Bowel obstruction: symptoms, causes, treatment and when to get urgent help

Symptoms depend on where the blockage is and how complete it is. Dudley Group NHS Foundation Trust lists cramping tummy pain that comes and goes in waves, feeling sick and sometimes vomiting, feeling bloated or full, heartburn, constipation (not passing wind or a bowel motion) and noisy gurgling from the abdomen.

Cancer Research UK adds vomiting large amounts, including undigested food or bowel fluid, and says diarrhoea is usually seen in people with a partial obstruction. Patient.info explains that vomiting tends to be early in high-level obstruction and faeculent (smelling of stool) vomiting is limited to low obstruction, abdominal distension is more marked the lower the blockage, and absolute constipation appears earlier in low blockages and later in high ones.

• Cramping tummy pain that comes in waves (colic).

• Feeling sick and vomiting.

• Feeling bloated and full.

• A swollen tummy.

• Not opening your bowels or passing wind.

• Noisy gurgling from the abdomen.

• Diarrhoea, usually if the obstruction is partial.

Cancer Research UK says treatments for a blocked bowel can include drips and drains, surgery, stents and medicines, and that it is important to understand what your doctors are trying to achieve. Patient.info says that in uncomplicated obstruction, management is conservative, with fluid and electrolyte replacement, intestinal decompression and bowel rest. When obstruction results in ischaemia (loss of blood supply), perforation or peritonitis, emergency surgery is required.

Patient.info, written by UK doctors for health professionals, says small intestinal obstruction may be due to adhesions, strangulated hernia, malignancy or volvulus. It states that the majority (75%) of small bowel obstructions are attributed to intra-abdominal adhesions from prior operations, and that large intestinal obstruction is most often the result of colorectal malignancies, often in people aged over 70.

Cancer Research UK describes cancer-related causes: cancer in the tummy pressing on the bowel, such as ovarian, bowel or stomach cancer, other cancers spreading to the abdomen, cancer growing into the nerve supply of the bowel, or a mass of indigestible material collecting in the bowel. People who have had surgery or radiotherapy to the tummy are at higher risk.

• Adhesions: scar-like bands that form after abdominal surgery.

• Hernias, including a strangulated hernia.

• Cancer in or pressing on the bowel.

• Volvulus: twisting of the bowel, most often the sigmoid colon.

• Severe constipation causing faecal impaction, Crohn's disease and gallstone ileus (Patient.info).

• Paralytic ileus or pseudo-obstruction, where the bowel stops working without a physical blockage.

Dudley Group NHS Foundation Trust says bowel obstruction is a condition in which the bowel cannot work properly due to a narrowing of the bowel. Food contents cannot pass through and cause symptoms. It can happen in the small bowel or the large bowel. Patient.info notes that most patients admitted to hospital with intestinal obstruction have small intestinal obstruction.

The term ileus is now most often used for non-mechanical obstruction, where the bowel is inactive, sometimes called paralytic ileus.

Leeds Teaching Hospitals says its four-stage diet should only be followed with the guidance of your dietitian or doctor. It is for people diagnosed with bowel obstruction, at risk of it, or with a mass in the bowel at risk of a blockage. You may move backwards and forwards through the stages depending on your symptoms. For example, if you are in pain or your bowels stop working you may need to return to fluids only for a while.

The leaflet explains that some foods pass through the body without being broken down properly and can get caught in a narrow space: skins, pips and seeds of fruit and vegetables, stringy fruit and vegetables such as rhubarb and celery, raw or undercooked vegetables, vegetables that are difficult to digest such as mushrooms and sweetcorn, and bread products. It says eating and drinking little and often will help with symptoms, and that a low-fibre diet is encouraged.

Cancer Research UK says your doctor or nurse will examine you and ask questions, and may arrange blood and urine tests, a CT scan or an abdominal X-ray, and possibly an MRI or ultrasound scan. Patient.info says CT scanning is now the gold standard for imaging of bowel obstruction, and notes that ultrasound can detect obstruction but is no substitute for CT. It also says that abdominal pain and vomiting can occur with gastroenteritis, but if the abdomen is bloated and there is little or no bowel movement, obstruction must be considered.

A suspected bowel obstruction needs urgent assessment. Dudley Group NHS Foundation Trust lists the risks as perforation (a hole in the bowel that leaks contents into the abdomen), aspiration (inhaling stomach contents into the lungs) and dehydration. Leeds Teaching Hospitals advises contacting your doctor or dietitian immediately if you have nausea, vomiting, feeling full after drinking, bowels not opening for more than two days, a feeling of tightness across the stomach, bloating or stomach pain, as these could be a sign that the bowel is blocked.

If you think you or someone you care for may have a blocked bowel, seek urgent medical help through NHS 111 or, if very unwell, 999. If you have been told you are at risk of obstruction, follow the plan you have been given by your hospital team.

Bowel obstruction is usually dealt with as an emergency through A&E or a surgical assessment unit, and treated by a general or colorectal surgical team. Diet advice is given by NHS dietitians. Private hospitals can see people for scans and surgical review, but a suspected blockage needs emergency assessment rather than a routine appointment.