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Clinical Reviews


Reducing the medicolegal risk of vacuum extraction

Focus on indications, informed consent, technique, and documentation to yield better outcomes

June 2007 · Vol. 19, No. 06

IN THIS ARTICLE

CASE Three hours of pushing

C.A., age 29 years, is 40 weeks’ pregnant with her first child. After an unremarkable pregnancy, she arrives at the hospital for cervical ripening and induction of labor. Oxytocin is given, and labor progresses uneventfully. When C.A.’s cervix is dilated 8 cm, however, labor stalls. The physician orders placement of a pressure catheter and increases the dosage of oxytocin, and the cervix dilates fully. Although C.A. pushes well, the vertex descends only from +1 to +2 station (of 5 stations) after 3 hours.

How would you manage this delivery?

One option in C.A.’s case is operative vaginal delivery using the vacuum extractor, which has replaced the forceps as the most commonly used approach for operative vaginal delivery. Like the forceps, the vacuum extractor has vociferous detractors as well as supporters. Liberal use of cesarean section and questions regarding the safety of operative vaginal delivery vis-à-vis cesarean section have fueled the debate over its role in obstetric practice.

Among the benefits of vacuum extraction are its cost-effectiveness and shorter hospital stay (TABLE 1). It also obviates the need for cesarean section, including repeat cesarean. Risks include an increased incidence of genital tract trauma and a greater risk of fetal subgaleal hemorrhage.

We review 4 critical spheres of concern in regard to vacuum extraction:

  1. Patient selection
  2. Informed consent
  3. Technique
  4. Documentation

Increased understanding of these aspects of vacuum extraction will improve outcomes for the patient and limit medicolegal risk.

In the case of C.A., the physician offered 3 options:

  • Continue maternal expulsive efforts to allow descent
  • Attempt delivery by vacuum extraction
  • Proceed to cesarean section on the basis of protracted descent.

Risks and benefits were reviewed with the patient, who chose to deliver by cesarean section. A 3,780-g infant in occiput posterior position was delivered safely.

TABLE 1

Delicate balance: Risks and benefits of operative vaginal delivery

WHO?

BENEFIT

RISK

Mother

Cost-effective
Less blood loss
Lower risk of febrile morbidity
Maternal preference
No need for cesarean section or repeat cesarean
Shorter hospitalization and convalescence

Increased incidence of genital tract trauma
Possible damage to pelvic floor, with urinary and anal incontinence

Fetus

Fewer respiratory difficulties at birth

Increased risk of subgaleal hemorrhage
Association with shoulder dystocia

1. Patient selection: Maternal and fetal indications

Vacuum extraction may be justified for maternal or fetal indications.1,2 Maternal indications include prolongation or arrest of the second stage of labor, or the need to shorten the second stage, for reasons such as maternal cardiac disease, complex congenital cardiovascular disorders, and maternal exhaustion.

No definitive time limit for the second stage of labor

There is more flexibility today than in the past about what constitutes a “safe” length of the second stage. Recommendations concerning when the mother should begin pushing—and for how long—have evolved from a strict time limit to a focus on progression. If the fetal heart rate (FHR) tracing is reassuring, the second stage no longer needs to be limited to 2 or 3 hours. On the contrary, if the patient is still able and willing to push, changes in positioning and further expectant management remain acceptable in contemporary practice.3 Otherwise, a trial of vacuum extraction may be appropriate.

Vacuum extraction is particularly useful when the mother has difficulty pushing because of exhaustion and the fetal head has descended enough that it distends the labia between contractions, as in outlet deliveries.

Fetal indications

Fetal indications for operative vaginal delivery include distress, jeopardy, or a “nonreassuring” FHR tracing. Such a tracing may include late and prolonged decelerations, baseline bradycardia or tachycardia with or without variable decelerations, or, occasionally, a normal baseline rate with diminished variability.

Use vacuum or forceps?

The choice depends on which device would achieve delivery in the safest manner with the lowest risk of fetal injury. With the vacuum, force is exerted directly on the fetal scalp and only secondarily on the fetal skull. This puts fetal vessels that traverse the subgaleal space at risk for injury (FIGURE). With forceps, force is exerted directly on the fetal skull and mitigated by the petrous bone. Little or no force is exerted on the fetal scalp, lessening the risk of traumatic injury such as potentially fatal subgaleal hemorrhage.

