Ultrasound gender determination. How to identify?
How to measure genital tubercle?
Examine fetus in mid sagittal plane with in a natural position
(neither hyperflexed or hyperextended)
Measure the angle of the genital tubercle to a horizontal line through the lumbosacral skin surface
*Assign as male fetus if the angle is greater than 30°
*Assign as female fetus if genital tubercle is parallel or convergent ( less than 10°) to the horizontal line
*Assign as undetermined if the angle is intermediate (10–30°)
Female gender at 2nd trimester:
- Transverse image just below the level of the bladder, best taken with the knees separated.
- No penis is seen between the thighs, rather there are three lines representing the labia visible.
- Mid-sagittal image of the lower abdomen to show the flat mons pubis caudal to the cord insertion.
Male gender at 2nd trimester:
-Transverse image just below the level of the bladder, best taken with the knees separated, shows penis and scrotum between the thighs.
-Testes are undescended at this gestation, and usually descend later in the third trimester.
-Mid-sagittal image of the lower abdomen below the cord insertion demonstrates penis and scrotum caudally to the cord insertion.
#ultrasound #ultrasoundgender #obstetrics
References/ Articles for reading:
Efrat Z, Perri T, Ramati E, Tugendreich D, Meizner I. Fetal gender assignment by first trimester ultrasound. Ultrasound Obstet Gynaecol 2006; 27: 619–21.
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Bethune, M., Alibrahim, E., Davies, B. and Yong, E. (2013), A pictorial guide for the second trimester ultrasound. Australasian Journal of Ultrasound in Medicine, 16: 98-113.
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