Ileus (Paralytic Ileus)

What ileus is

Normally, waves of muscle contraction called peristalsis move food and fluid through about 6 meters (20 feet) of small intestine and the colon. These waves are controlled by nerves in the gut wall, the nervous system and hormones. In ileus the waves weaken or stop. Gas and fluid collect in the stalled bowel, which swells and causes pain, nausea and vomiting.

"Ileus" and "paralytic ileus" are used for the same thing. The key point is that the problem is functional: the pipe is open, but the pump is not working. When ileus mainly affects the large bowel, it is called acute colonic pseudo-obstruction or Ogilvie syndrome.

Signs and symptoms of ileus

• a swollen, bloated abdomen (abdominal distention)
• not passing gas or stool, or passing very little
• nausea and vomiting, sometimes of large volumes
• a dull, diffuse ache or cramping, usually milder than in a mechanical blockage
• loss of appetite and a feeling of fullness
• quiet or absent bowel sounds when a doctor listens with a stethoscope

Signs that may point to a complication include fever, a fast heart rate, severe localized tenderness and a rigid belly.

Causes and risk factors

After surgery

Postoperative ileus is the most common type. Handling the bowel during surgery, inflammation, stress hormones and pain medicines all slow the gut. After abdominal surgery, the small bowel usually recovers within about a day, the stomach within 1 to 2 days and the colon within 2 to 3 days. Ileus that lasts longer than this is called prolonged postoperative ileus.

Medicines

• Opioids such as morphine, oxycodone and hydromorphone are a leading cause.
• Anticholinergic medicines, some antidepressants and antipsychotics, and calcium channel blockers.

Electrolyte and metabolic problems

• low potassium (hypokalemia), low magnesium, low or high calcium and low sodium
• uncontrolled diabetes and diabetic ketoacidosis
• an underactive thyroid

Inflammation or infection in the abdomen

• peritonitis, appendicitis and diverticulitis
• pancreatitis
• bleeding behind the abdominal lining, for example from a spinal or pelvic fracture

Other illnesses

• sepsis and serious infections such as pneumonia
• heart attack, heart failure and stroke
• kidney stones and kidney failure
• spinal cord injury
• severe illness requiring intensive care

Ileus vs bowel obstruction

Ileus and a mechanical bowel obstruction cause similar symptoms, but obstruction is caused by something physically blocking the bowel, such as adhesions (scar tissue from previous surgery), a hernia, a tumor or a twisted bowel. Telling them apart matters because obstruction can need surgery.

Diagnosis

The doctor will ask about recent surgery, medicines, other illnesses and when you last passed gas or stool. They examine the abdomen for swelling, tenderness and bowel sounds, and check hernia sites.

Tests often include:

• blood tests: electrolytes (especially potassium and magnesium), kidney function, blood count, inflammation markers and lactate
• abdominal X-ray: shows swollen loops of bowel with gas throughout
• CT scan: the most useful test to rule out a mechanical blockage and look for causes such as an abscess or pancreatitis

Treatment

Most people recover with supportive care while the cause is treated:

• Bowel rest: little or nothing by mouth until the bowel wakes up.
• Intravenous fluids to prevent dehydration.
• Correcting electrolytes, especially potassium and magnesium.
• Reducing opioids: using other pain relievers such as acetaminophen (paracetamol) where possible. Medicines that block opioid effects on the gut, such as alvimopan or methylnaltrexone, may be used in some settings.
• Nasogastric tube: a thin tube through the nose into the stomach to drain fluid and gas, used if vomiting is persistent or the belly is very swollen.
• Walking: early mobilization after surgery is encouraged.
• Treating the cause: antibiotics for infection, managing pancreatitis or controlling blood sugar.

For Ogilvie syndrome with a very swollen colon, doctors may use the medicine neostigmine or a colonoscopy to remove gas. Surgery is needed only if the bowel is at risk of bursting.

Prevention after surgery

Enhanced recovery programs reduce postoperative ileus with:

• keyhole (laparoscopic) surgery where possible
• limiting opioids
• avoiding excess IV fluid
• early eating and drinking
• getting out of bed on the day of or the day after surgery
• chewing gum, which can stimulate the bowel

Complications

If ileus lasts a long time, complications can include dehydration and kidney injury, electrolyte imbalance, malnutrition, aspiration pneumonia from vomiting, and, rarely, bowel perforation when the colon is very distended.

Outlook

Most postoperative and medicine-related ileus resolves within a few days with supportive care. The return of passing gas and bowel sounds signals recovery, and eating is then restarted gradually. Ileus caused by a serious underlying illness improves as that illness is treated.

Frequently asked questions

What are the signs of ileus?

The main signs are a swollen, bloated belly, nausea and vomiting, not passing gas or stool, and a dull ache. Doctors also notice quiet or absent bowel sounds. Fever, severe pain or a rigid belly suggest a complication and need urgent care.

How long does ileus last after surgery?

Normal gut function usually returns within 2 to 3 days after abdominal surgery. Ileus that lasts beyond about 4 days is considered prolonged and may need more investigation. Walking, limiting opioids and early eating help recovery.

Is ileus the same as a bowel obstruction?

No. In ileus the bowel muscles stop moving contents along, but nothing physically blocks the bowel. In a mechanical obstruction, scar tissue, a hernia, a tumor or twisting blocks the bowel. A CT scan helps tell them apart.

Can opioid painkillers cause ileus?

Yes. Opioids slow the muscle movement of the gut and are a common cause of ileus, especially after surgery. Doctors limit their use and add other pain relievers. Anyone on long-term opioids should ask about preventing constipation.

Can ileus be treated at home?

Generally no. Ileus usually needs hospital care for IV fluids, blood tests and monitoring to make sure it is not a mechanical blockage. Mild slowing of the bowels with constipation can be managed at home, but bloating with vomiting and no gas needs assessment.