ULTRASONOGRAPHIC MEASUREMENT OF CROWN-RUMP LENGTH IN HIGH-ORDER MULTIFETAL PREGNANCIES

The objective of the study was to evaluate the crown-rump length (CRL) in high-order multifetal Pregnancies (three or more fetuses). The rec ords of patients who underwent multifetal pregnancy reduction were rev iewed. The following parameters were defined: the mean CRL (CRLMEAN) a nd the difference between the largest and smallest CRL (CRLRANGE) for each pregnancy CRLMEAN was plotted Versus gestational age (GA) and the line of best fit was derived. The residual for each CRL (CRLRES) was calculated by subtracting the value predicted by the regression line f rom the individual CRL (CRLIND). Regression lines for singletons with confirmed GA from four previously reported studies were used for compa rison. A total of 82 Patients were included (29 triplets, 38 quadruple ts and 15 quintuplets; mean GA 10.7 +/- 0.78 weeks). CRLMEAN correlate d with GA (CRLMEAN = 38.88 - 8.78(GA) + 0.82(GA)(2); R=0.83; R-2=0.70) . This second-degree polynomial remained within the range for singleto ns. No significant differences in maternal age, GA and CRLMEAN were no ted between the patients with different numbers of fetuses. The median CRLRANGE was largest in quintuplets, followed by quadruplets and trip lets. The CRLRANGE correlated poorly with GA. The mean CRL in multifet al Pregnancies increases with GA similarly to that in singletons. The variability of individual measurements increases with the number of fe tuses and CRLs are lower in quintuplets.