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Adynamic Ileus

What Is It, Symptoms, Treatment, and More

Author: Nikol Natalia Armata

Editors: Ahaana Singh, Ian Mannarino, MD, MBA

Illustrator: Jillian Dunbar


What is adynamic ileus?

Adynamic ileus, also known as paralytic ileus, is when food or drink does not pass through the bowel (i.e., intestines). In order to move food or drink through the digestive tract, the smooth muscle of the intestine moves in a series of waves, called peristalsis. Loss or reduction of these peristaltic movements can lead to adynamic ileus and a consequent buildup of stomach contents in the intestine

Is an adynamic ileus an emergency?

In most cases, adynamic ileus is not considered an emergency if treated appropriately. Regardless, medical attention is highly recommended in order to avoid further complications. If left untreated, adynamic ileus could possibly lead to extended bowel dilation, known as toxic megacolon, which is considered a medical emergency. This condition could potentially be fatal, as it can cause a rupture of the intestine.

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What causes adynamic ileus?

The most common cause of adynamic ileus is abdominal or pelvic surgery, which can activate a stress response that can immobilize the digestive tract. As a result, the bowel typically takes about 24 to 72 hours after surgery to resume its normal function, though certain factors—such as longer surgical operation time and open surgical procedures—can increase the duration of the ileus. Another frequent cause of adynamic ileus is infection or inflammation of various parts of the digestive tract, like the stomach or intestines (i.e., gastroenteritis), pouches in the intestine (i.e., diverticulitis), the pancreas (i.e., pancreatitis), or the peritoneum, which is the inner membrane that covers the abdominal organs and cavity (i.e., peritonitis).

A variety of other factors may also lead to ileus, such as electrolyte imbalances, vascular or neural impairment, or use of certain medications. 

Is there a difference between an ileus and a bowel obstruction?

Ileus is a specific type of bowel obstruction, or interruption in the normal flow of contents through the intestine. The causes of bowel obstruction can either be mechanical or functional. If the underlying cause is functional, meaning the bowels are obstructed because peristalsis has stopped or slowed, the obstruction is known as an ileus.

Meanwhile, a mechanical obstruction is caused by a physical blockage in the small or large intestine. Mechanical obstructions are often complete blockages, and they are typically the result of conditions that cause sliding (intussusception) or twisting (volvulus) of the intestines onto itself, ultimately cutting off blood vessels and causing tissue death. Other physical blockages in the digestive tract can include masses -- such as tumors, hernias, or gallstones -- as well as adhesions that can form while healing from surgery.

What are the signs and symptoms of adynamic ileus?

Individuals with adynamic ileus may have different clinical presentations depending on the underlying cause and how long the bowel has been obstructed. Often, individuals with adynamic ileus appear asymptomatic or present with vague clinical features, like abdominal discomfort, bloating, constipation, nausea, and vomiting. In some cases, continuous and persistent abdominal pain may also occur. Abdominal tenderness is usually due to peritoneal irritation, or inflammation of the membrane covering the abdominal wall and organs. Another, though uncommon, symptom is fecal vomiting. Fecal vomiting involves reverse peristalsis, in which the contents of the digestive tract flow upwards from the intestine to the stomach as a result of increased pressure built up in the bowel

How do you diagnose adynamic ileus?

To diagnose adynamic ileus, a detailed review of medical history and physical examination are necessary. Assessment of the abdomen can reveal reduced or absent bowel sounds, suggesting adynamic ileus. When physical examination cannot clarify the diagnosis, blood tests may be performed to examine electrolyte levels. In addition, imaging studies -- such as X-Rays, computerized tomography (CT) scans, or abdominal ultrasounds -- may be helpful in determining the underlying cause of the ileus. 

How do you treat adynamic ileus?

The treatment of adynamic ileus is mostly conservative and focuses on relieving the present symptoms. However, if the discomfort is persistent, more aggressive treatment may be appropriate to avoid further complications. Additionally, diagnosing and treating the underlying cause can potentially minimize the duration of an ileus. 

Bowel rest, through restriction of food consumption, and intravenous (IV) fluid therapy is often suggested for individuals with ileus. If the individual is unable to eat food or drink liquids for over 7 days, total parenteral nutrition (TPN), which is  a feeding method that bypasses the gastrointestinal tract, may be necessary. Severe or prolonged ileus with continuous vomiting often requires insertion of a tube extending from the nose to the stomach (i.e., nasogastric tube) in order to remove gastrointestinal contents and thus relieve pressure. 

If symptoms do not improve or there are complications, such as rupture of the bowel, surgery might be required.

What are the most important facts to know about adynamic ileus?

Adynamic ileus, also known as paralytic ileus, is when food or drink does not pass through the bowel due to loss or reduction of the bowel’s peristaltic movement. The causes of ileus vary and include abdominal surgery or inflammation, as well as systemic conditions like electrolyte imbalance, use of certain medications, or vascular and neural impairment. Abdominal pain, bloating, nausea, and vomiting are common clinical features of individuals with adynamic ileus. Reduced or absent bowel sounds and a distended abdomen are features that can be observed through physical examination. When diagnosis is uncertain, blood tests and imaging studies are suggested. The treatment of adynamic ileus is rather conservative, focusing on restricted food and drink consumption and treatment of the underlying causes. In rare instances, surgery may be required. 

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Related links

Bowel obstruction
Bowel obstruction: Clinical practice
Postoperative evaluation
Gastrointestinal system anatomy and physiology
Small bowel ischemia and infarction

Resources for research and reference

Beach, E., & De Jesus, O. (2020). Ileus. In StatPearls [Internet]. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK558937/ 

Carreiro, F., Coelho, S., Horta, A., & Sá, J. (2015). Adynamic ileus and diarrhoea: A rare adverse effect of antidepressants. BMJ Case Reports, 2015(bcr2014208095). DOI: 10.1136/bcr-2014-208095

Desai, J., Elnaggar, M., Hanfy, A., & Doshi, R. (2020). Toxic megacolon: Background, pathophysiology, management challenges and solutions. Clinical and Experimental Gastroenterology, 13: 203-210. DOI: 10.2147/CEG.S200760

Doherty, G. (2020). CURRENT diagnosis & treatment: Surgery (15th ed.). McGraw Hill.

Knipe, H. (n.d.). Adynamic ileus. In Radiopaedia. Retrieved November 29, 2020, from https://radiopaedia.org/articles/adynamic-ileus 

McLatchie, G., Borley, N., & Chikwe, J. (2013). Oxford handbook of clinical surgery (4th ed.). Oxford: Oxford University Press.

Ochsner, A., & Gage, I. (1933). Adynamic ileus. The American Journal of Surgery, 20(2): 378-404. DOI: 10.1016/s0002-9610(33)90738-2

Smith, D., Kashyap, S., & Nehring, S. (2020). Bowel obstruction. In StatPearls [Internet]. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK441975/