Operative Vaginal Delivery Riskier at Lower Volume Hospitals

Hospitals doing fewer operative vaginal deliveries (OVDs) had higher rates of adverse perinatal outcomes for these cases than higher volume centers did, according to a population-based retrospective cohort study from California.

Hospitals with less than 5.2% of all deliveries done vaginally with forceps or vacuum device assistance had around 30% more shoulder dystocia and obstetric anal sphincter injury, 73% more brachial plexus injury, and 2.57-fold higher subgaleal hemorrhage risk compared with high OVD volume hospitals (≥7.4%), all statistically significant.

Even intermediate volume hospitals had a 72% higher risk of subgaleal hemorrhage and 35% more brachial plexus injury than high-volume hospitals, both significant, reported Aaron Caughey, MD, PhD, of the department of obstetrics and gynecology at Oregon Health & Science University in Portland, and colleagues in JAMA Network Open.

“We know from other literature that higher volumes of procedures are needed to maintain lower complication rates, so we wondered if the same were true for operative vaginal deliveries,” Caughey told MedPage Today.

OVD rates have been decreasing in the U.S. — from 9.4% of deliveries in 1994 to just 3% in 2014 — but increasing in popularity in European countries. Conversely, cesarean delivery has been on the rise in the U.S., though other factors like patient choice and comorbidities play a role in that trend. Previous research has shown that hospitals with higher OVD rates had lower cesarean delivery rates.

Reasons for low OVD rates are hypothesized to include lack of clinician comfort and experience, patient preference, and fear of litigation, which may influence doctors to opt for cesarean delivery instead.

Caughey’s group concluded that their findings “underscore the importance of further research and interventions aimed at improving neonatal outcomes, particularly in low-volume settings.”

Pamela Berens, MD, an ob/gyn at the McGovern Medical School at UTHealth Houston, who was not involved with the study, pointed out that the authors couldn’t account for diabetes, which is a huge risk factor for adverse outcomes like shoulder dystocia. She also noted that even though OVD is less prevalent than it once was, guidelines for OVD have gotten better with time.

“I don’t think you should take this article and say, ‘oh, you shouldn’t have a vacuum or forceps delivery at a low volume hospital’ — because I think that will make those low-volume hospitals then not give that as an option,” Berens said.

She cautioned that lack of experience can cascade: “If it’s something that you might be sued for, you’re going to do it less, and then you’re going to be less experienced at it, and then you’ll be less good at it, and then you’ll do it even less.”

Both Berens and Caughey noted that simulations could be a way to have less experienced doctors get more OVD experience and thus get better at it.

The study used linked birth and fetal death certificates from the California Department of Public Health and hospital discharge data from the Department of Health Care Access and Information, all from 2008 to 2020. Pregnant individuals with singleton, non-anomalous deliveries with vertex presentation at full-term (37-42 weeks) were included. Spontaneous vaginal deliveries, cesarean deliveries, or unknown mode of delivery were excluded.

Among the 306,818 OVDs, the mean birth parent’s age was 28.5, and half of patients had public insurance. Demographics were fairly comparable across groups, although high OVD volume hospitals had slightly more Asian or Pacific Islander patients and low OVD volume hospitals had more Hispanic patients.

Hospital OVD volume was estimated by the number of OVDs among all deliveries. The 274 California hospitals were broken into tertiles, with 96 hospitals having low OVD volume, 90 having intermediate volume, and 88 having high volume.

Hospitals with low OVD volume had more adverse perinatal outcomes than intermediate and high volume hospitals, including:

• Shoulder dystocia (3.84% vs 3.50% vs 2.80%)
• Subgaleal hemorrhage (0.27% vs 0.18% vs 0.10%)
• Brachial plexus injury (0.41% vs 0.30% vs 0.20%)

Low OVD volume hospitals also had more obstetric anal sphincter injury compared to hospitals with medium and high volumes (12.16% vs 11.07% vs 9.45%; adjusted RR 1.36 for low vs high, 95% CI 1.14-1.62).

In terms of limitations, the authors noted that using administrative data collected for non-research purposes introduces variability in reliability and accuracy. The dataset also didn’t include variables like the hospital’s trauma level, physician type, or patient medicine coverage, which could be confounders. They also noted that the findings should be applied with caution to areas that have different hospital policies, obstetric practices, and demographics than California.

Caughey explained that while the data didn’t allow analysis by provider, looking at each hospital reflects the average operative vaginal delivery rate per provider.

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