Crown-rump length audit plots with the use of operator-specific PAPP-A and ß-hCG median MoM.

OBJECTIVE: Audit the crown-rump length (CRL) measurements taken at 11 to 13 weeks scan, using operator-specific median multiples of the median (MoM) for pregnancy-associated plasma protein-A (PAPP-A) and free ß-human chorionic gonadotropin (ß-hCG) plots, to identify deviations potentially related to a systematic CRL bias. METHODS: Study population included consecutive singleton pregnancies undergoing first trimester combined screening, scanned by sonologists with at least 100 scans, during the 2011 to 2012 period. Previously described plots for PAPP-A and ß-hCG median MoM points, with their 95% confidence intervals circles, in relation with the expected deviation line were used. These plots have been modified to adjust the deviation line to the sonologist-specific expected MoM variation for each CRL millimetre bias according to each sonologist-specific median gestational ages at both blood sampling and ultrasound. RESULTS: Twenty-eight sonologists performing 9472 scans were included, accounting for 36% of the 77 sonologists and 70% of the 13 643 scans initially considered. Mean gestational age was 10 + 2 weeks at blood sampling and 12 + 4 weeks at ultrasound. Fifteen sonologists (53%) did not demonstrate any CRL bias, 10 (36%) present with a significant CRL underestimation, being above 2 mm in 6 (21%), and in 3 (11%) the observed deviation could not be explained by a systematic CRL bias. CONCLUSIONS: In sonologists with more than 100 NT measurements, operator-specific PAPP-A and ß-hCG median MoM plots are able to identify deviations potentially related to a systematic CRL bias. Systematic underestimation above 2 mm was observed in 1/5 of them. © 2016 John Wiley & Sons, Ltd.

Cumulative sum plots and retrospective parameters in first-trimester ductus venosus quality assurance.

OBJECTIVE: This study aimed to evaluate the application of two quality assurance methods to the ductus venosus pulsatility index (DVPI), as a first-trimester aneuploidy marker, including retrospective assessment of distribution parameters and cumulative sum (CUSUM) plots. METHODS: The DVPI was measured in 14 444 singleton fetuses at 11+0 to 13+6 weeks in two Fetal Medicine centers during a 4-year period. Sonologist-specific quality assurance distribution parameters, previously described for nuchal translucency, were assessed: the median multiples of the median (MoM), the logarithmic standard deviation of DVPI MoMs and the weekly DVPI percent decrease. Quality assurance results were compared between median MoMs and MoM-based CUSUM plots. RESULTS: When sonologist-specific DVPI distribution parameters were retrospectively applied for quality assurance, a 1.0 median MoM, a 0.1 median logarithmic standard deviation and a 3.4 median weekly DVPI drop percentage were observed. CUSUM plots showed good agreement with 0.9-1.1 MoMs range for median MoM, in the assessment of sonologist-specific performances. CONCLUSION: Retrospective and prospective DVPI quality assurance methods appear to be applicable to DVPI at 11+0 to 13+6 weeks. Its use should be encouraged if DVPI is to be added to first-trimester Down syndrome or cardiac defects screening.

Updated reference ranges for the ductus venosus pulsatility index at 11-13 weeks.

OBJECTIVE: To update the reference ranges for the ductus venosus pulsatility index (DVPI) at 11+0 to 13+6 gestational weeks. METHODS: DVPI was calculated in 14,444 singleton fetuses at 11+0 to 13+6 weeks in two Fetal Medicine Centers, during a 4-year period. Using previously described medians, DVPI evolution was assessed both over the study period on a yearly basis and over gestation, grouping fetuses according to 5-mm crown-rump length (CRL) ranges. Weighted DVPI medians, the 5th and 95th percentiles and distribution parameters for unaffected and trisomy 21 fetuses were newly calculated. RESULTS: A significant DVPI multiple of the median decrease was observed over both the study period (p < 0.01) and over gestation (p < 0.01) using previous medians, in the two centers. Newly calculated weighted medians were lower than those previously described, decreasing with CRL. Distribution parameters calculated using the new medians were different from those previously described. CONCLUSION: DVPI reference ranges were lower than those previously reported and decreased with CRL. Updated medians and distribution parameters should be considered to include the DVPI as a Gaussian marker in trisomy 21 screening and for quality control purposes.