Large Bowel Obstruction

General Considerations

• In this case, we are talking about mechanical obstruction of the colon
• Causes include
• Carcinoma (60%)
• Diverticulitis (20%)
• Volvulus
• Strictures, such as from Crohn disease
• Fecal impaction
• Hernia
• Imperforate anus or meconium ileus in pediatric population
• Increases in prevalence with age

Clinical Findings

• Abdominal distension
• Nausea and vomiting
• Crampy abdominal pain
• Constipation, diarrhea, change in bowel habits

Imaging Findings

• Air in dilated colon, usually to the point of obstruction
• Dilated cecum
• Small bowel is not dilated unless ileo-cecal valve becomes incompetent and air flows backwards from colon to small bowel
• CT is imaging study of choice

Differential Diagnosis

• Generalized ileus – air in dilated large and small bowel down to and including rectosigmoid
• Ogilvie Syndrome (pseudo-obstruction) – absent or reduced bowel sounds, usually associated with other co-morbidities

 
Large Bowel Obstruction. The ascending, transverse and proximal descending colon (black arrows) are all dilated. There is an abrupt cut-ff of the air column in the distal descending colon (red arrow). This was the site of a colonic carcinoma, which was removed..