There is little objective study of the maneuvers employed for shoulder dystocia and their effectiveness in preventing neonatal injury, let alone prospective studies comparing the effectiveness of one maneuver vs. another. The choice of maneuvers thus remains provider specific. The maneuvers that are most commonly employed for shoulder dystocia, however, are utilized in order to disimpact the anterior shoulder from behind the symphysis pubis by effecting its rotation.
It is important to appreciate that the McRoberts maneuver, with or without suprapubic pressure, may be successful in only approximately 50% of shoulder dystocia cases.
Unfortunately, many young obstetricians have had limited exposure to shoulder dystocia and may have employed only this maneuver, and not others, in their clinical training. At some point, they will likely encounter a shoulder dystocia case that does not respond to the McRoberts and/or suprapubic pressure maneuvers. It is critical to be competent in performing a full repertoire of potentially effective maneuvers.
There is increasing evidence that obstetricians should have a low threshold for utilizing delivery of the posterior shoulder in the management of shoulder dystocia.
In one recently published, multicenter review of shoulder dystocia maneuvers, for instance, investigators identified women who had incurred a shoulder dystocia during delivery and compared cases involving neonatal injury with injury-free cases. Delivery of the posterior shoulder was associated with the highest rate of successful delivery, when compared with other maneuvers, and with similar rates of neonatal injury (Obstet. Gynecol. 2011;117:1272-8).
The value of posterior arm release lies in its ability to reduce the anterior-posterior diameter of the fetus more significantly than any other maneuver. It has been associated with a marked decrease in anterior nerve stretch and the force required to effect delivery (Obstet. Gynecol. 2003;101:1068-72; Am. J. Obstet. Gynecol. 2010;203:339.e1-5).
In many litigated cases involving shoulder dystocia and brachial plexus injury, it is asserted that unnecessary excess traction must have been employed for a permanent injury to have occurred. Such assertions imply that the obstetrician can perfectly gauge the amount of traction or force necessary to deliver the infant and yet avoid injury in the setting of shoulder dystocia, which is not the case.
Increasing evidence suggests that many cases of brachial plexus injury accompanying shoulder dystocia are multifactorial in origin, and are not simply a result of operator-induced traction and stretching of the nerves. Obstetricians are continually instructed early on in their careers that excess traction should be avoided, as should any fundal pressure that might further disimpact the shoulders.
I simply recommend abandoning any traction efforts once shoulder dystocia is clearly recognized. When the complication occurs, a team consisting of additional nursing personnel, anesthesia, and the most experienced obstetrician available should be immediately summoned, and expulsive efforts on behalf of the mother should be curtailed while maneuvers are being undertaken to disimpact the shoulders.
If two obstetricians are present, it often is helpful for the stronger of the two to deliver appropriate suprapubic pressure from above. The goal is to move the shoulders to an oblique position by exerting pressure from the back of the fetus. This maneuver cannot really be done effectively by a single operator or from below as has been depicted in some textbooks. Again, if this fails to work, a low threshold should exist for attempting a posterior arm release.
Maintaining accurate documentation in the medical record of all events preceding and surrounding the shoulder dystocia is important. This includes but is not limited to the following:
▸ Consideration of significant risk factors for macrosomia, including diabetic pregnancy management and results of gestational diabetes screening tests.
▸ Estimation of fetal size, either clinically or by ultrasound. Most experts believe that diabetic mothers should undergo ultrasound at term to assess fetal size.
▸ Description of instrumental delivery, including indication and station at application and duration of use.
▸ A detailed step-by-step description of the maneuvers used to disimpact the shoulders. The anterior shoulder should be identified as part of the documentation.
Training and Simulation
During the past few years, simulation and drills and other enhanced teaching methods have become an increasingly common part of the curriculum for training residents and nursing personnel in the management of shoulder dystocia. Because the complication occurs relatively infrequently but can have devastating consequences when it does, shoulder dystocia is one of only several obstetric emergencies to be targeted in efforts to improve patient safety.
As with the few other obstetric events that receive such attention, data on the impact of enhanced training on perinatal outcomes remain limited. There clearly is evidence that simulation and drills improve team performance, and it has been hoped that improved team performance will ultimately translate to better outcomes. At present, two studies have indicated that the incidence of brachial plexus injury may decline with the implementation of targeted training for maternity staff.