Management of Shoulder Dystocia
Contemporary management of shoulder dystocia requires a calm operator and a well-thought-out plan of action. It is imperative that if not already present, help is summoned immediately after shoulder dystocia is recognized. This help may include additional nursing staff, an anesthesiologist, a pediatrician or neonatologist and an additional obstetrician or midwife. Future coordination may demonstrate that rapid response teams are best suited to attend to this emergency.
Once shoulder dystocia is identified, pushing should pause and the operator should prepare to implement maneuvers to relieve the dystocia. Appropriate positioning of the patient on the delivery table or bed with her buttocks at the end of the table is critical and will later allow for appropriate downward traction to facilitate delivery. The position of the fetal head should be noted, as this will need to be documented; knowledge of the head position will also allow for the appropriate application of suprapubic pressure.
Although many maneuvers have been described to alleviate shoulder dystocia, there are few prospective studies that have compared the various maneuvers. Retrospective studies have not demonstrated that any one maneuver is superior to the other at preventing birth injury.
McRoberts' maneuver, which involves flexing the maternal thighs against the maternal abdomen, is commonly used as a first maneuver since it is easy to do. It is also sometimes performed prophylactically in an attempt to decrease the risk of shoulder dystocia or to shorten the second stage of labor. A randomized trial designed to assess whether prophylactic McRoberts' maneuver and suprapubic pressure decreased the head-to-body interval in at-risk patients noted that the use of these combined maneuvers did not shorten the head-to-body delivery interval when compared with controls (24 ± 18 s vs 27 ± 20 s; p = 0.38). Gherman evaluated the success rate of McRoberts' maneuver when used as the initial maneuver for shoulder dystocia and compared morbidity between those cases relieved by McRoberts' maneuver and those that required additional maneuvers. In this cohort, the use of McRoberts' maneuver was associated with a high degree of success in relieving the dystocia and decreased morbidity compared with other maneuvers. Gonik has reported that this position reduces shoulder extraction forces, brachial plexus injury and clavicular fracture; however, it should be noted that some patients, particularly those who are obese, may not be able to be placed in an effective McRoberts' position.
Suprapubic pressure may be used as the first maneuver, or may be used in addition to McRoberts' maneuver or in conjunction with rotational maneuvers. It is advised that this pressure be applied with the operator's hand placed directly above the symphysis pubis and directed either posteriorly or laterally, toward the fetal face. This posterior or lateral directional force allows for further abduction of the fetal anterior shoulder. The combination of McRoberts' maneuver and suprapubic pressure has been reported to have a success rate of 58%. Fundal pressure should be completely avoided as it may worsen the obstruction and can also be associated with uterine rupture.
Some shoulder dystocias will not be relieved with McRoberts' maneuver and suprapubic pressure and rotational maneuvers will be required. Although obstruction of the bony pelvis will not be released by the performance of episiotomy, this step may best assist the operator in achieving room to perform rotational maneuvers or to deliver the posterior arm.
The Woods' screw maneuver and the Rubin's maneuver are the most commonly described rotational maneuvers used to deliver the posterior arm. Woods originally advised that although the shoulders might be too large to be directly delivered through the maternal pelvis by pushing alone, using the model of a screw, he described a technique wherein by applying pressure to the anterior aspect (clavicular) of the posterior shoulder and abducting and rotating that shoulder, the posterior shoulder could be rotated 180° degrees to the anterior, and this would disimpact the obstructed anterior shoulder. The subsequent addition of gentle downward traction with a contraction would then result in delivery.
Rubin described a modification to the Woods' maneuver that recommended that either the anterior or posterior shoulder, which ever was more accessible, be adducted and brought toward the fetal chest. In this maneuver the operator would place their hand on the posterior aspect (scapular) of the anterior or posterior shoulder and also rotate the baby 180° to reduce the obstruction. Rubin's original maneuver also included the concurrent application of lateral suprapubic pressure. After the application of either rotational maneuver, delivery is attempted through the application of gentle downward traction in conjunction with maternal expulsive efforts.