Indications and contraindications for vacuum extraction are similar, but not identical, to those for forceps delivery (TABLE 2).2,3 The most important determinant for either device is the experience of the operator. You must be familiar with the instrument and technique before making any attempt to assist delivery. An inability to accurately assess fetal position or station, fetopelvic proportion, adequacy of labor, engagement of the fetal head, or any degree of malpresentation (including minor degrees of deflexion) is a contraindication to a trial of operative vaginal delivery.

Vacuum extraction should be reserved for fetuses at more than 34 weeks’ gestation because of the increased risk of intracranial hemorrhage associated with prematurity.

All decisions involving vacuum extraction should be made with caution. The adequacy of the pelvis, estimated fetal size, and any suggestions of fetopelvic disproportion are of particular significance.3


FIGURE

Subgaleal hemorrhage, a deadly complication

Blood can accumulate in a large potential space between the galea aponeurotica and the periosteum of the cranial bones after vacuum extraction. An infant with subgaleal hemorrhage will exhibit a boggy scalp, with swelling that crosses the suture lines and expands head circumferenceTABLE 2

Factors that predict success—or failure—of vacuum extraction

When a woman fits overlapping categories, the decision to use vacuum extraction—or not—may be a judgment call*

GOOD CANDIDACY

Multiparous

Term pregnancy

Occiput anterior position, well-flexed

Wide subpubic arch

Compliant

MARGINAL CANDIDACY

Primiparous

Post-term

Occiput posterior position

Average subpubic arch

Gestational diabetes

Arrest disorders in second stage

POOR CANDIDACY

Protraction disorders in second stage

Narrow subpubic arch

Uncertain position of fetal head

Deflexion or asynclitism

Anticipated large-for-gestational-age infant

Poor maternal compliance

* When faced with a good indication in a marginal candidate, we recommend delivery in a “double setup” situation in which preparations are made for both vacuum extraction and cesarean section. If the vacuum can be properly applied, the first application of traction is crucial. We will only proceed if significant descent is achieved. If the fetal head (not the scalp) can be advanced a full station, then we proceed cautiously. If not, ready access to cesarean section allows for completion of the delivery in a timely manner.

2. Informed consent: Elicit the patient’s desires

Thorough discussion with the patient and her family—to explain the reasoning behind the clinical decision to use the vacuum extractor and delineate the alternatives—is paramount. Moreover, the patient should be encouraged to actively participate in this discussion.

Among the alternatives to vacuum extraction are expectant observation and expedited delivery by cesarean section. Because patients increasingly are requesting elective cesarean section in the absence of obvious obstetric indications, this option should receive extra attention.

Most women still consider vaginal delivery an important milestone of female adulthood. When safety concerns arise and the situation makes vaginal delivery unwise, many women experience disappointment and postpartum depression over their “failed” attempt at vaginal delivery. These perceptions need to be addressed in discussions with the patient.

The risk–benefit equation

Vacuum extraction lessens the risk of maternal lacerations, either of the lower genital tract in the case of obstetric forceps, or of the cervix and lower uterine segment in the case of cesarean section. In addition, vacuum extraction can be performed comfortably in the absence of regional anesthesia.

Avoiding cesarean section can produce multiple benefits

Another maternal benefit of vacuum extraction is the decreased need for cesarean section. A reduction in the primary cesarean rate also lowers the need for repeat cesarean section, which can be more technically challenging than primary C-section due to the presence of dense scar tissue and intra-abdominal adhesions. Cesarean section also increases the risk of placenta accreta, increta, or percreta in subsequent pregnancies. These complications increase the likelihood of emergency hysterectomy, massive blood loss, and serious maternal morbidity and mortality.

Even in the absence of placenta accreta, both primary and repeat cesarean sections raise the risk of hemorrhage and febrile morbidity, prolong convalescence, and increase cost, compared with vaginal delivery. For these reasons, avoiding primary cesarean section can obviate the need for multiple surgical procedures and their attendant risks. The degree to which these factors favor vaginal delivery over cesarean section is subject to debate.

