Shoulder dystocia: Predictors and outcome

Shoulder dystocia: Predictors and outcome A five-year review Susan J. Gross, M.D., Jerry Shime, M.D., and Dan Farine, M.D. Toronto, Ontario, Canada Shoulder dystocia is an uncommon complication of delivery with a high morbidity rate. Ninety-one cases were coded for shoulder dystocia at the Toronto General Hospital from 1980 through 1985. True shoulder dystocia was found in 24 cases, an incidence of 0.23%. There was no significant difference in average weight and percentage of macrosomia between cases of true shoulder dystocia and those merely coded as such. True shoulder dystocia was associated with a neonatal morbidity rate of 42%, consisting of a respiratory arrest and neurological and orthopedic damage. Fundal pressure, in the absence of other maneuvers, resulted in a 77% complication rate and was strongly associated with orthopedic and neurologic damage. Delivery of the posterior shoulder and the corkscrew maneuver were associated with good fetal outcome. (AM J OBSTET GYNECOL 1987;156:334-6.)

Key words: Shoulder dystocia, complications, obstetrics, delivery maneuvers Although shoulder dystocia is an uncommon complication of delivery with a suspected incidence of 0.15% to 0.3%,' it is associated with a relatively high morbidity rate of 16% to 48% 2· 3 and potentially devastating outcome. The risk factors for shoulder dystocia are often seen with macrosomia (birth weight of >4000 gm) and include multiparity, postdatism, previous macrosomic infant, and obesity. Diabetes carries a twofold risk of shoulder dystocia that is due to a combination of macrosomia and altered body configuration.•· 5 Prolonged second stage of labor and midforceps delivery (alone and in combination),' as well as protraction and arrest disorders, 6 have also been identified as risk factors for shoulder dystocia. True shoulder dystocia refers to deliveries requiring maneuvers to deliver the shoulders in addition to downward traction and episiotomy. 1 The following study documents our experience with shoulder dystocia during a 5-year period. Deliveries complicated by true shoulder dystocia were compared to deliveries that were merely coded as such. The risk factors listed above were compared in these two groups. Management of shoulder dystocia and its relationship to fetal outcome and maternal morbidity were analyzed as well. Material and methods All vaginal deliveries ( 10,662 cases) performed at the Toronto General Hospital from April 1980 to March From the Division of Maternal and Fetal Medicine, Toronto General Hospital and The Perinatal Complex, University of Toronto. Presented at the Forty-second Annual Meeting of The Society of Obstetricians and Gynaecologists of Canada, Charlottetown, Prince Edward Island, Canada, June 23-27, 1986. Reprint requests: Dr.]. Shime, Department of Obstetrics and Gynecology, Toronto General Hospital, 200 Elizabeth St., Toronto, Ontario, Canada M5G 2C4.

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1985 were analyzed retrospectively. There were 91 deliveries coded for shoulder dystocia; 24 were cases of true shoulder dystocia (group l); and the remaining 67 cases, although coded as shoulder dystocia, merely required increased traction for delivery (group 2). Risk factors for shoulder dystocia were compared in both groups, with prolonged second stage referring to > 11/2 hours for a multiparous patient and >2 hours for a primiparous one. 7 Maternal and fetal outcome were also compared. Fetal morbidity included the presence of one of the following: fractures, neurological damage such as palsies, and Apgar scores of <5 at 5 minutes. Maternal morbidity refers to the presence of uterine rupture, postpartum hemorrhage, and fourth-degree lacerations of the vagina. The Fisher exact test and x2 with the Yates correction were used for statistical analysis. Results The risk factors for shoulder dystocia in both groups are described in Table 1. There was no significant difference in average weight or percentage of macrosomia between the two groups. Diabetes was present in only one patient in group 2 in a case with induction at 38 weeks and delivery of a 3880 gm infant. There was no significant difference in the risk factors related to macrosomia between the two groups. Midforceps delivery and a prolonged second stage were more common in group 1 compared to group 2; however, the difference between the two groups was not statistically significant. Although the combination of these two risk factors was 3.5 times more common in group 1 (21 %) versus group 2 (6%), this difference did not prove to be statistically significant. The neonatal and maternal complications are given in Table II. The morbidity associated with true shoul-

Shoulder dystocia 335

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Table I. Risk factors in true and coded shoulder dystocia True shoulder dystocia (n = 24)* Risk factor

n

Macrosomia Multiparity Previous macrosomia Obesity Diabetes Postterm Prolonged second stage Midforceps delivery Prolonged second stage and midforceps delivery

15 2 4 0 2 6 12 5

*Average weight ± SD t Average weight ± SD

I

Table II. Neonatal and maternal complications of shoulder dystocia Coded shoukier dystocia (n = 67)t

%

n

63 8 17 0 8 25 50 21

38 11 6 1 9 8 20 4

I

% 57 16 9 1 13 12 30 6

gm. 3979 ± 4 72 gm.

