What is Vacuum Extraction or Ventouse Delivery?
Vacuum extraction or ventouse delivery is a procedure where an instrument known as the vacuum extractor or ventouse is used to assist and speed up delivery. A suction cap is applied to the baby’s head and gentle intermittent traction is given simultaneously with the uterine contractions and the mother’s bearing-down efforts.
One of the main concerns is the possibility of scalp injury and complications such as subgaleal hematoma (bleeding between the skull bone and overlying fibrous tissue) and intracranial hemorrhage (bleeding in the brain and cranium), although in experienced hands and when used correctly, the vacuum extractor is a relatively safe instrument.
Vacuum extraction delivery is an alternative to forceps delivery with the advantage in that it is less likely to cause maternal trauma.
The Vacuum Extractor or Ventouse
The vacuum extractor was introduced by Malmstrom in 1954 to assist delivery by the application of traction to a metal suction cup attached to the fetal scalp. It consists of :
- A specially designed suction cup, smaller at the rim than above, which holds the scalp tight against the base of the cup. There are 3 cup sizes available – 40 mm, 50 mm, and 60 mm.
- A hose connecting the suction cup to a suction pump.
- Intervening trap bottle and manometer
- A chain inside the hose connecting the suction cup to a crossbar for traction.
Various modifications have been made to this design. Bird’s modification of the suction cup allows better traction, while at the same time doing away with the need to thread the chain through the hose. The metal cup may be replaced by a soft silicone rubber cup, which is easier to manipulate and causes fewer fetal scalp injuries. Hand-held vacuum pumps and mechanical pumps with built-in regulators have further enhanced the safety of the procedure.
Indications for Vacuum Extraction
- Delay or maternal exhaustion in the second stage of delivery
- Uterine inertia
- Malposition of the fetal head
- Suspected fetal distress
- Epidural block with decreased ability to push
- To shorten the second stage of labor when there are maternal problems such as cardiac, respiratory, or cerebrovascular disease
Contraindications for Vacuum Extraction
- Known cephalopelvic disproportion
- Overlapping of the cranial bones, which may suggest cephalopelvic disproportion
- Breech, brow, or face presentation
- If the head is not engaged
- If membranes are not ruptured
- When there is high fetal risk
- When application of the ventouse proves difficult
- Fetal position or station is not definitely known
- If the fetus is less than 34 weeks
- Following failed forceps
- Large baby
- An underlying fetal condition such as bleeding diathesis or bone demineralizing disease which can result in intracranial hemorrhage or skull fracture.
Vacuum Extraction or Ventouse Procedure
- The mother lies in lithotomy position after emptying her bladder.
- Anesthesia by epidural or pudendal block may be given, although in many cases, no anesthesia may be necessary.
- The vulva and perineum are cleaned with an antiseptic fluid.
- The fetal presentation and position is checked by doing a pelvic examination.
- The largest cup that can be safely introduced is chosen.
- The soft cup is applied by compressing it and gently inserting it into the vagina.
- The cup is positioned to cover the posterior fontanelle.
- Care should be taken to avoid cervical or vaginal tissue from entering the cup.
- Negative pressure of about 0.6 kg/cm2 is induced.
- Well-sustained, even traction is given during uterine contraction but discontinued between contractions.
- The traction should be in line with the pelvic axis and should be perpendicular to the cup.
- Usually, 3 to 5 pulls should be enough to accomplish delivery when there is descent with each episode of traction.
- If there is no descent or the cup gets dislodged after 2 to 3 pulls, it is preferable to abandon the procedure and prepare for cesarean section, since failure of vacuum extraction indicates the possibility of cephalopelvic disproportion.
- The cup should not be applied for more than 30 minutes as it may damage the scalp.
- Any sign of injury to the fetal scalp demands immediate discontinuation of the procedure.
- Forceps can be used safely in premature infants as opposed to vacuum extraction.
- Forceps can be used to effect rotation of the fetal head, which is not possible with ventouse.
Complications of Vacuum Extraction or Ventouse
Complications usually occur due to improper use of the ventouse, such as use in circumstances where it is contraindicated, incorrect application, use of excessive negative pressure, overlong application of the suction cup on the fetal scalp, and not taking care to avoid cervical or vaginal tissue from entering the cup.
Maternal trauma and other complications are less common and may be less severe with ventouse than with forceps delivery. Maternal complications may include
- Perineal pain during delivery.
- Perineal injuries.
- Postpartum hemorrhage.
- Pain in the immediate postpartum period.
- Urinary retention.
- Urinary and fecal incontinence.
Fetal complications may include :
- “Chignon” or caput formation on the scalp, which looks like a lump, and usually resolves in 2 to 3 days.
- Scalp bruising.
- Subgaleal hematoma – bleeding in the potential space between the skull periosteum and the scalp galea aponeurosis – causing a boggy mass to develop over the scalp.
- Intracranial hemorrhage.
- Increased chance of retinal hemorrhage.
- Skull fracture.
Comparison of Vacuum Extraction or Ventouse with Forceps Delivery
- Although it is preferable that the cervix be fully dilated, in certain circumstances the ventouse can be used through a partially dilated cervix if the head is below the ischial spines. Forceps should never be used unless the cervix is fully dilated.
- Anesthesia requirements are less for ventouse than for forceps delivery. In some cases anesthesia may not be necessary at all.
- Except for “chignon” formation on the scalp, bruises and other injuries on the skin are less frequent with vacuum extraction than with forceps delivery.
- Cephalohematomas are more common in babies delivered by ventouse but unlike other cephalohematomas they tend to vanish in 2 to 5 days.
- Delivery may be quicker with ventouse than with forceps.
- Less maternal injuries with ventouse than with forceps.
- With vacuum extraction, there is less chance of anal sphincter injury than with forceps.
- An episiotomy is not always necessary for vacuum extraction but usually needs to be given for forceps delivery.
- Vacuum extraction is more likely to fail than forceps procedures during delivery.
- If vacuum extraction fails, forceps delivery may be tried in some cases, but vacuum extraction should not be tried after failed forceps.
- Facial nerve injuries are more common with forceps delivery.
- Vacuum extraction is contraindicated in breech presentation but forceps may be used to deliver the after-coming head in such cases.