Expert Commentary
Is neonatal injury more likely outside of a 30-minute decision-to-incision time interval for cesarean delivery?
Not according to this study.
With such limitations, the application and use of the 30-minute “standard” by hospitals, professional societies, and the medicolegal community may not be appropriate. The literature may not justify using this arbitrary rule as the standard of care. Clearly, there are gaps in our knowledge and understanding of FHR abnormalities and the optimal interval for cesarean delivery. Therefore, it may be unfair and inappropriate to group all cases and clinical situations together.
CASE 2: 25 minutes from decision to preterm delivery
J. P. (G2P1) undergoes an ultrasonographic examination at 33.4 weeks’ gestation because of concern about a discrepancy between fetal size and gestational age. The estimated fetal weight is in the 5th percentile. Amniotic fluid level is normal, but the biophysical profile is 6/8, with no breathing for 30 seconds. Umbilical artery Doppler imaging reveals absent end-diastolic flow, and FHR monitoring reveals repetitive late decelerations.
The patient is admitted immediately to the labor and delivery unit and placed on continuous electronic fetal monitoring. Betamethasone is given to enhance fetal lung maturity. FHR monitoring continues to show repetitive late decelerations with every contraction.
After 10 minutes on the labor floor, a decision is made to proceed to emergent cesarean delivery. Within 25 minutes of that decision, a female infant weighing 1,731 g (3rd percentile) is delivered, with Apgar scores of 1, 1, and 4 at 1, 5, and 10 minutes, respectively. The infant is eventually diagnosed with moderate cerebral palsy.
Could this outcome have been prevented?
Published reports on the association between abnormal FHR patterns and adverse perinatal outcomes in preterm infants are even more scarce than they are for infants delivered at term. Case 2 highlights the fact that achievement of a 30-minute interval from decision to delivery doesn’t necessarily eliminate the risk of adverse neonatal outcomes and long-term morbidity.
One of the best evaluations of this association was published by Shy and colleagues in the 1980s.6 In that study, investigators randomly assigned 173 preterm infants to intermittent auscultation or continuous external fetal monitoring. Use of external fetal monitoring did not improve neurologic outcomes at 18 months of age. Nor did the duration of FHR abnormalities predict the development of cerebral palsy.6
A recent secondary analysis from a randomized trial evaluating the use of antenatal magnesium sulfate to prevent cerebral palsy revealed that preterm FHR patterns labeled as “fetal distress” by the treating physician were associated with an increased risk of cerebral palsy in the newborn.7 Although this analysis revealed an association, a causal link could not be established. Damage to a preterm infant’s central nervous system can occur before the mother presents to the ultrasound unit or clinic, and alterations to FHR patterns can reflect previous injury. In such cases, a short decision to incision interval would not prevent damage to the central nervous system of the preterm infant.
CASE 3: 5 minutes from decision to incision after uterine rupture
G. P. is a patient (G2P1) at 38 weeks’ gestation who has had a previous low uterine transverse cesarean delivery. She strongly wishes to attempt vaginal birth after cesarean (VBAC) and has been extensively counseled about the risks and benefits of this approach. This counseling has been appropriately documented in her chart. Her predicted likelihood of success is 54%.
Upon arrival in the triage unit, she reiterates that she hopes to deliver her child vaginally. Upon examination, she is found to be dilated to 4 cm. She is admitted to the labor and delivery unit, with reevaluation planned 2 hours after epidural administration. At that time, her labor is noted to be progressing at an appropriate rate.
After 5 hours of labor, the baseline FHR drops into the 70s. Immediate evaluation reveals significant uterine bleeding, with the fetus no longer engaged in the pelvis. The attending physician immediately suspects uterine rupture.
The patient is rushed to the OR, and delivery is complicated by the presence of extensive adhesions to the uterus and anterior abdominal wall. After 20 minutes, a female infant is delivered, with Apgar scores of 0, 0, and 1 at 1, 5, and 10 minutes, respectively. Medical care is withdrawn after 3 days in the NICU.
In a true obstetric catastrophe such as uterine rupture, should the decision to incision interval be 30 minutes?
Although it is rare, uterine rupture is a known complication of VBAC attempts. The actual rate varies across the literature but appears to be approximately 0.5% to 0.9% in women attempting vaginal birth after a prior lower uterine incision.8
If uterine rupture develops, both mother and fetus are at increased risk of morbidity and mortality. The risk of hypoxic ischemic encephalopathy after uterine rupture is about 6.2% (95% confidence interval [CI], 1.8–10.6), and the risk of neonatal death is about 1.8% (95% CI, 0–4.2).9 Uterine rupture also has been linked to an increase in: