Early fetal sex determination by
Presented by R3 邱邱邱
Supervisor VS 邱邱邱
• Fetal gender assignment during ultrasound
evaluation: parent’s curiosity, identification
of normal gender development, heritable
sex –linked disease.
• Especially X- linked disorder: Hemophilia,
Duchenne’s muscular dystrophy.
• Britt-Marie, Acta Obstet Gyne Scand, 1981:
- Fetal sex determination in the 17th, 32nd
and the 38th week of gestation: easiest in
the 32nd week ( 74 % ).
• With the improvement of the ultrasound
improvement, earlier fetal sex identification
• Second trimester sex determination:
Male: scrotum and penis were seen.
Female: labia majora were visualized.
• Reece et al. Am J Obstet Gynecol:
- Can ultrasonography replace amniocentesis
in fetal gender determination during the
early second trimester? ( overall prediction
rate: 92.7% )
• “ The Sagittal Sign”: Donald S. Emerson, J
Ultrasound Med, 1989:
- An early second trimester sonographic
indicator of fetal gender. ( fig )
- Cranial notch vs caudal notch.
- From 14 to 20weeks, sagittal sign yields a
gender prediction in 82% of fetuses ( 86%
of males, 79% of females )
• Fig. Late embryonic development of external
• Toward the middle of the 2nd trimester, when the
notches are not as clearly visualized, the sign loses
Clitoris and vestibule: become relatively small
compared to trunk size.
Penis: fails to maintain consistent cranial
Material and method
Seventy-five pregnant women on whom routine ultrasound screening
was done in our obstetric clinic were enrolled in our study during
All had gestational ages between 11 and 16 weeks, singleton. ( on the
basis of ultrasound findings)
Ultrasound unit: ALOKA Prosound 5000
All by transabdominal route.
Within 15 minutes.
Midsagittal or transverse view.
Confirmatory as ultrasound examination follow up by reviewing of
charts or telephone interview.
Material and methods
• Midsagittal plane: assigned as male if the angle
of the genital tubercle to a horizontal line through
the lumbosacral skin surface was greater than 30
degree and female when the genital tubercle was
parallel or convergent ( less than 30 degree ) to the
horizontal line. No extension of limbs and spine.
Material and Methods
• Transverse plane: Male genitalia were
identified when a uniform, dome-shapes structure
was seen at the base of the fetal penis. Female
genitalia were identified by visualizing two or four
• Most of the cases were not aware of sex
identification during ultrasound examination.
• Totally seventy-five cases. Thirteen cases
were lost of follow up and still had two
cases having no sex identification yet.
• Sixty cases were enrolled in this study
Table 1.Gender determination in 60 fetuses between 11 and 16 weeks of gestatuon
wuth the use of ultrasonography
Total positive rates: Male: 18/23= 78.3%
True positive rates: Female: 30/37= 81.1%
• Male was wrongly assigned as female (7 cases including
one twin pregnancy):
11+ week: 2 cases
12+ week: 3 cases
13+ week: 2 cases
• Female was wronged assigned as female ( 5 cases ):
12+ week: 1 case
13+ week: 1 case
15+ week: 2 cases
16+ week: 1 case
11 - 11+ 6
12 - 12+ 6
13 - 13+ 6
14 - 14+ 6
15 -15+ 6
16 --16+ 6
• Factors associated with nonvisualization:
maternal obesity, fetal axis, fetal movement,
skill and experience.
• D.A,L.Pedreira, Ultrasound in Obstetrics and
“ Fetal phallus ‘erection’ interfering with the
sonographic determination of fetal gender in the
first trimester”. ----- more common in the early
first trimester, suggest a progressive maturation of
the mechanism responsible for maintaining the
phallus erect in male fetuses. It may happen in
• Genital tuberclePhallusPenis or Clitoris
• B Benoit doubt???
Whitlow and Elfrat: gender identification between
11 and 14 weeks. ( 78% accuracy for Whitlow and
70.3% accuracy for Elfrat at 11 weeks. )
Transverse planes should be used after 14 weeks