Adynamic ileus is the failure of passage of enteric contents through small bowel and colon that is not mechanically obstructed. Essentially it represents the paralysis of intestinal motility.
Patients may be asymptomatic or present with symptoms similar to a mechanical bowel obstruction such as nausea/vomiting, distension and reduced or absent bowel movements. Bowel sounds may also be absent.
Adynamic ileus can be caused by a number of conditions:
- drugs: e.g. opioids
- metabolic: e.g. hyponatremia
- sepsis: especially gram-negative bacteria
- abdominal trauma or surgery (see below)
- myocardial infarction / congestive heart failure
- head injury or neurosurgery
- intra-abdominal inflammation and peritonitis
- retroperitoneal haematoma
The cause of ileus is thought to be complex and multifactorial, involving bowel inflammation 6, inhibitory neural reflexes 7, and neurohormonal peptides 8.
Postoperative ileus vs. paralytic ileus
Some degree of ileus is a normal and expected finding after abdominal surgery. Conventional recovery times have been reported at 4:
- small intestine: 0-24 hours
- stomach: 24-48 hours
- colon: 48-72 hours
These times however may be overestimates 5.
Prolonged postoperative ileus (>72 hours) has been termed "paralytic" ileus by some and is concerning for small bowel obstruction, bowel perforation, peritonitis and intra-abdominal abscess.
Improving postoperative ileus is often determined as much clinically as radiographically, with resumption of oral intake and flatus.
- generalised, uniform, gaseous distension of the large and small bowel
- involvement of large bowel and lack of a transition point help distinguish it from small bowel obstruction
- when localised, there may be a sentinel loop
History and etymology
"Ileus" ultimately derives from είλειν ("to twist"), which also gave rise to the section of the bowel termed the "ileum". At one time what we now call ileus had been called the "iliack passion" because it was believed that the intestines were twisted 3.
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