Diagnosis and Management of Macrosomia and Shoulder Dystocia: A Comprehensive Review of Major Guidelines.

Importance: Macrosomia represents the most significant risk factor of shoulder dystocia (SD), which is a severe and emergent complication of vaginal delivery. They are both associated with adverse pregnancy outcomes. Objective: The aim of this study was to review and compare the most recently published influential guidelines on the diagnosis and management of fetal macrosomia and SD. Evidence Acquisition: A comparative review of guidelines from the American College of Obstetricians and Gynecologists (ACOG), the Royal College of Obstetricians and Gynaecologists, the National Institute for Health and Care Excellence, the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG), and the Department for Health and Wellbeing of the Government of South Australia on macrosomia and SD was conducted. Results: The ACOG and RANZCOG agree that macrosomia should be defined as birthweight above 4000-4500 g regardless of the gestational age, whereas the National Institute for Health and Care Excellence defines macrosomia as an estimated fetal weight above the 95th percentile. According to ACOG and RANZCOG, ultrasound scans and clinical estimates can be used to rule out fetal macrosomia, although lacking accuracy. Routine induction of labor before 39 weeks of gestation with the sole indication of suspected fetal macrosomia is unanimously not recommended, but an individualized counseling should be provided. Exercise, appropriate diet, and prepregnancy bariatric surgery are mentioned as preventive measures. There is also consensus among the reviewed guidelines regarding the definition and the diagnosis of SD, with the "turtle sign" being the most common sign for its recognition as well as the poor predictability of the reported risk factors. Moreover, there is an overall agreement on the algorithm of SD management with McRoberts technique suggested as first-line maneuver. In addition, appropriate staff training, thorough documentation, and time keeping are crucial aspects of SD management according to all medical societies. Elective delivery for the prevention of SD is discouraged by all the reviewed guidelines. Conclusions: Macrosomia is associated not only with SD but also with maternal and neonatal complications. Similarly, SD can lead to permanent neurologic sequalae, as well as perinatal death if managed in a suboptimal way. Therefore, it is crucial to develop consistent international practice protocols for their prompt diagnosis and effective management in order to safely guide clinical practice and improve pregnancy outcomes.

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.

Obstetrics injuries during shoulder dystocia in a tertiary perinatal center.

OBJECTIVES: This study will present our results in management of fetal shoulder dystocia with special consideration of maternal and neonatal outcome. STUDY DESIGN: A retrospective study was performed at a university tertiary perinatal center. The study included data of singleton vaginal term deliveries in the period of 15 years (2006-2020). Analized informations include: obstetrics maternal and neonatal data and outcomes. RESULTS: This period included 45,687 deliveries with diagnosed shoulder dystocia in 254 (0.7 %) cases in vaginal deliveries. Most of the deliveries were spontaneous births 69.7 %, induced deliveries 30.3 %, 47.2 % primiparas and preexisting or gestational diabetes in 21.7 %. The delivery was managed by vacuum extraction in 13.8 %, mediolateral episiotomy in 48.0 % of births, most of the shoulder dystocia were unilateral anterior, while only two cases were diagnosed as more difficult bilateral and 5 cases were recurrent. 87.4 % cases were resolved by McRobert's maneuver, 7.8 % by Barnum's 3.9 % by Wood's maneuver and one case was managed by Menticoglou and by Bourgoise-Siegemundin maneuver. 4.3 % injuries were classified as OASIS of III/IV degree, early postpartum hemorrhage due in 1.6 %. 54.3 % of newborns were male sex, 61.0 % of newborns had birth weight of above 4000 g (mean 4071 g). Maximal Apgar scores were atributed to 92.5 % in first and to 97.2 % in fifth minute, one case that requaired resuscitation. Clavicle fracture was found in 9.5 %, humerus fracture in 0.4 %, transient form of Duchenne Erb obstetrics brachial palsy was diagnosed in only in 7.5 % newborns, while we have not found any case of permanent brachial palsy. CONCLUSIONS: Our results confirmed that strategy of prompt identification of shoulder dystocia accompanied by cessation of axial fetal head traction decrease the risk of brachial plexus strain, injury or tear, while performance of exact obstetrical maneuvers resulted in decanceration of fetal shoulders without permanent obstetrics brachial palsy or cerebral morbidity. We think that our good results corelate with our opinion that the performance of external obstetrical manoeuvres should be done without one minute postpone since efforts should be put in sooner shoulder liberation decreasing the time of fetal hypoxia.

Accelerated fetal growth velocity across the third trimester is associated with increased shoulder dystocia risk among fetuses who are not large-for-gestational-age: A prospective observational cohort study.

