The variety of intestinal ‘foreign bodies’ is enormous and is limited only by the imagination and appetites of patients. Although ingestion of foreign bodies is common, the symptoms from ingestion are not: the diagnosis is only made by history, if available, or following the appearance of a complication. The definition of foreign body is problematic, as certain ‘foreign bodies’ such as a food bolus, or phytobezoar would be considered food, whereas other ‘foreign bodies’ such as enteroliths and gallstones originate within the digestive system of the host (Table 1) 324. However, all these are included as foreign bodies by virtue of the complications that may arise from their presence in the gut lumen.

The complications of small intestinal foreign bodies requiring surgical treatment include obstruction, perforation, and bleeding. In the absence of a history of unusual ingestion or of the finding of a radio-opaque foreign body, the specific cause is rarely identified preoperatively. The clinical presentation and the indications for surgery in patients with complications of foreign body ingestion are indistinguishable from other causes of obstruction, perforation, and bleeding.

Only 1 to 2 per cent of all cases of acute small bowel obstruction are due to obturation by a foreign body. The site of obstruction is most commonly in areas of narrowing: the distal ileum, the ileocaecal valve, or sites of preexisting inflammatory disease with stricture, neoplasm, or diverticula. Choices of operative treatment include manual displacement of the intraluminal object, if safe, into the colon, removal via enterotomy, or resection if the object is imbedded or has caused transmural necrosis. Perforation due to presence of a foreign body may result in diffuse peritonitis, but more commonly it presents itself as contained sepsis with a localized abscess or as fistulization into an adjacent viscus or parenchymatous organ. Treatment includes, in addition to antibacterial agents, removal of the foreign body, closure of the enterotomy or resection as dictated by the local findings, and drainage of abscess if it is present. Bleeding from a small bowel foreign body arising through mucosal pressure necrosis and ulceration is infrequent.

The management of patients with an ingested foreign body in the absence of the above complications is dictated by the nature of the foreign body. Once objects have left the stomach more than 95 per cent of them proceed through the small intestine and colon unimpeded and without untoward effects. The population of patients suffering foreign body ingestion includes children, those with psychiatric disorders, alcoholics, prisoners, and denture wearers who have diminished palatal sensation. A relative, although controversial indication for surgery, is failure to pass a foreign body as evidenced by lack of progress on serial radiographs. In children, the average time for passage of an object through the small intestine is 5 days. If their parents are reliable, children can be managed as outpatients to await passage confirmed by observation of stools or occasional radiographs.

Certain categories of foreign objects have special features that may dictate surgical removal.

Certain patients with severe psychiatric disorders or incarcerated felons repeatedly ingest an astonishing variety of objects, including pins, eating utensils, bedsprings, razor blades, bolts, and scissors. Evidence of self mutilation and drug use is common. Once these objects reach the small bowel they are likely (>90 per cent) to further traverse the gastrointestinal tract safely. Perforation or obstruction occurs in only 0.5 per cent of instances. Inasmuch as these patients have a remarkable propensity for eating their environment, as manifested in particular by ingesting parts of hospital beds, if surgery becomes indicated, radiographs should be obtained immediately prior to exploration.

Although alkaline disc batteries can potentially leak their caustic contents in the stomach, other types of batteries (mercury, lithium, silver) are innocuous; the risk of mercury poisoning is low. Once such smooth round batteries reach the small intestine virtually all will pass.

In contrast to metallic foreign bodies, pointed wooden objects such as splinters or toothpicks, and fish or chicken bones are more hazardous owing to their length and sharp ends, which make them more likely to perforate the bowel wall. Up to one-third of such objects which reach the small bowel may cause perforation. These patients most often present with an acute abdomen, radiographs and history being unrevealing. Perforation usually results in intra-abdominal abscess or fistula: this may occur at any site in the bowel wall but in particular in the ileocaecal region, including Meckel's diverticulum, where the differential diagnosis includes more common inflammatory lesions. Toothpick perforations are particularly prone to produce fistulae with late septic complications.

