Failed Vacuum Delivery

Failed vacuum delivery is failure to deliver with a vacuum cup after 3 pulls with no descent, 2 cup detachments, or 20 minutes of application. It results from an incorrect cup position, poor traction direction, an occiput posterior or transverse head, disproportion, a large caput or poor expulsive effort. It matters because persistence causes scalp injury, subgaleal haemorrhage and intracranial haemorrhage, and caesarean section is then needed.

• Risk factors: occiput posterior position, station above +2, large baby, obesity, maternal exhaustion, preterm baby (below 34 weeks vacuum is avoided).
• Vacuum is not used for face or brow presentation, bleeding disorders in the fetus, or before 34 weeks.
• A well positioned flexion point cup improves success.

The cup detaches (pops off) or the head fails to advance with traction, and a chignon (caput under the cup) appears. The woman is tired, and the fetal heart may show decelerations during pulls.

• Cup detaching twice or no descent with 3 pulls.
• Caput that spreads beyond the cup site.
• Differential diagnosis: wrong cup placement, occiput posterior or transverse position, cephalopelvic disproportion, weak maternal effort, deflexed head, obstructed second stage.
• Complications: scalp laceration, cephalohaematoma, subgaleal haemorrhage, intracranial haemorrhage, retinal haemorrhage, neonatal jaundice, third and fourth degree tears, caesarean section, maternal vaginal tears.

The diagnosis is made at the time of failure, by reviewing application, position and the number of pulls.

• Confirm full dilatation, station, position and flexion; check cup placement (centre of the cup over the flexion point, about 3 cm in front of the posterior fontanelle on the sagittal suture).
• Count pulls, detachments and minutes; check the vacuum pressure (0.8 kg/cm2, or 500 to 600 mmHg).
• Cardiotocography between pulls; maternal pulse and blood loss.
• Examine the baby for scalp swelling, bleeding and head circumference after birth.

The principle is to stop vacuum at the limit and deliver by caesarean section, with attention to the newborn scalp.

• Supportive: stop and release the vacuum; paediatric team called; empty the bladder; two cannulae and group and cross-match 2 units; senior help; consent for caesarean section; mark the time of the first application.
• Pharmacological: cefazolin 2 g IV as a single dose before incision (3 g above 120 kg); oxytocin 10 IU IM after birth, then 20 IU in 1 litre Ringer's lactate at 125 mL per hour for 4 hours; tranexamic acid 1 g IV over 10 minutes if bleeding exceeds 500 mL; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); newborn vitamin K 1 mg IM and, for suspected sepsis, benzylpenicillin 50 mg/kg IV 12-hourly plus gentamicin 5 mg/kg IV 24-hourly.
• Procedures: caesarean section for failed vacuum; forceps only if a skilled operator judges the head low, the position is certain and the fetus is not compromised, and never after 3 detachments; no further vacuum attempts.
• Red flags: scalp swelling that crosses suture lines and spreads (subgaleal haemorrhage), pallor, tachycardia, floppy baby, abnormal fetal heart rate, bleeding above 500 mL.
• Follow-up: newborn observation for 24 to 48 hours with scalp checks, head circumference 4-hourly for 12 hours, haemoglobin at 6 and 24 hours and bilirubin from day 2; maternal review at 6 weeks.