Shoulder dystocia: an analysis of risks and obstetric maneuvers

A critical evaluation of the external and internal maneuvers for resolution of shoulder dystocia

In the management of shoulder dystocia, it is often recommended to start with external maneuvers, such as the McRoberts maneuver and suprapubic pressure, followed by internal maneuvers including rotation and posterior arm delivery. However, this sequence is not based on scientific evidence of its success rates, the technical simplicity, or the related complication rates. Hence, this review critically evaluates the success rate, technique, and safety of different maneuvers. Retrospective reviews showed that posterior arm delivery has consistently higher success rates (86.1%) than rotational methods (62.4%) and external maneuvers (56.0%). McRoberts maneuver was thought to be a simple method, however, its mechanism is not clear. Furthermore, McRoberts position still requires subsequent traction on the fetal neck, which presents a risk for brachial plexus injury. The 2 internal maneuvers have anatomic rationales with the aim of rotating the shoulders to the wider oblique pelvic dimension or reducing the shoulder width. The techniques are not more sophisticated and requires the accoucher to insert the correct hand (according to fetal face direction) through the more spacious sacro-posterior region and deep enough to reach the fetal chest or posterior forearm. The performance of rotation and posterior arm delivery can also be integrated and performed using the same hand. Retrospective studies may give a biased view that the internal maneuvers are riskier. First, a less severely impacted shoulder dystocia is more likely to have been managed by external maneuvers, subjecting more difficult cases to internal maneuvers. Second, neonatal injuries were not necessarily caused by the internal maneuvers that led to delivery but could have been caused by the preceding unsuccessful external maneuvers. The procedural safety is not primarily related to the nature of the maneuvers, but to how properly these maneuvers are performed. When all these maneuvers have failed, it is important to consider the reasons for failure otherwise repetition of the maneuver cycle is just a random trial and error. If the posterior axilla is just above the pelvic outlet and reachable, posterior axilla traction using either the accoucher fingers or a sling is a feasible alternative. Its mechanism is not just outward traction but also rotation of the shoulders to the wider oblique pelvic dimension. If the posterior axilla is at a higher sacral level, a sling may be formed with the assistance of a long right-angle forceps, otherwise, more invasive methods such as Zavanelli maneuver, abdominal rescue, or symphysiotomy are the last resorts.

Studying the Effects of Shoulder Dystocia and Neonate-Focused Delivery Maneuvers on Brachial Plexus Strain: A Computational Study

The purpose of this computational study was to investigate the effects of neonate-focused clinical delivery maneuvers on brachial plexus (BP) during shoulder dystocia. During shoulder dystocia, the anterior shoulder of the neonate is obstructed behind the symphysis pubis of the maternal pelvis, postdelivery of the neonate's head. This is managed by a series of clinical delivery maneuvers. The goal of this study was to simulate these delivery maneuvers and study their effects on neonatal BP strain. Using madymo models of a maternal pelvis and a 90th-percentile neonate, various delivery maneuvers and positions were simulated including the lithotomy position alone of the maternal pelvis, delivery with the application of various suprapubic pressures (SPPs), neonate in an oblique position, and during posterior arm delivery maneuver. The resulting BP strain (%) along with the required maternal delivery force was reported in these independently simulated scenarios. The lithotomy position alone served as the baseline. Each of the successive maneuvers reported a decrease in the required delivery force and resulting neonatal BP strain. As the applied SPP force increased (three scenarios simulated), the required maternal delivery force and neonatal BP strain decreased. A further decrease in both delivery force and neonatal BP strain was observed in the oblique position, with the lowest delivery force and neonatal BP strain reported during the posterior arm delivery maneuver. Data obtained from the improved computational models in this study enhance our understanding of the effects of clinical maneuvers on neonatal BP strain during complicated birthing scenarios such as shoulder dystocia.

Impact of fetal manipulation on maternal and neonatal severe morbidity during shoulder dystocia management

PURPOSE

There are few data on maternal and neonatal morbidities associated with shoulder dystocia (SD), depending on the use of fetal manipulation (FM). A prior 5-year study was conducted in our center in 2012 for this purpose. Our objective was to compare severe maternal and neonatal morbidities according to FM execution in a larger cohort.

METHODS

We conducted a retrospective study between 2007 and 2020. SD was considered when additional maneuvers were required to complete a delivery. Severe maternal morbidity was defined as the occurrence of obstetric anal sphincter injury (OASI). Severe neonatal morbidity was defined as Apgar < 7 at 5 min and/or cord arterial pH < 7.1 and/or or a permanent brachial plexus palsy. We studied these data in the FM group compared to the non- FM group.

RESULTS

FM was associated with increased OASI rates (21.1% vs. 3.8%, OR = 6.72 [2.7-15.8]). We found no significant difference in severe neonatal morbidity. Maternal age > 35 and FM appear to be associated with the occurrence of OASI, with ORa = 13.3 [1.5-121.8] and ORa = 5.3 [2.2-12.8], respectively. FM was the only factor associated with the occurrence of severe neonatal morbidity (ORa = 2.3 [1.1-4.8]. The rate of episiotomy was significantly decreased (20% versus 5% p < 0.05) and there was an increase in the rate of SD managed with FM in our center.

CONCLUSION

FM is the only factor associated with an increased risk of OASI. In case of failure of non-FM maneuvers, the rapid implementation of FM maneuvers resulted in no difference regarding severe neonatal morbidity.

