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:
- Patient selection
- Informed consent
- Technique
- 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.