Effect of pregnancy on intestinal transit: comparison of results using radioactive and non-radioactive test meals.

Studies were performed to determine the effect of pregnancy on both gastrointestinal transit and small intestinal transit. Gastrointestinal transit was examined by determining the leading edge of distribution within the small intestine of a charcoal marker placed directly into the stomach. Intestinal transit was evaluated by quantifying the distribution of a radiolabelled marker placed directly into the duodenum. The distribution of the marker was determined (1) by calculating the slope of the distribution curve and (2) by calculating the geometric center of distribution of the radioisotope. In all studies the data from animals in either the second or third trimester of pregnancy were compared with the results obtained from non-pregnant females. The results confirm previous observations that gastrointestinal transit is reduced during the latter stages of pregnancy. This can be explained, at least in part, by a decreased intestinal transit. The data also suggest that analysis of the geometric center of distribution provides a more sensitive and reliable measure of intestinal transit than does analysis of the slope of the distribution curve.