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Closing discussion by Dr Mehta
Mehta et al forces.8 These forces result in continued descent of the fetal head and body without any downward movement of the impacted shoulder(s). In those cases of Erb’s palsy without SD, the shoulder impaction is transient and probably overcome by spontaneous rotation, although delayed, of the shoulders into the longer oblique diameter of the pelvic inlet. Therefore, after the fetal head delivers, there is no longer any obstruction to descent of the shoulders (shoulder dystocia) but the stretching and injury have occurred before the clinician touching the infant. Finally, I would like to use this opportunity to make a plea for the recording of the position of the fetal head at the time of delivery. This allows the determination of the location of the arm which was injured. Cases with the posterior location of the injured arm are easier to defend than when compared with the anterior, although both are defendable.
References 1. Cunningham F, MacDonald PC, Gant NF, Leveno K, Gilstrap LC III, Hankins G, et al. Dystocia: abnormal presentations, position and development of the fetus. Williams Obstetrics, 20th ed. Norwalk (CT): Appleton and Lange; 1997. p. 451. 2. Gherman R, Ouzounian JG, Miller DA, Kwok RN, Goodwin TM. Spontaneous vaginal delivery: a risk factor for Erb’s palsy? Am J Obstet Gynecol 1998;178:426. 3. Jennett R, Tarby T, Kreinick C. Brachial plexus palsy: an old problem revisited. Am J Obstet Gynecol 1992;166:1677. 4. Sandmire HF, O’Halloin. Shoulder dystocia: its incidence and associated risk factors. Int J Gynaecol Obstet 1988;26:65-73. 5. Acker DB, Sachs BP, Friedman EA. Risk factors for shoulder dystocia. Obstet Gynecol 1985;66:762-8. 6. Baskett TF, Allen AC. Perinatal implications of shoulder dystocia. Obstet Gynecol 1995;86:14-7. 7. Gross SJ, Shine J, Farine D. Shoulder dystocia: predictors and outcome. Am J Obstet Gynecol 1987;156:334-6.
1881 8. Sandmire HF, DeMott RK. Erb’s palsy: concepts of causation. Obstet Gynecol 2000;95:940-2.
DR MEHTA (Closing) This article is unique in the literature in demonstrating that errors in estimated fetal weight, and specifically underestimation of EFW, are not associated with an increased risk of shoulder dystocia. It does so with adequate power. This is especially important given the number of lawsuits involving shoulder dystocia cases. The purpose of this study is not to suggest that EFW is unimportant and should not be performed. It remains clinically useful as part of the full picture of the patient and should be factored in with the patient’s body mass index, diabetes status, previous deliveries, and labor course. In fact, our study suggested that, in general, EFWs were surprisingly accurate in the groups studied. Median percent accuracies in each group were well within (or less than) the expected 10% to 15% error of EFW; for the shoulder dystocia group, for example, the median error was a 6% underestimation. We do not believe that there were specific unrecorded cases of shoulder dystocia in our population; in fact, our rate of shoulder dystocia (0.8%) falls well within the documented range of shoulder dystocia (0.6%-1.4% as cited in the ACOG practice bulletin). In general, though, the documentation of shoulder dystocia remains a limitation of all retrospective studies, as it is a subjective diagnosis. Finally, we agree with the discussant that documentation remains a key component of shoulder dystocia cases, as many injuries may result from the laboring process rather than the delivery itself and may actually involve the posterior arm. Our article’s aim, though, is to assist those physicians with errant EFWs by demonstrating that ‘‘failure to diagnose fetal macrosomia’’ in shoulder dystocia is not an inherent breach of standard of care.
References 1. Cunningham F, MacDonald PC, Gant NF, Leveno K, Gilstrap LC III, Hankins G, et al. Dystocia: abnormal presentations, position and development of the fetus. Williams Obstetrics, 20th ed. Norwalk (CT): Appleton and Lange; 1997. p. 451. 2. Gherman R, Ouzounian JG, Miller DA, Kwok RN, Goodwin TM. Spontaneous vaginal delivery: a risk factor for Erb’s palsy? Am J Obstet Gynecol 1998;178:426. 3. Jennett R, Tarby T, Kreinick C. Brachial plexus palsy: an old problem revisited. Am J Obstet Gynecol 1992;166:1677. 4. Sandmire HF, O’Halloin. Shoulder dystocia: its incidence and associated risk factors. Int J Gynaecol Obstet 1988;26:65-73. 5. Acker DB, Sachs BP, Friedman EA. Risk factors for shoulder dystocia. Obstet Gynecol 1985;66:762-8. 6. Baskett TF, Allen AC. Perinatal implications of shoulder dystocia. Obstet Gynecol 1995;86:14-7. 7. Gross SJ, Shine J, Farine D. Shoulder dystocia: predictors and outcome. Am J Obstet Gynecol 1987;156:334-6.
1881 8. Sandmire HF, DeMott RK. Erb’s palsy: concepts of causation. Obstet Gynecol 2000;95:940-2.
DR MEHTA (Closing) This article is unique in the literature in demonstrating that errors in estimated fetal weight, and specifically underestimation of EFW, are not associated with an increased risk of shoulder dystocia. It does so with adequate power. This is especially important given the number of lawsuits involving shoulder dystocia cases. The purpose of this study is not to suggest that EFW is unimportant and should not be performed. It remains clinically useful as part of the full picture of the patient and should be factored in with the patient’s body mass index, diabetes status, previous deliveries, and labor course. In fact, our study suggested that, in general, EFWs were surprisingly accurate in the groups studied. Median percent accuracies in each group were well within (or less than) the expected 10% to 15% error of EFW; for the shoulder dystocia group, for example, the median error was a 6% underestimation. We do not believe that there were specific unrecorded cases of shoulder dystocia in our population; in fact, our rate of shoulder dystocia (0.8%) falls well within the documented range of shoulder dystocia (0.6%-1.4% as cited in the ACOG practice bulletin). In general, though, the documentation of shoulder dystocia remains a limitation of all retrospective studies, as it is a subjective diagnosis. Finally, we agree with the discussant that documentation remains a key component of shoulder dystocia cases, as many injuries may result from the laboring process rather than the delivery itself and may actually involve the posterior arm. Our article’s aim, though, is to assist those physicians with errant EFWs by demonstrating that ‘‘failure to diagnose fetal macrosomia’’ in shoulder dystocia is not an inherent breach of standard of care.