The manometric findings at the human pylorus. The evidence against the presence of a tonic sphincter.

The results of pyloric manometric studies conflict, some showing evidence of a sphincter at the pylorus, others not: hence the term 'the fickle pylorus'. In this study we used perfused catheters to investigate the manometric properties of the human pylorus, in an attempt to explain the different results of similar experiments. A high-pressure zone (HPZ) of 5.9 mmHg (mean) was found at the pylorus in 53% of 170 measurements. The subjects' position had no effect on the HPZ, nor had duodenal acidification. Eating a meal increased the pressure from 5.0 mg Hg in the fasting state to 8.0 mm Hg after a meal. The results and those of 11 other manometric studies are considered; the evidence is against the presence of a tonic sphincter at the pylorus.