Vacuum-assisted vaginal delivery

Abstract

Approximately 5% (1 in 20) of all deliveries in the United States are operative vaginal deliveries. The past 20 years have seen a progressive shift away from the use of forceps in favor of the vacuum extractor as the instrument of choice. This article reviews in detail the indications, contraindications, patient selection criteria, choice of instrument, and technique for vacuum-assisted vaginal delivery. The use of vacuum extraction at the time of cesarean delivery will also be discussed. With vacuum extraction becoming increasingly popular, it is important that obstetric care providers are aware of the maternal and neonatal risks associated with such deliveries and of the options available to effect a safe and expedient delivery.

Keywords: Operative vaginal delivery; Vacuum; Vacuum-assisted vaginal delivery.

Figure 1

Malmström ventouse. The original vacuum extractor developed in the 1950s by the Swedish obstetrician Dr. Tage Malmström is shown, including the metal mushroom cup (M cup), traction bar, and suction device.

Figure 2

Types of vacuum cups. The 2 main types of hand-held disposable vacuum devices are shown: (A) The soft cup, which is pliable and funnel- or bell-shaped. (B) The rigid cup, which is firm and mushroom-shaped (M cup). They can be made of plastic, polyethylene, or silicone. The freely rotating stem of the hand-held device (shown as an arrow) prevents torque (rotation) of the cup and resultant cookie-cutter injuries to the fetal scalp.

Figure 3

Placement of the obstetric vacuum. Correct placement of the suction cup on the fetal scalp is shown. The suction cup should be placed symmetrically astride the sagittal suture at the median flexion point (also known as the pivot point), which is 2 cm anterior to the posterior fontanelle or 6 cm posterior to the anterior fontanelle.

Figure 4

Fetal scalp injuries associated with vacuum extraction. Caput succedaneum (scalp edema) is a normal finding, but may be exaggerated by vacuum-assisted delivery. Use of a vacuum device can cause a cephalohematoma (which refers to bleeding into the fetal scalp that is located in the subperiosteal space and, as such, is contained anatomically to a single skull bone) or a subgaleal hematoma (bleeding into the fetal scalp which is subaponeurotic and therefore not confined to a single skull bone). The most serious complication is an intracranial hemorrhage, which includes subarachnoid, subdural, intraparenchymal, and intraventricular hemorrhage.