and Marcelo Zugaib4

São Paulo University, Bauru, Brazil

Parisian University, Bauru, France

Member of International Fetal Medicine and Surgery Society, Bauru, Brazil

Obstetrics, University of São Paulo, Bauru, Brazil


The accuracy of fetal sex determination on ultrasound improves as pregnancy advances. Genital morphology is similar for both genders up to the 11th gestational week, and the external genital differentiation takes place by the 14th week owing to hormonal influence on the genital tubercle. Therefore, ultrasound diagnosis of fetal sex is inaccurate before the 11th gestation week.


Fig. 11.1
Mid-sagittal view of a fetus showing normal male sex at 13 weeks and 2 days’ gestation. This is the standard view for the assessment of the first-trimester genital tubercle and determination of fetal sex. A crown–rump length measurement above 75 mm has nearly 100% diagnostic accuracy


Fig. 11.2
. Low transverse view of the fetal perineum showing regular male genitalia (arrow)


Fig. 11.3
After obtaining a transversal cut from the same case of last figure one can obliquate the view to get fetal scrotum and penis analysed (arrow)


Fig. 11.4
Fetal penis erection at 25 weeks gestation. P = penis, BE =scrotum, F = femur


Fig. 11.5
Male fetal genitalia showing physiological hydrocele. BE = scrotum, arrow = penis, CU = umbilical cord


Fig. 11.6
Male genitalia demonstrating penile urethra (arrows)


Fig. 11.7
Typical male external genitalia. arrow = penis, BE scrotum, U urethra


Fig. 11.8
Longitudinal (left) and coronal (right) views of the fetal perineum showing a case of ectopic testis. The abnormally small scrotum due to the absence of testes is noticed. When the ectopic testes are associated with renal dilatation, it is advisable to consider the hypothesis of prune belly syndrome. Otherwise, it may be only an occasional finding. The assisting neonatologist should always be informed about such findings


Fig. 11.9
Fetal hydrocele (arrows). Notice the topic testis (t)


Fig. 11.10
Fetal hydrocele and dilated penile urethra (arrow)

Dec 28, 2017 | Posted by in GYNECOLOGY | Comments Off on Genitals
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