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Early fetal sex determination newesttest

Early fetal sex determination by
Ultrasound
Presented by R3 邱邱邱
Supervisor VS 邱邱邱
91.3.13


Introduction
• 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.


Introduction
• 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
became possible.


Introduction
• 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% )


Introduction
• “ 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 )


Introduction
• Fig. Late embryonic development of external
genitalia.
• Toward the middle of the 2nd trimester, when the
notches are not as clearly visualized, the sign loses
significance:
Clitoris and vestibule: become relatively small
compared to trunk size.
Penis: fails to maintain consistent cranial
angulation.


Material and method










Seventy-five pregnant women on whom routine ultrasound screening
was done in our obstetric clinic were enrolled in our study during
December, 2001.
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.
Prospective investigation.


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
parallel lines.
• Most of the cases were not aware of sex
identification during ultrasound examination.



Results
• 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
finally.


Table 1.Gender determination in 60 fetuses between 11 and 16 weeks of gestatuon
wuth the use of ultrasonography






Confirmed


Male

Ultrasound








Female

Total

No

%

No

%

No

%

Male

18

30%

7

11.70%

25

41.70%

Female

5

8.30%

30

5%

35

58.30%

Total

23

38.30%

37

16.70%

60

100%

Total positive rates: Male: 18/23= 78.3%
True positive rates: Female: 30/37= 81.1%
Ovarall: 48/60=80%


Results
• 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










Gender identified

Gestatiomal




age (weeks)



n



n



%

11 - 11+ 6



8



6



75%

12 - 12+ 6

18

14

77.80%

13 - 13+ 6

9

7

77.80%

14 - 14+ 6

6

6

100%

15 -15+ 6

11

9

81.80%

16 --16+ 6

8

6

75%

Total



60



48



80%


Discussion
• Factors associated with nonvisualization:
maternal obesity, fetal axis, fetal movement,
skill and experience.


Discussion
• D.A,L.Pedreira, Ultrasound in Obstetrics and
Gynecology,:
“ 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
both sexes.




Discussion
• Genital tuberclePhallusPenis or Clitoris
11 week
12 week
• 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
only.



13+
weeks, female






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