Accuracy of Ultrasonography Performed by Thai Maternal Fetal Medicine Fellowship at Songklanagarind Hospital for Fetal Sex Determination during Second Trimester Genetic Amniocentesis
Tharangrut Hanprasertpong MD*,**, Ounjai Kor-anantakul MD*, Alan Geater PhD***, Chitkasaem Suwanrath MD*, Surachai Ponglopisit MD*, Chusana Petpichetchein MD*, Manaphat Suksai MD*
Affiliation : * Department of Obstetrics and Gynecology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand ** Department of Obstetrics and Gynecology, Faculty of Medicine, Srinakharinwirot University, Nakhon Nayok, Thailand *** Epidemiology unit, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
Objective : To evaluate the accuracy of fetal sex determination using ultrasonography performed by Thai Maternal Fetal
Medicine fellowships during second trimester genetic amniocentesis and also identify the possible factors of inaccurate
determination.
Material and Method: A prospective non-random study was conducted to evaluate the accuracy of fetal sex determination
using ultrasonography performed by Thai Maternal Fetal Medicine fellows at Songklanagarind Hospital during second
trimester genetic amniocentesis and also identify the possible factors of inaccurate determination.
Results : Five hundred and sixty singleton pregnant women were enrolled. Eight cases were excluded due to abnormal
fetal karyotype. No pregnancy loss or fetal ambiguous genitalia presented. The sex of 11/552 (1.99%) fetuses could not be
adequately determined by ultrasonography. Overall, 491 of the 541 diagnose were correct – an accuracy of 90.8% (CI 88.0-
93.1) given an ultrasonographic diagnosis could be made. Among phenotypic females, the accuracy was 226/246, (91.9%;
95% CI 87.7-95.0) and among phenotypic males, the accuracy was 265/295 (89.8%; 95% CI 85.2-92.4). The ultrasonographic
diagnosis of female sex was correct in 226/256, (88.3%; 95% CI 84.0-92.0), and the ultrasonographic diagnosis of male sex
was correct in 265/285, (93.0%; 95% CI 89.4-95.7). For both sexes combined and for female fetuses, year of fellowship was
only significant variable associated with correct sex determination by ultrasonography [2nd year vs. 1st year: overall ORS
2.55, (95% CI 1.44-4.61); female fetuses ORS 6.54, (95% CI 2.48-17.26)].
Conclusion : Fetal sex determination using ultrasonography by Thai Maternal Fetal Medicine Fellows at Songklanagarind
Hospital during second trimester genetic amniocentesis is possible. Less experienced physicians should be had increased
awareness especially in case of female external genitalia diagnosis.
Keywords : Amniocentesis, Sex determination, Ultrasonography, Advance maternal age
