Expert offers Vacuum extraction strategies

OB/GYN News,  Feb 15, 2002  by Sherry Boschert

• E-mail
• Print
• Link

KAUAI, HAWAII -- Vacuum extraction gained popularity as a form of operative vaginal delivery in the 1990s despite a lack of formal guidelines on how to do it, Dr. Julian T. Parer said at a conference on obstetrics, gynecology, perinatal medicine, neonatology, and the law.

In 1994, the American College of Obstetricians and Gynecologists offered a general guideline on how to best perform a vacuum extraction: Descent of the fetus should accompany each traction. But ACOG cited a lack of consensus regarding the optimal number of pulls, a limit to the number of times the vacuum cup may pop off before abandoning the procedure, and a maximum time limit for attempted vacuum delivery, he said.

Dr. Parer, director of perinatal medicine and genetics and professor of ob.gyn. at the University of California, San Francisco, offered his own, more detailed recommendations on vacuum extraction at the meeting, which was sponsored by Boston University:

* Place the vacuum cup on the occiput of the fetal cranium toward the anterior fontanelle. Check for vaginal tissue, especially anteriorly, before engaging pressure or traction.

* Bring the vacuum pressure to 100 mm Hg. With contractions, increase the pressure to 600 mm Hg.

* Apply axis traction with maternal pushing for a full minute, using a fetal heart rate monitor to time it. Short pushes are best, and grunting should be encouraged. Try to avoid the yelling or vigorous coaching others in the room may offer when it comes time to push. Vacuum extraction is "a relatively subtle technique. The person doing the traction should be the coach," he said.

Many clinicians at his institution prefer to lower the suction pressure between contractions to reduce pain on the baby's head. Constant high pressure is safe and effective, however, according to a randomized, controlled trial of 322 patients. The study found no differences in times to delivery rates of successful vacuum extraction, maternal or fetal injury, or neonatal outcomes whether pressure was maintained or lowered between contractions (Obstet. Gynecol. 89[5, pt. 1]:758-62, 1997).

* Check the tissue around the vacuum cup again between each contraction and attempted extraction. Some fetal descent should occur with each traction. Dr. Parer usually allows no more than three pulls but occasionally may do four, consistent with previous recommendations published by other obstetrical authorities.

* Don't allow more than two pop-offs of the vacuum cup. Other experts have suggested abandoning the procedure after one to three pop-offs. Vacuum cup pop-offs tend to occur mainly with clinicians who are learning how to do vacuum extraction, he said.

Dr. Parer did not put a time limit on vacuum extraction attempts, but some published opinions suggest applying traction for no more than 15-25 minutes. The longer the duration of vacuum extraction, the greater the likelihood that the baby will develop a cephalhematoma. Vacuum extractions that last longer than 5 minutes from application to delivery cause cephalhematomas in 28% of neonates.

A failed operative vaginal delivery increases fetal risk, so be extremely judicious in attempting a forceps delivery after a failed vacuum extraction. "It would be very rare for us to consider going to forceps after a failed vacuum," he said.

Most clinicians would say that vacuum extraction should be reserved for fetuses of at least 34 weeks' gestation, but there's not a lot of evidence to provide guidance concerning fetal age, he added.

COPYRIGHT 2002 International Medical News Group
COPYRIGHT 2008 Gale, Cengage Learning