Intestinal pseudo-obstruction (paralytic ileus)

An intestinal pseudo-obstruction, or pseudo-obstruction for short, describes a type of muscle paralysis that can occur in the intestines (gut). As a result, ingested food cannot make its way through the gut as normal and becomes blocked there, meaning that the bowel cannot be emptied.

Normally, the peristaltic motion (i.e. coordinated contraction and relaxation) of the muscles in the gut ensures that ingested food is pushed forward through the gut as it is digested, until it reaches the rectum as waste to be expelled from the body. However, if a pseudo-obstruction occurs, these movements are weakened or lose their coordination to such an extent that this normal motion is no longer possible.

Chyme (a mixture of gastric juices and partially digested food), gases and fluid build up in the gut, causing the wall of the gut to become increasingly stretched. The gut may become severely distended (bloated) as a result. If the blockage is not treated promptly, there is a risk that the gut wall could be damaged or that necrosis (tissue death) could even occur in some sections of the gut.

The symptoms of a pseudo-obstruction often develop slowly over several days. The first symptom is mild abdominal pain, followed by increasing bloating of the abdomen. Typically, the abdominal pains do not diminish over time.

Other symptoms of a pseudo-obstruction are:

• nausea
• vomiting
• constipation
• trapped wind – air and gases cannot be expelled from the body

A pseudo-obstruction occurs when the functioning of the nerves or muscles in the wall of the gut is impaired. It is usually caused by another disease or disorder. However, it is not yet fully understood what exactly causes the muscle paralysis to occur.

Possible triggers include:

• surgery, particularly in the abdomen
• severe injury, e.g. of the pelvis or spine
• cancer
• nervous system disorders, such as Parkinson’s disease, Alzheimer’s disease or multiple sclerosis
• metabolic disorders caused by liver or kidney diseases, diabetes mellitus or excessive alcohol consumption
• a deficiency of minerals, such as potassium, calcium or magnesium
• circulatory disorders of the intestines
• certain medication, including strong painkillers (opioids), drugs used to treat depression or anesthetics

Following some surgical procedures in the area of the abdomen, pelvis or gastrointestinal tract, the normal passage of the products of digestion through the intestines may become obstructed for longer than usual, even though no mechanical blockage is present.

Other factors that increase the risk of a pseudo-obstruction are as follows:

• prolonged surgery
• complications following surgery
• the use of certain pain medication during surgery
• delayed ingestion of food or artificial feeding with a feeding tube after surgery
• inflammation in the abdominal cavity

Temporary pseudo-obstruction is a fairly common condition. Following abdominal surgery, around 10 percent to 30 percent of people experience temporary interruption of the normal functioning of the muscles in their gut.

The small intestine normally becomes active again a couple of hours after surgery. The large intestine, meanwhile, takes 2 to 3 days to resume normal functioning.

If the pseudo-obstruction persists for more than 3 to 5 days, this is known as prolonged ileus. In this case, the patient will suffer symptoms as a result. Supportive treatment helps to restore normal intestinal function.

Can complications arise?

Complications may arise if the gut becomes severely distended (bloated) due to an accumulation of ingested food and gases or because the pseudo-obstruction has lasted for more than 6 days.

Possible consequences include peritonitis (inflammation of the lining of the abdomen), impaired blood flow to the gut or necrosis (tissue death) of some sections of the gut.

There are various steps that can be taken to avoid a pseudo-obstruction following surgery. Getting up and moving about and eating shortly after surgery help to stimulate normal muscle activity in the intestines. Chewing gum may also help.

The doctor will discuss the patient’s symptoms with them and conduct a physical examination. A distended abdomen, constipation and a lack of intestinal noises are indicators of a pseudo-obstruction.

The doctor will also take an x-ray of the patient’s abdomen. The dilated bowel loops can be easily identified on an x-ray.

A computed tomography (CT) and magnetic resonance imaging (MRI) scan may also be used to exclude a mechanical blockage as the cause of the intestinal obstruction.

Blood tests are also performed to identify possible causes for the pseudo-obstruction. Doctors check the patient’s blood values for signs of impaired blood flow or inflammation.

If the pseudo-obstruction is caused by a medical condition, doctors will treat that condition first, if possible.

In the first 1 to 2 days after a pseudo-obstruction develops, the most important treatment is to empty the bowel. The following measures are normally used for this purpose:

• Patients are initially required to stop eating and drinking.
• Intravenous fluids are used to keep them hydrated.
• A nasogastric tube may be used to drain the blocked contents of the stomach and intestines.
• An enema administered via the rectum helps to empty the bowel.
• Walking around and changing body position regularly can help the intestinal muscles to get moving again.

If these measures are unsuccessful, medication may also be used to stimulate intestinal motion. The active agent neostigmine is often used, although its efficacy is limited. Possible side effects include a drop in blood pressure and tremors.

If medication is unsuccessful or cannot be used due to its side effects, doctors may use a colonoscopy to drain the intestinal contents using a special tube inserted into the colon through the anus.

Surgical intervention is rarely necessary. However, an operation is sometimes necessary, e.g. if there is a risk of intestinal bleeding.