stool and gas, which muddies the picture. The combination of colicky pain, vomiting, swelling, and no gas is the pattern that means hospital now.
Can a bowel obstruction clear on its own?
Some do, under hospital conditions. Partial obstructions and ileus often resolve with the bowel rested, nothing by mouth, IV fluids, and a drainage tube from the nose, while doctors watch closely. Complete obstructions and twisted bowel do not get that luxury. The decision between waiting and operating is made with scans and serial examination, in hospital, never at home.
What is the difference between obstruction and ileus?
An obstruction is a physical blockage: adhesions, a hernia, a tumor, a twist. An ileus is the bowel's muscle temporarily switching off, usually after abdominal surgery or with serious illness or certain medicines, so nothing moves despite no blockage. Symptoms overlap heavily. Ileus is treated by treating the cause and resting the bowel; obstruction may need surgery. Imaging tells them apart.
Who is at risk of bowel obstruction?
Anyone with previous abdominal or pelvic surgery, since adhesions are the leading cause. Also people with hernias, inflammatory bowel disease, abdominal cancers, prior radiation, and severe constipation in older adults. If you carry any of that history, the symptom pattern of colicky pain, vomiting, and no gas should send you in early rather than after days of hoping.
Will I need surgery for a bowel obstruction?
It depends on the cause and whether the bowel is threatened. Adhesive partial obstructions frequently settle without surgery. Complete obstruction, signs of strangled bowel, fever, rising pain, deteriorating blood tests, or failure to improve in a day or two of conservative management push toward an operation. When surgery happens, it relieves the blockage and removes any bowel that lost its blood supply.
Is severe constipation the same as a bowel obstruction?
No, but the boundary can blur. Severe constipation builds gradually, gas still passes, and vomiting is unusual. Obstruction is more acute, gas stops entirely, the abdomen distends, and vomiting enters. Untreated severe fecal loading in frail or elderly people can itself obstruct. The practical rule: abdominal pain with vomiting and no passage of gas is assessed as obstruction until proven otherwise.