On the mechanical aspects of shoulder dystocia and birth injury

This article presents objective evidence about shoulder dystocia and its associated mechanical injuries, namely clavicle fractures, and brachial plexus injuries. Specifically, the review focuses on the mechanical response of the fetus to forces applied to it or its anatomic components, including possible force thresholds for injury. This is followed by presenting the medical and engineering literature on the mechanical aspects of shoulder dystocia with emphasis on kinematics, the forces associated with labor and with traction forces associated with delivery. Finally, the paper discusses the mechanical characteristics of maternal and fetal maneuvers for shoulder dystocia and demonstrates how shoulder dystocia models can be used to train clinicians in the performance of maneuvers that stress the fetus the least. From a mechanical point of view, there are obstetric methods and training that can be employed to reduce the stresses induced by the fetus while alleviating shoulder dystocia, thereby reducing, but not eliminating, the risk of mechanical injury.     

Shoulder dystocia: Management and documentation

Shoulder dystocia is an obstetric emergency that occurs when the fetal shoulders become impacted at the pelvic inlet. Management is based on performing maneuvers to alleviate this impaction. A number of protocols and training mnemonics have been developed to assist in managing shoulder dystocia when it occurs. This article reviews the evidence regarding the performance, timing, and sequence of these maneuvers; reviews the mechanism of fetal injury in relation to shoulder dystocia; and discusses issues concerning documentation of the care provided during this obstetric emergency.     

MANAGEMENT OF ANTICIPATED AND ACTUAL SHOULDER DYSTOCIA

Shoulder dystocia is a rare but serious obstetric complication that can result in significant neonatal and maternal morbidity and in costly litigation. Conflict exists in the literature regarding definition, incidence, predictability and preventability, relationship to neonatal injury, and appropriate management models. Anticipatory clinical interventions for potential shoulder dystocia have included ultrasound assessment of macrosomia; elective induction of labor, elective caesarean section; altered place of birth, and generous episiotomy/episioproctotomy. The authors note that these interventions often conflict with client desires and nurse-midwifery philosophy of birth, generate significant risks and costs in themselves, and do not address the poor predictability of shoulder dystocia. In recent literature, the safety and efficacy of maternal position change maneuvers (such as McRoberts maneuver, hands-knees position, and squatting) have been presented as methods to resolve most cases of shoulder dystocia Despite the success of these more benign, external maneuvers, the episiotomy mandate remains in nearly all obstetric and midwifery texts and handbooks (1–8) and journal references (9–19). A literature review of related professional disciplines was undertaken to study these conflicts and to identify support for applying a philosophy of minimal, appropriate intervention to the complex issue of shoulder dystocia.     

肩难产处理的要点与难点

肩难产是较为常见的产科急症,难以预测并可导致严重的母儿并发症。肩难产处理的关键是设法解除前肩或后肩的嵌顿,这需要规范的操作及团队的协作。本文重点围绕肩难产处理的要点及难点进行阐述。     

Evaluation of healthcare professionals’ understanding of eponymous maneuvers and mnemonics in emergency obstetric care provision

Objective

To evaluate whether eponymous maneuvers and mnemonics taught for the management of shoulder dystocia, vaginal breech delivery, and uterine inversion were remembered and understood in practice.

Methods

A questionnaire was distributed to obstetricians and midwives collecting information about the HELPERR and PALE SISTER mnemonics. Three extended matching questions evaluated participants’ knowledge of the correct maneuvers, with their matching eponyms, used in the management of shoulder dystocia, vaginal breech delivery, and uterine inversion.

Results

Of the 112 participants, 90% were familiar with the HELPERR mnemonic, with 79% using it in their practice. Of those who used it, only 32% could correctly decipher it (P = 0.032). PALE SISTER was mostly unfamiliar. The percentages of correct maneuvers used for managing shoulder dystocia, breech delivery, and uterine inversion were 84.6%, 58.3%, and 28.6%, respectively. However, the eponyms were correctly matched to their maneuvers in only 33.3%, 14.3%, and 0% of cases, respectively (P < 0.01).

Conclusion

The meanings of the mnemonics for obstetric emergencies were frequently recalled incorrectly. This, together with the poor correlation between knowledge of maneuvers and their eponyms, limits their usefulness and indicates that teaching should focus on learning without relying on mnemonics and eponyms.     

