Fast facts

  • Bowel obstruction happens when your intestine becomes blocked. The blockage prevents food, drink, gas and faeces from moving through your bowel. It can have many causes.
  • Common signs of bowel obstruction are abdominal pain (tummy pain), a feeling of swelling and fullness in the abdomen, inability to pass faeces, and nausea and vomiting.
  • Bowel obstruction is a medical emergency that requires immediate medical attention.

Abdomen

The part of the body that lies between the chest and the pelvis.

What is bowel obstruction?

Bowel obstruction occurs when you have a complete or partial blockage of your bowel. The blockage stops liquids, solids and gas passing through your small or large intestine (bowel).

Bowel obstruction is a serious condition that requires prompt medical treatment. It can occur at any age, but is more common in the young and in the elderly. 

Causes

Anatomy of the bowel

The bowel is a major part of the digestive system, which also includes the liver and the stomach. The bowel is made up of the small and large intestines. When food leaves the stomach, it enters the small intestine, a long and narrow tube (about six metres long and 2.5 centimetres wide) that is important for absorbing most of the nutrients in our food. The small intestine is made up of three sections - the duodenum, the jejunum and the ileum. The jejunum and ileum move freely within the abdominal cavity, and are therefore at risk of twisting and forming a mechanical obstruction known as a volvulus (see below). 

The small intestine empties into the large intestine, a wider and shorter tube (about 1.5 metres long and 6 cm wide). It is mostly used for storing faeces and absorbing water. The large intestine is made up of the caecum, the ascending colon, the transverse colon, the descending colon, the sigmoid and the rectum. The caecum and sigmoid are generally mobile and so are also at risk of twisting. 

The digestive system. 

 

All parts of the bowel are at a risk of developing a bowel obstruction. Obstructions can be either mechanical or non-mechanical:

Mechanical obstruction

A mechanical obstruction is when the bowel becomes physically blocked from the inside, or is compressed from the outside. Common causes include:

  • Severe constipation: large, dry stools form in your intestines, often as a result of constipation. These stools are hard to move and can block your rectum; 
  • A hernia: parts of the intestine can protrude into another area of your body, creating a blockage;
  • Intestinal adhesions: inflammation inside the abdominal cavity, which often occurs as a result of abdominal surgery or abdominal infections, can create bands of scar tissue. These bands can stick together, blocking the intestine.
  • Masses: tumours and cancers that develop within the bowel can block it. Bowel cancer is more common in the large intestines; 
  • Volvulus: a segment of the intestine becomes twisted, blocking the bowel and/or its blood supply; 
  • Intussusception: one segment of the intestine telescopes into another part. This is most common in babies aged 10-15 months;  
  • Intestinal strictures: the bowel abnormally narrows following damage to it, commonly due to infection (such as diverticulitis) or inflammation (such as Crohn's disease or ulcerative colitis); 
  • Gallstones: in very rare cases a gallstone can block the small intestine, and;
  • Swallowing foreign objects (happens very rarely).

Different causes of bowel obstruction. 

Non-mechanical obstruction

In a healthy intestine, the intestinal muscles produce a rhythmic movement, known as peristalsis, that helps move the intestine's contents along (much like a wave, or like squeezing toothpaste from a tube). A non-mechanical obstruction, also known as paralytic ileus or pseudo-obstruction, is a condition in which peristalsis does not occur. The bowel is essentially paralysed. This is usually reversible. 

Common causes may include:

  • Appendicitis, or other intestinal infections such as gastroenteritis;
  • Mineral, chemical or electrolyte imbalances, such as low potassium levels;
  • A low supply of blood to your intestines (mesenteric ischaemia);
  • Certain medications, such as antidepressants and opioids;
  • Lung or kidney disease, and;
  • Ogilvie syndrome - a rare condition in which the large bowel suddenly distends (swells out). This typically occurs in critically ill individuals and/or in those who are chronically bedridden.

Caecum

A pouch at the beginning of the large intestine that receives digested food from the small intestine.