OBJECTIVE: To investigate whether fetuses with accelerated third trimester growth velocity are at increased risk of shoulder dystocia, even when they are not large-for-gestational-age (LGA; estimated fetal weight (EFW) >95th centile). METHODS: Fetal growth velocity and birth outcome data were prospectively collected from 347 nulliparous women. Each had blinded ultrasound biometry performed at 28 and 36 weeks' gestation. Change in EFW and abdominal circumference (AC) centiles between 28-36 weeks were calculated, standardised over exactly eight weeks. We examined the odds of shoulder dystocia with increasing EFW and AC growth velocities among women with 36-week EFW ≤95th centile (non-LGA), who went on to have a vaginal birth. We then examined the relative risk (RR) of shoulder dystocia in cases of accelerated EFW and AC growth velocities (>30 centiles gained). Finally, we compared the predictive performances of accelerated fetal growth velocities to 36-week EFW >95th centile for shoulder dystocia among the cohort planned for vaginal birth. RESULTS: Of the 226 participants who had EFW ≤95th centile at 36-week ultrasound and birthed vaginally, six (2.7%) had shoulder dystocia. For each one centile increase in EFW between 28-36 weeks, the odds of shoulder dystocia increased by 8% (odds ratio (OR [95% Confidence Interval (CI)]) = 1.08 [1.04-1.12], p<0.001). For each one centile increase in AC between 28-36 weeks, the odds of shoulder dystocia increased by 9% (OR[95%CI] = 1.09 [1.05-1.12], p<0.001). When compared to the rest of the cohort with normal growth velocity, accelerated EFW and AC velocities were associated with increased relative risks of shoulder dystocia (RR[95%CI] = 7.3 [1.9-20.6], p = 0.03 and 4.8 [1.7-9.4], p = 0.02 respectively). Accelerated EFW or AC velocities predicted shoulder dystocia with higher sensitivity and positive predictive value than 36-week EFW >95th centile. CONCLUSIONS: Accelerated fetal growth velocities between 28-36 weeks' gestation are associated with increased risk of shoulder dystocia, and may predict shoulder dystocia risk better than the commonly used threshold of 36-week EFW >95th centile.

Antenatal risk prediction of shoulder dystocia: influence of diabetes and obesity: a multicenter study.

PURPOSE: To estimate the risk of shoulder dystocia (SD) in pregnancies with/without maternal diabetes or obesity; to identify antenatal maternal and fetal ultrasound-derived risk factors and calculate their contributions. METHODS: A multicenter retrospective analysis of 13,428 deliveries in three tertiary hospitals (2014-2017) with fetal ultrasound data ≤ 14 days prior to delivery (n = 7396). INCLUSION CRITERIA: singleton pregnancies in women ≥ 18 years old; vertex presentation; vaginal delivery at ≥ 37 weeks of gestation. Estimated fetal weight (EFW) and birth weight (BW) were categorized by steps of 250 g. To evaluate risk factors, a model was performed using ultrasound data with SD as the dependent variable. RESULTS: Diabetes was present in 9.3%; BMI ≥ 30 kg/m2 in 10.4% and excessive weight gain in 39.8%. The total SD rate was 0.9%, with diabetes 2.0% and with obesity 1.9%. These increased with BW 4250-4499 g compared to 4000-4249 g in women with diabetes (12.1% vs 1.9%, P = 0.010) and without (6.1% vs 1.6%, P < 0.001) and at the same BW threshold for women with obesity (9.6% vs 0.6%, P = 0.002) or without (6.4% vs 1.8%, P < 0.001). Rates increased similarly for EFW at 4250 g and for AC-HC at 2.5 cm. Independent risk factors for SD were EFW ≥ 4250 g (OR 3.8, 95% CI 1.5-9.4), AC-HC ≥ 2.5 cm (OR 3.1, 95% CI 1.3-7.5) and diabetes (OR 2.2, 95% CI 1.2-4.0). HC/AC ratio, obesity, excessive weight gain and labor induction were not significant. CONCLUSION: Independent of diabetes, which remains a risk factor for SD, a significant increase may be expected if the EFW is ≥ 4250 g and AC-HC is ≥ 2.5 cm.

The association of vacuum-assisted delivery and shoulder dystocia among macrosomic newborns: a retrospective study.

