P02.11: Feasibility and duration of a complete 11 + 0 − 13 + 6 wks fetal assessment

Abstract

Objective: The use of additional US markers during the first trimester screening permitted an increase of sensibility of the test and/or reduction of the false positive rate. The objective of this study was to analyze the feasibility and the duration of a complete structural examination of the fetus. Methods: All examinations included evaluation of nuchal translucency, nasal bone, tricuspid valve, ductus venosus, facial angle, head, brain, stomach, bladder, spine, kidneys, abdominal wall, umbilical arteries and extremities. When was not possible to conclude the examination due to the fetal position the patient was invited for a walk and re-examined later. When the visualization of the fetal structures was not satisfactory due to increased maternal MBI or retroverted uterus a TV examination was added. Facial angle was measured in 2D sections or volumes were acquired after a midsagittal section was obtained. Results: In the period May 2008 – January 2009, 838 screening test were performed. Mean CRL was 62mm. The mean duration was 16,8 (5–60) min. TV examination was needed in 12% of cases. 62% of the examinations were done in a single section while 10% were seen in 3 or more sections. The duration was increased with maternal BMI, additional TV approach and number of sections performed. The need of TV scan was associated with maternal BMI while the number of US sections depended on the fetal position. Fetal bladder and kidneys were the most frequently difficult to assess structures. Nuchal translucency, nasal bone and tricuspid valve were successfully examined in all scans. Ductus venosus waves were not satisfactory in 1% of our series. Facial angle was not feasible in 2,5% of the cases. Conclusion: A complete examination of all the fetal structures and of all US markers for abnormalities is feasible with a mean duration of 16–17min. The only factors increasing the time of the examination were maternal BMI and fetal position.