The surgery of ascariasis

Obstruction of the gut by Ascaris worms is the classical indication for non-operative treatment. Heavy infestations can obstruct a child's gut, partly or completely. The children of impoverished shanty-towns are most heavily infected, but in only a few of them is the infection so heavy that it obstructs their guts. The number of worms a child has is directly proportional to the number of ova he has swallowed. So the prevalence of Ascaris obstruction is a sensitive indicator of very poor hygienic conditions indeed. Sadly, the environment of many cities is deteriorating, and Ascaris obstruction is becoming more common.

A child between the ages of 2 and 14, or occasionally a young adult, usually has several mild attacks of central abdominal pain and vomiting, before his small gut finally obstructs. Often, he vomits worms, or they may come out of his nose, but this by itself is unimportant. If obstruction is partial, as it usually is when it is caused by a bolus of living worms, non-operative treatment commonly succeeds. Even if a solid mass of tightly-packed dead worms obstructs his gut completely, you can usually treat him nonoperatively.

Complete obstruction commonly follows an attempt to deworm a heavily infested child. It paralyses the worms, and so makes them even more likely to form a ball and obstruct his gut. So wait to deworm a child until his obstruction has passed. Don't operate if you can avoid it. If you have to operate, try not to open or resect gut. This is a particularly dirty and contaminating procedure in Ascaris obstruction, because an obstructed small gut contains bacteria that are normally only found in the large one. Instead, try to milk the worms through the small gut into the large one, whence they will be expelled naturally. The danger of opening the small gut or resecting it is that a fistula may follow[md]the patient with the fistula in Fig. 9-25 had his gut resected for Ascaris obstruction.

Ascaris worms occasionally obstruct a child's biliary tract and cause jaundice, or his appendix and cause appendicitis. Sometimes, they block drainage tubes. They can also penetrate a recent suture line, or the site of an injury, and cause peritonitis.

OBSTRUCTION DUE TO ASCARIS For the general method for gut obstruction see Sections 10.1 and 10.3.

HISTORY. Enquire for: (1) Recent attacks of colicky abdominal pain. (2) Vomiting worms, or passing them rectally or nasally.

EXAMINATION. The child is unwell and vomits. Distension is mild to moderate. There may be visible peristalsis. Feel for a mobile irregular mass in the centre of his abdomen, 5 to 10 cm in diameter, firm but not hard, and only moderately tender. This feels like a mass of worms, and he may have more than one mass. It may change in position and you may be able to feel the worms wriggling under your hand. If his abdomen is very distended the mass will be difficult to feel. Signs of peritoneal irritation are absent.

Examining stools for ova is of no help in a community where most children have worms.

X-RAYS show multiple fluid levels, and you may see the worms, as in Fig. 10-10. If you do see them, they are not necessarily the cause of his symptoms. Often, X-rays are not necessary, because you can make the diagnosis clinically.

THE DIFFERENTIAL DIAGNOSIS includes the other common causes of intestinal obstruction in childhood.

Suggesting intussusception[md]a more regular sausage-shaped mass, the passage of blood and mucus rectally, and tenderness which is more acute.

Suggesting an appendix abscess causing obstruction[md]the mass is not mobile, tenderness is more acute; a swinging temperature and toxaemia.

Suggesting an abdominal injury[md]tenderness and guarding are more prominent than the symptoms of obstruction and a mass; a bruise on the abdomen.

Suggesting congenital (Ladd's) bands[md]no characteristic mass, a very young child (28.3).

NON-OPERATIVE TREATMENT [s7]FOR ASCARIS OBSTRUCTION INDICATIONS. The child's general condition is good, his colic is intermittent, and his vomiting is mild. There are no signs of peritoneal irritation.

METHOD. Give him nothing by mouth. Continue nasogastric suction until his obstruction resolves, or you decide to operate (rare). Give him intravenous fluids, as in Section A 15.5.

CAUTION ! (1) Don't try to deworm a child with partial or complete obstruction. Wait until the obstruction has gone[md]see below. (2) Don't give him purgatives[md]they may precipitate intussusception or volvulus.

LAPAROTOMY [s7]FOR ASCARIS OBSTRUCTION INDICATIONS. A laparotomy is not often needed. The absolute indications for one are: (1) signs of perforation, which is usually caused by: (a) perforation of the gut by a worm (uncommon), or (b) by associated intussusception or volvulus (both uncommon). (2) Jaundice which you think might be caused by a worm in his bile duct.

The relative indications are less important, and are: (a) failure of the obstruction to resolve, (b) failure of the mass of worms to disappear.

INCISION. Make a right paramedian incision and inspect his gut. You will find a ball of worms blocking it.

If possible, try to break up the ball and milk the worms through to his caecum, where they will be safely expelled. If they are in his terminal ileum, this should be easy. If they are more proximal, try to milk them up into his stomach. This is less satisfactory, but it will relieve his obstruction.

If you cannot milk his worms upwards or downwards, and the wall of his gut is healthy, isolate the mass carefully with abdominal packs. Make a 2 cm longitudinal incision through the antemesenteric border of his healthy gut over the mass, and then remove the worms from the lumen with sponge forceps. Telescoping his gut over the forceps will help you to remove them proximally and distally.

Try to remove as many worms as you can by milking them down to and through the opening you have made. Most of them will probably be in his upper small gut. If you can remove most of them, there will be less chance of them working their way through the suture line later. If you have difficulty milking them out of his retroperitoneal duodenum[md]leave them. Close the enterotomy transversely in two layers, just as you would if you were doing a gut anastomosis (9.3). One contributor advises you to use non-absorbable sutures of silk, cotton, or nylon, on the grounds that the enzymes produced by the worms dissolve catgut, so that the wound is likely to fall open, leading to abscesses and fistulae. Make sure your nonabsorbable sutures are interrupted, so that they don't constrict his gut as he grows (9.3).

If the mass of worms has thinned, devitalized, or eroded his gut, resect it and do an end-to-end anastomosis (9-9 or 9-10). Some surgeons prefer this to an enterotomy, which is apt to be a septic process, even if the gut wall is healthy.

CAUTION ! If you have difficulty, don't be tempted to do an ileotransverse colostomy (9.6) above the level of the worms.

If you have done an enterotomy, his wound may become infected, so close his abdominal muscles as a single layer and leave his skin unsutured (9.8).

POSTOPERATIVE DEWORMING. Don't deworm him until 48 to 72 hours after all signs of obstruction have gone, and he has no palpable masses of worms. Then give him a single dose of piperazine citrate 4 g, which will paralyse his worms so that he passes them rectally. Or, give him mebendazole 100 mg twice daily for 3 days.