Should a rotational maneuver fail, or in lieu of attempting a rotational maneuver first, an attempt may be made to deliver the posterior arm. It is not incorrect for this maneuver to be used first to reduce shoulder dystocia and this is advocated by some authors. Poggi describes a geometrical model wherein the delivery of the posterior shoulder results in reducing the obstruction by a factor of two, relative to the performance of McRobert's maneuver. Baskett and Allen reported no neonatal injuries when posterior arm delivery was used as a primary method of delivery. When shoulder dystocia is not responsive to the above measures, more extreme methods may be undertaken. Deliberate fracture of the clavicle will reduce the bisacromial diameter and facilitate delivery. Cephalic replacement, involving the replacement of the fetal head through the pelvis so abdominal delivery can occur, is a last resort effort and is associated with both maternal and fetal morbidity and mortality.[48–51]
A search for an improved understanding of shoulder dystocia-related injury has prompted the development of mechanical models to understand the forces that are generated during a delivery where a shoulder dystocia has occurred. Using a mathematical model, Gonik described that exogenous forces applied to the fetal neck are not the only forces operating on this area. In this model, uterine and maternal expulsive forces were noted to be four-times greater than the clinically applied forces. Similar research on a mathematical model has demonstrated that the McRoberts' position is associated with a reduction in the force applied to the fetal neck. It is likely that the future development of models, and the ability to measure force in vivo, will provide more insight on shoulder dystocia and its optimal management.
Medical simulation is a relatively new field and is well suited to provide training in events that are rare, potentially catastrophic and that require coordinated teamwork. Shoulder dystocia is well suited for simulation training. Such training allows for trained individuals to recognize the problem and to effectively apply the maneuvers so that the fetal shoulder is disimpacted and the neonate is handed off to the pediatricians in a timely fashion. Simulations have been used in the military and in airline injury as well as in other medical specialties to educate staff and to prepare teams for infrequently occurring catastrophes. The obstetric birth simulator NOELLE (Gammard Scientific, FL, USA) is one such model. The effectiveness of the use of this model on improving resident competency in the management of shoulder dystocia was prospectively evaluated by comparing competency among a group of residents who received simulation training with a cohort where no training was received. Trained residents demonstrated higher scores in timelines and performance of maneuvers and completed delivery more quickly than the untrained cohort. Using a novel birth simulator, designed by engineers at Johns Hopkins University in Baltimore, Maryland, USA, Rubin's maneuver was found to require the least amount of traction when compared with McRoberts' maneuver for the initial management of shoulder dystocia. Improvements not only in the use of maneuvers, but also in neonatal injury were seen when a retrospective review of management and outcomes before and after the introduction of a mandatory shoulder dystocia simulation training program was performed. In this study the rate of shoulder dystocia was not different between the two time periods; however, after training was introduced, there was more documented use of McRoberts' position, suprapubic pressure, rotational maneuvers and delivery of the posterior arm. Although the injury rate was 2.04% before training and 2.00% post-training, a reduction in neonatal injury after training was noted. Crofts evaluated the effectiveness of simulation by introducing a high-fidelity mannequin, which incorporates force perception training. Training using this method of force perception was compared with the use of a low-fidelity mannequin without force perception training. Training improved delivery rates, communication with patients, and use of maneuvers. Although peak applied force did not differ between the two groups, the total applied force was lower among those who had undergone force perception training. Further studies using this model will demonstrate whether decreases in applied force are achieved after training.
Shoulder dystocia documentation is critical for both clinical and research purposes. If a precise sequence of events has been memorialized, this may allow for better understanding when an injury has occurred. Goffman used simulation training to evaluate whether documentation of the shoulder dystocia would improve post-training. Documentation and communication improved post-training but remained suboptimal and the authors concluded that the use of a standardized form may be the best way to obtain appropriate documentation. Maslovitz additionally described the use of simulation-based hands-on training for obstetrical emergencies. This author reports that simulation allowed for detection of multiple management errors among teams, including inadequate documentation of the shoulder dystocia. Osman similarly describes that one of the benefit of drills is to allow for identification of system problems. Crofts evaluated skill retention post-shoulder dystocia training and found that most trainees retained these skills for 6 and 12 months. The Joint Commission for Hospital Accreditation, which accredits and certifies more than 17,000 healthcare organizations in the USA, in its Sentinel Alert #30: Preventing Infant Death and Injury During Delivery, reviewed 40 cases of infant injury and seven cases of death and advised that organizations reduce risks of adverse events via various mechanisms including the use of team training, mock obstetrical emergency drills, shoulder dystocia drills and postevent debriefing to improve team performance.
Women's Health. 2010;6(6):861-869. © 2010 Future Medicine Ltd.