PURPOSE: Although shoulder dystocia (ShD) is associated with fetal macrosomia and vacuum-assisted delivery (VAD), the independent role of the latter in the occurrence of ShD is yet to be completely elucidated, as it is difficult to study its true independent contribution to ShD formation in the presence of many confounding factors. Therefore, we aimed to study whether VAD is independently associated with an increased risk for ShD among macrosomic newborns. METHODS: A retrospective cohort study from a single tertiary medical center including all women who delivered vaginally a macrosomic infant during 2011-2020. We allocated the study cohort into two groups: (1) VAD (2) spontaneous vaginal deliverys, and analyzed risk factors for ShD. A multivariate regression analysis was performed to identify determinants independently associated with ShD occurrence. RESULTS: Of 2,664 deliveries who met the study inclusion criteria, 118 (4.4%) were VAD. The rate of ShD in the entire cohort was 108/2664 (4.1%). The following factors were more frequent among the VAD group: no previous vaginal delivery [odds ratio (OR) 2.4 (95% confidence interval (CI) 1.4-4.0, p < 0.001)], prolonged second stage (OR 11.9; 95% CI 8.1-17.6, p < 0.01), induction of labor (OR 2.4; 95% CI 1.5-3.8, p < 0.01) and ShD (OR 2.0; 95% CI 1.0-4.1, p = 0.04). ShD was associated with higher rates of maternal height < 160 cm (OR 2.0; 95% CI 1.3-3.1, p < 0.01), pregestational diabetes (OR 7.2; 95% CI 2.0-26.8, p = 0.01), hypertensive disorder (OR 2.6; 95% CI 1.1-6.2, p = 0.02) and higher birthweight (mean 4,124 vs. 4,167 g, p < 0.01). On multivariate regression analysis, the following factors remained independently associated with ShD occurrence: increased birthweight (aOR 1.0; 95% CI 1.0-1.0, p < 0.01), pregestational diabetes (aOR 5.3; 95% CI 1.1-25.0, p = 0.03), while maternal height was negatively associated with ShD (aOR 0.9; 95% CI 0.9-0.9, p < 0.01). CONCLUSION: In deliveries of neonates above 4000 g, VAD did not independently increase the risk of ShD occurrence. Therefore, when expeditious delivery of a macrosomic infant is required, VAD is a viable option.

Pathophysiologic Origins of Brachial Plexus Injury.

OBJECTIVE: To analyze the origins and consequences of cases of brachial plexus injuries and their relationship to shoulder dystocia. METHODS: We conducted a retrospective cohort study and identified all neonates with brachial plexus injury delivered at our institution between March 2012 and July 2019. A review was performed of the maternal and neonatal records of each neonate to identify obstetric antecedents, including the occurrence of shoulder dystocia and persistence of the injury. Experience of the delivering clinician was also examined. Statistical analysis was performed with the Fisher exact test, χ test for trends, and two-tailed t tests. RESULTS: Thirty-three cases of brachial plexus injury were identified in 41,525 deliveries (0.08%). Fourteen (42%) of these cases were not associated with shoulder dystocia; three (9%) followed cesarean delivery. Brachial plexus injury without shoulder dystocia was related to the absence of maternal diabetes, lower birth weights, and a longer second stage of labor. Persistent brachial plexus injury at the time of discharge was seen with equal frequency among neonates with (17/19, 89%, 95% CI 0.52-100%) and without shoulder dystocia (10/14, 71%, 95% CI 34-100%), P=.36). Whether brachial plexus injury was transient or persistent after shoulder dystocia was unrelated to the years of experience of the delivering clinician. Despite ongoing training and simulation, the already low incidence of brachial plexus injury did not decrease over time at our institution. CONCLUSION: Brachial plexus injury and shoulder dystocia represent two complications of uterine forces driving a fetus through the maternal pelvis in the presence of disproportion between the passage and the shoulder girdle of the passenger. Either or both of these complications may occur, but often are not causally related.

Trends of changes in the specific contribution of selected risk factors for shoulder dystocia over a period of more than two decades.

Objectives Shoulder dystocia (SD) is an obstetrical emergency with well-recognized risk factors. We aimed to identify trends of changes in the specific contribution of risk factors for SD over time. Methods A nested case control study comparing all singleton deliveries with and without SD was undertaken. A multivariable logistic regression model was used in order to identify independent risk factors for SD and a comparison of the prevalence and the specific contribution (odds ratio (OR)) of the chosen risk factors in three consecutive eight-year intervals from 1988 to 2014 was performed. Results During the study period, there were 295,946 deliveries. Of them 514 (0.174%) were complicated with SD. Between 1988 and 2014 the incidence of SD has decreased from 0.3% in 1988 to 0.1% in 2014. Using a logistic regression model grandmultiparity, diabetes mellitus (DM), fetal weight, and large for gestational age (LGA) were found to be independent risk factors for SD (OR 1.25 95% CI 1.04-1.51, p=0.02; OR 1.53 95% CI 1.19-1.97, p=0.001; OR 1.002 95% CI 1.001-1.002, p < 0.001; OR 3.88 95% CI 3.09-4.87, p < 0.001; respectively). While the OR for grandmultiparity, fetal weight, and LGA has significantly changed during the study period with a mixed trend, the OR of DM has demonstrated a significant linear increase over time. Conclusions The individual contribution of selected risk factors for the occurrence of SD has significantly changed throughout the years. The contribution of DM has demonstrated a linear increase over time, emphasizing the great impact of DM on SD.