The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 38 (page 189)

Keet l952 examined 10 normal stomachs approximately 24 hours post-mortem and found that a fold of pyloric mucous membrane (the mucosal/submucosal component of the pyloric ring) projected into the lumen of the duodenum in every case, confirming the observation of Cole (l928). Surgical forceps were used to determine to what extent the mucosa could be elevated from, or shifted on, the underlying layers in a 2.0 cm wide band on the oral side of the pyloric aperture, i.e. in the pyloric sphincteric cylinder. In a child 8 years of age it was not possible to elevate or shift the mucosa. In all adults the mucous membrane could be lifted from 5.0 mm to 1.0 cm from the muscular coat. Such a fold could be pulled beyond the pyloric ring (right pyloric loop) for a distance of 5.0 to 10.0 mm into the duodenum. At distances greater than 2.0 cm from the aperture it was still possible to elevate the mucosa into folds, which could be moved in all directions but could not be drawn into the duodenum. It was concluded that a certain degree of prolapse of the gastric mucosa could be produced artificially in adults at autopsy by traction on the mucosa close to the pyloric aperture. The greatest extent to which the mucosa could be drawn into the duodenum was one centimeter. Anything greater than this should probably be regarded as abnormal, and in young persons the distance was probably much less.

Williams (l962) examined aspects of the mucosa in 48 fresh post-operative partial gastrectomy specimens, removed because of gastric or duodenal ulceration. The gastric mucosa was found to be soft and pliable and to move easily over the muscularis externa. This was due to the fact that the gastric submucosal coat is normally much wider than that of the duodenum (Chapter 4). Finger pressure could push the mucosa into the pyloric ring, but owing to its attachment at the ring it rose in thebase of the duodenal bulb in a circumferential, two-layered fashion, like a clerical collar. In all cases a mucosal protrusion of 1.0 to 3.0 cm into the duodenum could be produced in this way. According to Williams (l962) a similar minor degree of physiological herniation of gastric mucosa into the base of the duodenal bulb frequently occurs during forceful contraction of the "pyloric press".

Pathoanatomical Diagnosis

In the 2 cases of Hawley et al. (l949) which came to autopsy it was found that the gastric mucosa slid easily over the muscularis and could be lifted through the pylorus for distances of as much as 2.5 cm. This was considered to be definitely abnormal. In 2 of the 6 cases studied by Manning and Gunter (l950) the submucosa was very loose, slipping freely over the muscularis, and the redundant antral folds could be drawn into the duodenum for a distance of 2.0 cm. In both cases the entire circumference of the mucosa was involved. Histological examination showed chronic inflammatory change in the prolapsed mucosa, submucosa and muscularis mucosae. There appeared to be some hypertrophy of the musculature of the pyloric "sphincter". In 2 of the cases the prolapse consisted of tongue-like projections of gastric mucosa extending into the duodenum. In the 2 other cases in whom a radiological diagnosis of prolapsed gastric mucosa had been made, the patho-anatomical findings were not quite convincing and in our opinion could have been due to post mortem projection of the mucosal part of the pyloric ring into the duodenum.

Zimmer (l950) as well as Manning and Gunter (l950) stated that many pathologists failed to search for the condition at autopsy. The following features were considered to be typical of gastric mucosal prolapse: (1) gross protrusion of gastric mucosa into the duodenal bulb which is quite evident as soon as the stomach and duodenum are opened; (2) the mucosa may not protrude through the aperture but can easily or readily be drawn through it. The latter statement should probably be qualified by the provision that normally the gastric mucosa can be drawn into the bulb for a distance of one centimeter.

Surgical Diagnosis

If the stomach and duodenum are exposed and inspected at operation, no abnormality will be seen in uncomplicated cases. At palpation no abnormality may be felt in either the stomach or duodenum, as the prolapsing mucosa is so soft that it cannot be felt through the walls (Rendich l923; Eliason et al. l926). A softish mass may be felt in the duodenum (Ferguson l948) or in the pyloric region while the duodenum feels normal (Schmiedin 1911; Norgore and Shuler 1945; MacKenzie et al. 1946; Zacho 1948; Nygaard and Lewitan 1948; Teng 1962). In some cases a doughy, tumor-like mass could be felt in the duodenum, which disappeared under palpation (Eliason et al. 1926; Bohrer and Copleman 1938). In others it could be slipped back and forth between the stomach and duodenum (MacKenzie et al. 1946; Nygaard and Lewitan 1948).

Because of these features all stomachs should be opened at operation whenever the condition is suspected (Scott 1946). In the cases quoted above, folds of redundant gastric mucosa were seen after the stomach had been opened. In several cases big prepyloric folds occluded the aperture, acting like a valve (Schmieden 1911; Eliason et al. 1926; Zacho 1948; Keet 1952, 1953). In other ocases the incision was carried through into the duodenum. When both the stomach and duodenum were opened, redundant folds of gastric mucosa protruding into the duodenum were usually quite evident (Meyer and Singer 1931; Bohrer and Copleman 1938; MacKenzie et al. 1946). In most cases the prepyloric folds were movable on the muscular coat and could easily be pulled into the duodenum for variable distances (Rees 1937; Ferguson 1948; Hawley et al. 1949). In the case of Hawley et al. (1949) for instance, the pyloric mucosa could be drawn through the aperture for a distance of 2.0 cm. In one of the cases described by Rees (1937) the largest gastric mucosal fold was 3.0 cm in height and 4.0 cm in length. It could be pushed through the pylorus into the duodenum with ease.

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