Ileus overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Ileus is a disruption of the normal propulsive gastrointestinal motor activity from non-mechanical mechanisms.[1][2] Motility disorders that result from structural abnormalities are termed mechanical bowel obstruction. Some mechanical obstructions are misnomers, such as gallstone ileus and meconium ileus, and are not true examples of ileus by the classic definition. [3]
Historical Perspective
The word ileus has been derived from the Greek word "είλειν" which means to twist. In 1958, Robertson, Eddy, and Vosseler were the first to describe a case of adynamic ileus associated with cecal perforation.
Classification
There is no specific system for classification of postoperative ileus. However, based on etiology, postoperative ileus may be classified into drug induced ileus, metabolic and electrolyte abnormalities induced ileum, and systemic disorder induced ileus.
Pathophysiology
Causes
Ileus can be caused by both mechanical obstructions and non-mechanical obstructions.
Differentiating Ileus overview from Other Diseases
Ileus must be differentiated from other diseases that cause abdominal pain, constipation, nausea and vomiting such as small bowel obstruction, gastric outlet obstruction, gastroparesis, gastrointestinal perforation, acute cholecystitis, acute pancreatitis, chronic pancreatitis, liver abscess and spontaneous bacterial peritonitis.
Epidemiology and Demographics
Ileus is most commonly seen in patients undergoing surgical treatment. The incidence and prevalence of ileus varies with the type of surgery performed. Patients with large incisions are relatively at a higher risk of developing ileus as compared to patients undergoing minor surgical procedures with small incisions. The incidence of ileus in patients undergoing laparotomy is approximately 9000 per 100,000 cases worldwide. The prevalence of ileus is not precisely known. However, it is estimated that that around 10 percent of the people undergoing surgical procedures develop ileus lasting more than three days. Patients of all age groups may develop ileus but more commonly seen in elderly due to underlying comorbidities. There is no racial predilection for ileus and both men and women are affected equally.
Risk Factors
Common risk factors in the development of iuleus include increasing age, electrolyte abnormalities , previous history of abdominal surgery, prolonged abdominal or pelvic surgery (laprotomy of lower GI procedures), delayed enteral nutrition, use of preoperative albumin, postoperative deep venous thrombosis, and hypothyroidism. Less common risk factors include spinal cord injury (thoracic cord), obesity, and peripheral vascular disease.
Screening
There is insufficient evidence to recommend routine screening for ileus.
Natural History, Complications, and Prognosis
If left untreated, patients with ileus may progress to develop abdominal pain, abdominal distention, nausea and vomiting with postprandial discomfort. Common complication of ileus include electrolyte imbalance, malabsorption, dehydration, intestinal perforation, ascites, sepsis, jaundice, and pulmonary complications. Depending on the duration of the postoperative ileus at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as good. Most cases of postoperative ileus resolve spontaneously and do not require any further treatment.
Diagnosis
Diagnostic Study of Choice
History and Symptoms
Obtaining a history gives important information in making a diagnosis of ileus. The areas of focus should be on onset, duration, and progression of symptoms with special focus on past medical history and current medications. Previous history of hypothyroidism, diabetes and renal failure can hasten the onset of ileus. Common symptoms of ileus include postprandial abdominal discomfort, abdominal distension, nausea and vomiting, feeding intolerance, constipation, flatulence, and belching. Less common symptoms include wound dehiscence and impaired wound healing.
Physical Examination
Physical examination of patients with ileus is usually remarkable for abdominal distension, abdominal tenderness, and minimal or absent bowel sounds. Patients with prolonged ileus may progress to develop peritoneal signs such as rigidity, guarding and rebound tenderness.
Laboratory Findings
There are no diagnostic laboratory findings associated with ileus. However, laboratory evaluations must be done to identify the severity and presence of other complications of ileus such as electrolyte abnormalities and hypovolemia. Common laboratory test include complete blood count, liver function test, renal function test, serum electrolytes, serum lipase and amylase, serum albumin, and measurement of inflammatory markers.
X-ray
An abdominal x-ray with barium meal (small bowel series) may be helpful in the diagnosis of ileus. Findings on an x-ray suggestive of ileus include multiple air–fluid levels throughout the abdomen, elevated diaphragm with dilatation of both large and small intestine, slow movement of barium with a patent intestinal lumen. Serial X rays may also differentiate paralytic ileus from mechanical small intestinal obstruction.
CT
An abdominal and pelvic CT scan is used to confirm the diagnosis of postoperative ileus only in cases when x ray is not diagnostic. Abdomen and pelvis CT scan (with intravenous contrast and oral water soluble contrast) can also distinguish early postoperative ileus from mechanical obstruction. Findings on CT scan diagnostic of postoperative ileus include multiple air–fluid levels throughout the abdomen, elevated diaphragm, dilatation of both large and small intestine with no evidence of mechanical obstruction.
MRI
There are no MRI findings associated with ileus.
Ultrasound
There are no specific ultrasound findings associated with ileus. However, patients with ileus for more than seven days (prolonged ileus) may be evaluated with an abdomen and pelvic ultrasound to determine the underlying cause. Prolonged ileus is generally due to mechanical obstruction and an ultrasound can be done to determine the etiology.
Other Imaging Findings
There are no other imaging findings associated with ileus.
Other Diagnostic Studies
Other diagnostic studies for ileus include enteroclysis. Enteroclysis is done when abdominal x ray and CT scan are inconclusive but patient is still suspected of underlying ileus. In enteroclysis, water-soluble radio-opaque contrast material such as Gastrografin is used to observe the movements of intestine. Enteroclysis can also help in differentiating ileus from small bowel obstruction.
Treatment
Medical Therapy
The majority of cases of ileus are resolved with correction of underlying electrolyte disorder and only require supportive care. Intravenous hydration is advised with appropriate rapid supplementation for electrolyte abnormalities. NSAID are used as baseline analgesic medications and opiates are used in case of severe intractable pain. Patients are put on NPO and nasogastric tube to relieve recurrent vomiting or abdominal distention associated with pain. Prokinetic agents such as erythromycin are not routinely recommended.
Surgery
Surgery may be needed to relieve the obstruction if the tube does not relieve the symptoms, or if there are signs of tissue death.
Prevention
Prevention depends on the cause. Treating conditions, such as tumors and hernias, that can lead to obstruction may reduce your risk of getting an obstruction. Some causes of obstruction cannot be prevented.
References
- ↑ Townsend CM, Beauchamp RD, Evers BM, Mattox KL. Sabiston Textbook of Surgery. The biological basis of modern surgical practice. 17/e. Elsevier Saunders, 2004.
- ↑ Livingston EH, Passaro EP. Postoperative ileus. Dig Dis Sci 1990;35:121.
- ↑ Feldman M, Friedman LS, Brandt LJ, Sleisenger MH. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. Intestinal Obstruction and Ileus. 8/e. Elsevier Saunders, 2006.