AGANGLIONIC MEGACOLON - HIRSCHPRUNG’S DISEASE
Aganglionic Megacolon - Hirschprung’s disease - is due to lack of peristaltic movements in some part of the gastrointestinal canal caused by congenital lack of nervous components (ganglions). The segments involved are in the vast majority the lower part of colon and rectum, but in principle any part of the gastrointestinal canal can be affected.
The absence of peristalsis causes retention of stool and dilatation proximal to the aganglionic segment (the affected segment). The disease is in other words localized to the contracted part of the bowel– not the dilated.
The diagnosis is usually easy on the history and the clinical picture: the somewhat malnourished child is passing stool only once or twice a week, the abdomen is distended and a finger in the rectum confirms the condition by a tight grip by the contracted anus. Gas and loose stool escapes from the rectum at removal of the exploring finger.
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The abdomen is most often grossly distended when the child is brought to the hospital and a decompressive colostomy has to be done as a first stage.
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When the abdomen is no longer grossly distended and the general condition has improved the second stage is performed – usually 6 weeks to 3 months after the colostomy is done.
The patient is positioned on the operating table in such a way that unhindered access to the anus is secured.
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Through a generous midline incision the contracted and dilated segments are identified and by mainly blunt dissection the distal part of the rectum is mobilized deep in the pelvis until the perineum is reached. Then the contracted segment is resected.
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The anus and distal part of rectum is inverted with a forceps through the anal orificium. The proximal colon is brought through an anterior incision in the inverted anus and secured before the redundant parts of the anus and colon are excised.
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Then a colo-anal anastomosis in two layers is done exteriorly
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After finishing the anastomosis the anus is returned back into where it belongs, and the colostomy is closured.
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