The assumption that elective repeat cesarean will result in significantly fewer cases of long-term neurologic impairment is unproven at this time.
Similarly, Gregory et al reported on a cohort of 66,856 women with prior cesarean deliveries whose records were gathered from 1995 discharge data from the California Office of Statewide Health Planning and Development.7 In this cohort, 39,096 women attempted vaginal delivery, and 61.4% were successful. There were 209 uterine ruptures among women having a TOL (0.5%) and 79 ruptures among those having ERC (0.3%).
Perhaps the most influential recent investigation is a population-based longitudinal study by McMahon and colleagues suggesting that maternal morbidity might be greater with a TOL than with ERC.8 This study included 6,138 women with prior cesarean deliveries. Of these, 3,249 had a TOL, and 2,889 underwent ERC. There were 10 uterine ruptures (0.3%) among those in the TOL group, and 1 uterine rupture (0.0%) among those in the ERC group. There were no significant differences in hysterectomy, puerperal fever, or the need for transfusion. However, operative injuries were significantly more common among women having a TOL, while abdominal wound infections were significantly more frequent among those undergoing elective repeat cesarean.
McMahon et al classified uterine ruptures, hysterectomies, and operative injuries as “major complications,” and puerperal fever, transfusions, and abdominal-wound infections as “minor complications.” They found that pooled major complications were significantly more frequent in the TOL group, but that there was no difference between groups in pooled minor complications. This finding contradicted much earlier research, which suggested maternal morbidity would be reduced when a TOL was undertaken.
This influential study contributed greatly to the decrease in enthusiasm for a TOL. However, a careful examination of its data reveals that though there was greater risk of uterine rupture among women experiencing labor, that number was a quite low 0.3%. And while the difference was not significant, fewer hysterectomies were performed in the TOL group than in the ERC group. Overall maternal morbidity did not differ between the groups. Further, the classification of operative injury as a major complication and the need for blood transfusion as a minor complication is, at least, debatable.
Cutting the legal risks of VBAC
Medical liability claims spurred by complications associated with vaginal birth after cesarean (VBAC) are a disturbing fact. Although the risks of VBAC generally are very low, foremost among them is uterine rupture, which can have dire consequences for both mother and infant.
Of course, when a trial of labor (TOL) is successful—as it usually is—maternal morbidity is lower than with elective repeat cesarean (ERC). For this reason, properly selected and counseled patients should be allowed a TOL if they desire. Other recommendations to help minimize the possibility of litigation include:
Know the risks. As mentioned above, there is a low but significant risk of uterine rupture. In addition, placenta previa and placenta accreta are more likely to occur in women with a history of primary cesarean. If the TOL is unsuccessful, the likelihood of maternal and fetal complications increases further.1 Contraindications to a TOL include a previous uterine rupture, a prior classic or T-shaped uterine incision, a contracted pelvis, and maternal or fetal conditions that preclude vaginal delivery.1
Select patients carefully. Candidates for a TOL include women who have undergone a previous low-transverse cesarean and have no evidence of fetopelvic disproportion.1 Even women who have undergone up to (but not more than) 2 previous cesareans may be allowed a TOL, provided they have no other uterine incisions or contraindications to vaginal delivery. However, they should be counseled that the risk of uterine rupture is greater when there is more than 1 previous incision.
Assess the incision. If the previous incision was low transverse, and no other contraindications are present, the risk of rupture is 0.2% to 1.5%. Other incisions carry a significantly greater risk. These include low vertical (1% to 7% risk), T-shaped (4% to 9%), and classical uterine scars (4% to 9%).1
Appeal global mandates. Some insurers require all women with a previous cesarean delivery to undergo a TOL. Unfortunately, such policies can lead to attempted VBAC in cases where ERC is indicated.1 If a TOL would be unwise for your patient, bring her to the insurer’s attention rather than adhere to potentially harmful requirements.
Be conservative. Adopt a cautious approach in obstetric situations in which TOL is controversial, such as gestational diabetes, multiple gestation, postdate pregnancy, and suspected macrosomia.1,2
Ensure back-up. The obstetrician should offer a TOL only when he or she can ensure immediate access to surgical facilities for emergent cesarean, including skilled health-care personnel, anesthesia, pediatric specialists, and the proper instrumentation. When these are not available, the patient should undergo ERC or be transferred to a hospital that can provide them.1,3
Be vigilant. Continuous fetal monitoring is recommended. Support staff should be well educated about the signs of uterine rupture (nonreassuring fetal heart rate [FHR], abdominal pain, vaginal bleeding, hypovolemia, or a loss of station of the presenting part), and the obstetrician should remain nearby until the infant is delivered. If FHR tracings indicate a long deceleration to 60 to 70 bpm or severe and unresponsive variable decelerations, the obstetrician should intervene immediately. Note that epidural analgesia rarely obscures the signs of rupture.1,3
Write it down. In a number of cases, physicians have had to defend their actions in court based on their memory of how the delivery proceeded, since documentation in the patient’s chart was sparse. The solution? Write everything down. It’s better to have a thorough record and not need it than to need documentation that doesn’t exist.—ELLEN MOZURKEWICH, MD, MS
REFERENCES
1. American College of Obstetricians and Gynecologists. Vaginal birth after previous cesarean delivery. Practice Bulletin #5. Washington, DC: ACOG; 1999.
2. Coleman TL, Randall H, Graves W, et al. VBAC among women with gestational diabetes. Am J Obstet Gynecol. 2001;184(6):1104-1107.
3. Flamm BL. Vaginal birth after cesarean: reducing medical and legal risks. Clin Obstet Gynecol. 2001;44(3):622-629.