Patient information from BMJ

Small bowel obstruction

Last published:Jul 06, 2020

A small bowel obstruction causes a blockage of your small intestine (bowel) that stops food and liquid from passing through your digestive system. The obstruction can be partial or complete. A bowel obstruction is a medical emergency that needs urgent treatment.

What is a small bowel obstruction?

The small bowel is the upper part of the intestine that links the stomach to the large bowel, which is the lower part of the digestive system. The small bowel is where we absorb most of the nutrients from our food.

When there is a small bowel obstruction food and liquid can’t pass easily through the bowel. With a total obstruction it can’t pass through at all. These obstructions are usually caused by something pressing on the outside of the bowel or causing it to twist, and not by something inside the intestine.

If the blockage is not removed the obstructed part of the bowel starts to die. It then becomes perforated (torn). This leads to infection, multiple organ failure, and death.

In adults, causes of small bowel obstruction include:

• scar tissue from previous surgery

• a type of hernia called an inguinal hernia. This happens when a part of your bowel slips out of its usual position and pokes down into the groin

• Crohn’s disease, a condition that causes inflammation (swelling) in the bowel

• bowel cancer

• appendicitis.

In children, causes of small bowel obstruction include:

• appendicitis

• intussusception - ‘telescoping’ of the bowel, when part of the bowel folds into itself

• volvulus - twisting of the bowel

• atresia - narrowing of the bowel.

What are the symptoms?

The main symptom of small bowel obstruction is that you won’t be able to pass stools or pass gas (break wind) normally. If the obstruction is total you won’t be able to pass them at all. This leads to other symptoms such as:

• pain in the abdomen (tummy)

• swelling and bloating in the abdomen

• nausea

• vomiting

• fever. This can happen if you develop an infection in the lining of the abdomen

• fatigue.

If your doctor thinks you have a small bowel obstruction he or she will want to find out for sure as soon as possible. This is because tissue damage in the bowel can happen quickly.

Your doctor will examine you, listen to the sounds in your abdomen with a stethoscope, and ask you about your symptoms and your general medical history.

For example, your doctor will want to know about whether you have ever had surgery in your abdomen, or if you have a condition that affects your digestive system, such as Crohn’s disease.

He or she will also want to do some tests. These might include taking images of your abdomen: for example, an x-ray or CT (computerised tomography) scan. These scans can help your doctor find out the cause of the obstruction. You may also have a blood test to find out whether other organs, such as your liver, have been affected.

What treatments work?

A small bowel obstruction is a medical emergency and you will need treatment in hospital. If you have a complete obstruction you will almost certainly need surgery. But if your bowel is only partly obstructed you might not need an operation.

First treatments

The first thing your doctor will do is to relieve your immediate symptoms. You will be treated with:

• intravenous (IV) fluids to make sure you are not dehydrated

• nasogastric decompression. A tube is inserted through one of your nostrils down into your stomach. The contents of your stomach can then be sucked out through the tube. This relieves some of the pressure in your bowel

• pain relief.

If you have an infection in your abdomen, or you are about to have surgery, you will also need intravenous antibiotics.

During this first stage of treatment your doctor will also assess whether surgery is the right treatment for you.

Surgery

Surgery is not always needed.

• If you have a small partial obstruction it might go away without surgery. Your doctor might suggest waiting a few days to see if non-surgical treatments work.

• People who have a bowel obstruction caused by Crohn’s disease don’t usually need surgery. People with Crohn’s disease usually get better with drugs or other treatments.

But many people need surgery, especially for a complete obstruction. The type of surgery you have will depend on what has caused the obstruction.

For example, if your bowel obstruction has been caused by appendicitis you will need an operation to remove your appendix. If your obstruction has been caused by a hernia you will need an operation to repair the hernia.

What will happen?

A small bowel obstruction is a medical emergency. But if you get treatment quickly the outlook is very good. So if you have the symptoms listed above, don’t delay: get medical help straight away.

Bowel obstructions that go untreated lead to serious complications and death.

You might need to have part of your bowel removed. After having this operation you will have what’s called short bowel syndrome. You will need to take supplements prescribed by your doctor for the rest of your life, to make sure you get enough of the right nutrition.

If you have had treatment for a small bowel obstruction your doctor will want to check on you regularly, probably once a year. Bowel obstructions can come back. So you should be aware of any unusual digestive symptoms, and get medical help if you think the problem is happening again.