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Stomach and Duodenum

The radiological abnormalities which need to be considered are obstruction to the outlet of the stomach, gastric ulceration, and gastric tumors (hiatus hernia has been considered with the esophagus).

Outlet Obstruction. In infants, outlet obstruction due to congenital pyloric stenosis occurs throughout the tropics and is being recognized more often: at present, it is undoubtedly less commonly seen in the tropics than in Europe or North America. When it does occur, it is more common in males but not necessarily in first-born sons (only 20% in one series): it has been suggested that babies who have been breast fed in the first week of life are less likely to have pyloric stenosis: if this were correct, it has been estimated that there could be 35% less cases. The suggestion is in accord with the fact that in most tropical countries babies are breast fed from birth. So far, it has not been reported in Australian aborigines and is rare in Malaysia.

Peptic Ulceratiom. The recognition of Helicobacter pylori has provided an explanation for the geographical differences in the frequency of peptic ulcers. Its causal relationship with duodenal ulcer is firm, particularly where there is an antral gastritis. In the stomach, although clearly associated with antral gastritis, 35% of gastric ulcers and chronic gastritis do not seem to be associated with H. pylori. If the diagnosis of peptic ulceration is made on a clinical basis, then it occurs in many parts of the tropics: a large proportion of patients seen at any general medical clinic will have dyspeptic symptoms. Unfortunately, these can be caused by schistosomiasis and amebiasis, amongst other parasites. The patient with a stomach full of ascarids may only complain of indigestion. Whether there is an ulcer or not must be confirmed by endoscopy or an upper GI series, depending on the local facilities and staff.

Gastric Ulceration. Gastric ulcers on the lesser curvature of the stomach are rare anywhere in the tropics; the majority of ulcers in the stomach are in or close to the pylorus and there is a considerable geographic variation in incidence. For example, in Ibadan, Nigeria, chronic juxtapyloric ulceration is a frequent cause of gastric outlet obstruction (Fig. 44.5); its relief is one of the more common surgical procedures. Yet, a few hundred miles to the north in Kano, northern Nigeria, neither pyloric ulceration nor fibrosis is common and this type of pyloric obstruction is rare. In any tropical country, tuberculosis must be considered as an occasional cause of both gastric ulceration and pyloric obstruction, and may closely resemble malignancy.

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Fig. 44.5. (A) Scarring and constriction of the second part of the duodenum from postbulbar ulceration is not uncommon in some countries, for example Nigeria. In this patient there is reflux into the biliary tract because of the duodenal fibrosis. (B) A high-fiber diet has its risks, particularly if there is narrowing or alteration to the gastric outlet. This patient had a partial gastrectomy and has a large bezoar. Many tropical fruits are popular but not easily absorbed or passed.

Neoplasms of the Stomach. Neoplasms of the stomach are considered in Chapter 43 on Geographic Variations of Malignant Neoplastic Diseases. They can be mimicked by tuberculosis; furthermore, "tumors" are often phytobezoars because malnourished children will eat almost anything, including dirt (see Fig. 44.8 A). The name "bezoar" was originally given to the hard green concretion which is found in the fourth stomach of the Syrian goat and which for centuries was thought to be a good antidote for poisoning. The causes vary, but are usually related to the commonest fruit and are therefore seasonal. Persimmon is a frequent source because when it is unripe it forms a glutinous mass with the hydrochloric acid in the stomach. In Africa it is the ripening marula fruit which causes the same problem (and legend has it that .when eaten in large quantities by elephants, it may ferment and result in intoxication). Any fruit or food with a high fiber content can be responsible, particularly in those patients who have had a partial gastrectomy and vagotomy, or any bypass operation. Aggregations of roundworms can cause the same problem (see Chapter 10 on Ascariasis).

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