Accuracy of Fetal Biacromial Diameter and Derived Ultrasonographic Parameters to Predict Shoulder Dystocia: A Prospective Observational Study

Background and Objectives: Shoulder dystocia (ShD) is one of most dangerous obstetric complication. The objective of this study was to determine if the ultrasonographic fetal biacromial diameter (BA) and derived parameters could predict ShD in uncomplicated term pregnancies. Materials and Methods: We conducted a prospective observational study in a tertiary care university hospital from March 2021 to February 2022. We included all full-term pregnancies accepted for delivery that received an accurate ultrasonography (USG) scan before delivery. USG biometry and estimated fetal weight (EFW) were collected. Therefore, we evaluated the diameter of the mid-arm, the transverse thoracic diameter (TTD) and the biacromial diameter (BA). BA was estimated using Youssef’s formula: TTD + 2 mid-arm diameters. The primary outcome was the evaluation of BA and its related parameters (BA/biparietal diameter (BPD), BA/head circumference (HC) and BA–BPD in fetuses with ShD versus fetuses without ShD. Diagnostic accuracy for ShD of BA, BA/BPD, BA/HC and BA–BPD was evaluated using receiver operator curve (ROC) analysis. Results: 90 women were included in the analysis, four of these had ShD and required extra maneuvers after head delivery. BA was increased in fetuses with ShD (150.4 cm; 95% CI 133.2 cm to 167.6 cm) compared to no-ShD (133.5 cm; 95% CI 130.1 cm to 137.0 cm; p = 0.04). Significant differences were also found between ShD and no-ShD groups for BA/BPD (1.66 (95% CI 1.46 to 1.86) vs. 1.44 (95% CI 1.41 to 1.48); p = 0.04), BA/HC (0.45 (95% CI 0.40 to 0.49) vs. 0.39 (95% CI 0.38 to 0.40); p = 0.01), BA–BPD (60.0 mm (95% CI 42.4 to 77.6 cm) vs. 41.4 (95% CI 38.2 to 44.6); p = 0.03), respectively. ROC analysis showed an overall good accuracy for ShD, with an AUC of 0.821 (p = 0.001) for BA alone and 0.881 (p = 0.001), 0.857 (p = 0.016) and 0.867 (p = 0.013) for BA/BPD, BA–BPD and BA/HC, respectively. Conclusions: BA alone, as well as BA/BPD, BA/HC and BA–BPD might be useful predictors of ShD in uncomplicated term pregnancies. However, such evidence needs extensive confirmation by means of additional studies with large sample sizes, especially in case of pregnancies at high risk for ShD (i.e., gestational diabetes).

Risk of major labour-related complications for pregnancies progressing to 42 weeks or beyond

BACKGROUND

Post-term gestation beyond 41⁺⁶ completed weeks of gestation is known to be associated with a sharp increase in the risk of stillbirth and perinatal mortality. However, the risk of common adverse outcomes related to labour, such as shoulder dystocia and post-partum haemorrhage for those delivering at this advanced gestation, remains poorly characterised. The objective of this study was to examine the risk of adverse, labour-related outcomes for women progressing to 42 weeks gestation or beyond, compared with those giving birth at 39 completed weeks.

METHODS

We performed a state-wide cohort study using routinely collected perinatal data in Australia. Comparing the two gestation cohorts, we examined the adjusted relative risk of clinically significant labour-related adverse outcomes, including macrosomia (≥ 4500 at birth), post-partum haemorrhage (≥1000 ml), shoulder dystocia, 3rd or 4th degree perineal tear and unplanned caesarean section. Parity, maternal age and mode of birth were adjusted for using logistic regression.

RESULTS

The study cohort included 91,314 women who birthed at 39 completed weeks and 4317 at ≥42 completed weeks. Compared to 39 weeks gestation, those giving birth ≥42 weeks gestation had an adjusted relative risk (aRR) of 1.85 (95% CI 1.55-2.20) for post-partum haemorrhage following vaginal birth, 2.29 (95% CI 1.89-2.78) following instrumental birth and 1.44 (95% CI 1.17-1.78) following emergency caesarean section; 1.43 (95% CI 1.16-1.77) for shoulder dystocia (for non-macrosomic babies); and 1.22 (95% CI 1.03-1.45) for 3rd or 4th degree perineal tear (all women). The adjusted relative risk of giving birth to a macrosomic baby was 10.19 (95% CI 8.26-12.57) among nulliparous women and 4.71 (95% CI 3.90-5.68) among multiparous women. The risk of unplanned caesarean section was 1.96 (95% CI 1.86-2.06) following any labour and 1.47 (95% CI 1.38-1.56) following induction of labour.

CONCLUSIONS

Giving birth at ≥42 weeks gestation may be an under-recognised risk factor for several important, labour-related adverse outcomes. Clinicians should be aware that labour at this advanced gestation incurs a higher risk of adverse outcomes. In addition to known perinatal risks, the risk of obstetric complications should be considered in the counselling of women labouring at post-term gestation.

Outcomes of Late Microsurgical Nerve Reconstruction for Brachial Plexus Birth Injury

PURPOSE

Microsurgical nerve reconstruction has been advocated between 3 and 9 months of life in select patients with brachial plexus birth injury (BPBI), yet some patients undergo indicated surgery after this time frame. Outcomes in these older patients remain poorly characterized. We analyzed outcomes of nerve reconstruction performed after 9 months of age and hypothesized that (1) Active Movement Scale (AMS) scores improve after surgery, and (2) there are no differences in AMS scores between patients undergoing nerve transfers versus those undergoing nerve grafting.

METHODS

From 2000 to 2014, 750 patients at 6 U.S. centers were prospectively enrolled in a multicenter database. We included patients treated with nerve reconstruction after 9 months of age with minimum 12 months' follow-up. Patients were evaluated using AMS scores. To focus on the results of microsurgery, only outcomes prior to secondary surgery were analyzed. We analyzed baseline variables using bivariate statistics and change in AMS scores over time and across treatment groups using linear mixed models.

