P34.17: Fetal sex diagnosis in normal 11–14 weeks' scan setting. Is it as in the papers?

Abstract

Gender determination in first trimester scan is widespread. Nevertheless, professional softwares do not have the field for gender assignation at that scan, and usually is informed verbally to the patients, avoiding to give written information. Therefore, it is difficult to evaluate this in clinical use. We aimed to evaluate our diagnostic capacity in this clinical setting. Retrospective off-line analysis of images from routine 11–14 scans. The sagital image of the fetus at the genitalia was considered. A single independent observer assigned male gender when the line was over 30° the column and female when it was below 30°. Definite sex was confirmed in 22–24 scan or at birth, when the patient delivered at our institution. First trimester scans in a 4 month period with images from our ViewPoint database were analyzed. 225 could be confirmed by ultrasound or at delivery. 108 of 118 female diagnoses were confirmed and 98 of 107 male diagnoses were confirmed. Sensitivity for male and female was 90.7% and 92.3%. Positive predictive value was similar in both groups, 91.5%. This study confirms positive predictive values of 91% in both genders. An independent observer could determine a correct diagnosis, confirming that it is a qualitative parameter that can be re-evaluated. A bias could have been introduced as only good images could have been saved, therefore, these rates should be considered only in cases where the operator decided to keep an image. Despite this, we proved that an independent observer can perform sex diagnosis, even if some images were not aimed for this purpose.