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MS WordPerinatologist Corner - C.E.U/C.M.E. Modules
Shoulder Dystocia
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3. Risk Factors for Shoulder Dystocia
Case Scenario
Mrs. Y is a 38 y/o G8P7 at 39 weeks by a midtrimester ultrasound consistent with her dates who is in labor and has been pushing for over 2 hours. The fetal vertex is at zero station and caput is present. All her other babies have weighed 8-9 pounds, but she states that none of them have taken this long to deliver. You estimate the fetus weighs at least 9 pounds. Variable decelerations are occurring irregularly. Your facility has cesarean and operative vaginal delivery capabilities. What problems might you anticipate in this scenario and what might be your best plan of action?
Shoulder dystocia occurs in 0.5-1.5 per cent of all births, and in up to 8 per cent of infants weighing over 4000 g (Dildy). Diabetic women with a fetus weighing more than 4000 g have an even higher incidence, probably as a consequence of the anthropometrics of diabetic infants (Conway) (Sacks). Such fetuses / infants may have truncal obesity, with a smaller head diameter relative to their torso. Other risk factors include maternal obesity, excessive weight gain during pregnancy, grand multiparity, advanced maternal age, post dates, and a history of a prior infant with shoulder dystocia (up to a 16 per cent recurrence rate for the latter) (See table 2).
As you are probably noticing, a great many of our patients have one or more of these risk factors. While there is a paucity of evidence, prolonged labor, especially a protracted second stage, should also be a “red flag” for shoulder dystocia, particularly in a woman with suspected fetal macrosomia. Instrumental vaginal deliveries are ill-advised in such women. You may be able to deliver the head with the vacuum, but the shoulders may not want to follow…
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Table 2 |
Risk Factors for Shoulder Dystocia |
MaternalShort stature |
FetalSuspected macrosomia< |
Labor relatedOperative vaginal delivery |
