Trauma Rates With OVD Unexpectedly High, Study Finds

A new investigation has found that rates of physical trauma following operative vaginal delivery (OVD) in Canada are higher than previously reported.

The cohort study of more than 1.3 million deliveries in the country found trauma rates were highest with forceps delivery, with more than 1 in 4 pregnancies resulting in maternal trauma and 1 in 105 infants experiencing neonatal trauma. Maternal and neonatal trauma following vacuum deliveries was less common, occurring in 1 in 8 pregnancies and 1 in 104 infants, according to the researchers, who reported their findings in the January issue of the Canadian Medical Association Journal.

Dr Giulia Muraca

“The rates of trauma following OVD in Canada are higher than previously reported, irrespective of region, level of obstetric care, and volume of instrument use among hospitals,” lead author Giulia Muraca, PhD, MPH, assistant professor of obstetrics and gynecology at McMaster University, Hamilton, Ontario, Canada, told Medscape Medical News. “While OVDs may be associated with low rates of morbidity in carefully selected circumstances, the uniformly high rates of trauma among forceps and vacuum deliveries documented across regions, levels of obstetric care, and hospitals show that such conditions do not apply to routine obstetric practice in Canada.”

The American College of Obstetricians and Gynecologists considers OVD a way to reduce the rate of cesarean deliveries. However, the group has also pointed to a decline in familiarity with the procedures among clinicians new to the field.

Current reports also show that while OVD accounts for up to 15% of deliveries in Canada, Australia, and the United Kingdom, the risks associated with the approach are heavily dependent on the expertise of the provider. Declining use of OVD in favor of cesarean delivery has reduced opportunities for clinicians to acquire proficiency in performing these deliveries, according to the researchers.

Given these various factors, the investigators said the consensus on the safety of OVD is under scrutiny.

“An examination of maternal and neonatal trauma among OVD in contemporary practice is necessary to ensure that healthcare providers, policymakers, and pregnant individuals are informed regarding the risks of OVD typically experienced in routine obstetric practice, rather than those encountered under ideal conditions,” Muraca said.

Over 1 Million Deliveries Studied

Muraca and her colleagues looked at 1,326,191 deliveries occurring across Canada (except Quebec) between April 2013 and March 2019. The researchers included all singleton, term (≥ 37 weeks), in-hospital deliveries to women who had not undergone a previous cesarean delivery.

The study’s primary outcome measures were composite maternal trauma and composite neonatal trauma. Maternal trauma included obstetric anal sphincter injury (OASI); cervical or high vaginal laceration; pelvic hematoma; obstetric injury to the pelvic organs, pelvic joints, or ligaments; injury to the bladder or urethra; and other pelvic trauma. Neonatal trauma comprised intracranial hemorrhage and laceration, skull fracture, severe injury to the central or peripheral nervous system, fracture of the long bones, injury to the liver or spleen, seizures, and neonatal death.

The analysis found that 38,500 (2.9%) of the cases involved attempted forceps deliveries while 110,987 (8.4%) were attempted vacuum deliveries. Of the attempted forceps deliveries, 1606 (4.2%) failed, while 8791 (7.9%) of attempted vacuum deliveries failed.

Maternal trauma was observed in 25.3% of all forceps deliveries (n = 9728) and 13.2% of all vacuum deliveries (n = 14614), the researchers reported. The most common form of maternal trauma was OASI, which was observed in 21.52% of women undergoing forceps delivery and 11.67% of those undergoing vacuum delivery, they said. The rates of all other forms of maternal trauma were higher among patients undergoing attempted forceps delivery than among their counterparts undergoing attempted vacuum delivery.

After adjusting for possible confounders, rates of maternal trauma remained higher with forceps than with vacuum deliveries (adjusted rate ratio, 1.70).

The rate of neonatal trauma was comparable for forceps (9.56/1000 live births) and vacuum deliveries (9.58/1000 live births). In these cases, damage to the peripheral nervous system was the most common form of neonatal trauma, occurring in 4.85/1000 live births with forceps delivery and 3.41/1000 live births for vacuum delivery, the researchers found.

Consider Morbidity Following OVD Against Potential Alternatives, Authors Say

According to Muraca, the rates of maternal trauma in her study — along with accumulating evidence of the severe long-term consequences of these injuries — demonstrates the importance of reporting timely, empirically derived risk measures that accurately reflect those that pregnant individuals may encounter in typical obstetric practice.

“Although there is merit in understanding the estimates of risk that can be achieved when conditions are optimal, the interpretation of these estimates can be misleading, especially given secular shifts in patterns of practice,” she said. “The failure to do so compromises women’s autonomy in making evidence-informed decisions regarding childbirth interventions, such as evaluating the short- and long-term risks of OVD and cesarean delivery.

Her group recommends that morbidity following OVD be weighed against potential alternatives to such procedures, which carry their own risks. “This includes an extended second stage of labor and a spontaneous vaginal delivery, or a second-stage cesarean delivery, both of which are associated with significant morbidity,” Muraca said. “However, a comprehensive consideration of high population rates of OVD morbidity also prompts questions about choice of instrument, obstetrician training in OVD use, and for recognizing cases that would benefit from a cesarean delivery earlier in labor.”

Alan Peaceman, MD, professor of obstetrics and gynecology at the University of Chicago’s Feinberg School of Medicine, said he was not surprised by the rates of sphincter injury, but that the rate of severe neonatal injury rate was higher than he expected. However, he added, “I don’t think clinicians should change their approach based on a single study. They should continue with the approach that they are most skilled at and is appropriate for the clinical circumstances.”

The study was funded by a grant from the Canadian Institutes of Health Research. Muraca and Peaceman have disclosed no relevant financial relationships.

CMAJ. 2022;194(1):E1-E12. Full text

A five-time Globe & Mail best-selling author, Michael Vlessides has been writing for the medical trade for more than two decades, covering a broad range of specialties.

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