Electrolyte

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

Opioids

A class of drugs that contain opium, derivatives of opium, or have similar effects to opium. They are powerful painkillers that act on the central nervous system and cause drowsiness and include drugs such as morphine and pethidine.

Rectum

The final part of the large intestine, leading to the anus.

Sigmoid

The part of the large intestine before the rectum.

Risk factors

Risk factors for bowel obstruction include:

Abdomen

The part of the body that lies between the chest and the pelvis.

Signs and symptoms

With a bowel obstruction, the signs and symptoms are the result of the build-up of gases, liquids and faeces within the bowel. The type of pain and other symptoms experienced will depend greatly on the location of the blockage, but the following are common:

  • Abdominal pain and cramping that comes and goes;
  • Abdominal fullness and swelling (distension);
  • Inability to pass gas or have a bowel movement;
  • Constipation or diarrhoea;
  • Loss of appetite;
  • Nausea and vomiting, and;
  • Dehydration - a fast heart rate, low blood pressure and not passing much urine are all signs of dehydration.

A bowel obstruction can cause abdominal pain and cramping. 

Methods for diagnosis

Your doctor will usually perform a physical examination, feeling your abdomen for any lumps or areas of pain, and listening to your bowel sounds with a stethoscope.

Other tests may include:

Blood tests

Your doctor may want you to have blood tests done. These will likely include a full blood count and tests for inflammation, electrolyte levels and kidney function. 

Scans

X-ray

An abdominal X-ray is a simple, fast and very useful test used in the diagnosis of bowel obstruction. X-rays are taken while you are lying down and sitting or standing up. Observing the air and fluid patterns in your bowel can show the presence, type and location of the obstruction.

Computerised tomography (CT) scan

Computerised tomography (CT) scans send X-ray beams from multiple angles using a machine that circles your body. A CT of the abdomen can give a detailed picture of the type, location and cause of the bowel obstruction, and can help diagnose any complications.

Barium enema 

A barium enema is a bowel X-ray that uses a dye containing barium. A dye-filled tube is inserted through the anus, and releases the fluid into the colon. An X-ray is then taken of the bowel. This can help determine the presence and location of a large bowel obstruction. 

Colonoscopy

A colonoscopy can be used to examine the entire length of the large bowel. A colonoscope, which is a long tube with a camera at the end, is inserted into your bowel through the anus. Air is then pumped into the bowel to allow your doctor to see it properly. This is typically performed under light sedation (anasthaesia), so you remain relaxed and comfortable during the procedure. A colonoscopy may be useful in investigating certain large bowel obstructions, particularly where a volvulus is present.

A colonoscopy procedure can diagnose a bowel obstruction.The colonoscopy procedure. 

Abdomen

The part of the body that lies between the chest and the pelvis.

Electrolyte

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

X-ray

A scan that uses ionising radiation beams to create an image of the body’s internal structures.

Types of treatment

Bowel obstruction is a serious medical emergency that requires immediate attention. If it is not promptly treated, you can become severely dehydrated. The wall of the bowel is thin, and can burst (perforate) if the pressure inside the bowel builds up (see 'Potential complications' below).

Immediate treatment

Bowel obstructions should be managed in a hospital, where you can be closely monitored. Your doctor will likely stabilise your condition by giving you pain-relief medications, anti-nausea medications and fluids through a drip (intravenous). 

A thin tube, called a nasogastric tube, may be inserted into your stomach through the nose, to release any pressure that has built up in your stomach and to stop further vomiting and nausea. The tube is usually left in place to drain away excess fluid and gas, relieving pain, pressure and discomfort. Your will be advised to not eat any food until the condition resolves. Usually, intravenous fluid is enough to sustain your body for several days.   

Further treatment depends on the underlying cause of the obstruction:

Mechanical obstruction

Some types of mechanical obstruction, such as constipation and intestinal adhesions, can be successfully treated without surgery:

  • Constipation is usually managed with laxatives and stool softeners;
  • Occasionally, hard impacted faeces that cause the obstruction may need to be manually removed by a health professional, and;
  • Bowel obstructions due to intestinal adhesions may settle with a nasogastric tube and fasting. This can take up to a few days.

