Nuchal translucency screening in triplets: Down syndrome risk calculation taking account of between-fetus correlations.

OBJECTIVE: To describe a method for calculating fetus-specific Down syndrome risk in triplets, allowing for nuchal translucency (NT) correlation between fetuses. METHODS: The between-fetus correlation coefficient of log NT, in multiples of the median, was estimated from a series of 95 unaffected triplets. A trivariate log Gaussian model was used to calculate likelihood ratios for discordant and concordant Down syndrome. Applying these to the prior maternal age-specific risk yielded risks in monozygous, dizygous and trizygous triplets. The weighted average risk was then computed with weights relating to chorionicity and assisted reproduction. The method was illustrated. RESULTS: The correlation coefficient in unaffected pregnancies was 0.408 (P < 0.0001; 95% confidence interval 0.30-0.50) and estimated to be 0.205 and 0.107 in triplets pairs with one or two affected fetuses. The illustration showed that very large differences could be obtained in the risks when the extent of correlation in NT between fetuses is taken into account compared with when the measurements are treated as independent. CONCLUSION: Fetus-specific Down syndrome risks in triplets should be calculated using its own NT value and that in the other fetuses, chorionicity, and method of conception.

Model-predicted performance of second-trimester Down syndrome screening with sonographic prenasal thickness.

OBJECTIVE: The purpose of this study was to estimate the Down syndrome detection and false-positive rates for second-trimester sonographic prenasal thickness (PT) measurement alone and in combination with other markers. METHODS: Multivariate log Gaussian modeling was performed using numerical integration. Parameters for the PT distribution, in multiples of the normal gestation-specific median (MoM), were derived from 105 Down syndrome and 1385 unaffected pregnancies scanned at 14 to 27 weeks. The data included a new series of 25 cases and 535 controls combined with 4 previously published series. The means were estimated by the median and the SDs by the 10th to 90th range divided by 2.563. Parameters for other markers were obtained from the literature. RESULTS: A log Gaussian model fitted the distribution of PT values well in Down syndrome and unaffected pregnancies. The distribution parameters were as follows: Down syndrome, mean, 1.334 MoM; log(10) SD, 0.0772; unaffected pregnancies, 0.995 and 0.0752, respectively. The model-predicted detection rates for 1%, 3%, and 5% false-positive rates for PT alone were 35%, 51%, and 60%, respectively. The addition of PT to a 4-serum marker protocol increased detection by 14% to 18% compared with serum alone. The simultaneous sonographic measurement of PT and nasal bone length increased detection by 19% to 26%, and with a third sonographic marker, nuchal skin fold, performance was comparable with first-trimester protocols. CONCLUSIONS: Second-trimester screening with sonographic PT and serum markers is predicted to have a high detection rate, and further sonographic markers could perform comparably with first-trimester screening protocols.

Inadvertent rupture of benign cystic teratoma does not impair future fertility.

OBJECTIVE: We sought to investigate the reproductive outcomes of women who underwent laparoscopic removal of benign cystic teratoma with or without intraoperative spillage. STUDY DESIGN: The reproductive outcomes of reproductive age women following laparoscopic removal of benign cystic teratoma from 1997 through 2007 were investigated by a telephone questionnaire. RESULTS: In all, 128 reproductive age women underwent benign cystic teratoma removal, and reproductive outcomes were available for 45. Among those 45 women, intraoperative spillage occurred in 16 (35.6%). The rate of spontaneous pregnancies was significantly lower for the nonspillage compared to the intraoperative spillage groups (20/29 [68.9%] vs 16/16 [100%], respectively; P = .01). However, the median time from surgery to the first pregnancy was similar (22 and 18.5 months, respectively; P = .9). From the 9 remaining women in the nonspillage group, 4 conceived with ovulation induction, 2 conceived with in vitro fertilization, and 3 were infertile. CONCLUSION: Intraoperative spillage of benign cystic teratomas does not lead to long-term infertility.