FETAL SHOULDER MEASUREMENTS WITH MRI

Objective: We studied the ability of MRI to predict fetal shoulder wid th (FSW). Materials and Methods: In 30 patients referred for MR pelvim etry, measurement of FSW was performed and compared with caliper measu rements at term. We report here the feasibility of a method using axia l and coronal MR images oriented to the fetal body axes. Results: Shou lder width by MRI (mean = 12.76 +/- 1.42 cm) correlated significantly with postnatal orthopedic caliper measurements (mean = 12.99 +/- 1.37 cm; r = 0.955, SEE = 4.29 mm, p = 0.00001) and with birth weight (r = 0.63, p = 0.0005). Mean paired differences showed a statistically sign ificant 2.3 +/- 4.2 mm underestimation of FSW by MRI (p = 0.01). This reasonably quick nonionizing technique seems to have the potential for evaluating shoulder dystocia and deserves further evaluation.