Midpelvic forceps and vacuum deliveries are more traumatic than cesarean section

Taking a decision in favor of cesarean section is considerably safer than attempting midpelvic operative vaginal delivery in terms of reducing severe birth trauma and obstetric trauma reports a study finding published June 5, 2017 in Canadian Medical Association Journal (CMAJ).

Midpelvic arrest in second stage of labor and operative interventions are a test of obstetrician’s skills and experience. In recent year, there has been a shift towards cesarean section, increasing the rates of cesarean section worldwide.

In 2014, a consensus statement by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine supported operative vaginal delivery over cesarean delivery to bring down the cesarean rate and improve maternal and neonatal outcome. Although, ACOG statement was not specific for midpelvic operative vaginal delivery but included it in more general sense.

Studies on the risk and benefits of these two procedures are lacking and not stratified by the station of fetal head in pelvis, which is an important decisive factor for maternal and fetal outcome.

The researcher team involved in the current study looked at data across a span of 10 years including 187,234 singleton births which included all mid pelvic live or stillbirths via forceps or vacuum and C-section deliveries between 37 and 41 weeks of gestation that resulted in a singleton live birth or stillbirth.

In all the cases, the head was engaged and the leading point of fetal head was as above station +2 cm but below 0 station.

It was seen that infants born by midpelvic operative vaginal delivery in women having dystocia, with prolonged second stage of labor has 81% more chances of severe morbidity and mortality as compared to when they were delivered by cesarean section. It included higher rates of birth asphyxia, meconium aspiration syndrome and intracranial hemorrhage.

Forceps delivery and vacuum delivery exposed the neonate to nearly 5 times the risk of birth trauma, but the rates were considerably high (9.5 times ) in sequential application.

Rates of obstetric trauma were also quite higher using forceps (5 times the risk), vacuum (2.7 times the risk) and sequential instruments (3 times the risk) as compared to delivery by cesarean section. In addition, significant more third and fourth degree perineal tear occurred in women who had midpelvic forceps (19%), midpelvic vacuum (12%), and 20% among women who delivered using a combination of midpelvic vacuum and forceps.

Rates of maternal morbidity and mortality did not differ much in the two groups, but midpelvic forceps and vacuum use was associated with significantly higher rates of post-partum hemorrhage.

In that subset of women in which the midpelvic forceps application was done for fetal distress, the composite maternal morbidity and mortality was 48% lower in vacuum group, but nearly 3 times higher rates of obstetric trauma and higher rates of PPH was observed.

The association between midpelvic operative vaginal delivery and composite severe perinatal morbidity and mortality were significantly stronger in those women who had dystocia but not prolonged second stage of labor. Similar outcomes were seen in women who had fetal distress but not prolonged second stage of labor. Midpelvic forceps and vacuum deliveries are more traumatic than cesarean section.

The study showed that encouraging higher rates of operative vaginal delivery to reduce the rate of cesarean delivery comes at the cost of increase in severe perinatal and maternal morbidity and mortality, especially neonatal birth trauma, severe postpartum hemorrhage and obstetric trauma.

"It is important to understand that similar to cesarean deliveries, midpelvic forceps and vacuum deliveries are invasive procedures with their own risks -- risks that we have now quantified and that should be communicated to women who may encounter them, especially when the risk is as high as one in five," says lead author, Giulia Muraca, a doctoral researcher at the School of Population and Public Health, University of British Columbia (UBC). "Women who are delivered by midpelvic forceps or midpelvic vacuum should be afforded the same standard of informed consent as women who consent to cesarean delivery. Ideally, this should take place prior to labour when women are considering their birth plans."

The full text of the journal article can be accessed here.