Bowel Obstruction

What is a bowel obstruction?

A bowel obstruction happens when something blocks part of your small or large intestine, partly or fully, stopping food, fluid and gas moving through as they should. It's considered a medical emergency, since a blocked bowel can quickly lead to serious complications if it isn't treated.

What symptoms does a bowel obstruction cause?

Symptoms vary depending on where the blockage sits and what's causing it, but commonly include:

• cramping tummy pain that comes in waves, or gurgling noises from your abdomen
• bloating or feeling unusually full
• feeling sick or being sick
• being unable to pass wind or empty your bowels, or, if the blockage is only partial, constipation that alternates with diarrhoea
• loss of appetite
• signs of dehydration, such as a racing heartbeat or dark-coloured urine.

A blockage in your small intestine tends to bring on short, sharp waves of pain fairly quickly, often centred around one spot. A blockage further along, in your large intestine, more often builds gradually, with steadier, more spread-out cramping.

What are the causes of a bowel obstruction and who is at risk?

Scar tissue left over from previous abdominal or pelvic surgery, known as adhesions, is the single most frequent cause, since these bands of tissue can pull or trap a loop of bowel and pinch it shut. Hernias are another common cause, where part of the intestine pushes through a weak spot in the abdominal wall and becomes squeezed.

Tumours are a further major cause, whether they develop in the bowel itself (bowel cancer) or press on it from elsewhere, including cancers of the pancreas, ovary, womb, cervix, or lymphoma.

Other, less frequent causes include:

• Crohn's disease or other inflammation that leads to scarring and narrowing of the bowel wall
• diverticulitis, where small pouches in the bowel wall become inflamed and cause swelling
• a section of bowel folding in on itself (intussusception) or twisting on itself (volvulus)
• radiotherapy to the abdomen or pelvis, which can scar tissue over time
• swallowing something that can't pass through, including certain gallstones
• long-standing, severe constipation.

Having had abdominal surgery before raises your risk. So does living with an inflammatory bowel condition, or a cancer that affects your abdomen or pelvis.

Are there different types of bowel obstruction?

Doctors classify a bowel obstruction by where it sits: small bowel obstructions make up around 80% of cases, with the remaining 20% or so affecting the large bowel.

They're also described by how severe the blockage is:

• complete, where nothing at all can get past, not even gas
• partial, where the bowel is narrowed but some content can still squeeze through
• pseudo-obstruction, sometimes called a functional obstruction, where you have all the usual symptoms but there's no physical blockage, instead your bowel muscles aren't contracting properly.

If a blockage cuts off the blood supply to a section of your bowel, it's described as complicated rather than simple, and needs treating as a matter of urgency.

How is a bowel obstruction diagnosed?

A doctor will examine your abdomen and ask what you've been experiencing, along with your wider health history, including any previous surgery. They may also carry out a gentle internal examination of your rectum to check for anything unusual.

You'll usually need:

• blood tests, which can pick up infection or dehydration and show how well your organs are working
• an abdominal X-ray, which can often show a blockage's rough location
• a CT scan, the test doctors turn to most often, giving a detailed picture of precisely where the blockage sits and what's behind it.

How is a bowel obstruction treated?

Treatment depends on where the blockage is, how severe it is, and what is causing it. Many people are admitted to hospital for monitoring and initial treatment before a decision is made on next steps.

Non-surgical care usually comes first and may include:

• fluids given directly into a vein to treat or prevent dehydration
• a nasogastric tube passed through your nose into your stomach, to drain off trapped fluid and gas and ease bloating and sickness
• medicines to control pain and nausea
• resting your bowel by not eating or drinking for a period, sometimes alongside a low-fibre diet, laxatives, or steroids to reduce swelling, once you're able to eat again.

If the blockage is caused by a tumour and surgery isn't suitable, a doctor may be able to fit a stent, a small expandable tube that holds the bowel open so contents can pass through again.

Surgery is usually needed for a complete obstruction, or when blood supply to the bowel is at risk. It may also be recommended if non-surgical treatment hasn't resolved things. This can involve:

• adhesiolysis, dividing the scar tissue that's causing the blockage
• removing the affected section of bowel and rejoining the healthy ends
• a bypass procedure, rerouting the bowel around a blockage that can't be removed
• forming a stoma, where the bowel is brought out through an opening in your abdomen and stools are collected in a bag, which may be temporary or permanent.

When should I see a doctor?

A bowel obstruction needs urgent medical attention. Go straight to your nearest emergency department, or call 999, if you have the symptoms described above, particularly if you can't pass wind or empty your bowels at all, or if your pain won't ease up and stays constant.

Don't eat or drink anything once you suspect a blockage, and don't wait to see if it settles on its own: left untreated, some obstructions can turn life-threatening.