Assisted vaginal delivery is an important part of obstetric care. Indications for its use include prolonged second stage of labour, actual or potential fetal compromise or distress and to shorten labour. The established method is to grasp the fetal head with obstetric forceps and turn and position the head to facilitate the descent and birth of the infant. A vacuum extractor is becoming the method of choice as it is less likely to injure the mother although failure of attempted vacuum extraction may occur more often than with forceps. The vacuum extractor is contraindicated with face, brow or breech presentation and if the gestational age of the fetus is less than 34 weeks because of the risk of damage to the scalp (cephalhematoma) and intracranial bleeding.
The pressure for vacuum extraction can be increased in a stepwise procedure, to ensure attachment, or more rapidly. Rapid application would address the concern that vacuum extraction is too slow to be used when rapid delivery is required. Potential adverse effects of rapid application include detachment of the cup and injury of the infant’s scalp and blood vessels. Only one good quality randomised controlled trial involving 94 women was identified. Rapid negative pressure application for vacuum assisted vaginal birth reduced the duration of the procedure without any evidence of differences in outcomes for the mother or infant. Rapid application reduced procedure time by some six minutes (range 8.8 to 3.4 minutes). Rate of detachment of the cup, degree of perineal tears, low Apgar scores, acidic umbilical cord venous blood, damage to the scalp and number of tractions were not clearly different with rapid and stepwise negative pressure application for vacuum extraction assisted vaginal delivery. The small number of participants in the single included trial means that the evidence is limited.