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.