Objective: To evaluate delivery mode management decisions and the rate of shoulder dystocia recurrence for women with a prior delivery complicated by shoulder dystocia.
Study design: We used a computerized perinatal database and ICD-9 codes to identify all vaginal deliveries complicated by shoulder dystocia from 1996 to 2001. Subsequent deliveries over the next three years were identified and reviewed for relevant clinical, obstetric, and delivery outcomes. Management including use of labor induction, labor augmentation, operative vaginal delivery, and delivery mode (elective cesarean section (CS) vs. trial of labor (TOL)) were reviewed. The recurrence rate of shoulder dystocia was calculated and the characteristics of these cases further described.
Results: Over the initial 5-year study, there were 25 995 vaginal deliveries, 205 shoulder dystocia cases (0.8%), 36 (17.5%) with neonatal injury. Of the 205 initial shoulder dystocia cases, 39 patients had 48 subsequent deliveries at our institution (a subsequent delivery rate of 23% at our institution, significantly less than the overall population (42%, p < 0.001)). Complete data were available for 47 deliveries. Four women had elective CS without labor (one due to prior shoulder dystocia), 43 (91.5%) had a TOL, and 42 (88%) achieved vaginal delivery. Recurrent shoulder dystocia complicated 9.5% (4/42) of deliveries; one case included neonatal brachial plexus injury that resolved prior to hospital discharge. Of the four recurrent shoulder dystocia cases, none were complicated by maternal diabetes, macrosomia, prolonged second stage of labor, or underwent an operative vaginal delivery. No statistically significant univariate differences were seen between the recurrence group and the no-shoulder dystocia vaginal delivery group; however birth weight and nulliparity at initial shoulder dystocia pregnancy jointly demonstrated a relationship of recurrence (p = 0.048).
Conclusion: In TOL cases that result in a vaginal delivery, the rate of recurrence of shoulder dystocia is high--approximately 10 times higher than the rate for the general population. Often the only identifiable risk factor is the prior history itself, which may influence delivery management in subsequent pregnancies. Birth weight and nulliparity at initial shoulder dystocia pregnancy may influence clinical decision-making in cases of prior shoulder dystocia.