Comparison of the nipple stimulation and exogenous oxytocin contraction stress tests. A randomized, prospective study

In a prospective, randomized trial, 103 women underwent a total of 203 antenatal stress tests. One hundred four nipple stimulation contraction stress tests (BSTs) and 99 oxytocin challenge tests (OCTs) were performed. The patient populations were similar for the two groups. Uterine hyperstimulation with abnormal fetal heart rate patterns occurred with 2.9% and 1% of the BSTs and OCTs, respectively. The failure rate for the BST group was 22%. Maternal age and weight, parity and gestational age were not associated with test failure. Only one patient failed more than one BST, but she did not fail every such test. When test time (time from initiation to completion of the test) was compared between the two groups, a significant difference was found when the BST was successful. However, when test time in the total BST group (successful and unsuccessful BSTs followed by an OCT was compared to that in the OCT group, no difference could be found. Though an OCT following an unsuccessful BST took longer to perform than did a primary OCT, the difference was not statistically significant. It appears that BST test failure may relate more to the technique of nipple stimulation used than to intrinsic patient factors.