Shoulder dystocia: etiology, common risk factors, and management

Shoulder dystocia and brachial plexus injury occur in 0.5% to 1.5% of all births. Risk factors for both include maternal obesity, excessive prenatal weight gain, maternal diabetes, protracted labor, and fetal macrosomia. These factors are involved in only about 50% of births complicated by shoulder dystocia or brachial plexus injury. Shoulder dystocia has a low recurrence rate (9.8%-16.7%), although history of previous shoulder dystocia is the most reliable predictor of occurrence. Brachial plexus injury is the most common morbidity associated with shoulder dystocia, but 50% of newborns who present with this injury were not subject to shoulder dystocia at birth. Most brachial plexus injuries are transient, although 5% to 22% become permanent. Shoulder dystocia followed by permanent brachial plexus injury or mental impairment is one of the leading causes of malpractice allegations. Prompt assessment and management of shoulder dystocia and preparation to maximize the efficiency of shoulder dystocia maneuvers are critical. Documentation of the appropriate use of maneuvers to relieve shoulder dystocia demonstrates standard of care practice, thereby decreasing the potential for successful malpractice allegations.     

Improving resident competency in the management of shoulder dystocia with simulation training

OBJECTIVE: To determine whether a simulation training scenario improves resident competency in the management of shoulder dystocia. METHODS: Residents from 2 training programs participated in this study. The residents were block-randomized by year-group to a training session on shoulder dystocia management that used an obstetric birthing simulator or to a control group with no specific training. Trained residents and control subjects were subsequently tested on a standardized shoulder dystocia scenario, and the encounters were digitally recorded. A physician grader from an external institution then graded and rated the resident's performance with a standardized evaluation sheet. Statistical analysis included the Student t test, chi(2), and regression analysis, as appropriate. RESULTS: Trained residents had significantly higher scores in all evaluation categories, including timelines of their interventions, performance of maneuvers, and overall performance. They also performed the delivery in a shorter time than control subjects (61 versus 146 seconds, P =.003). CONCLUSION: Training with a simulation-training scenario improved resident performance in the management of shoulder dystocia. LEVEL OF EVIDENCE: I     

Evaluation of residents' delivery notes after a simulated shoulder dystocia

OBJECTIVE: To describe and analyze delivery notes after a shoulder dystocia drill with a birthing simulator METHODS: A total of 33 residents from 2 university training programs underwent testing on a standardized shoulder dystocia scenario with an obstetric birthing simulator. After the completion of the delivery, each resident was informed of the infant's Apgar scores and birth weight and told that the infant was moving all extremities. The resident was then given a blank progress note and asked to write a delivery note. The notes were evaluated for 15 key components. RESULTS: Seventy-six percent (n = 25) of residents recorded less than 10 of 15 key components of a delivery note after a shoulder dystocia. The majority of residents (91%, 30/33) included the correct order of the maneuvers used during the delivery, but most did not note which shoulder was anterior (18%, 6/33) or how long the head-to-body interval was during delivery (45%, 15/33). CONCLUSION: Residents' delivery notes after a shoulder dystocia simulation often lacked critical elements. Training in documentation is needed in residency training. The addition of the delivery note and feedback regarding the note represents a simple innovation in this teaching scenario that may help identify deficiencies in documentation. LEVEL OF EVIDENCE: III     

Optimizing shoulder dystocia management to prevent birth injury

A practical clinical review of those aspects of shoulder dystocia management that are directly relevant to birth injury is presented. In contrast to more popular viewpoints, the tenets of this paper are that, with few exceptions, clinically relevant, permanent brachial plexus injury is nearly universally associated with shoulder dystocia, injury is causally related to mechanical stresses induced during shoulder dystocia delivery, and management algorithms can be optimized to reduce the incidence of mechanical birth injury from shoulder dystocia. Advantages of direct rotational manipulation of the fetus within the birth canal are emphasized, supported by critical analysis of maneuver-related outcomes research. The competing issue of potential asphyxial insult with prolonged shoulder dystocia is addressed in light of evidence for differential time-dependency between central and peripheral nerve injury as head-to-body interval increases. The importance of proper execution of shoulder dystocia maneuvers for maximizing favorable outcome of shoulder dystocia is iterated, as is coordination of teamed response by multiple healthcare providers. To avoid permanent neurologic sequelae from shoulder dystocia, clinicians are encouraged to be ever mindful of traction applied to the fetal head and neck, to become adept at performance of alternative maneuvers that instead concentrate on finesse rather than force, and to be more favorably disposed to the use of such maneuvers early and often in shoulder dystocia management algorithms.     

