Vacuum Extraction

Feb 19 2009

Many efforts have been made over the years to replace the steel forceps with a gentler instrument that can deliver the baby without putting as much pressure on the sides of the baby’s head. The first such instrument to gain widespread use was the vacuum extractor, introduced in Sweden in 1954.

The vacuum extractor uses a metal cup about 3 inches in diameter and about 1 inch deep. The original metal cup has been largely replaced in the United States by a soft cone-shaped cup of a synthetic material, which works on the same principle. The vacuum extractor is used for much the same reasons as forceps are used.

To use the vacuum, the cup is placed over the baby’s scalp and a carefully controlled vacuum is created inside the cup with a pump. This gradually sucks the baby’s scalp into the cup and holds it there, forming an artificial caput succedaneum or swelling between the scalp and the bones of the skull. By maintaining this hold on the scalp, the birth attendant can use the instrument as a handle on the baby’s head. The scalp is quite loosely applied to the skull, and the artificial caput is as harmless as the caput that normally forms on the head of most babies. With this handle, the birth attendant can rotate the head into a more favorable position and then make traction by pulling on the suction cup with a chain attached for that purpose.

It is important to palpate around the edges of the cup to be certain that no vaginal tissue has been sucked into it along with the baby’s scalp. This will make the cup pop off and may cause lacerations and bleeding in the mother.

An advantage of the vacuum extractor is that it is attached at the leading part of the baby’s head, rather than the sides of the baby’s head. Thus, it does not take up any space in the vagina or pelvis and can be applied with less discomfort than the forceps. The baby’s head can adapt itself to the pelvis instead of adapting to the delivery instrument. There also is less chance of traumatizing the mother’s tissues.

Bearing down by the mother facilitates progress during traction with the vacuum extractor. With local anesthesia to the perineum, pudendal block, or a low epidural block, the mother can bear down in cooperation with the traction made by the physician or midwife. A vacuum birth can in fact mimic spontaneous birth. An episiotomy can be done but may not be needed.

In some European countries, the vacuum extractor has virtually replaced forceps, and obstetricians there are quite satisfied with its safety and efficiency. It does produce a conspicuous purple bruise on the top of the baby’s head at the site of the artificial caput, and can cause bleeding under the skin. This can lead to the baby’s developing hyperbilirubinemia. Hyperbilirubinemia is an excess of bilirubin in the blood, which occurs when red blood cells are destroyed, as happens with this extra bleeding. Hyperbilirubinemia can lead to newborn jaundice. These complications are more common with the metal cup than with the soft cup.

As with forceps, a vacuum delivery may not be successful, and a cesarean may be necessary.