Sonographic Examination of The Fetus Vis-à-Vis Shoulder Dystocia: A Vexing Promise

Abstract

Since antepartum and intrapartum risk factors are poor at identifying women whose labor is complicated by shoulder dystocia, sonographic examination of the fetus holds promise. Though there are several measurements of biometric parameters to identify the parturient who will have shoulder dystocia, none are currently clinically useful. Three national guidelines confirm that sonographic measurements do not serve as appropriate diagnostic tests to identify women who will have shoulder dystocia with or without concurrent injury. In summary, biometric measurements of the fetus should not be used to alter clinical management with the aim of averting shoulder dystocia.

Sonographic Estimated Fetal Weight among Diabetics at ≥ 34 Weeks and Composite Neonatal Morbidity

“…Despite the increased risk in CNM in patients with SEFW > 90th percentile, we caution clinicians neither to induce for estimated fetal weight alone nor to proceed with CD because of accelerated growth. Indeed, if the SEFW is 4,500 g or greater, ACOG recommends considering CD among diabetics, 13 27 33 and our findings should not be exploited to modify the national guidelines. There are several reasons not to modify the current management of diabetes because of our findings.…”

“… 30 31 Thus, studies assessing the link between SEFW and adverse outcomes are pragmatic for the management of pregnancy complicated by diabetes. 32 33 34 …”

“…Regardless of the diabetic status, earlier reports suggest that shoulder dystocia occurred in 12% (95% CI, 7–20%) if the SEFW was above 90th percentile. 34 The plausible reasons that an SEFW above 90th percentile is a risk factor for shoulder dystocia are: (1) it is associated with macrosomia, a known risk factors for impacted shoulder; 32 33 (2) diabetes is a risk factors for shoulder dystocia; 16 24 and (3) there are anthropometric differences among newborns with and without shoulder dystocia and these are attenuated among diabetics pregnancies. 32 35 36 37 …”

“…There is a paucity of publications on SEFW among diabetic women and its association with CNM. 6 While others have focused on shoulder dystocia related to SEFW, 33 we explored other neonatal morbidity linked with SEFW. Our findings of increased likelihood of shoulder dystocia and of hypoglycemia have biological plausibility.…”