RESULTS

We identified 32 patients (63% female) with median follow-up of 29.8 months. Median age at microsurgery was 11.2 months. Twenty-five (78%) had an upper trunk injury. Compared with before surgery, total AMS scores improved modestly at 1 year and 2 or more years follow-up. At 1 year follow-up, AMS scores improved for shoulder function (abduction, external rotation) and elbow flexion. Between-group comparisons found no differences in total AMS scores or AMS subscales between graft and transfer groups at 1 year or 2 or more years after surgery, so we cannot recommend one strategy over the other based on our findings.

CONCLUSIONS

Overall, nerve reconstruction in patients with BPBI after 9 months of age resulted in improved function over time. There was no difference in outcomes between nerve transfer and nerve graft groups and 1 or 2 or more years follow-up.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Risk factors for neonatal brachial plexus palsy: a systematic review and meta-analysis

AIM

To provide a comprehensive update on the most prevalent, significant risk factors for neonatal brachial plexus palsy (NBPP).

METHOD

Cochrane CENTRAL, MEDLINE, Web of Science, Embase, and ClinicalTrials.gov were searched for relevant publications up to March 2019. Studies assessing risk factors of NBPP in relation to typically developing comparison individuals were included. Meta-analysis was performed for the five most significant risk factors, on the basis of the PRISMA statement and MOOSE guidelines. Pooled odds ratios (ORs), 95% confidence intervals (CIs), and across-study heterogeneity (I² ) were reported. Reporting bias and quality of evidence was rated. In addition, we assessed the incidence of NBPP.

RESULTS

Twenty-two observational studies with a total sample size of 29 419 037 live births were selected. Significant risk factors included shoulder dystocia (OR 115.27; 95% CI 81.35-163.35; I² =92%), macrosomia (OR 9.75; 95% CI 8.29-11.46; I² =70%), (gestational) diabetes (OR 5.33; 95% CI 3.77-7.55; I² =59%), instrumental delivery (OR 3.8; 95% CI 2.77-5.23; I² =77%), and breech delivery (OR 2.49; 95% CI 1.67-3.7; I² =70%). Caesarean section appeared as a protective factor (OR 0.13; 95% CI 0.11-0.16; I² =41%). The pooled overall incidence of NBPP was 1.74 per 1000 live births. It has decreased in recent years.

INTERPRETATION

The incidence of NBPP is decreasing. Shoulder dystocia, macrosomia, maternal diabetes, instrumental delivery, and breech delivery are risk factors for NBPP. Caesarean section appears as a protective factor.

WHAT THIS PAPER ADDS

The overall incidence of neonatal brachial plexus palsy is 1.74 per 1000 live births. The incidence has declined significantly. Shoulder dystocia, macrosomia, maternal diabetes, instrumental delivery, and breech delivery are the main risk factors. Prevention is difficult owing to unpredictability and often labour-related risk.

The Association of Clavicle Fracture With Brachial Plexus Birth Palsy

PURPOSE

Shoulder dystocia is the strongest known risk factor for brachial plexus birth palsy (BPBP). Fractures of the clavicle are known to occur in the setting of shoulder dystocia. It remains unknown whether a clavicle fracture that occurs during a birth delivery with shoulder dystocia increases the risk of BPBP or, alternatively, is protective. The purpose of this study was to use a large, national database to determine whether a clavicle fracture in the setting of shoulder dystocia is associated with an increased or decreased risk of BPBP.

MATERIALS AND METHODS

The 1997 to 2012 Kids' Inpatient Database (KID) was analyzed for this study. International Classification of Diseases, Ninth Revision (ICD-9) codes were used to identify newborns diagnosed with shoulder dystocia and BPBP as well as a concurrent fracture of the clavicle. Newborns with shoulder dystocia were stratified into 2 groups: dystocia without a clavicle fracture and dystocia with a clavicle fracture. Multivariable logistic regression was used to quantify the risk for BPBP among shoulder dystocia subgroups.

RESULTS

The dataset included 5,564,628 sample births extrapolated to 23,385,597 population births over the 16-year study period. A BPBP occurred at a rate of 1.2 per 1,000 births. Shoulder dystocia complicated 18.8% of births with a BPBP. A total of 7.84% of newborns with a BPBP also sustained a clavicle fracture. Births with shoulder dystocia and a clavicle fracture incurred BPBP at a rate similar to that for newborns with shoulder dystocia and no fracture (9.82% vs 11.77%). Shoulder dystocia without a concurrent clavicle fracture was an independent risk factor for BPBP (odds ratio, 112.1; 95% confidence interval, 103.5-121.4). Those with shoulder dystocia and clavicle fracture had a risk for BPBP comparable with those with shoulder dystocia but no fracture (odds ratio, 126.7 vs 112.1).

CONCLUSIONS

This population-level investigation suggests that, among newborns with shoulder dystocia, clavicle fracture is not associated with a significant change in the risk of BPBP.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

Impact of shoulder dystocia, stratified by type of manoeuvre, on severe neonatal outcome and maternal morbidity

BACKGROUND

Shoulder dystocia is an uncommon and unpredictable obstetric emergency. It is associated with significant neonatal, maternal and medico-legal consequences.

AIM

To ascertain the impact shoulder dystocia has on severe neonatal and maternal outcomes specific to the type of manoeuvre.

MATERIALS AND METHODS

This was a retrospective study of 48 021 term singleton vaginal deliveries the Mater Mothers' Hospital in Brisbane between 2007 and 2015. Maternal and neonatal outcomes were compared between deliveries complicated by shoulder dystocia and those uncomplicated.

RESULTS

Deliveries complicated by shoulder dystocia are associated with low Apgar scores (≤3) at five minutes (odds ratio (OR) 5.25, 95% CI 3.23-8.56, P < 0.001), acidosis (OR 3.10, 95% CI 2.76-3.50, P < 0.001), postpartum haemorrhage (OR 2.28, 95% CI 1.90-2.75, P < 0.001) and perineal trauma (OR 1.92, 95% CI 1.54-2.39, P < 0.001). Compared to McRoberts' manoeuvre and suprapubic pressure alone, the odds of serious neonatal outcome are increased with internal rotational manoeuvres (OR 3.82, 95% CI 2.54-5.74, P < 0.001) and delivery of the posterior arm (OR 4.49, 95% CI 3.54-5.69, P < 0.001). The OR of maternal injury is 2.07 (95% CI 1.77-2.45, P < 0.001), 2.26 (95% CI 1.21-4.21, P < 0.001) and 2.29 (95% CI 1.58-3.32, P < 0.001) with McRoberts'/suprapubic pressure, internal rotation and posterior arm delivery, respectively. Brachial plexus injuries and fractures complicate 1.4 and 0.9% of deliveries, with the risk of injury increasing when greater than one manoeuvre is required.

CONCLUSION

The risk of neonatal and maternal trauma is strongly associated with the number and types of manoeuvres. Given the associated implications, adequate antenatal counselling, simulation training and enhanced labour surveillance are essential.

Shoulder dystocia: prediction and management

Shoulder dystocia is a complication of vaginal delivery and the primary factor associated with brachial plexus injury. In this review, we discuss the risk factors for shoulder dystocia and propose a framework for the prediction and prevention of the complication. A recommended approach to management when shoulder dystocia occurs is outlined, with review of the maneuvers used to relieve the obstruction with minimal risk of fetal and maternal injury.

[Management of shoulder dystocia]

OBJECTIVE

The objective of this review is to propose recommendations on the management of shoulder dystocia.

MATERIALS AND METHODS

The PubMed database, the Cochrane Library and the recommendations from the foreign obstetrical societies or colleges have been consulted.

RESULTS

In case of shoulder dystocia, if the obstetrician is not present at delivery, he should be systematically informed as quickly as possible (professional consensus). A third person should also be called for help in order to realize McRoberts maneuver (professional consensus). The patient has to be properly installed in gynecological position (professional consensus). It is recommended not to pull excessively on the fetal head (grade C), do not perform uterine expression (grade C) and do not realize inverse rotation of the fetal head (professional consensus). McRoberts maneuver, with or without a suprapubic pressure, is simple to perform, effective and associated with low morbidity, thus, it is recommended in the first line (grade C). Regarding the maneuvers of the second line, the available data do not suggest the superiority of one maneuver in relation to another (grade C). We proposed an algorithm; however, management should be adapted to the experience of the operator. If the posterior shoulder is engaged, Wood's maneuver should be performed preferentially; if the posterior shoulder is not engaged, delivery of the posterior arm should be performed preferentially (professional consensus). Routine episiotomy is not recommended in shoulder dystocia (professional consensus). Other second intention maneuvers are described. It seems necessary to know at least two maneuvers to perform in case of shoulder dystocia unresolved by the maneuver McRoberts (professional consensus).

CONCLUSION

All physicians and midwives should know and perform obstetric maneuvers if needed quickly but without precipitation.

Neonatal brachial plexus palsy: a permanent challenge

Neonatal brachial plexus palsy (NBPP) has an incidence of 1.5 cases per 1000 live births and it has not declined despite recent advances in obstetrics. Most patients will recover spontaneously, but some will remain severely handicapped. Rehabilitation is important in most cases and brachial plexus surgery can improve the functional outcome of selected patients. This review highlights the current management of infants with NBPP, including conservative and operative approaches.

Gestational diabetes: A clinical update

Gestational diabetes mellitus (GDM) is increasing in prevalence in tandem with the dramatic increase in the prevalence of overweight and obesity in women of childbearing age. Much controversy surrounds the diagnosis and management of gestational diabetes, emphasizing the importance and relevance of clarity and consensus. If newly proposed criteria are adopted universally a significantly growing number of women will be diagnosed as having GDM, implying new therapeutic challenges to avoid foetal and maternal complications related to the hyperglycemia of gestational diabetes. This review provides an overview of clinical issues related to GDM, including the challenges of screening and diagnosis, the pathophysiology behind GDM, the treatment and prevention of GDM and the long and short term consequences of gestational diabetes for both mother and offspring.

Prevention of shoulder dystocia related birth injuries: Myths and facts

Traditionally, brachial plexus damage was attributed to excessive traction applied on the fetal head at delivery. Recently, it was proposed that most injuries occur spontaneously in utero. The author has studied the mechanism of neurological birth injuries based on 338 actual cases with special attention to (1) fetal macrosomia; (2) maternal diabetes; and (3) methods of delivery. There was a high coincidence between use of traction and brachial plexus injuries. Instrumental extractions increased the risk exponentially. Erb’s palsy following cesarean section was exceedingly rare. These facts imply that spontaneous neurological injury in utero is extremely rare phenomenon. Literary reports show that shoulder dystocia and its associated injuries increased in the United States several-fold since the introduction of active management of delivery in the 1970’s. Such a dramatic change in a stable population is unlikely to be caused by incidental spontaneous events unrelated to external factors. The cited investigations indicate that brachial plexus damage typically is traction related. The traditional technique which precludes traction is the optimal method for avoiding arrest of the shoulders and its associated neurological birth injuries. Effective prevention also requires meticulous prenatal care and elective abdominal delivery of macrosomic fetuses in carefully selected cases.

Shoulder dystocia: definitions and incidence

Though subjective in nature, both the American College of Obstetricians and Gynecologists practice bulletin and the Royal College of Obstetricians and Gynaecologists green guideline are in agreement on the descriptor of shoulder dystocia: requirement of additional obstetric maneuvers when gentle downward traction has failed to affect the delivery of the shoulders. The rate of shoulder dystocia is about 1.4% of all deliveries and 0.7% for vaginal births. Compared to non-diabetics (0.6%), among diabetics, the rate of impacted shoulders is 201% higher (1.9%); newborns delivered by vacuum or forceps have 254% higher likelihood of shoulder dystocia than those born spontaneously (2.0% vs. 0.6%, respectively). When the birthweight is categorized as <4000, 4000-4449, and >4500 g, the likelihood of shoulder dystocia in the US vs. other countries varies significantly. Future studies should focus on lowering the rate of shoulder dystocia and its associated morbidities, without concomitantly increasing the rate of cesarean delivery.

Neonatal brachial plexus palsy: incidence, prevalence, and temporal trends

Epidemiological knowledge of the incidence, prevalence, and temporal changes of neonatal brachial plexuses palsy (NBPP) should assist the clinician, avert unnecessary interventions, and help formulate evidence-based health policies. A summary of 63 publications in the English language with over 17 million births and 24,000 NBPPs is notable for six things. First, the rate of NBPP in the US and other countries is comparable: 1.5 vs. 1.3 per 1000 total births, respectively. Second, the rate of NBPP may be decreasing: 0.9, 1.0 and 0.5 per 1,000 births for publications before 1990, 1990-2000, and after 2000, respectively. Third, the likelihood of not having concomitant shoulder dystocia with NBPP was 76% overall, though it varied by whether the publication was from the US (78%) vs. other countries (47%). Fourth, the likelihood of NBPP being permanent (lasting at least 12 months) was 10-18% in the US-based reports and 19-23% in other countries. Fifth, in studies from the US, the rate of permanent NBPP is 1.1-2.2 per 10,000 births and 2.9-3.7 per 10,000 births in other nations. Sixth, we estimate that approximately 5000 NBPPs occur every year in the US, of which over 580-1050 are permanent, and that since birth, 63,000 adults have been afflicted with persistent paresis of their brachial plexus. The exceedingly infrequent nature of permanent NBPP necessitates a multi-center study to improve our understanding of the antecedent factors and to abate the long-term sequela.

Emergency department management of shoulder dystocia

BACKGROUND

Precipitous obstetric deliveries can occur outside of the labor and delivery suite, often in the emergency department (ED). Shoulder dystocia is an obstetric emergency with significant risk of adverse outcome.

OBJECTIVE

To review multiple techniques for managing a shoulder dystocia in the ED.

DISCUSSION

We review various techniques and approaches for achieving delivery in the setting of shoulder dystocia. These include common maneuvers, controversial interventions, and interventions of last resort.

CONCLUSIONS

Emergency physicians should be familiar with multiple techniques for managing a shoulder dystocia to reduce the chances of fetal and maternal morbidity and mortality.

Precipitous and difficult deliveries

Any delivery in the emergency department is considered a precipitous birth and is an anxiety-producing event. Many deliveries proceed without incident. However, the emergency physician must be prepared for several dreaded scenarios, such as nuchal cord, shoulder dystocia, and breech birth. This article reviews the basics, complications, and management of such deliveries.

[Prediction, prevention and management of shoulder dystocia]

Shoulder dystocia is one of the most tragic, fatal and unexpected obstetrical events, which is mostly unpredictable and unpreventable. This clinical picture is defined as a delivery that requires additional obstetric maneuvers to release the shoulders after gentle downward traction has failed. Shoulder dystocia occurs when the fetal shoulder impacts on the maternal symphysis or sacral promontory. The incidence of shoulder dystocia is 0.2-0.6%. High perinatal mortality and morbidity is associated with the condition, even when it is managed appropriately. Obstetricians should be aware of the existing risk factors, but should always be alert to the possibility of shoulder dystocia in all labors. Maternal morbidity is also increased, particularly postpartum hemorrhage, rupture of the uterus, injury of the bladder, urethra and the bowels and fourth-degree perineal tears. Complications of the newborn include asphyxia, perinatal mortality, fracture of the clavicula and the humerus. Brachial plexus injuries are one of the most important fetal complications of shoulder dystocia, complicating 4-16% of such deliveries. The purpose of this article is to review the current evidence regarding the possible prediction, prevention and management of shoulder dystocia.

Risk of shoulder dystocia: associations with parity and offspring birthweight. A population study of 1 914 544 deliveries

OBJECTIVES

We estimated the associations of parity and offspring birthweight with the risk of shoulder dystocia, and studied whether the association of offspring birthweight differed by parity.

DESIGN

Population-based register study.

SETTING

The Medical Birth Registry of Norway was used to identify all deliveries between 1967 and 2006.

POPULATION

All vaginal deliveries of a singleton offspring in cephalic presentation during the period 1967-2006 (n=1,914,544).

MAIN OUTCOME MEASURE

Shoulder dystocia at delivery.

RESULTS

Shoulder dystocia occurred in 0.68% (13,109/1,914,544) of all deliveries. There was a strong positive association of birthweight with risk of shoulder dystocia, and 75% (9765/13,109) of all cases occurred in deliveries of offspring weighing 4000g or more. The association of birthweight displayed similar patterns across parities, but the association was slightly stronger in parous than in primiparous women. Among first-time mothers, 0.12% (320/276,614) with offspring weighing 3000-3499g (reference) experienced shoulder dystocia, compared with 13.30% (169/1244) with offspring birthweight higher than 5000g [odds ratio (OR) 135.7, 95%CI 111.6-165.1]. The corresponding results for women with one previous delivery were 0.08% (161/201,572) and 16.45% (501/3054) (OR 246.4, 95%CI 205.4-295.5).

CONCLUSIONS

High offspring birthweight is the major risk factor for shoulder dystocia, constituting most cases. The positive association of birthweight with shoulder dystocia showed similar patterns across parities, but high birthweight parous women were at greater risk of shoulder dystocia compared with primiparous women.

Complications of labor and delivery: shoulder dystocia

This article reviews one of the less common but most dreaded complications of labor and delivery, shoulder dystocia, an infrequent but potentially devastating event that results from impaction of the fetal shoulders in the maternal pelvis. Shoulder dystocia occurs most commonly in patients without identified risk factors, and can result in both maternal and fetal morbidity. Because the vast majority of cases of shoulder dystocia are unpredictable, obstetric care providers must be prepared to recognize dystocia and respond appropriately in every delivery. Detailed documentation is essential after any delivery complicated by shoulder dystocia.

Is an episiotomy necessary with a shoulder dystocia?

OBJECTIVE

The objective of the study was to determine whether a decrease in the use of episiotomy was associated with a change in the frequency of brachial plexus injury.

STUDY DESIGN

All births at Brigham and Women's Hospital from Sept. 1, 1998, through Aug. 31, 2009, were reviewed. The total number of births, mode of delivery, shoulder dystocias, episiotomies with and without shoulder dystocias, and brachial plexus injuries were recorded. A nonparametric test of trend was performed.

RESULTS

There were a total of 94,842 births, 953 shoulder dystocias, and 102 brachial plexus injuries. The rate of episiotomy with shoulder dystocia dropped from 40% in 1999 to 4% in 2009 (P = .005) with no change in the rate of brachial plexus injuries per 1000 vaginal births.

CONCLUSION

Despite historical recommendations for an episiotomy to prevent brachial plexus injury when a shoulder dystocia is encountered, the trend we observed does not suggest benefit from this practice.

Is it possible to reduce obstetrical brachial plexus palsy by optimal management of shoulder dystocia?

Obstetrical brachial plexus palsies (OBPP) have been historically attributed to the impaction of the fetal shoulder behind the symphysis pubis and to excessive lateral traction of the fetal head during maneuvers to deliver the fetal shoulders in shoulder dystocia. Shoulder dystocia is indeed a major risk factor as it increases the risk for OBPP 100-fold. The incidence of OBPP following shoulder dystocia varies widely from 4% to 40%. However, a significant proportion of OBPPs are secondary to in utero injury. The propulsive forces of labor, intrauterine maladaptation, and compression of the posterior shoulder against the sacral promontory as well as uterine anomalies are possible intrauterine causes of OBPP. Many risk factors for OBPP may be unpredictable. Early identification of risk factors for shoulder dystocia, as well as appropriate management when it occurs, may improve our ability to prevent the occurrence of OBPP in those cases that are caused by shoulder dystocia.

Shoulder dystocia without versus with brachial plexus injury: A case–control study

OBJECTIVE

To delineate factors that differentiate shoulder dystocia with and without brachial plexus injury (BPI).

STUDY DESIGN

A case-control study culled from an established shoulder dystocia database. Cases of shoulder dystocia-related BPI were identified and matched (1:1) with a control group of shoulder dystocia in which BPI did not result. Odds ratios (OR) and 95% confidence intervals (CI) were calculated.

RESULTS

From 1980 to 2002, there were 89 978 deliveries with 46 cases of dystocia and BPI. The rate of dystocia with BPI was 0.5 per 1000 births and of permanent BPI, 0.9/10 000 deliveries. The two groups were similar for maternal demographics, diabetes, gestational age, induction, use of epidural, the duration of labor, operative vaginal delivery, rate of macrosomia, and maneuvers used to relieve the dystocia. Fracture of the clavicle occurred significantly less often among those without (2%) vs. with BPI (17%; OR 0.10, 95% CI 0.01, 0.88).

CONCLUSIONS

Neither antepartum nor intrapartum factors can differentiate the patient who will have shoulder dystocia with vs. without BPI.

Review of shoulder dystocia at the Birmingham Women's Hospital

A retrospective audit was performed of all deliveries between 1 January 1991 and 31 December 1995 at the Birmingham Women's Hospital, the main University Teaching Hospital in the West Midlands. This was performed by using the computer database of all hospital deliveries, at the Women's Hospital during the above-mentioned period, by entering a CCL code for shoulder dystocia. During that period of time there were 28 932 deliveries with a mean caesarean section rate of 16.7%. One hundred and fifty-four cases were identified, of which 134 case notes were available for review. The incidence of shoulder dystocia was 0.53%. Audit was performed of pre-pregnancy, antepartum and intrapartum risk factors, the severity of shoulder dystocia, the category of person delivering the baby, fetal outcome at birth and subsequent pregnancy outcome in cases of those with subsequent pregnancies. Overall, the majority of cases of shoulder dystocia were mild, and dealt with by midwives (101 cases 74%). No severe cases were encountered, however three out of eight moderate cases delivered by obstetricians had evidence of fetal trauma (one Erbs palsy and two limb fractures). Twenty women had a pregnancy after the pregnancy complicated by shoulder dystocia. Of these, 18 women delivered vaginally and there were two cases (10%) of repeat shoulder dystocia.

Risk of shoulder dystocia in second delivery: does a history of shoulder dystocia matter?

OBJECTIVE

Our aim was to estimate the relative and absolute risk of shoulder dystocia in the second delivery according to history of shoulder dystocia and offspring birthweight.

STUDY DESIGN

A retrospective cohort study including all women in Norway with 2 consecutive singleton vaginal deliveries with fetus in cephalic presentation, during the period 1967-2005 (n = 537,316).

RESULTS

In the second delivery shoulder dystocia occurred in 0.8% of all women. In women with a prior shoulder dystocia the recurrence risk was 7.3%. Most cases of shoulder dystocia in second delivery were in women without such history (96.2%). Offspring birthweight was the most important risk factor for shoulder dystocia in second delivery: crude odds ratio, 292.9 (95% confidence interval, 237.8-360.7) comparing birthweight > 5000 g with 3000-3499 g.

CONCLUSION

Prior shoulder dystocia increased the risk of shoulder dystocia in the second delivery. However, offspring birthweight was by far the most important risk factor.

[Shoulder dystocia: a ten-year descriptive study in a level-III maternity unit]

OBJECTIVE

Shoulder dystocia is one of the most dreadful complications of vaginal deliveries. The aim of this observational study was to evaluate risk factors of dystocia, maternal and neonatal complications and recurrent risk factors.

PATIENTS AND METHODS

Sixty-six cases of shoulder dystocia occurring between January 1998 and August 2008 in our university hospital were identified. Demographic data, labor management, management of the shoulder dystocia and neonatal outcome were recorded.

RESULTS

The incidence of shoulder dystocia was 0.3%. Multiparity, weight gain greater than 12 kg, and post-term delivery were more present in our study group. McRoberts' manoeuver and symphyseal pressure were first realised. Brachial plexus injuries affected 9% of neonates with skeletal fractures in 7.5% of cases. Maternal morbidity was evaluated at about 8%. Twenty per cent had a recurrent shoulder dystocia.

DISCUSSION AND CONCLUSION

Shoulder dystocia is an obstetric emergency which requires a prompt management of trained personnel. Despite the difficulty of being able to prevent shoulder dystocia, training the obstetric staff could probably improve management of shoulder dystocia.

Newborn brachial plexus palsy

Understanding the causation of newborn brachial plexus injuries and why they are not decreasing in frequency.

Shoulder dystocia in a Jamaican cohort

OBJECTIVE

To assess the risk factors for shoulder dystocia in Jamaica.

METHODS

A retrospective cohort analysis of all cases of shoulder dystocia, and birth weight-matched controls identified from January 1, 2000 to December 31, 2004. Multiple factors were analyzed individually and in combination to identify risk factors.

RESULTS

The incidence of shoulder dystocia was 0.83%. Nulliparity, a first stage of labor greater than 7 hours, a second stage lasting more than 1 hour, and use of oxytocin augmentation were found to be statistically significant factors with unadjusted odds ratios (95% confidence interval) of 1.78 (0.86-3.34), 1.89 (0.91-3.94), 2.78 (0.24-31.47), and 1.56 (0.77-3.15), respectively. The incidence of shoulder dystocia decreased as parity increased when adjusted for age.

CONCLUSION

Individual risk factors for shoulder dystocia remain obscure. The nulliparous pelvis, when controlled for neonatal weight, was associated with a statistically increased risk of shoulder dystocia; this risk decreased with increasing parity.

Shoulder dystocia

Shoulder dystocia is an unpredictable obstetrical emergency that results in serious complications especially to the neonate. Such complications include fracture of the clavicle, brachial plexus injury, fracture of the humerus and asphyxia.1-4 The incidence of shoulder dystocia appears to be increasing5 and its unpredictability continues to be the nightmare of the obstetrician. The following is a review of risk factors which are associated with shoulder dystocia, a critical review of the usefulness of antenatal ultrasound in the prediction of the macrosomic fetus and a discussion of the controversies surrounding the management of shoulder dystocia.

Long-term neurologic outcome of infants born by cesarean section

Prevention of neurologic injury to the fetus through skilled and attentive care during the peripartum period is designed to identify signs of fetal distress so that appropriate obstetric interventions can occur. The impact of mode of delivery on neurologic outcome varies depending on the clinical indication for cesarean delivery and the associated maternal and fetal conditions. This review summarizes current knowledge of the impact of mode of delivery on long-term neurologic outcome.

The epidemiology of neonatal brachial plexus palsy in the United States

BACKGROUND

The nationwide incidence of neonatal brachial plexus palsy in the United States is unknown. The purpose of this study was to determine the incidence of this condition in the United States and to identify potential risk factors for neonatal brachial plexus palsy.

METHODS

Data from the 1997, 2000, and 2003 Kids' Inpatient Database data sets were utilized for this study. Patients were identified with use of the International Classification of Diseases, Ninth Revision (ICD-9), code 767.6 for neonatal brachial plexus palsy. Previously reported risk factors for this condition, including shoulder dystocia, instrumented delivery, breech delivery, an exceptionally large baby (>4.5 kg), heavy infant weight for gestational dates, multiple birth mates, and cesarean delivery, were also identified with use of ICD-9 codes. Multivariate logistic regression analysis was utilized to assess the association of neonatal brachial plexus palsy with its risk factors, after adjusting for sociodemographic characteristics, such as gender, race, and payer status; hospital-based characteristics, such as number of hospital beds, hospital location, region, type, and teaching status; and the effect of time.

RESULTS

Over eleven million births were recorded in the database, and 17,334 had a documented brachial plexus injury in the total of three years, yielding a nationwide mean and standard error of incidence of neonatal brachial plexus palsy in the United States of at least 1.51 +/- 0.02 cases per 1000 live births. The incidence of this condition has shown a significant decrease over the years (p < 0.01). In the multivariate analysis, shoulder dystocia had a 100 times greater risk, an exceptionally large baby (>4.5 kg) had a fourteen times greater risk, and forceps delivery had a nine times greater risk for injury. Having a twin or multiple birth mates and delivery by cesarean section had a protective effect against the occurrence of neonatal brachial plexus palsy. Forty-six percent of all children with neonatal brachial plexus palsy had one or more known risk factors, and fifty-four percent had no known risk factors.

CONCLUSIONS

This nationwide study of neonatal brachial plexus palsy in the United States demonstrates a decreasing incidence over time. Shoulder dystocia poses the greatest risk for brachial plexus injury, and having a twin or multiple birth mates and delivery by cesarean section are associated with a protective effect against injury. Most children with neonatal brachial plexus palsy did not have known risk factors.

