Early determination of fetal sex using transvaginal sonography: Technique and pitfalls

Abstract

Transvaginal sonography (TVS) enables sex determination at an early stage of pregnancy. The morphologic features of fetal external genitalia at 13 weeks to 16 weeks, menstrual age, are different from those seen later in pregnancy; therefore an attempt to determine fetal gender at this early stage by the same criteria as those used later is hazardous, especially for determining the male sex. The main diagnostic criteria for male gender determination by TVS are the "dome" sign representing the sonographic visualization of the fetal scrotum, the cranially directed phallus, and the longitudinal raphe at the base of the penis. The diagnostic criteria for female gender are the 2 or 4 parallel lines representing the labial folds and the caudally directed phallus (clitoris). The length of the fetal phallus at this early stage is not diagnostic and may be the main pitfall to the unexperienced sonographer. Between weeks 13 and 14 sex diagnosis was possible in 130/171 pregnancies (76%) in our first 2 years and 188/235 (80%) in our last 2 years of experience. Between weeks 15 and 16 sex diagnosis was possible in 122/139 pregnancies (88%) during our first 2 years and 96.7% (528/546) during the last 2 years of experience. The accuracy rate for fetal male gender identification increased from 91.7% during the first 2 years of TVS experience to 99.7% during the last 2 years of TVS experience, and the accuracy rate for female gender identification, increased from 93.3% to 100%, respectively, applying the above criteria and based on acquired experience of early fetal sex identification by TVS early in gestation. Early and precise determination of fetal sex is possible and might avoid invasive procedures such as amniocentesis.

Effect of Gender on Perinatal Outcome in Pregnancies Complicated by Diabetes

“…The presence or absence of these risk factors may be helpful to the clinician in determining which pregnancies are at risk for having poor outcome. Fetal gender can be accurately determined utilizing sono graphic techniques [14,15]. Those pregnancies with no risk factor could be considered low risk, those with any one risk factor could be considered moderate risk, and those with any two or all three risk factors would be at high risk.…”

Fluorescent in situ hybridization for sex chromosome determination before and after fertilization in mice

“…Pre-birth gender determination techniques, such as transvaginal sonography [11], ultrasound or computed tomography [12] or PCR gender determination of fetal cells in cervical mucus [13], while successfully applied in humans, have limitations for gender determination in rodents due to the small size of these animals. Moreover, such analyses can be costly for routine use where large numbers of measurements are required and have no value at early developmental stages prior to the emergence of sexually dimorphic landmarks.…”

Sonographic Prenatal Diagnosis of Ambiguous Genitalia

“…One of the major problems in the evaluation of the fetal genitalia is to obtain an adequate view of the perineal area. The accuracy of detecting fetal gender correlates with the operator's experi ence and the gestational age of the fetus [9], It should be stressed that in cases like the one presented in which a high index of suspicion exists it is possible to diagnose accurately the fetal gender in close to 100% of the cases. However, ambiguity can be missed on routine mid-trimester scans.…”