Maternal risks include pelvic floor trauma

Both vacuum extraction and forceps delivery increase the risk of anal sphincter injury and can impair fecal continence.4 Both methods also appear to increase trauma to the genital tract in comparison with spontaneous delivery and may predispose the woman to pelvic floor dysfunction, including urinary and anal incontinence.5-10 However, anal sphincter trauma was less frequent after vacuum extraction than after forceps delivery.1

Other maternal injuries associated with vacuum extraction include perineal lacerations and injuries to the vulva, vagina, and cervix. Vacuum extraction also has been implicated as a significant risk factor for postpartum hemorrhage11 and genital-tract infection.1

Fewer neonatal respiratory problems with vaginal delivery

Compared with cesarean section, vaginal delivery is thought to diminish the risk of intrapartum aspiration and respiratory problems in the newborn. It also may facilitate the transition from fetal to neonatal circulation and reduce the need for immediate resuscitation at birth.

Neonatal risks include soft-tissue injury and potential hemorrhage

Infants delivered by vacuum extraction have a significantly higher rate of intracranial hemorrhage, brachial plexus injuries, convulsions, central nervous system depression, and the need for mechanical ventilation, compared with spontaneously delivered infants (TABLE 3).12,13

Although vacuum extraction is associated with a wide range of soft tissue injuries, they are often less serious than the fetal scalp injuries associated with obstetric forceps. Cup marks, bruising, and minor lacerations of the scalp and caput succedaneum are common fetal injuries, although the majority resolve without apparent sequelae.14

Subgaleal hemorrhage is the most serious neonatal complication of vacuum extraction, occurring in 1% to 3.8% of vacuum extractions (FIGURE).15 It coexists with neonatal coagulopathy in 19% to 29% of newborns16 and increases the risk of progression to hemorrhagic shock and death. Subgaleal hemorrhage has a mortality rate ranging from 2.7% to 22.8%.15-17

Cephalhematoma is another complication associated with vacuum extraction. It involves an accumulation of blood beneath the periosteum of a cranial bone (usually the parietal bone), and it almost always resolves spontaneously. The incidence of cephalhematoma varies. It is significantly more common in deliveries involving vacuum extraction (9.8%) than in forceps deliveries (4.1%).18 Its incidence increases with the length of time the vacuum cup is applied and with paramedian application.18

Intracranial hemorrhage occurs in 1 of 860 vacuum extractions, 1 of 664 forceps deliveries, 1 of 954 cesarean deliveries, and 1 of 1,900 spontaneous deliveries.12 Subdural hemorrhage is the most common form of intracranial hemorrhage and is almost invariably the result of birth trauma. However, asymptomatic subdural hematoma occurs in up to 6.1% of uncomplicated vaginal deliveries.19

Other, less common types of intracranial hemorrhage, such as subarachnoid, intraventricular, and intraparenchymal hemorrhage, have a more complex etiology, which includes birth asphyxia, hemorrhagic diathesis, infection, and vascular abnormalities.20

Retinal hemorrhage also may occur after vacuum extraction, with an incidence of 49% to 77.8%, compared with 30.3% after forceps delivery, 30.4% after normal vaginal delivery, and 8.3% after cesarean delivery.21 It generally resolves spontaneously without any permanent damage.22

TABLE 3

Vacuum extraction can injure the fetus

DIRECT INJURY

Cephalhematoma

Intracranial hemorrhage (parenchymal, subdural, intraventricular, subarachnoid)

Nerve injury

Scalp laceration, abrasion, ecchymoses, necrosis

Skull fracture

Subgaleal hemorrhage

INDIRECT INJURY

Anemia, hyperbilirubinemia

Brachial plexus injury

Scalp infection or abscess

SOURCE: O’Grady et al31

Shoulder dystocia and brachial plexus palsy

Vacuum extraction also is associated with shoulder dystocia and brachial plexus palsy, although the primary risk factor for these complications is thought to be increased fetal size.23-25 The incidence of shoulder dystocia with vacuum extraction is 3.5%, compared with 1.5% for forceps delivery.25

The risk of brachial plexus palsy also increases with vacuum extraction, especially as the duration of the procedure increases.25

Less common complications associated with vacuum extraction are skull fractures, fetal hemorrhage from bleeding at the site of scalp electrodes, sepsis originating from infected scalp trauma, and corneal injury.

No long-term impairment

Long-term outcome studies of children delivered by vacuum extraction show no differences in physical or cognitive functioning or intelligence scores, compared with other modes of delivery.26

3. Technique: Create conditions that ensure success

Continued...
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