Pseudo-Obstruction

Definition:
Intestinal pseudoobstruction involves a functional, but not a real blockage the bowel that results in the failure of the intestinal contents to pass through.  This may be neuropathic (an absence of the nerves normally present in the bowel wall that stimulate the muscle to contract and propel food and nutrients) or caused by disordered smooth muscle (the type of muscle found in the small intestine) so that it does not contract normally.

Alternative Names:
Ileus (this is only a temporary condition usually related to a disease state, infection, or electrolyte imbalance)

Causes, incidence, and risk factors:
Pseudoobstruction of the bowel may be caused by  a congenital problem such as being born without the myenteric plexus (a web of nerves that acts as the intestine’s own brain and causes the muscle surrounding the bowel  to contract and propel food independently from the brain) or a problem with the muscle that surrounds the bowel that causes it to contract ineffectively.  These may be “aquired” conditions that develop later in life as well.  Pseudoostruction may involve the esophagus, stomach, small, and/or large intestine (colon).  Secondary causes of pseudoostrcution include:

• Medications, especially narcotics and some chemotherapy agents 9used for cancer treatment)
• Connective tissue diseases such as scleroderma
• Infections
• Mesenteric ischemia (decreased blood supply to the support structures in the abdomen)
• Neurological conditions such as stroke, Parkinson’s disease)
• Complications of intra-abdominal surgery
• Hypothyroidism
• Congestive heart failure
• Metabolic disturbances (such as decreased potassium levels)

Pseudoobstruction is marked by nausea, vomiting, abdominal distention, absent bowel sounds (no noise heard when listening to abdomen) and abdominal pain (caused by the distention of the bowel).
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 or strictures from tumors, radiation, or Crohn’s disease
• Impacted feces (stool)
• Gallstones
• Tumors blocking the intestines
• Intussusception (when one loop of intestine moves within another loop and gets stuck)
• Volvulus (twisted intestine)
• Foreign bodies (ingested materials that obstruct the intestines)

Bacterial overgrowth may occur as a complication of pseudoobstrction because the way in which the body normally moves bacteria through the intestine and gets rid of them is just like the process for moving food.
Treatment