Obstruction of the bowel may be caused by ileus, in which the bowel doesn't function correctly but there is no "mechanical" (anatomic) problem, or by mechanical causes. Paralytic ileus, also called pseudo-obstruction, is one of the major causes of obstruction in infants and children.

The causes of paralytic ileus may include the following:

• Medications, especially narcotics
• Intraperitoneal infection
• Mesenteric ischemia (decreased blood supply to the support structures in the abdomen)
• Injury to the abdominal blood supply
• Complications of intra-abdominal surgery
• Kidney or thoracic disease
• Metabolic disturbances (such as decreased potassium levels)

Paralytic ileus may lead to complications causing jaundice and electrolyte imbalances. In the newborn, paralytic ileus that is associated with destruction of the bowel wall (necrotizing enterocolitis) is life-threatening and may lead to infecting the blood and lungs (pneumonia) in infants.

In older children, gastroenteritis may be a cause of paralytic ileus, which is sometimes associated with peritonitis and a ruptured appendix.

Paralytic ileus is marked by abdominal distention, absent bowel sounds (no noise heard when listening to abdomen) and relatively little pain (as compared to mechanical obstruction).

Mechanical obstruction occurs when movement of material through the intestines is physically blocked. The mechanical causes of obstruction are numerous and may include the following:

• Hernias
• Postoperative adhesions or scar tissue
• Impacted feces (stool)
• Gallstones
• Tumors blocking the intestines
• Granulomatous processes (abnormal tissue growth)
• Intussusception
• Volvulus (twisted intestine)
• Foreign bodies (ingested materials that obstruct the intestines)

• Abdominal fullness, gaseous
• Abdominal distention
• Abdominal pain and cramping
• Vomiting
• Failure to pass gas or stool (constipation)
• Diarrhea
• Breath odor

While listening to the abdomen with a stethoscope your health care provider may hear high-pitched bowel sounds at the onset of mechanical obstruction. If the obstruction has persisted for too long or the bowel has been significantly damaged, bowel sounds decrease, eventually becoming silent.

Early paralytic ileus is marked by decreased or absent bowel sound.

Tests that show obstruction include:

• Barium enema
• Abdominal CT scan
• Upper GI and small bowel series
• Abdominal film

• Infection
• Gangrene of the bowel
• Perforation (hole) in the intestine

Prevention depends on the cause. Treatment of conditions (such as tumors and hernias) that are related to obstruction may reduce the risk.

Some causes of obstruction are not preventable.