Introduction. The combined first-trimester screening test is the international recommendation for prenatal screening of trisomy 21. The combined plus screening test adds one or more ultrasound markers (ductus venosus, tricuspid flow, nasal bone). The contingent test is a two-step protocol of risk assessment that considers all markers only as a contingency in the group with an inconclusive result. Objective: Assessment of the performance of the Kagan biochemical contingent protocol in our population. Methods. All pregnant women between 11 and 13 weeks attended in our unit were assessed with the first-trimester combined plus screening test. We followed the Fetal Medicine Foundation published quality criteria and the International Society of Ultrasound in Obstetrics and Gynaecology guidelines. Results 2 578 single pregnancies were assessed; the foetuses were classified by an initial ultraso...

Umbilical arteries (UA) resistance is assessed to detect growth restriction due to an inadequate placentation in small infants at risk of perinatal death and longterm incapacity. The umbilical artery pulsatility index (UA PI) must be compared with a statistically selected reference chart. Objective: To identify the pulsatility index (PI) reference curve whose critical value best matches our population data. Methods: The cohort was described in a previous study of 1 753 fetuses with 2 031 measurements of the PI of the uterine arteries and umbilical arteries with normal maternal-perinatal outcome. Results: PI UA had a significant negative correlation (r= -0.42) with gestational age (GA). The 95th percentile of our patients was significantly different from those published by Arduini, Acharya, Ciobanu, Baschat and Limay. Conclusion: The umbilical artery pulsatility index figures obtained con...

Uterine artery resistance is assessed to detect inadequate placentation in pregnant women, that increases the risk to develop preeclampsia, intrauterine growth restriction and other complications associated with placental insufficiency. Objective: To identify the uterine arteries pulsatility index (UtAPI) reference chart that best fits our institutional data. Methods: Retrospective, cross-sectional study that evaluated 1 753 single pregnancies; 2 031 UtAPI measurements of the uterine arteries were obtained. Mean UtAPI was compared with the reference charts published by Gomez, Limay and Weichert. Results: There was a mild but significant (r=0.16) negative correlation between UtAPI and gestational age between 24 and 40 weeks of gestation; 6.5%, 7.5% and 15% of our measurements were above the 95 centile of respectively Weichert, Limay and Gomez reference charts. Conclusions: In our populati...