A popular method of narcotic smuggling involves the placement of drugs, commonly cocaine or heroin, in latex packages or condoms into body cavities or by swallowing, their retention being favoured by the use of constipating agents. In addition to the risk of obstruction (6 per cent), acute narcotic toxicity and death has occurred. The fatal oral dose of cocaine is 1 to 3 g; a single packet of cocaine contains 3 to 12 g, and carriers ingest many packets. The likelihood of ruptured packets and resultant mortality has decreased, however, as smugglers have grown more sophisticated, and immediate surgery is no longer mandatory. Mild cathartics may be used and patients may be discharged when proved free of packets by radiological and serial stool examinations. Older types of packets (containing loose cocaine covered by two to four layers of condoms or latex) are more prone to rupture. If this type of packaging can be identified by history or by recovery of packets from the rectum or stool, or if toxicity is present, surgical removal is indicated. Packets are frequently visible on plain films.

Small intestinal obstruction due to bezoar is a common form of obturating obstruction, usually occurring as a late sequela of gastric surgery. Bezoars consisting of concretions of vegetable fibres (phytobezoar) reach the small bowel either directly through the pylorus or through a gastroenterostomy, or after fragmentation consequent upon attempted gastroscopic removal. Caution must be exercised at laparotomy not to overlook other bezoar fragments in addition to the one provoking the obstruction. Small bowel bezoars may also originate in duodenal or jejunal diverticula, as well as in Meckel's diverticulum. Trichobezoar may involve the small bowel by extension for a considerable distance distal to a large gastric hairball.

Although not true foreign bodies, large boluses of certain foods may cause small intestinal obturating obstruction. These include masses of citrus fruit fibres, desiccated fruits, any high fibre food such as coarse bread at times of famine or following religious fasts, turtle eggs, and grasshoppers. Food bolus obstruction in non-temperate zones can often be managed without laparotomy, as the obstruction is usually partial. Additional factors that predispose to food bolus obstruction include prior gastric surgery and inadequate dentition. In cases of obstruction by food bolus or bezoar, postoperative education of patients to avoid binge eating, modification of fibre intake, and fitting of dentures may be useful in preventing recurrence. The operative management of obstruction by food bolus or by bezoar is similar, with attempts to squeeze the mass or fragment into the colon. When firmly impacted, an enterotomy may be needed.

Enteroliths or intestinal calculi are presumed to form de novo in the bowel lumen. They consist of calcium or magnesium salts or, contain cholesterol and bile acids. They were, in earlier reports, considered to be common ‘foreign bodies’. Their appearance is, however, rare, and a specific diagnosis preoperatively is rarer still. They may form in the stagnant milieu of duodenal or jejunal diverticula, in blind loops, and in areas of Crohn's disease or tuberculosis.

Small bowel obstruction may result from medications, including antacids and boluses of hydrophilic colloid laxatives, which absorb water and swell into a gelatinous mass. Antacid obstruction is seen particularly in patients undergoing haemodialysis. Concretions in the small bowel can also occur in those with more bizarre forms of ingestion, such as drinking alcoholic solutions of shellac, and cement powder used for producing mortar or concrete.

Infestation by the round worm Ascaris lumbricoides accounts for 10 to 15 per cent of cases of intestinal obstruction in endemic tropical areas in Africa and Asia. Following appendicitis, ascariasis is the second most common cause of acute abdomen in children in those area. Massive ascariasis can cause low grade intestinal obstruction, which can often be managed conservatively with fluids, gastric drainage, and repeated doses of antihelmintics. However, acute complete obstruction may occur, sometimes following the use of a vermifuge. The dead or dying worms impacted in the terminal ileum and right colon are capable of causing tissue necrosis and perforation. In addition to the presenting symptoms of small bowel obstruction the masses of worms may be palpable or visible on plain films. Worms may be present in the vomitus or stool. Although intestinal obstruction may be due to obturation, volvulus, or intussusception, irritative intestinal spasm due to the worms may contribute. At surgery, if the obstructing bolus of worms cannot be advanced distally, resection may be necessary, particularly if local gangrene, volvulus, or intussusception has occurred.

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