Bowel obstruction: a case-based approach

The presentation

Imagine an adult who develops cramping tummy pain that comes in waves, a swollen, bloated abdomen, and repeated vomiting — sometimes of dark or foul-smelling fluid. They stop passing wind or opening their bowels, and eating or drinking makes things worse. The pattern depends on where the blockage is: a blockage high up in the small bowel tends to cause vomiting early, while one lower down causes more bloating and constipation before vomiting starts. Common causes include scar tissue from previous surgery, a hernia trapping a loop of bowel, or a growth narrowing the passage. Whatever the cause, a bloated, painful abdomen with vomiting and not passing wind should always be taken seriously and assessed promptly.

Why it makes people unwell

When the gut is blocked, food, fluid and gas pile up behind the blockage and have nowhere to go. The bowel stretches and swells, which causes the crampy, wave-like pain as it strains to push contents past the obstruction. Fluid that would normally be absorbed stays trapped in the gut or is lost through vomiting, so the body quickly becomes dehydrated and salts fall out of balance. If the swelling squeezes the blood supply to a segment of bowel, that section can be starved of oxygen and begin to die — a serious complication called strangulation. A dying or bursting bowel can leak its contents into the abdomen, causing severe infection. This is why doctors act quickly rather than waiting to see if the blockage clears itself.

When to seek urgent help

Bowel obstruction usually needs same-day assessment, and severe cases are an emergency. Seek urgent help — through your GP, NHS 111 or A&E — if you have a swollen, painful abdomen with vomiting and you cannot pass wind or open your bowels, especially after previous abdominal surgery or with a lump in the groin or tummy that has become painful. Call 999 or go to the emergency department if the pain becomes constant and severe rather than crampy, if the abdomen is very tender or hard, if you vomit repeatedly and cannot keep fluids down, or if there is fever, a racing heart, faintness or blood in vomit or stool. Do not keep eating or drinking, and do not try laxatives to force things through — get assessed first.

What happens in hospital

Most people with a suspected blockage are admitted. The team give fluids into a vein to correct dehydration and salt imbalances, and often pass a thin tube through the nose into the stomach to drain trapped fluid and gas, which eases vomiting and takes pressure off the bowel — sometimes called drip and suck. They check the tummy carefully, take blood tests, and arrange imaging, usually a CT scan, to find the cause and site of the blockage and to check the bowel is not strangled. Many blockages caused by scar tissue settle with this supportive care over a day or two. If the bowel is at risk of dying, if there is a trapped hernia, or if the blockage does not clear, an operation is needed to relieve it and remove any damaged bowel.

Recovery and the safe pathway

Recovery depends on the cause and whether surgery was needed. Blockages that settle with rest and drainage often allow a gradual return to eating once the gut starts working again, shown by passing wind or opening the bowels. After surgery, recovery takes longer and the team watch closely for the bowel waking up. Because scar tissue can cause repeat blockages, people are usually told what warning signs to watch for and when to come back. The practical message is about acting early: a bloated, painful abdomen with vomiting and not passing wind is not something to wait out at home. Get assessed the same day, and treat constant severe pain, a hard tender tummy or feeling very unwell as an emergency.