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Purpose: The purpose of this study is to evaluate the incidence of maternal cell contamination (MCC) in the first few milliliters of amniotic fluid withdrawn during amniocentesis., Methods: A prospective observational study was performed. The initial 2-3 ml of amniotic fluid withdrawn during amniocentesis was divided into direct analysis (uncultured) and cultured samples. A matching maternal buccal swab was obtained for MCC testing. MCC was determined by short-tandem repeat analysis. The primary outcome was measurement of clinically significant contamination (MCC >5%). Secondary outcomes included the determination of risk factors associated with MCC >5%. Outcomes were assessed by fisher's exact, independent t-test, binary logistic regression, and ANOVA., Results: Direct analysis measured clinically significant contamination (MCC > 5%) in 26% of specimens, while any amount of MCC was present in 68% of specimens. Cultured specimens had MCC > 5% in 2%, and any amount of MCC in 24%. Only blood-tinged fluid was associated with an increased risk for MCC > 5%. Larger volumes of the discard sample were not associated with increased incidence of MCC greater than 5%., Conclusion: A significant amount of MCC is present with direct analysis of the initial few milliliters of amniotic fluid withdrawn and is not influenced by the volume of the discard sample. Our results suggest that the first few milliliters of amniotic fluid be removed and discarded when direct analysis is utilized for prenatal genetic testing.

Objective: To assess the utility of cervical funnel volume as a predictor of cerclage failure., Methods: We performed a retrospective cohort study of pregnant women with a McDonald cerclage and sonographic evidence of cervical funneling between 1/2008 and 2/2014. Funnel volume (FV) was calculated and used as a correction factor for cervical length (CL) or cerclage height (CH). Receiver operating characteristic (ROC) curves were used to compare the predictive value of CL, CL:FV, CH and CH:FV for cerclage failure at <28 or <34 weeks. CL:FV was further stratified to the <5th, <10th and >10th percentiles and analyzed for prediction of preterm delivery., Results: Subjects with cerclage failure (n = 30) delivered at a mean gestational age of 29.8 +/- 5.3 weeks compared to 38.1+/- 1.39 weeks in those without failure (n = 27; p < 0.001). ROC curves demonstrated CL:FV was the best predictor of delivery <28 weeks (AUC 0.80), while CL was the best predictor of delivery <34 weeks (AUC 0.76). Stratification of CL:FV into <5th versus >10th percentile groups was predictive of early preterm delivery (25.1 weeks versus 34 weeks, p = 0.01)., Conclusions: Volumetric assessment of cervical funneling may improve prediction of cerclage failure in the mid-trimester.

Pseudomonoamniotic gestations are increasingly recognized through sonographic surveillance of monochorionic twins, though etiologic factors remain undefined. We present a case of spontaneous pseudomonoamniotic twins and propose umbilical cord insertion proximity as a sonographic marker. Systematic review of the literature was performed and additional cases with similar findings were noted. Approximately 75% of reported cases (28/37) were deemed spontaneous and several included short inter-cord distances. Shunting of blood away from the membranes in the region between the cord insertions may be responsible for membrane rupture. Further investigation is needed into short inter-cord distance as a marker for monochorionic twins at risk to become a pseudomonoamniotic gestation.