Aira Hospital

A special type of small bowel obstruction peculiar to the third world - where worm infestation is common - is caused by impaction of dead ascaris worms. As long as the worms are alive there is no danger, but when all worms die at once they tangle up and impacts causing complete obstruction.

This happens usually after a full dose of antihelmintic  (worm killer) such as Mebendazole. That is why only half a dose - repeated after a week - is recommended when you suspected massive worm infestation in a patient.

Often the diagnosis is suspected clinically. In children you can often feel the impacted worms as a movable sausage like tumor, and the differential diagnosis is then intussusceptio (see page INTUSSUSCEPTIO). You can reach a definitive conclusion with ultrasound scanning where the worms inside the intestine usually are easily identified. Usually it is sufficient to ask if the patient had a full dose of worm medicine before. If the answer is yes, it is almost sure that you are dealing with bowel obstruction due to an ascaris impaction. Anyway both conditions need laparotomy.

If you can milk the worms distally into the large intestine the problem is solved. The dead worms are expelled the natural way with the peristalsis of the colon. The lumen of the large bowel is too wide to be occluded by the impacted worms.

Ascaris Impaction - Milking ← click for video

Otherwise you have to remove the dead worms by an enterotomy. The inflicted part of the small intestine is isolated between soft clamps and the worms removed via a transverse enterotomy.

 

Ascaris Impaction - Enterotomy ← click for video