Clinical or ultrasonic estimation of birthweight: which is more accurate?

P. Sherman, S. Arieli, J. Tovbin, E. Caspi, I. Bukovsky

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: Accurate determination of fetal weight is of paramount significance to the obstetrician. Clinical assessment of birthweight (BW) is believed to be less accurate than ultrasonic estimate. The present study compares the accuracy of routine ultrasonic and clinical BW estimation. STUDY DESIGN: The study sample included 1717 singleton pregnancies, admitted in early tabor with a level I ultrasonic estimation of fetal weight (EFW-U/S), performed during the preceding week. Clinical estimation of BW (EFW-Cln) was obtained prior to rupture of the membranes by the attending senior resident, who was unaware of the EFW-U/S. Accuracy was determined by the mean error (Estimated BW - Actual BW, gm), the mean absolute error (ABS{Estimated BW - Actual BW} × 100/Actual BW, %) and the proportion of estimates within 10% of the actual BW (BW±10%). Statistical analysis was done by the paired t-test and X2 test. Actual BW in the study sample averaged 3334±15 gm and ranged between 690-5320 gm. RESULTS: Both mean error and mean absolute error of the EFW-Cln (-30±8 gm and 7.9% of actual BW, respectively) were significantly smaller than those of the EFW-U/S (-70±8 gm and 8.4% of actual BW, respectively). However, the rates of estimates within 10% of BW were not significantly different (71 and 69%, respectively). In the <2500 gm BW mean error of the EFW-U/S (134±23 gm) was significantly smaller than that of the EFW-Cln (208±28 gm). In the 2500-4000 gm BW mean error of the EFW-Cln (-7±8 gm) was significantly smaller than that for the EFW-U/S (-50±9 gm). In the >4000 gm BW mean errors and the rates of estimates within 10% of BW were similar for both methods (-360 gm and 60%, respectively). CONCLUSIONS: Clinical estimation of BW in early labor is as accurate as routine ultrasonic estimation. In the lower range of BW (<2500 gm) ultrasonic estimation is more accurate, in the medium range clinical estimation is more accurate and in the higher range of BW (>4000 gm) both methods have similar accuracy.

Original languageEnglish
Pages (from-to)S22
JournalActa Diabetologica Latina
Volume176
Issue number1 PART II
StatePublished - 1997

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