Nearly Half of Brachial Plexus Injury Cases Occur Without Shoulder Dystocia

Jeff Craven

October 01, 2020

Brachial plexus injury often is thought to co-occur with shoulder dystocia, but the two complications appear to be unrelated, according to research published in Obstetrics & Gynecology.

Grace J. Johnson, MD, and colleagues at Baylor College of Medicine in Houston performed a medical review of 41,525 deliveries at Texas Children's Hospital between March 2012 and July 2019, identifying cases of brachial plexus injury, with and without shoulder dystocia, occurring and persisting. The researchers also evaluated whether clinical experience (5 years or fewer, 6-15 years, or more than 15 years since training) and education impacted the risk of children developing shoulder dystocia or brachial plexus injury.

There were 547 cases of shoulder dystocia in 26,163 vaginal births (2.1%) and 9 cases in 15,362 cesarean births (0.06%), while 33 cases of brachial plexus injury occurred overall. Nearly all brachial plexus injuries were in vaginal deliveries (30 cases; 0.1%), while 3 cases occurred in cesarean deliveries (0.02%). Of these, 14 cases (42%) of brachial plexus injury did not co-occur with shoulder dystocia. Brachial plexus injury that persisted to discharge was similar for children with shoulder dystocia (17 of 19 cases; 89%) and without shoulder dystocia (10 of 14 cases; 71%). In the 27 children with persistent brachial plexus injury, 2 of 23 children who received follow-up care continued to experience persistent brachial plexus injury at 9 months (1 case with shoulder dystocia) and 12 months (1 case without shoulder dystocia).

"The frequent co-occurrence of shoulder dystocia and brachial plexus injury coupled with the equally frequent occurrence of isolated brachial plexus injury suggests that both brachial plexus injury and shoulder dystocia often reflect two causally unrelated complications of uterine forces driving a fetus through the birth canal in the presence of disproportion between the passage and the shoulder girdle of the passenger," Johnson and colleagues wrote.

Results Unchanged by Clinician Experience

Factors that impacted the risk of brachial plexus injury in children without shoulder dystocia were lack of maternal diabetes (0 women vs. 6 women; P = .03) and second-stage labor length (mean 103 minutes vs. 53 minutes; P = .08). Johnson and colleagues found no significant between-group differences regarding operative delivery, maternal age, or gestational age.

The researchers also examined the experience of the clinician who delivered children with brachial plexus injuries, and discovered there were no significant differences in children who had transient as opposed to persistent brachial plexus injury based on the number of years a clinician had been in practice (P = .97). There also were no significant changes in the "ratios of brachial plexus injury per total deliveries, brachial plexus injury per vaginal deliveries, and brachial plexus injury per shoulder dystocia" despite the presence of education and training for shoulder dystocia.

Questions Require Further Study

Torri Metz, MD, MS, a maternal-fetal medicine subspecialist and associate professor of obstetrics and gynecology at University of Utah Health in Salt Lake City, said in an interview that the review by Johnson and colleagues was able to address limitations in previous studies by looking at the medical records of shoulder dystocia cases at a single tertiary care center.

"Brachial plexus injury occurs both with and without a diagnosis of shoulder dystocia. The finding that the non–shoulder dystocia brachial plexus injuries were associated with a longer second stage of labor suggests that these injuries can occur even prior to delivery of the fetal head and are often not related to maneuvers employed by an obstetrician during delivery," Metz said.

The findings that brachial plexus injury severity was unrelated to clinician experience suggests "the occurrence, severity, and persistence of brachial plexus injury may be unrelated to maneuvers by the practitioner at the time of delivery," she said.

Although Johnson et al. found education and training initiatives did not significantly impact the ratio of brachial plexus injury cases, "importantly, there are likely many other benefits to shoulder dystocia simulation including team communication and comfort of the practitioner in an obstetrical emergency. Thus, the conclusion should not be that simulation training should be abandoned," Metz explained.

The results of the study should be confirmed in future research, she noted. "Despite looking at all cases of shoulder dystocia at a tertiary center over a 7-year period, the incidence of brachial plexus injury is low enough that only 33 cases were evaluated. As such, many questions about obstetrical management and the risk of brachial plexus injury still require further study," said Metz, who was asked to comment on the study.

The authors reported no relevant financial disclosures. Metz is an editorial board member for Obstetrics and Gynecology. She was not involved in the review of this manuscript or the decision to publish it.

SOURCE: Johnson GJ et al. Obstet Gynecol. 2020 Oct. doi: 10.1097/AOG.0000000000004013.

This article originally appeared on, part of the Medscape Professional Network.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: