A scoring system for detection of macrosomia and prediction of shoulder dystocia: A disappointment

Objective. To develop a scoring system for the detection of a macrosomic fetus (birth weight (BW) ≥ 4000 g) and predict shoulder dystocia among large for gestational age fetuses.

Study design. We retrospectively identified all singletons with accurate gestational age (GA) that were large for GA (abdominal circumference (AC) or estimated fetal weight (EFW) ≥ 90% for GA) at ≥37 weeks with delivery within three weeks. The scoring system was: 2 points for biparietal diameter, head circumference, AC, or femur length ≥90% for GA, or if the amniotic fluid index (AFI) was ≥24 cm; for biometric parameters <90% or with AFI <24 cm, 0 points. The predictive values for detection of shoulder dystocia were calculated.

Results. Of the 225 cohorts that met the inclusion criteria the rate of macrosomia was 39% and among vaginal deliveries (n = 120) shoulder dystocia occurred in 12% (15/120; 95% confidence interval (CI) 7–20%). The sensitivity of EFW ≥4500 g to identify a newborn with shoulder dystocia was 0% (95% CI 0–21%), positive predictive values 0% (95% CI 0–46%), and likelihood ratio of 0. For a macrosomia score >6, the corresponding values were 20% (4–48%), 25% (5–57%) and 2.3.

Conclusion. Though the scoring system can identify macrosomia, it offers no advantage over EFW. The scoring system and EFW are poor predictors of shoulder dystocia.     

Fetal macrosomia as a risk factor for shoulder dystocia during vacuum extraction

Objective: Vacuum extraction of a macrosomic fetus is considered a risk factor for shoulder dystocia (SD). We evaluated maternal and fetal outcomes following vacuum extraction of macrosomic infants.

Methods: A retrospective cohort study conducted in two large teaching hospitals. All deliveries of macrosomic infants by vacuum extraction and vaginal delivery were compared. The primary outcome measure was SD. Secondary outcome measures were severe perineal lacerations and postpartum hemorrhage. For statistical analysis, we used McNemar’s test and χ² or Fisher’s exact tests. Odds ratios were analyzed via a logistic regression model.

Results: From 2003 to 2013, there were 6019 (5.45%) deliveries of macrosomic fetuses, and 230 (0.21%) were delivered by vacuum extraction. There were 23 (10%) and seven (3.04%) cases of SD in the study and control groups, respectively. The risk of SD was significantly higher in the study group (p?>?0.05). We found a significant association between SD and vacuum delivery [p?=?0.003; OR?=?3.54 (95% CI: 1.49–8.42)]. The composite adverse neonatal outcome rate was 6.5% (15/230) and 1.7% (4/230) in the study and control groups, respectively (p?=?0.009).

Conclusion: Vacuum extraction of a macrosomic infant is a risk factor for shoulder dystocia but not for postpartum hemorrhage or severe vaginal tears.     

Antenatal and intrapartum prediction of shoulder dystocia

Objectives

To (1) develop algorithms to calculate the risk of shoulder dystocia at individual deliveries; (2) evaluate screening for shoulder dystocia.

Study design

Retrospective analysis of 40284 consecutive term cephalic singleton pregnancies using a ‘train and test’ method. Four models were derived using logistic regression and tested (birthweight alone; birthweight and other independent antenatal variables; birthweight and all independent antenatal and intrapartum variables; and all independent variables excluding birthweight).

Results

Shoulder dystocia occurred in 240 deliveries (0.6%). Birthweight was the most important risk factor although 98 cases (41%) occurred in babies weighing <4.0 kg. Birthweight and maternal height were the only independent antenatal variables; for intrapartum use, only these and instrumental delivery were independent. The antenatal model could calculate an individual's risk; the intrapartum model could also calculate the risk if an instrumental delivery were undertaken. Both showed 0.7% women to have a risk of shoulder dystocia of >10%. Although the antenatal model had high predictability (area under curve 0.89), it was no better than birthweight alone and had a sensitivity of 52.4%. Where birthweight was excluded, prediction of shoulder dystocia was poor.

Conclusion

Antepartum and labour calculation of the risk of shoulder dystocia is possible. Whilst greatly hindered by the inaccuracy of estimating weight, it allows due weight to be given to factors which may already be influencing clinical practice. However, shoulder dystocia cannot be predicted with sufficient accuracy to allow universal screening.     

McRoberts maneuver for shoulder dystocia: a survey.

A survey of 108 major teaching institutions in the United States regarding the utilization of the McRoberts maneuver for shoulder dystocia was conducted. Only 40% taught the procedure but 64% reported being familiar with its use. Among users, only 32% used it as the initial step. Surprisingly, only 40% thought it reduced fetal trauma.     

Fetal abdominal circumference measurements of 35 and 38 cm as predictors of macrosomia. A risk factor for shoulder dystocia

OBJECTIVE: To determine if ultrasound measurements of fetal abdominal circumference (AC) can be used to predict macrosomic infants. STUDY DESIGN: Using a computer database, 1,996 women at > or = 36 weeks' gestation, delivering a singleton infant and having an ultrasound examination within one week of delivery were studied. Fetal AC was evaluated to determine if it was useful in predicting the birth of a macrosomic infant, > 4,000 or > 4,500 g. RESULTS: AC predicted infants > 4,500 g better than those > 4,000 g. Almost all macrosomic infants > 4,500 g had an AC of > or = 35 cm (68/69, or 99%), but many nonmacrosomic infants were also in this group (683). AC of > or = 38 cm occurred in 99 infants, and 37 of the 69 (53.6%) weighing > 4,500 g were identified. Most infants (78%) with AC > or = 38 cm weighed > 4,000 g. CONCLUSION: Fetal AC was very helpful in identifying potential macrosomic infants. If AC was < 35 cm, the risk of infant birth weights > 4,500 g was < 1%. If AC was > or = 38 cm, the risk was 37% (37/99), and > 50% of these infants were identified (37/69, or 53.6%).     

Maternal risks for newborn macrosomia, incidence of a shoulder dystocia and of damages of the plexus brachialis

PATIENTS RESPECTIVELY AND METHODS: In the HEPE 619 242 births have been analysed (1990 - 2000) to calculate the incidence of a birthweight between 4000 and 4499 g and of a weight > or = 4500 g in relationship to maternal obesity, high maternal weight gain and of a duration of pregnancy more than 298 days. RESULTS: The risk of a macrosomia > or = 4500 g is in cases of obesity 3.4 times higher, in cases of obesity and prolongation of pregnancy 6.6 times higher and in the presence of all 3 risk factors 10 times higher. Data of the Frauenklinik Wiesbaden (HSK) (n = 6075 births) complete the results, because a correlation between macrosomia, shoulder dystocia and a damage to the plexus brachialis has been found. The incidence of a damage to the plexus brachialis is in case of a shoulder dystocia and a birth weight of < or = 4000 g 6.3%, at a birth weight between 4000-4499 g 25% and in newborns with a weight > or = 4500 g 40%. CONCLUSIONS: Because of the low sensitivity (60%) of the ultrasonic weight measurement the 3 maternal risk factors--if they exist--of a shoulder dystocia and of a damage of the plexus brachialis should be discussed with the pregnant woman to help her about the decision of an alternative cesarean section. Still one third of the newborns weigh more than 4000 g if all 3 maternal risk factors exist.     

A shoulder dystocia mnemonic for homebirth

There are other shoulder dystocia mnemonics to be found on the internet, in obstetric textbooks and in assorted hospital protocols. Clearly there is mileage in the same mnemonic being used throughout hospital-based practice within the UK to avoid any confusion and streamline clinical practice, and the HELPERR mnemonic seems to have assumed this role admirably. However, for the midwife working at home it does not appear to be appropriate because: * it is not in the most useful order; * it does not allow for several other; manoeuvres that midwives have found helpful; * it is not always user-friendly and memorable. It is hoped that this article will prompt debate and discussion around the appropriate management of this rare emergency at home; and that midwives, should they choose, will be able to employ MAGIC R. PSAZZ as their mnemonic of choice in the homebirth setting. However, it is important to end by emphasising that no mnemonic or protocol should ever be more important than the clinical judgement of the clinician, which remains paramount throughout. The precise order of manoeuvres and actions will vary according to the situation and the midwife's communication with the woman, and her analytical and decision-making abilities remain crucial.     

非巨大儿肩难产发生的高危因素及其临床预测

目的 探讨非巨大儿肩难产发生的高危因素、临床预测及分娩过程中的处理.方法 2009年1月2013年12月间于中国医科大学附属盛京医院经阴道分娩的产妇中发生肩难产11例,同期经阴道分娩产妇7 811例,肩难产发生率为0.14％(11/7 811);其中,巨大儿肩难产1例,非巨大儿肩难产10例(肩难产组).随机抽取每例非巨大儿肩难产病例发生前后1周内经阴道分娩的10例产妇为对照组.分析巨大儿及非巨大儿肩难产的发生趋势及其高危因素,比较两组产妇的宫高、腹围、体质指数(BMI)增长、胎儿双顶径、股骨长、各产程时间、新生儿出生体质量、头围、胸围及Apgar评分.结果 (1)7 811例产妇中共分娩巨大儿213例,巨大儿发生率为2.73％(213/7 811),其中发生巨大儿肩难产1例(0.46％,1/213);非巨大儿肩难产10例(0.13％,10/7 598).(2)2009-2013年的5年间,巨大儿发生率分别为2.32％(24/1 034)、3.61％(42/1 164)、2.60％ (46/1 772)、3.01％(62/2 060)、2.19％(39/1 781),分别比较,差异均无统计学意义(P＞0.05);10例非巨大儿肩难产在5年间的发生比例分别为0.10％(1/1 034)、0.26％(3/1 164)、0.11％(2/1 772)、0.10％(2/2 060)、0.11％(2/1 781),分别比较,差异均无统计学意义(P＞0.05).(3)肩难产组10例产妇中,胎膜早破5例(5/10)、高龄4例(4/10)、经产妇3例(3/10)、妊娠期糖尿病3例(3/10)、第一产程枕后位3例(3/10)、第二产程延长3例(3/10)、常规侧切分娩6例(6/10);对照组产妇中,发生胎膜早破3例(3/10)、高龄1例(1/10)、经产妇2例(2/10)、妊娠期糖尿病3例(3/10)、第二产程时间延长1例(1/10)、常规侧切分娩7例(7/10).(4)两组产妇宫高、BMI、胎儿双顶径、股骨长及第一产程时间分别比较,差异均无统计学意义(P＞0.05).肩难产组及对照组产妇BMI增长[(6.8±3.1)及(4.8±1.4)kg/m2]、第二产程时间[(86±65)及(38±28) min]及腹围[(108±8)及(101±7)cm]分别比较,差异均有统计学意义(P＜0.05).(5)肩难产组及对照组新生儿胸围[(34.0±1.6)及(32.2±1.9) cm]及胸围/头围比值(0.99±0.03及0.97±0.03)比较,差异均有统计学意义(P＜0.05).肩难产组新生儿1分钟Apgar评分[(7.4±2.8)分]明显低于对照组[(10.0±0.0)分],两组比较,差异有统计学意义(P＜0.01).肩难产组新生儿锁骨骨折3例,新生儿发生臂丛神经损伤4例,其余3例无明显副损伤.结论 临床预测非巨大儿肩难产的发生难度较大,通过产前超声测量胎儿头围、胸围及胸围/头围比值可能评估其发生风险;发生非巨大儿肩难产的高危因素为合并胎膜早破、第一产程胎位异常及第二产程延长.     

肩难产的预防和处理

肩难产是难以完全预测的高危产科急症,发生率0.2%～3.0%。可引起严重母儿并发症,以新生儿臂丛神经损伤最为常见（4%～40%）,产科从业人员应该注意肩难产发生的危险因素并在任何一次分娩时均需要警惕其发生。一旦发生需要立刻采取正确的处理。了解其高危因素并制定针对性预防措施,熟练掌握正确的处理技术以有效降低严重并发症的发生率。     

Use of birth weight threshold for macrosomia to identify fetuses at risk of shoulder dystocia among Chinese populations

ObjectiveTo assess the incidence of macrosomia and the influence of birth weight on shoulder dystocia risk among a cohort of Chinese women.MethodsA retrospective analysis was conducted of 80 953 singleton deliveries recorded at the Prince of Wales Hospital, Hong Kong, between 1995 and 2009. The incidences of macrosomia (birth weight ≥ 4000 g) and shoulder dystocia were assessed by birth weight; risk factors for shoulder dystocia were examined by multiple logistic regression analysis.ResultsThe incidence of macrosomia was 3.4%. The overall incidence of shoulder dystocia was 0.3%; however, the incidence rose with increasing birth weight. The odds ratio (OR) for a birth weight of 4000–4199 g was 22.40, while the OR for a birth weight of 4200 g or above was 76.10. Other independent risk factors for shoulder dystocia included instrumental delivery (OR 12.11), short stature (OR 2.16), maternal diabetes mellitus (OR 1.78), and obesity (OR 1.58).ConclusionAlthough the overall incidences of macrosomia and shoulder dystocia were low, the risk of shoulder dystocia was strongly linked to increasing birth weight. International guidelines for elective cesarean delivery in suspected cases of macrosomia may not, therefore, apply to Chinese women.     

肩难产综合预防措施的荟萃分析

目的 探讨肩难产的综合预防措施.方法 计算机检索2014年5月以前的PubMed数据库、美国EBSCO数据库、荷兰医学文摘数据库、Cochrane图书馆数据库,以“shoulder dystocia and prevention”为主题词检索英文文献.对检索到的文献进行质量评价,文献研究类型仅限于随机对照临床试验(RCT)研究;研究对象为经阴道分娩产妇,干预措施包括孕期管理、预防性引产、预防性剖宫产术,预防性肩难产处理.纳入的文献采用RevMan 5.1软件进行荟萃分析,以肩难产发生率作为终点指标.结果 共有16篇英文文献纳入荟萃分析,发表时间为1993-2009年.(1)对妊娠期糖尿病(GDM)孕妇的孕期干预:有2篇文献比较了GDM孕妇的孕期干预(干预组)与不干预(不干预组)对肩难产发生率的影响,结果显示,干预组肩难产发生率显著低于不干预组(OR=0.40,95％ CI为0.21～0.75,P=0.004).(2)对GDM孕妇的孕期严格干预:5篇文献比较了GDM孕妇的孕期严格干预(饮食控制+胰岛素应用;严格干预组)与不严格干预(单纯饮食控制等;不严格干预组)对肩难产发生率的影响,结果显示,严格干预组肩难产发生率显著低于不严格干预组(OR=0.29,95％CI为0.11～ 0.73,P=0.009).(3)非糖尿病孕妇可疑巨大儿者引产:有4篇文献比较了非糖尿病孕妇可疑巨大儿者提前引产(提前引产组)对肩难产发生的影响,结果显示,提前引产组肩难产发生率与对照组比较,差异无统计学意义(OR=0.85,95％CI为0.41～ 1.75,P=0.660).(4)GDM孕妇引产:有2篇文献比较了GDM孕妇提前引产(孕38～ 39周;提前引产组)对肩难产发生的影响,结果显示,提前引产组肩难产发生率与对照组比较,差异有统计学意义(OR=0.18,95％CI为0.03～ 0.97,P=0.050);只与对照组中孕40周以后分娩者比较,提前引产组肩难产发生率显著低于对照组(OR=0.13,95％ CI为0.02～ 0.75,P=0.020).(5)GDM孕妇可疑巨大儿者提前终止妊娠:仅有1篇文献比较了GDM孕妇中可疑巨大儿者提前终止妊娠(提前终止妊娠)对肩难产发生率的影响,结果显示,提前终止妊娠组的肩难产发生率与对照组比较,差异有统计学意义(OR=0.34,95％CI为0.12～ 0.99,P=0.050).(6)产时预防性干预(产时干预组)对肩难产发生率的影响:有2篇文献比较了产时胎头娩出后行预防性干预对肩难产发生率的影响,结果显示,产时干预组肩难产发生率与对照组比较,差异无统计学意义(OR=0.44,95％CI为0.16～ 1.18,P=0.100).结论 对有肩难产高危因素的孕妇适当进行临床措施的干预,可明显降低肩难产的发生率.     

Breech presentation and shoulder dystocia in childbirth.

This review covers the recent literature relevant to breech presentation and shoulder dystocia. Further evidence in favor of external cephalic version at term has emerged, and the possibility of its use in women with previous cesarean section has been suggested. Attention has been given to trial of labor in selected cases of term breech presentation. The evidence to guide the method of delivery for preterm breech presentations remains inadequate. No perinatal differences have been demonstrated among the outcome of breech second-born twins delivered by external cephalic version, breech extraction, or cesarean section. The evidence in favor of elective cesarean for suspected macrosomia to prevent shoulder dystocia is unconvincing for nondiabetics and is doubtful for pregnant diabetics. The McRoberts maneuver for shoulder dystocia has not received the prominence that it deserves.     

Features of shoulder dystocia in a busy obstetric unit.

OBJECTIVE: To assess the incidence and complications of shoulder dystocia and whether those complications could be avoided. STUDY DESIGN: Retrospective analysis of shoulder dystocia between 1996 and 1999 to determine whether macrosomia, diabetes, height of head at full dilatation, length of second stage or instrumental delivery could predict shoulder dystocia. Fetal asphyxia, brachial plexus injury, maneuvers used to free the shoulders and experience of the attendant were also assessed. RESULTS: There were 56 cases of shoulder dystocia in 24,000 births, 59% after spontaneous delivery. McRoberts maneuver was used in 48 deliveries but sufficed as a solitary procedure in nine cases. The addition of suprapubic pressure was sufficient for 25 patients and 27 when bilateral episiotomy was also used. Corkscrew procedures were required in 12 patients. Midwives were involved in 35 cases and required assistance in 27. Macrosomia > 4,000 g was a feature in 20 infants and diabetes in 6. Neither the height of the head nor the length of the second stage was helpful. There were 13 cases of Erb's palsy, seven after vacuum delivery and six after spontaneous delivery. Eight of these cases were associated with McRoberts procedure and suprapubic pressure, two with no procedure and three with the corkscrew procedure. CONCLUSION: If all infants > 4,000 g had been delivered by cesarean section, there still would have been 36 cases of shoulder dystocia. If the ultrasonically estimated weight were used to select patients for cesarean section, seven cases would have been diagnosed. To lessen the degree and incidence of fetal injury, labor ward staff are urged to become as familiar as possible with the techniques of freeing the shoulders.