= 4069 ± 277 =

der dystocia (group I) was 42% (10 of 24 cases) as compared to 1.5% (one of 67 cases) in group 2 (p < 0.005). Morbidity in group I consisted of six cases of Erb's palsy, five fractured clavicles, and one respiratory arrest that was successfully recuscitated. In two cases the neonate had sustained more than one type of injury. In group 2 there was only one neonatal complication of a low Apgar score at 5 minutes, which resolved by I 0 minutes. There was only one case of maternal morbidity, a fourth-degree tear that occurred in group I. The relationship between the maneuvers performed and the fetal outcome is given in Table III. All orthopedic and neurological damage was associated with a combination of traction and fundal pressure. Delivery of the posterior shoulder and the corkscrew maneuvers were associated with complications in only one case, in which a series of maneuvers were attempted which resulted in the case of respiratory arrest mentioned above. The child was successfully resuscitated, and follow-up of more than a year failed to reveal any developmental abnormalities.

Comment Because of the retrospective nature of this paper, there is room for error. Those cases designated as coded shoulder dystocia may in fact be true shoulder dystocia if maneuvers were not appropriately documented. However, rigorous comparison between doctors' and nurses' notes revealed a high degree of consistency which we feel should minimize this source of error. Acker et al. 6 have determined protraction and arrest disorders to be significantly associated with shoulder dystocia. Likewise, Benedetti and Gabbe' have identified prolonged second stage combined with midforceps delivery as an intrapartum risk factor. Our study found

True shoulder dystocia (n = 24) Complications

Neonatal Low 5 min Apgar score Neurological Orthopedic Maternal Fourth-degree tear

I

Coded shoulder dystocia (n = 67)

%

n

1 6 5

4 25 21

0 0

0

0

n

I

I

% 1.5 0 0 1.5

Table III. Maneuvers for shoulder dystocia and neonatal complications Complications Maneuver

Fundal pressure Delivery of posterior shoulder Corkscrew Suprapubic

No. of patients

n

13

10

5 6 1

I* I* I*

I

% 77

20 17

*Only one patient underwent a series of maneuvers (suprapubic, corkscrew, delivery of posterior shoulder) which resulted in fetal hypoxia. the incidence of combined prolonged second stage with midforceps delivery to be considerably more common in true shoulder dystocia (ratio, 3.5: I). Although the Fisher exact test revealed a p value of 0.0508, the lack of significance with x2 with the Yates correction may be a reflection of the small numbers used for analysis. Macrosomia is a well-documented risk factor for shoulder dystocia. 8 There was only one instance of diabetes in group 2, and it was not associated with macrosomia. This may reflect the practice of diabetic patients being delivered before 40 weeks, often by a cesarean delivery, and possibly a better control of diabetes in pregnancy. Macrosomia was not more common in the true shoulder dystocia group, which suggests that body configuration in macrosomia may be more important than macrosomia per se. This concept was suggested by Modanlou et al., 5 who performed anthropometric studies post partum which revealed that macrosomic neonates with shoulder dystocia had a greater shoulder-head and chest-head disproportion regardless of birth weight. Their findings paralleled ultrasound studies in diabetic mothers in which a macrosomia index was calculated by subtracting biparietal diameter from chest diameter. Elliot et al.9 suggested that an index > 1.4 cm suggests shoulder dystocia. Such measurements may be indicated before labor if ultrasonographic estimated fetal weight is >4000 gm. The morbidity rate of 42% was high but not incon-

February 1987 Am J Obstet Gynecol

Gross, Shime, and Farine

sistent with other reports.2· 3 The corkscrew maneuver and delivery of the posterior shoulder were associated with good fetal and maternal outcome. It is interesting that there was no documentation of hip flexion (McRoberts maneuver), which is reported to be simple and effective.'° Fundal pressure in combination with traction was associated with neurological and orthopedic complications. The above findings would not be unexpected in light of the mechanism of fundal pressure which further impacts the anterior shoulder into the pubic bone, increases the risk of brachia! plexus injury, and necessitates increased traction to accomplish the delivery. Furthermore, the use of this maneuver delays the implementation of more effective techniques. Shoulder dystocia is a rare complication of labor that most obstetricians encounter infrequently. Management of shoulder dystocia is therefore often based on cumulative experience. A high index of suspicion should be maintained in the presence of certain risk factors. The present study also suggests that maneuvers such as the corkscrew maneuver or delivery of the posterior shoulder, which are mechanically logical, are safer than use of traction combined with fundal pressure, which only serves to compound the existing problem.

REFERENCES I. Resnick R. Management of shoulder girdle dystocia. Clin Obstet Gynecol 1980;23:559. 2. Golditch IM, Kirkman K. The large fetus-manageme nt and outcome. Obstet Gynecol 1978;52:26. 3. Benedetti TJ, Gabbe SG. Shoulder dystocia-a complication of fetal macrosomia and prolonged second stage of labor with midpelvic delivery. Obstet Gynecol 1978; 52:526. 4. Modanlou HD, Dorchester W, Thorosian A, Freeman RK. Macrosomia: maternal, fetal and neonatal implications. Obstet Gynecol 1980;55:420. 5. Modanlou HD, Komatsu G, Dorchester W, Freeman RK, B~su SK. Large-for-gestational-age neonates: anthropometric reasons for shoulder dystocia. Obstet Gynecol 1982;60:417. 6. Acker DB, Sachs BP, Friedman EA. Risk factors for shoulder dystocia in the average-weight infant. Obstet Gynecol 1986;67:614. 7. Zuspan FP, Quilligan EJ. Practical manual of obstetrical care. St. Louis: C. V. Mosby, 1982. 8. Harris BA. Shoulder dystocia. Clin Obstet Gynecol 1984; 27:106. 9. Elliot JP, Garite TJ, Freeman RJ, McQuown DS, Patel JM. Ultrasonic prediction of fetal macrosomia in diabetic patients. Obstet Gynecol 1982;60:159. 10. Gonik B, Stringer CA, Held B. An alternate maneuver for management of shoulder dystocia. AM J OBSTET GvNECOL 1983;145:882.

Cervical ripening and labor induction with prostaglandin E 2 gel: A placebo-controlled study Paul Bernstein, M.D., Nicholas Leyland, M.D., Paul Gurland, M.D., and Douglas Gare, M.D. Toronto, Ontario, Canada A randomized double-blind, placebo-controlled study was undertaken to evaluate the effect of a single intracervical application of prostaglandin E2 gel on the ripening of the cervix and on the subsequent induction of labor with oxytocin in patients with low Bishop scores (~4). Compared to controls receiving gel only, the group receiving prostaglandin E2 gel had significant increases in their cervical Bishop scores, shorter induction-to-delivery intervals, shorter time requiring use of oxytocin, and more successful labor induction without oxytocin. Systemic side effects were minimal and fetal outcomes were comparable, as were the routes of delivery. (AM J OasrET GYNECOL 1987;156:336-40.)

Key words: Induction of labor, cervical ripening, prostaglandin £ 2 From the Departments of Obstetrics and Gynecology, Mount Sinai Hospital and Toronto General Hospital, University of Toronto. Supported fry The Upjohn Company, Toronto, Ontario, Canada, and Kalamazoo, Michigan. Presented at the Forty-second Annual Meeting of The Society of Obstetricians and Gynaecologists of Canada, Charlottetown, Prince Edward Island, Canada, June 23-27, 1986. Reprint requests: Dr. Paul Bernstein, 600 University Ave., No. 467, Toronto, Ontario, Canada M5G JX5.

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Spontaneous labor and vaginal delivery in uncomplicated parturition follow a cascade of synchronous events that include the softening and effacement of the cervix. If this "ripening" of the cervix fails to occur, it may be accurately predicted that attempts at induction will be prolonged if not completely unsuccessful. 1 Various complications of pregnancy may necessitate