Vacuum extractors have replaced forceps for many situations in which assistance is required to achieve vaginal delivery. Compared with metal-cup vacuum extractors, soft-cup devices are easier to use and cause fewer neonatal scalp injuries; however, they detach more frequently. Vacuum extractors can cause neonatal injury. These devices should be employed when indicated, usually for a nonreassuring fetal heart tracing or failure to progress in the second stage of labor. Complications may be minimized if the physician recognizes contraindications to the use of vacuum extraction. Complete documentation is essential.

When spontaneous vaginal delivery is not possible, instrumental delivery may be attempted. In 1705, Yonge described an attempted vaginal delivery using a cupping glass. In 1848, the developer of the Simpson forceps devised a bell-shaped device called an "air tractor vacuum extractor." Multiple innovations followed, and a metal-cup extractor was developed by Malmström in 1953. More recently, bell-shaped and hemispheric silicone rubber cups have come into use. This article discusses the two basic types of vacuum extractors and their use in vaginal deliveries.

Types of Vacuum Extractors:

Metal Cup:
The metal-cup vacuum extractor is a mushroom-shaped metal cup varying from 40 to 60 mm in diameter. A centrally attached chain connects the cup to a detachable handle that is used to apply traction. A mechanical or electrical suction device is attached to the metal cup via a peripherally located vacuum port.

The advantages of metal-cup vacuum extraction over soft-cup extraction include a higher success rate and easier cup placement in the occipitoposterior (OP) position, especially when an OP cup is used. Unfortunately, the rigidity of metal cups can make application difficult and uncomfortable, and their use is associated with an increased risk of fetal scalp injuries. Metal-cup vacuum extractors are rarely used in the United States.

Soft Cups:
Compared with metal-cup devices, soft-cup vacuum extractors cause fewer neonatal scalp injuries. However, these instruments have a higher failure rate.

Soft-cup instruments can be used with a manual vacuum pump or an electrical suction device. Some have a built-in vacuum-release valve that allows pressure to be rapidly attained and accurately controlled. This results in easy maneuverability and simplicity of operation. Soft-cup vacuum extractors may be disposable or reusable.

Traditionally, the soft cups are bell or funnel shaped. A newer variety, the mushroom-shaped vacuum cup, or M-cup, combines the advantages of soft and metal cups. The soft sidewall of the M-cup minimizes infant scalp trauma compared with the Malmström metal cup.

Vacuum Extractors and Forceps:

In Europe, the vacuum extractor has long been the instrument of choice for assisted vaginal delivery. In the United States, the forceps has been preferred, although the vacuum extractor is becoming increasingly popular.