Vacuum Associated With More Dystocia Than Forceps


RENO, NEVADA — Forceps delivery is associated with more perineal tears than is vacuum delivery, but the vacuum is associated with more complications for the infant, including shoulder dystocia, Aaron B. Caughey, M.D., said at the annual meeting of the Society for Maternal-Fetal Medicine.

Dr. Caughey presented results of a review of 4,120 consecutive, operative, vaginal deliveries of singleton, term neonates at a University of California, San Francisco, hospital, and those results surprised him, he said during an interview.

His hypothesis at the start of the study was that he would see more shoulder dystocia in the neonates delivered with forceps, because doctors would choose the forceps for bigger babies. What he found, however, is consistent with another recent study, which looked at deliveries at many different institutions (Obstet. Gynecol. Surv. 2005;60:86-7).

In the study by Dr. Caughey and his colleagues at the university, shoulder dystocia occurred in 2% of the forceps deliveries, compared with 4% of the vacuum deliveries.

Cephalohematoma occurred in 4% of the forceps deliveries and 15% of the vacuum deliveries, Dr. Caughey wrote in a poster presentation.

On the maternal side, there was a difference in third- and fourth-degree perineal and cervical tears (37% for the forceps deliveries, versus 27% for the vacuum deliveries).

The study found no significant difference in more serious birth trauma, which included skull and clavicle fracture, intracranial hemorrhage, facial nerve palsy, and Erb's palsy (1.7% for forceps and 2.1% for vacuum).

But the children delivered with the vacuum were more likely to have a 5-minute Apgar score that was less than 7 (4% vs. 3%) and to have neonatal jaundice (13% vs. 10%).

In the interview, Dr. Caughey said his study adds to what the previous study reported because that study used a database of births nationwide—data in which coding and practices could differ.

His data, culled from a single institution, likely reflect more consistent practice, he said.

Of the study's 4,120 deliveries, 2,045 were forceps deliveries and 2,075 were vacuum-assisted deliveries.

The differences in outcome overall remained consistent even when the investigators took into account factors such as birth weight, station at delivery, length of the first and second stages of labor, and episiotomy.

The study results indicate that the trade-off in choosing which device to use is that one puts the mother at risk for tears, while the other entails risk for the neonate, Dr. Caughey noted.

In most of those situations, therefore, he is going to choose putting the mother at risk, he said.

Certainly, with multiparous women, the forceps make more sense because they have less likelihood of tearing, he added.

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