Risk factors for recurrent shoulder dystocia, Washington state, 1987-2004

OBJECTIVE

The objective of the study was to identify recurrent shoulder dystocia risk factors.

STUDY DESIGN

This was a population-based case-control study in Washington state (1987-2004). Primary and recurrent shoulder dystocia incidences were calculated. Logistic regression was used to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for subsequent shoulder dystocia risk factors.

RESULTS

Primary and recurrent shoulder dystocia annual incidences were 2.3 of 100 and 13.5 of 100. Of 26,208 women with shoulder dystocia deliveries, 8991 had subsequent vaginal births, and of those, 1060 (11.8%) had a recurrent shoulder dystocia. Index pregnancy birthweight was associated with an increased risk of subsequent shoulder dystocia: 3500-3999 g, aOR 1.8 (95% CI 1.5 to 2.3); 4000-4499 g, aOR 3.3 (95% CI 2.6 to 4.1); 4500-4999 g, aOR 3.1 (95% CI 2.3 to 4.3); and 5000 g or greater, aOR 3.8 (95% CI 2.0 to 7.3). Vacuum delivery, aOR 1.4 (95% CI 1.2 to 1.7), and severe shoulder dystocia, aOR 2.1 (95% CI 1.6 to 2.7) in the index delivery, were also significant.

CONCLUSION

Birthweight of 3500 g or greater, vacuum delivery, or severe shoulder dystocia in the index delivery were independent risk factors for shoulder dystocia recurrence.

Avoiding over diagnosis of shoulder dystocia

In this study, we aimed to distinguish true shoulder dystocia from mere difficulty with delivery of the shoulder, by investigating the risk factors that lead to shoulder dystocia. Shoulder dystocia is a bony problem which occurs when either the anterior or, less commonly, the posterior fetal shoulder impacts on the maternal symphysis pubis or sacral promontory. Failure to apply the Royal College of Obstetricians and Gynaecologists (RCOG) clinical diagnostic criteria for shoulder dystocia has made it susceptible to over-diagnosis due to inclusion of all difficult shoulder deliveries, including those related to an inappropriate maternal position. This was a retrospective analysis of risk factors associated with 56 cases of shoulder dystocia which occurred in West Middlesex University Hospital between 2003 and 2004. The cases were analysed in two categories, good outcome and poor outcome, and compared with each other. The poor outcome had represented true shoulder dystocia. The incidence of shoulder dystocia increased from 0.94% in 2003 to 1.37% in 2004. However, the incidence of those with a poor outcome decreased from 45.4% of the whole shoulder dystocia group in 2003, to 17.6% in 2004 (p = 0.03). There were no clear diagnostic criteria documented in the notes for the condition other than the birth attendants' opinion and the turtle sign. This may either reflect over-diagnosis from increased awareness or possibly improvement in the outcome due to training and education. Interestingly, at least four risk factors were identified in each of the cases with poor outcome. A registrar conducting the delivery, forceps delivery for delayed second stage and the turtle sign were significantly common findings among the true shoulder dystocia group. Multiple risk factors can be a good predictor for the occurrence of shoulder dystocia. Applying the RCOG diagnostic criteria for shoulder dystocia may lead to improvement in diagnosis and therefore a better understanding of the risk factors and future management of shoulder dystocia.

Obstetrical brachial plexus palsy

Obstetrical brachial plexus palsy, one of the most complex peripheral nerve injuries, presents as an injury during the neonatal period. The majority of the children recover with either no deficit or a minor functional deficit, but it is almost certain that some will not regain adequate limb function. These few cases must be managed in an optimal way. Considerable medical and legal debate has surrounded the etiologic factors of this traumatic lesion, and obstetricians are often considered responsible for the injury. According to recent studies, spontaneous endogenous forces may contribute substantially to this type of neonatal trauma. All obstetric circumstances that predispose to brachial plexus damage and that could be anticipated should be assessed. Correct diagnosis is necessary for the accurate estimation of prognosis and treatment. The most important aspect of therapy is timely recognition and referral, to prevent the various possible sequelae affecting the shoulder, elbow, or forearm. Since the early 1990s, research has increased the understanding of obstetrical brachial plexus palsy. Further research is needed, focused on developing strategies to predict brachial injury. This review focuses on emerging data relating to obstetrical brachial plexus palsy and discusses the present controversies regarding natural history, prognosis, and treatment in infants with brachial plexus birth palsies.

Management of shoulder dystocia: trends in incidence and maternal and neonatal morbidity

OBJECTIVE

To investigate trends in the incidence of shoulder dystocia, methods used to overcome the obstruction, and rates of maternal and neonatal morbidity.

METHODS

Cases of shoulder dystocia and of neonatal brachial plexus injury occurring from 1991 to 2005 in our unit were identified. The obstetric notes of cases were examined, and the management of the shoulder dystocia was recorded. Demographic data, labor management with outcome, and neonatal outcome were also recorded for all vaginal deliveries over the same period. Incidence rates of shoulder dystocia and associated morbidity related to the methods used for overcoming the obstruction to labor were determined.

RESULTS

There were 514 cases of shoulder dystocia among 79,781 (0.6%) vaginal deliveries with 44 cases of neonatal brachial plexus injury and 36 asphyxiated neonates; two neonates with cerebral palsy died. The McRoberts' maneuver was used increasingly to overcome the obstruction, from 3% during the first 5 years to 91% during the last 5 years. The incidence of shoulder dystocia, brachial plexus injury, and neonatal asphyxia all increased over the study period without change in maternal morbidity frequency.

CONCLUSION

The explanation for the increase in shoulder dystocia is unclear but the introduction of the McRoberts' maneuver has not improved outcomes compared with the earlier results.

LEVEL OF EVIDENCE

II.