Shoulder dystocia

Shoulder dystocia is an uncommon but not rare obstetric emergency. Death of the infant is unusual but perinatal morbidity is frequent and can result in permanent injury. These cases carry significant medico-legal implications. This chapter covers the mechanisms, predisposing factors and management of shoulder dystocia. A well-rehearsed sequence of manoeuvres to manage shoulder dystocia will minimize fetal trauma.     

Observations from 450 shoulder dystocia simulations: lessons for skills training

Poor neonatal outcomes after shoulder dystocia have been associated with inappropriate management. Until there are significant developments in the prediction and subsequent prevention of shoulder dystocia, improving shoulder dystocia management through practical training may be the most effective method of reducing the associated morbidity and mortality. Four hundred fifty simulated shoulder dystocia scenarios, managed by 95 midwives and 45 doctors from six U.K. hospitals during the course of 1 year, were video recorded during a study of obstetric emergency training. Analysis of recorded data revealed that, before training, 57% were unable to deliver the baby, almost two thirds failed to call for pediatric support, and 1 in 27 used fundal pressure. Recurring difficulties in management were observed: poor communication, inability to gain internal access, confusion over internal maneuvers, and the application of excessive traction. Significant improvements in management were observed after training and persisted up to 1 year after training. The lessons learned from this study can inform and improve future training and management. This article describes difficulties encountered by the participants and discusses how training may be focused to address these problems.     

Spiral fracture of the radius: an unusual case of shoulder dystocia-associated morbidity

BACKGROUND: The most common neonatal complications associated with shoulder dystocia include transient brachial plexus palsy, clavicular fracture, and humeral fracture. Fracture of the fetal radius has not been previously reported. CASE: We encountered a shoulder dystocia with the fetal head in the right occiput anterior position that necessitated the McRoberts maneuver, suprapubic pressure, the Wood and Rubin maneuvers, and extraction of the posterior fetal arm to effect delivery. The 4610-g infant experienced a spiral fracture of the right (anterior) radius and a fracture of the left (posterior) midhumeral shaft. CONCLUSION: Neonatal radial fracture can result from shoulder dystocia or the maneuvers employed for the alleviation of the shoulder dystocia.     

Shoulder dystocia: an update

Shoulder dystocia has no consensus definition or management algorithm. Its incidence ranges from 0.2% to 3% and its occurrence is unpredictable. Risk factors for shoulder dystocia may include macrosomia, maternal diabetes, operative vaginal delivery, history of macrosomic infant or shoulder dystocia, labor abnormalities, post-term pregnancy, maternal obesity, advanced maternal age, fetal anthropometric variations, and male fetal gender. Once identified, multiple maneuvers can be applied in a stepwise fashion in an attempt to alleviate the dystocia. While training clinicians to manage shoulder dystocia is difficult because of its rare occurrence and lack of standardized management, all clinicians must be able to manage shoulder dystocia at any time.     

Maternal morbidity associated with obstetrical maneuvers in shoulder dystocia

OBJECTIVES: To determine whether shoulder dystocia and obstetrical maneuvers used for its relief have detrimental effects on perineum or immediate postpartum outcome. DESIGN: Case-control study. SETTING: Tertiary maternity ward in Marseille, France. POPULATION: A total 140 cases with shoulder dystocia and 280 controls without shoulder dystocia were enrolled by reviewing charts for the period between January 1999 and December 2004. METHODS: Demographic data including obstetrical history, age, height, weight before pregnancy and at the time of delivery, and respective body mass index (BMI) and obstetrical data including analgesic technique, duration of first and second stage of labor were compared in function of outcome and of the type and number of maneuvers used to relieve shoulder dystocia. RESULTS: Resolving shoulder dystocia required one obstetrical maneuver in 41 cases (29.3%) and two obstetrical maneuvers in 48 cases (34.3%). Third-degree tears occurred in one patient in the case group versus five in the control group. No correlation was found between the number of obstetrical maneuvers needed to relieve shoulder dystocia and risk for third-degree tear (OR: 0.8; 95% CI: 0.1-7.6). Mean hemoglobin values were 96.1 g/l in the case group and 96.0 g/l in the control group (p=0.95). There was no difference between the two groups regarding duration of postpartum hospitalization. The incidence of urinary incontinence was similar in the group that underwent obstetrical maneuvers: 4.7% (6/127) and in the control group: 3.7% (13/352). Only two patients reported de novo anal symptoms, both in the control group. CONCLUSION: Shoulder dystocia and obstetrical techniques used for its relief did not result in adverse maternal outcome.     

