Chapter 13 (page 64)

The Pyloric Sphincteric Cylinder in Health and Disease

Go to chapter: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39
Chapter 13 (page 64)

Closure of Pyloric Aperture by Mucosal Folds

When the pyloric sphincteric cylinder is filled but inactive, its mucosal folds run in a circular or oblique direction; this was a regular feature seen in all our normal cases (Fig. 13.16). With the appropriate radiological double contrast or graduated compression techniques, these folds are seen to converge on the aperture (Fig. 13.19) or to surround it in an iris-like way, similar to the shutter leaves of a camera. At this stage barium is not seen to leave the stomach, and consequently its diameter cannot be measured; in other words, the aperture is plugged or closed. Not infrequently one of the radiolucent folds may extend for a distance of 3.0 or 4.0 mm through the aperture as far as the base of the duodenal bulb; extension of a single fold through the pylorus is considered to be normal (Torgersen l942), and does not constitute prolapse of gastric mucosa into the duodenum (Keet l952).

Fig. 13.19. Double contrast. Pyloric mucosal folds converge on aperture (arrow), causing mucosal closure

On the duodenal side, under these circumstances, a similar convergence of mucosal folds toward the pyloric aperture is evident.

On radiological evidence it is concluded that, at times when the pyloric sphincteric cylinder is filled but inactive, the aperture may be plugged by both gastric and duodenal mucosal folds converging on it, or it may be closed in a shutter-like way by oblique mucosal folds on the gastric side.

In a series of fresh partial gastrectomy specimens (removed because of gastric or duodenal ulceration), Williams (l962) demonstrated mucosal closure of the pylorus. These specimens, consisting of the distal half of the stomach and the first one or two centimeters of the duodenum, retained their pliability for some hours after operation. When barium was poured into such a gastric "bag" it did not always run out of the pylorus. In 8 of 40 specimens, the pylorus was watertight to a pressure of 4.0 to 10.0 cm of barium suspension with a specific gravity of 1.2. Williams (l962) called it a watertight, physiologically closed pylorus; viewed from the duodenal side, bulging, pliable gastric mucosal folds were seen to occlude the aperture. A probe 5.0 mm in diameter could be passed into the stomach, withdrawn and the pylorus remained watertight. When the probe reached a diameter of 10.0 mm it met the resistance of the muscular ring. Transverse anatomical sections of fresh specimens also showed the muscular ring to have a diameter of 10.0 mm, the opening being occluded by mucosal folds. In one of the cases nylon threads were tied to the mucosa on the gastric side of the pylorus. Pulling towards the fornix pulled the mucosal "plug" out of the ring into the stomach, causing the barium suspension to run out, i.e. the pylorus opened. When tension on the threads was released the mucosa returned, closing the pylorus.

It is concluded that radiological observations as well as experimental anatomical investigations show that the pyloric aperture may be closed by mucosal "plugging" or mucosal occlusion. This is seen during stages when the adjacent part of the stomach, i.e. the pyloric sphincteric cylinder, is filled but inactive. (A small collection of barium situated centrally at the base of the bulb may sometimes fill the hollow of the closed pyloric aperture; this we have called the duodenal "tail". In cases of pyloric carcinoma it may appear to be uninvolved, as described in Chapter 33).