Prolonged Resolution of Dystocia Is Well Tolerated.

Moderate delays not tied to fetal acidemia.

HOT SPRINGS, VA. -- A moderate delay in childbirth for the sake of resolving shoulder dystocia is not associated with clinically significant increases in umbilical artery acidemia, Dr. Shawn P. Stallings reported.

In fact, drops in fetal pH levels after the onset of shoulder dystocia probably occur much more gradually than physicians have generally assumed, challenging the notion that shoulder dystocia requires a crash or rushed delivery.

Increasing birthing delays did not correlate with worsening umbilical arterial values in a study of 43 cases of shoulder dystocia that occurred during vaginal deliveries at a hospital affiliated with the University of Florida, Gainesville, over a 4-year period. Nor was there a significant correlation between longer times to dystocia resolution and decreasing 5-minute Apgar scores, Dr. Stallings said at the annual meeting of the South Atlantic Association of Obstetricians and Gynecologists.

The results suggest that if the fetus is healthy, it will likely be able to tolerate a prolongation of delivery by 4-5 minutes. "It should not be the clinician's first impulse to increase the forces applied in a rushed attempt to deliver the fetus within an arbitrary 2-minute time limit," he said at the meeting, which was cosponsored by the American College of Obstetricians and Gynecologists. Dr. Stallings and his associates analyzed the medical records from all births at the university's Shands Hospital from Jan. 1, 1994, through Dec. 31, 1997. Of the 8,282 vaginal deliveries studied, there were 134 cases of shoulder dystocia, representing an incidence of 1,7%, he said

For purposes of the study, dystocia was defined as the use of ancillary maneuvers to complete delivery, said Dr. Stallings, who has since moved to Wake Forest University, Winston-Salem, N.C.

Of those births involving shoulder dystocia, maternal and infant medical charts were sufficiently complete in 43 cases to analyze the correlation between head-to-body intervals--as a measure of delivery time from the onset of dystocia--and fetal acidemia.