Shoulder dystocia: a fetal-physician risk

Trauma that occurs as a result of shoulder dystocia is an important cause of neonatal morbidity. If the occurrence of severe shoulder dystocia, resulting in fetal asphyxia and trauma, could be accurately predicted from maternal risk factors, then a cesarean section would be indicated to prevent the poor outcome. The information available in the obstetric literature, however, is contradictory regarding whether shoulder dystocia can be predicted. In the present study, the patients at greatest risk of shoulder dystocia (all 394 mothers delivering neonates with birth weights greater than or equal to 4000 gm over a 2-year period) were examined. A three-way discriminant analysis was used to determine if a model could be developed that could effectively predict those patients who would be included in each of the groups of no shoulder dystocia, shoulder dystocia without trauma (29 patients), and shoulder dystocia with trauma (20 patients). Three factors, including birth weight, prolonged deceleration phase, and length of second stage labor, were found individually to contribute significantly to the classification. However, when examined in detail, it was noted that while 94% of cases with no shoulder dystocia would be detected, only 16% of the cases of shoulder dystocia with trauma would be predicted by this model. We conclude that in the group of pregnancies delivering neonates greater than or equal to 4000 gm, the occurrence of shoulder dystocia cannot be predicted from clinical characteristics or labor abnormalities, and that the occurrence of shoulder dystocia is not evidence of medical malpractice.     

Shoulder dystocia: Simulation and a team-centered protocol

Shoulder dystocia is an obstetric emergency that has been reported to occur in 0.2–3% of all vaginal deliveries. Several characteristics of shoulder dystocia make it a particular challenge to manage effectively. It is relatively infrequent, the diagnosis cannot be made according to a single objective criterion that can be recognized to exist by all members of the care team who are present, it is unpredictable, and there is the need for coordinated actions of all members of the health care team who have come together on the day of the delivery and may not have worked together before or specifically during a shoulder dystocia. In general, there is evidence from different medical disciplines that checklists/protocols and simulation may be used to enhance team performance. There is also some evidence, albeit limited, that such techniques may be used to improve shoulder dystocia outcomes.     

Risikomanagement durch das geburtshilfliche Team

A successful and satisfactory obstetric operation for both mother and child, is based on human support and also on the spatial and technical conditions which are important to enable the team to provide the patient with an optimal performance. The hospital administration is primarily responsible for the supply of these resources as well as for the optimal cooperation of the various disciplines. In order to achieve the objective of optimal treatment, the personnel and the physician in particular need to have experience in cooperational organization and knowledge of forensic demands in addition to obstetric competency. The complexity of coordinating personnel, equipment and forensic requirements is demonstrated using the examples of emergency cesareans and shoulder dystocia. In order to anticipate shoulder dystocia, an EDP software based on risk evaluation provides the necessary algorithm prior to birth and allows factors which favor shoulder dystocia to be diagnosed.     

The diagnosis and management of dystocia of the shoulder.

Dystocia of the shoulder is an unpredictable obstetric emergency that may result in injury to the mother or fetus. In an effort to reduce such risks, attempts have been made to identify patients having a fetus who may subsequently develop shoulder dystocia. The literature, however, clearly reflects that even the combination of prenatal historic facts, estimated fetal weight and sequence of intrapartum events is ineffective in prospectively identifying infants whose births are complicated by shoulder dystocia. During a ten year period at the University of Mississippi Medical Center, the incidence of macrosomia, shoulder dystocia and subsequent brachial plexus injury was reviewed. The majority of instances (89 percent) of shoulder dystocia occurred in patients weighing less than 8 pounds 13 ounces at birth. In the current retrospective review, only 11 percent of the women had risk factors for macrosomia or shoulder dystocia and among these, none were identified prospectively. Additionally, 91 percent of patients with brachial plexus injury recovered with no sequelae. One instance of brachial plexus injury occurred at the time of cesarean section. These data reveal that macrosomia and subsequent shoulder dystocia cannot be predicted. Therefore, it is not feasible to prevent brachial plexus injury prospectively by prophylactic cesarean section. Great clinical acumen and technical expertise by the obstetrician using a variety of methods may be useful in avoiding, as much as possible, injury to the mother and fetus when shoulder dystocia does occur.