Demonstration of a physiologic sphincter at duodeno-jejunal junction.

Current evidence suggests that there are three sphincters that regulate the flow of chyme from stomach to the duodenum. We investigated the hypothesis whether a fourth 'physiologic sphincter' exists at the duodeno-jejunal junction. The pressure response of the jejunum, duodeno-jejunal junction and duodenum to individual balloon distension of the jejunum and duodenum was recorded in 28 healthy subjected before and after anesthesizing the jejunum, duodeno-jejunal junction and duodenum. The duodeno-jejunal junction length was measured by the station pull-through technique. Duodenal balloon distension with 2 and 4 ml of normal saline did not change the pressures in the duodenum, duodeno-jejunal junction or jejunum (p > 0.05). Distension with 6 ml saline produced an increase of duodenum pressure (p < 0.01), a decrease of duodeno-jejunal junction pressure (p < 0.01), and no change in the pressure of the jejunum (p > 0.05), the balloon was expelled to the jejunum. Eight, and 10 ml duodenum balloon distension produced pressure changes similar to those of the 6 ml distension (p > 0.05). Jejunum balloon distension with 2 and 4 ml saline induced no jejunum, duodeno-jejunal junction or duodenum pressure changes (p > 0.05). Six ml balloon distension effected increase of jejunum (p < 0.01) and duodeno-jejunal junction (p < 0.05) pressure, but no duodenum pressure changes (p > 0.05). Jejunum balloon distension with volumes more than 6 ml produced pressure changes similar to the 6 ml distension. Distension of the anesthetized duodenum, duodeno-jejunal junction or jejunum did not change the duodeno-jejunal junction pressure. A high pressure zone of 1.6+/-0.04 cm length was detected at the duodeno-jejunal junction. Together, the findings show that a high pressure zone exists at the duodeno-jejunal junction suggesting that this region might act as a physiological sphincter.