An ileus is a painful, temporary loss of the normal wavelike contractions in the bowel designed to propel food through the intestines. These normal contractions are called peristalsis, and your body controls them with complex interactions between intestinal muscles, hormones, nerve impulses and chemical signals released by the unique nerves of the intestine. Many conditions, both naturally occurring and resulting from medical treatment, can disrupt this delicate interplay.
Ileus Caused by Surgery
Surgery is arguably the most common cause of ileus. Postsurgical ileus generally lasts for 48 to 72 hours, but can be prolonged and last from three to five days. Interestingly, most surgery can cause an ileus, but surgery on the bowel itself has the most profound effect. Ileus after surgery results from inflammation and pain signals traveling from the intestine to the spine. Spinal anesthesia can blunt the disruption of intestinal function.
Painful Conditions Causing Ileus
Many painful conditions unrelated to surgery are associated with an ileus. These include pancreatitis, or inflammation of the pancreas gland; fractures of the vertebrae including compression fractures seen frequently in the elderly;and kidney stones. Fractured ribs and heart attacks can also cause an ileus. Pelvic fractures are a potential cause as well.
Illness Causing Ileus
Infections severe enough to cause a dangerous drop in blood pressure, pneumonia and lack of blood flow to the intestines are listed as causes of ileus. Lack of blood flow to the intestines can result from blocked blood vessels or a very distended intestine, as might happen in severe constipation. Appendicitis is a well-known cause of ileus, as are any conditions that dramatically alter the correct balance of potassium in the blood.
Medications Causing Ileus
Severe illeus can result from antipsychotics, medications taken by patients with a variety of mental illnesses. Tricyclics are an older type of antidepressant medication that can cause ileus, as can the most frequently implicated category, opiates. Opiates include narcotic pain medications used after surgery for the painful conditions listed above. Opiates cause increased tone of the intestinal muscle, and loss of the normal pattern of contraction and relaxation.
Rare Causes of Ileus
Dynamic ileus, as opposed to adynamic ileus discussed above, is a rare form of ileus characterized by extreme, prolonged contraction of the intestine. This has been seen in porphyria, a rare genetic blood disease; heavy metal poisoning; and extensive ulceration of the colon. Gallstone ileus is seen in older women when large gallstones erode from the gallbladder into the intestine and cause obstruction. Meconium illeus occurs in 20 percent of babies born with cystic fibrosis, and is a result of abnormally thick mucous blocking the intestine.