The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 27 (page 126)

Ehrlein (l98l) pointed out that the function of the pyloric sphincter in preventing duodenogastric reflux had not been clarified. (It was explained that the term "pyloric sphincter" in this context referred to the pyloric ring). It was difficult to record contractions over a long period of time in humans. In animals it was possible to measure the external diameter of the pylorus with induction coils, and to determine pressure changes simultaneously by means of implanted strain gauge transducers (Ehrlein l980). The method was used in canines to investigate possible co-ordination of gastric and duodenal motility, gastroduodenal reflux at the same time being observed fluoroscopically. In the digestive state the pylorus opened when a peristaltic wave involved the commencement of the "antrum", closing when the wave reached the pyloric sphincter. Contraction maxima of the duodenal bulb most often occurred a fraction of a second before, or after, contraction maxima of the pyloric sphincter. Consequently there was incomplete closure of the pylorus during duodenal contraction, allowing duodenogastric reflux to occur; it was produced by atypical segmental contractions of the bulb. In the interdigestive state different phases were encountered. In the first phase, in the absence of contractile activity in the stomach and duodenum, no reflux occurred. In the second and third phases imperfect timing of pyloric and duodenal contractions, as in the digestive state, sometimes resulted in duodenogastric reflux.

Various derivatives of 99mTc-IDA have now been used extensively in the study of duodenogastric reflux, notably 99mTc-BIDA (butyl iminodiacetic acid) and 99mTc-HIDA. These tests have certain minor limitations in common (Thomas et al, l984). For instance, anatomical definition of the stomach was often complicated by overlap of the left lobe of the liver and the duodeno-jejunal flexure; delineation of the gastric "antrum" was poor, and as it was close to the duodenal bulb, minor degrees of reflux might not be detectable; and computer analysis of small volumes of reflux might be difficult to interpret.

Two further limitations of the cholescintigraphic tests, in our view, are the following:
  1. As only bile constituents are labelled, the tests apply to reflux of bile into the stomach; they are not a measure of reflux of the other constituents of duodenal juice, of which pancreatic exocrine secretion is the most important. It may be useful to have a test able to demonstrate reflux of duodenal contents (as opposed to bile only), into the stomach.

  2. At present the tests do not visualize the pylorus clearly, i.e. it is not possible to determine the extent of contraction or relaxation of the pyloric region in relation to reflux.

A Double-Contrast Radiographic Test for Duodenogastric Reflux

As a modification of the double-contrast upper gastrointestinal radiographic examination, we have described the following radiographic test for duodenogastric reflux (Keet l982). In this test the pylorus is clearly visualized and its diameter can be determined during reflux; in addition, the relationship of reflux to pyloric and duodenal contractions may be studied. The test is non-invasive and does not entail the use of catheters, intubation or the administration of pharmacological agents (which may alter motility).

The patient, standing behind the radiological TV monitor after a 12-hour overnight fast, is instructed to swallow 4 to 5 mouthfuls of a micropulverized barium suspension, e.g. Micropaque (Adcock-Ingram, Johannesburg) ordinarily used for upper gastrointestinal radiographic examinations. Immediately afterwards a gas-producing agent is swallowed, e.g. 2 x 50 Gastrast tablets (Toho Kagaku Kenyusho, Tokyo), followed by 2 mouthfuls of water containing a few drops of Telament liquid (Adcock Ingram, Johannesburg). The barium accumulates in the lower part of the stomach while the gas distends the fornix. While the patient is instructed not to eructate, the table is immediately tilted into the horizontal position. With the arms abducted throughout the examination, the supine subject is now rotated into the left anterior oblique position (right side down) till barium enters the duodenal bulb. As soon as duodenal filling is achieved, the subject is rotated rapidly through 90 degrees into the right anterior oblique position. This causes the remaining barium in the stomach to descend into the fornix, while the gas is displaced and ascends into the pyloric region, which now constitutes the uppermost part of the stomach. Consequently the first part of the duodenum is filled with barium, while the pyloric region up to the ring is filled with gas (Fig. 27.1). The competence of the pylorus can now be studied, radiographs being taken at appropriate times. Duodenogastric reflux through the pylorus into the gas-containing part of the gastric lumen is clearly visible (Fig. 27.2). (This should not be confused with the normal orad movement of barium often seen during contraction of the pyloric sphincteric cylinder as described in Chap. 13). Should no reflux be observed, or should the duodenum empty its contents prematurely, positioning of the patient is repeated. Generally speaking, the manoeuvre is repeated 4 to 5 times during each test. The effects of compression of the second or third parts of the duodenum may also be studied.

Fig. 27.1. Duodenal bulb filled with barium. Pyloric sphincteric cylinder filled with gas and distended

Fig. 27.2. Reflux of barium (arrow) from the duodenum into the pyloric sphincteric cylinder, which is relaxed

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