Nuchal translucency It is a sonographic pre natal screening scan to detect cardiovascular abnormality in a fetus. NT can also detect altered extra cellular matrix composition and limited lymphatic drainage

1. Nuchal Translucency
Guided by: Dr. Sangeeta Saxena
Professor and Head
Department of Radiodiagnosis
Presented by : Dr. Vrishit Saraswat
I Year Resident
M.D. Radiodiagnosis

2. Nuchal Translucency
• It is a sonographic pre natal screening
scan to detect cardiovascular abnormality
in a fetus.
• NT can also detect altered extra cellular
matrix composition and limited lymphatic
drainage

3. Q. How NT develops
• The actual anatomoical structure which is
seen as “Translucency “ is most likely the
normal skin at the back of neck.

4. Physiology behind NT
Placental
Circulation
Fetal
Circulation
Between 11-14
wks of gestation
Increased Resistance Under develop Lymphatic
Channels
Later in gestation Decreased Resistance Improved Lymphatics which are
able to drain away excess fluid

6. • BUT whenever there is alteration in normal
embryological condition , NT may become
oedematous or in some cases , filled with
fluid by dilated lymphatic channels.
• Example in down syndrome due to cardio
vascular abnormality such as ASD or VSD
, the CVS and lymphatics are incompatible
to drain the excess fluid causing NT to
increase.

8. Other Chromosal abnormalities
associated with increase NT
• Turner Syndrome (45 X)
• Edward Syndrome (tri 18)
• Patau Syndrome (tri 13)
• Di-george Syndrome (del 11q22)

11. Non chromosomal abnormalities
associated with increased NT
• Altered extra cellular matrix composition,
i.e. defect in Proteoglycans & GAGs.
• Limited / underdeveloped lymphatic
drainage also cause NT to increase

12. OTHER CONDITIONS
ASSOCIATED
Several other structural abnormalities
might be seen at nuchal translucency
screening like :
1. Omphelocoele
2. Anencephaly
3. Micrognathia
4. Megacystis

14. FIRST TRIMESTER
SCREENING FOR
ANEUPLOIDY
• Nuchal Translucency :
>95 percentile for CRL
OR
>2.5mm is consider as
increased NT,
According to several studies , the
sensitivity of NT alone, for detection of
Tri-21 is around 60 – 70%.

15. • Serological Marker :
Triple Test
It is done by evaluating the levels of
A Alpha fetoprotein
B Beta HCG
C Triol i.e estratriol
with low level of PAPP-A
Serological marker alone have
sensitivity of 65% to detect Tri-21
Continue…..

16. • Combined Screening :
First Trim.Screening using NT and
Serological markers(increased b-HCG and
decreased PAPP-A)have been used in
various studies and it is found out to be
more sensitive than either of them
individually
The detection rate of Tri-21 was 87 , 85
and 82 % in 11, 12 and 13 wks. Gestation
respectively.
Continue….

17. • Exception to this is multiple pregnancy
where detection rate was 88% with NT
alone.

18. Q. Can NT alone be
considerable enough?
• According to several studies conducted :
• If NT more >3 mm , there is “minimal”
benefit in waiting for combined screening.
• If NT is >4mm , there is “NO” benefit in
waiting for combined screening.

19. Integrated and Sequential
Screening
• Involves two steps:
Step 1: In first trimester
NT + PAPP-A
Step 2: In second trimester
Quadriple Test ( Triple test+ Inhibin)

20. Nasal Bone assesment

21. Cystic Hygroma

24. Standardization of Nuchal
Translucency measurement
technique
1. Callipers must be able to be adjusted in
increments of 0.1 mm
2. Approximately 20 mins. should be given
to obtain required measurements
3. CRL must be between 38-84 mm
4. Clear NT margins
5. Fetus horizontal image
6. Fetus in mid sagittal plane

25. 7. Tip of nose in profile
8. Head , neck and upper thorax should fill
the image with no visualization of heart.
9. Head in Neutral Position
10. Pocket of fluid should be visible between
chin and neck
11. Angle of neck and chest should be <90
deg.

26. 12.Callipers are placed at inner border of
lucent line
13. Lucency measured perpendicularly and
in widest space
14. Measure NT three times and report the
largest of three technically correct
measurements.

27. Any Suggestion
or
Additional Information
is Welcomed
Thanks & Regards
Dr. Vrishit Saraswat