Most other types of mechanical obstruction may require one of the following procedures: 

Colonoscopy

Colonoscopy may be performed to untwist a volvulus and release the pressure on the affected bowel. If the volvulus is severe or too high up in the bowel, surgery will be required.

Surgery

Bowel resection surgery

Bowel resection is a type of surgery in which a part of your bowel is removed. You will be under general anaesthetic during the surgery, so will not feel any pain. Once the unhealthy part of your bowel is removed, your surgeon will either staple or sew the healthy parts together. 

Bowel diversion surgery

The colon is divided and rejoined on either side of the obstruction to create a 'bypass' around it. This technique is used in certain cases of bowel obstruction where the underlying cause cannot be surgically resected. The procedure is performed under general anaesthesia.

Another option is to divert the bowel to an artificial opening in the abdomen (a stoma). A bag is then attached to the stoma to collect the faeces. This may be a temporary or permanent solution, depending on the underlying cause. Your surgeon will discuss these options with you before your procedure. 

Stent

Stents are self-expanding mesh tubes made of metal or plastic that keep the bowel open. A stent can be inserted through an obstruction or narrowing inside the bowel using colonoscopy. Stents are typically used for cancers of the large bowel, where surgery may not help, or is too risky. 

Non-mechanical obstruction

Non-mechanical obstructions are generally managed by treating the underlying cause. Your doctor will generally admit you to hospital and keep you under observation. A nasogastric tube may be inserted to reduce fluid build-up and allow the bowel to rest. You may also receive fluids intravenously to prevent dehydration.

If normal bowel movements do not return, you may be given medications that cause muscle contractions. In addition, the underlying cause of the obstruction will need to be treated.

Abdomen

The part of the body that lies between the chest and the pelvis.

Potential complications

Bowel obstruction may be potentially fatal if the following complications occur:

  • Gangrene, due to the obstruction cutting off the blood supply to parts of the intestine;
  • Intestinal perforations: holes in the intestine wall, caused by gangrene or by pressure on the blocked bowel;
  • Infection in the abdominal cavity (peritonitis) - this occurs if the bowel bursts and releases faeces and bacteria into the abdominal cavity and into the blood. This is a life-threatening condition that requires immediate medical attention;
  • Lung or blood infections in new-born babies - an ileus can destroy parts of the intestine wall (necrotising enterocolitis), leading to blood or lung infections that can be fatal;
  • Electrolyte imbalance - a damaged or blocked intestine may not be able to excrete and absorb minerals and electrolytes. this disrupts the balance of these substances in the body, and;
  • Dehydration due to the inability to absorb fluids.

Electrolyte

Substances that form ions when dissolved in water. These include potassium and sodium minerals that are necessary for normal functioning of the body and all its cells.

Gangrene

The death of a mass of body tissue, usually resulting from obstructed blood supply or bacterial infection.

Prognosis

Non-cancerous bowel obstructions, in healthy individuals, tend to have a good outcome. However, untreated complications such as gangrene or perforations can lead to the need for longer-term management, or even death.

Certain causes of bowel obstruction can increase the risk of future obstruction episodes. Your doctor can discuss if this is a possibility for you, and the measures you can take to reduce your risk.

Gangrene

The death of a mass of body tissue, usually resulting from obstructed blood supply or bacterial infection.

Prevention

Prevention of intestinal obstruction will depend on the underlying cause. Some types of obstruction cannot be avoided.

You can lower your chances of constipation by drinking plenty of fluids, eating a healthy diet and exercising. Avoid developing a hernia by taking care when lifting heavy loads.

If you are suffering from a partial blockage, or are recovering from bowel surgery and are at risk of intestinal adhesions, your doctor may suggest that you take certain steps to ease your situation, such as eating smaller, more frequent meals, or avoiding certain foods (such as fatty or greasy foods, or foods that induce gas).

In some cases, your doctor may suggest that you eat a diet that is low in fibre and high in protein, to reduce the strain on your bowel and hasten healing. Since fibre is a necessary part of good nutrition, such a diet should only be followed if your doctor recommends it for your specific circumstances.