Simulation Training Assessment Tool (STAT)– Vacuum Assisted Delivery
Indications for operative vaginal delivery
The most recent ACOG Practice Bulletin on this subject (June 2000) states that “No indication for
operative vaginal delivery is absolute.” This being said, in the right hands, these procedures can allow
you to deliver a fetus safely and rapidly and they are an essential part of any obstetrician’s training.
Indications for an Operative Vaginal Delivery according to ACOG include:
-
Presumed or imminent fetal compromise (example – severe variable decelerations or
repetitive late decelerations with pushing)
Maternal indication for shortened/passive 2nd stage (example – severe maternal cardiac
disease or CNS disease)
Prolonged 2nd stage of labor (see below for definitions as they differ for
nulliparous/multiparous pts)
Aftercoming head of a vaginal breech delivery
Having stated the common indications for an operative delivery, there are other criteria which must be
met prior to performing an operative delivery. You must know the following:
-
Size of baby (EFW)
Leading part of fetal skull: at +2 station or lower
Adequate pelvis
Adequate pain control
Cervix is completely dilated
Known fetal head position (i.e. OA, OP, LOA, etc)
Ruptured membranes
Acronym: SLAACKR
Size of baby – The first parameter you must consider is whether or not you believe this infant is
small enough to be delivered vaginally. This is why performing Leopold maneuvers at the time of
admission is important in establishing an estimated fetal weight. If you feel that the child is large (fetal
weight > 4000gms) then, although you may attempt the delivery if you feel the pelvis is adequate (or
large enough to allow passage of the fetus), there is a higher chance of a shoulder dystocia and you
must be prepared for this complication.
Leading part of fetal skull at +2 station or lower – If the fetus is not at least at +2 station, then
you are performing a mid forceps delivery, which is only rarely used when it is felt that the fetus can be
more rapidly delivered by this method than be cesarean.
Adequate pelvis – If, on clinical pelvimetry, you determine that the patient has a contracted
pelvis, then performing an operative delivery is contraindicated. Regardless of how much traction you
apply, if the space is too small, the baby still won’t fit.
Adequate pain control – In general, some form of conduction anesthesia (spinal/epidural) is
required to perform a forceps delivery. The pressure from the application can be very painful. With a
vacuum device, less anesthesia is needed for the application, which is one reason this device is often
used. If the patient does not have conduction anesthesia, then a pudendal nerve block may be
attempted.
Cervix completely dilated – Unless the cervix is completely dilated, an operative vaginal delivery
should generally not be attempted. If any part of the cervix is caught in the forceps or vacuum device
then significant cervical lacerations and hemorrhage can occur.
Known fetal head position – In order to appropriately apply either forceps or a vacuum device, it
is imperative that you know the baby’s head’s position. This can be very difficult after a patient has
been pushing for several hours and developed caput, which is why is it important that you check the
fetal head position on EACH labor check and document it in the record.
Ruptured membranes—membranes must be ruptured if a vacuum delivery is to be attemped.
Vacuum Delivery (Basics)
Use of the vacuum device, although used by midwives and family practice physicians, can result
in complications just like forceps. After determining that an operative vaginal delivery is indicated, and
going through your acronym SLACCKR, consider whether you can use a vacuum. (i.e. gestational age at
least 34 wks, no known bleeding disorders, and no need for rotation) General reasons for choosing a
vacuum device over forceps are, experience with vacuum device and less need for pain control for
placement.
Application and Traction:
After counseling the patient and confirming fetal head position, empty the patient’s bladder.
Then place the vacuum device such that it covers in the midline the vertex. Make sure that it does not
overlap either the anterior or posterior fontanelles, and that there is no vaginal tissue trapped in
between the vacuum and the fetal scalp.
When the patient experiences a contraction, have your assistant bring the pressure up to an
appropriate level, which should not generally exceed 500-600mmHg or 0.6 to 0.8 kg/cm2 (This is where
you have to read the directions on the individual devices). After you have done this, apply traction with
each push in the appropriate axis (see the forceps portion for this description.) It is important to avoid a
“rocking” motion and gentle, steady traction should be used.
Between pushes RELEASE the pressure on the vacuum! This will decrease the incidence of
cephalohematoma as much as possible.
If the vacuum comes off three times, it is generally wise to abandon the procedure. Also, when
this happens, recheck the fetal head position, because, when the fetus is in the OP position, this will
often occur.
Contraindications for Operative Vaginal Delivery:
General Contraindications:
Specific for Vacuum:
-
Bone demineralization condition (Osteogenesis imperfecta)
-
Bleeding disorders (hemophilia, von Willebrand’s, etc)
Fetal head is not engaged
Head position is not known.
-
Preterm status (< 34 wks gestation) (because of risk of fetal IVH)
-
Face presentation
Complications of Operative Vaginal Delivery
There are potential complications involved in the use of both forceps and vacuum devices. It is
imperative that you are knowledgeable regarding both maternal and fetal complications so that you can
do your best to avoid them, and how to correct them should they occur.
Vacuum* –
Maternal Complications:
-
Vaginal lacerations: These tend to occur less often than with forceps, although if any
vaginal tissue is caught between the vacuum device and the fetal head, these can cause
significant hemorrhage afterwards. Any operative delivery, especially those that involve
an episiotomy, can result in third/fourth degree lacerations, although vacuum deliveries
are less likely than forceps to cause this.
Cervical lacerations
Postpartum hemorrhage
Endometritis (This occurs in 8% of vacuum deliveries. (Williams, 1991))
Fetal Complications:
-
Scalp lacerations (especially if a twisting movement, or “cookie-cutter” motion is
used to attempt to rotate the infant.)
- Cephalohematoma (approx 15%) (Johanson 1999)
- Subgaleal hematoma (bleeding between cranial periostium and epicranial
aponeurosis)
- Retinal hemorrhages
- Neonatal jaundice
*The overall incidence of serious complications with a vacuum extraction is approximately 5%.
(Robertson 1999)
Long-term Infant Consequences:
There have been two long-term studies of the cognitive development of children delivered by
forceps or vacuum extractor and these found no difference when compared to infants delivered
spontaneously. (Wesley BD 1993, Ngan HY 1990). The forceps study included nearly 1200 children
delivered via forceps and the vacuum study nearly 300 vacuum deliveries. Another study reported that
the risk on intracranial hemorrhage was not increased in over 7000 operative vaginal deliveries (both
vacuum and forceps) when compared with spontaneous vaginal delivery. (Garnella, 2001) These facts
are important to know when counseling patients as they are often nervous when you discuss these
interventions with them.
References:
Gailbraith RS. Incidence of neonatal sixth nerve palsy in relation to mode of delivery. Am J Obstet
Gynecol, 1994; 170:1158-1159.
Gardella C, Taylor M, Benedetti T, Hitti J, Critchlow C. The effect of sequential use of vacuum and
forceps for assisted vaginal delivery on neonatal and maternal outcomes. Am J Obstet Gynecol Oct
2001; 185(4):896-902.
Johanson RB, Menon BKV. Vacuum extraction versus forceps for assisted vaginal delivery (Cochrane
Review). In: The Cochrane Library, Issue 4, 1999. Oxford: Update Software.
Operative vaginal delivery. American College of OB/GYN Technical Bulletin #17, June 2000.
Ngan HY, Miu P, Ko L, Ma HK. Long-term neurological sequelae following vacuum extractor delivery.
Aust N Z J Obstet Gynaecol 1990; 30:111-114.