An obstruction within the large intestine could stem from within the cecum, colon (ascending, transverse, descending, sigmoid) or rectum. The blockage may be partial or complete, and like small intestinal obstruction, it should be treated as a medical emergency. Most of the causes of a large intestine obstruction are mechanical in nature.
Signs and Symptoms of a Blocked Large Intestine
The main clinical features include :
- Constipation, known as obstipation when severe constipation is due to bowel obstruction.
- Abdominal distention and bloating
- Abdominal pain (cramps)
- Failure to pass stool or gas indicates complete obstruction or diminished passage of stool and gas indicates partial obstruction. A change in the size and form of the stool may also be noticed.
Additional signs and symptoms include :
- Nausea and vomiting may arise as the condition progresses resulting in backed up contents as far as the small intestine (refer to Blocked Bowel)
- Diarrhea in a partial obstruction
- Melena or hematochezia may be noticed when passing some stool in a partial obstruction
- Increased bowel sounds (borborygmi) which may be followed by diminished sounds as the condition progresses
Causes of Large Intestine Obstruction
Many of the causes of small intestine obstruction may also affect the large intestine. This includes :
Portion of the colon is trapped within an outpouching (incarcerated hernia).
This is the collapsing of one part of the colon into a the adjacent distal portion in a telescopic manner. Intussusception is more likely to be seen in newborns and young infants.
Twisting of the large intestine resulting in strictures. It may also trap a portion of the small intestine in the twist. It is more likely to affect the cecum or sigmoid colon.
Tumors and polyps
In most cases, a mass is asymptomatic unless it grows to a degree that significantly occludes the lumen. In malignancies (colon or colorectal cancer), diarrhea and constipation may be more noticeable along with hematochezia (fresh blood in the stool).
Inflammatory bowel disease
Chronic inflammation of the colon results in hypertrophy and subsequent fibrosis of the colonic wall. This may be seen in both Crohn’s disease or ulcerative colitis and the latter may be associated with polyposis syndromes.
This is the inflammation of small pouches that arise in the colon known as diverticula. Persistent inflammation or even an infection can lead to the formation of scar tissue which may result in a partial obstruction.
The collection of a large, hard mass of stool in the rectum. This tends to occur in the frail or elderly, after the use of drugs that cause severe constipation, neurological disorders that affect involuntary defecation, and any condition that contributes towards painful defecation thereby causing the person to avoid defecating.
Acute colonic pseudo-obstruction
Also known as Ogilvie’s syndrome, it is the sudden painless distention of the proximal parts of the colon. Acute colonic pseudo-obstruction tends to arise in the following situations :
- Recent surgery
- Diabetes mellitus
- Certain drugs
- Severe dehydration
This is a congenital defect where the ganglion cells of a segment of the colon is missing or dysfunctional. It can result in an enlargement (dilatation) of the colon (megacolon) with no reflex contraction and colonic motility is disrupted. Fecal matter can collect in this area thereby resulting in an obstruction.
Ischemic Bowel Disease
While this is a complication of strangulating obstructions like a volvulus, any other cause of bowel ischemia or infarction may also contribute to an obstruction as a result of edema, disturbed motility or strictures.
Other causes :
- Gallstone ileus
- Foreign bodies
- Large tumor outside of the colon