This document discusses various techniques for prenatal screening and diagnosis of fetal abnormalities. It describes nuchal translucency screening as a non-invasive tool that is highly sensitive in detecting markers of chromosomal anomalies. It also discusses additional sonographic markers like echogenic foci, shortened long bones, and the measurement of nuchal skin folds to further assess risk. Overall, the document emphasizes the value of ultrasound screening in the first trimester for its ability to provide tangible information to patients and guide decisions about invasive diagnostic procedures.

3. NON - INVASIVE TOOL
PROVIDES A TANGIBLE & REALISTIC
MODALITY
PATIENTS CAN VISIBLY SEE FOR
THEMSELVES
COST EFFECTIVE
HIGH SENSITIVITY IN DETECTING
MARKERS/ANOMALIES
MORE SOPHISTICATED & HIGH-
RESOLUTION USG

4. OBSERVATION CHROMOSOMAL
ABNORMALITY
HEAD TRISOMY-18,13
•Strawberry skull TRIPLOIDY
•Hydrocephalus
•Holoprosencephaly
•Choroid plexus cyst
FACE TRISOMY-13,18
•Cleft lip/cleft palate Meckel-Gruber syndrome
•Low set ears TRIPLOIDY
HEART TRISOMY-13,18,21
•VSD,ASD
•Coarctation of aorta

5. OBSERVATION CHROMOSOMAL
ABNORMALITY
RENAL TRISOMY-13,18,21
• Horseshoe kidney TRIPLOIDY
• B/L dilatation of renal pelvis
• Cystic dysplasia
HANDS/FEET TRISOMY-18,13,21
•Flexed overlapping fingers
•Rocker bottom/club foot
•Polydactyly
•Wide gap b/w 1st &2nd toes
(Sandal-gap)
•Clinodactyly
•Short femur/humerus

6. OBSERVATION CHROMOSOMAL
ABNORMALITY
G.I SYSTEM TRISOMY-13,18
Omphalocele TRISOMY-21
Duodenal atresia
Echogenic bowel
GENERAL
Growth restriction TRISOMY-13,18,21
Hydrops TRIPLOIDY;45-XO

7. OBSERVATION CHROMOSOMAL
ABNORMALITY
PLACENTA Partial mole
ANEUPLOIDY
UMBILICAL CORD TRISOMY-18

8. NUCHAL TRANSLUCENCY
With severe
LYPHANGIECTASIA
→ overall swelling
of the fetal soft
tissue
↓
Thickening of the
nuchal soft tissues
↓
NUCHAL
TRANSLUCENCY

9. Refers to the normal
subcutaneous fluid filled space
between the back of the fetal neck
& the overlying skin.
The single most powerful marker
available today for differentiating
DS from euploid pregnancies.

11. POSSIBLE CAUSES OF ↑ FLUID FILLED SPACE(NT)
Cardic failure secondary to structural
malformation
Abnormality in the extracellular matrix
Abnormal or delayed development of
the lymphatic system

12. CAUSES
ANEUPLOIDIES SKELETAL DYSPLASIA
Carnelia de Lange Achondrogenesis
Noonan syndrome Ectrodactyly-ectodermal
Smith-Lemli-Opitz dysplasia
Joubert Multiple Pterygium Syndrome
Apert Robert Syndrome
Fryns
CHROMOSOMAL ANOMALIES
Trisomy-21 (most common)
Trisomy-13,18,22
Triploidy
Tetrasomy -12p

13. Imaged in the mid sagittal plane, ideally with the fetal
spine down.
Image should be adequately magnified so that only
the fetal head ,neck & upper thorax fill the viewable
area
The fetal neck should be neutral-avoid measurements
in the hyperflexed/hyper extended positions
The skin at the fetal back should be clearly
differentiated from the underlying amniotic membrane

14. Measurement calipers
should be optimized to
ensure clarity of the image
and of the borders of the
nuchal space in particular
(TVS)
The width of the lucency
alone, excluding the width
of the surface or occiput

16. PITFALLS
PRESENCE OF
 An Encephalocele
 Nuchal cord
 An Amniotic band
 A loose amnion that can be
mistaken for the nuchal skin edge

17. How to rectify?
MAGNIFY THE IMAGE
WAIT FOR SPONTANEOUS FETAL ACTIVITY
→ as the fetus bounces from the amnion ,the
edges can be distinguished more reliably
COLOR DOPPLER → presence of a umbilical
cord in the vicinity of the fetal neck.

18. Cut off value of 3mm as a threshold for an
abnormal nuchal translucency
Normal NT thickens with increasing GA
Currently, the more accepted method is to
base the cut off on a progressive rise
>95th percentile as a threshold.
MOM Vs SD: MOM-reduction in false +ve rates

19. •Equal success (Braithwaite & Economides)
METHOD Gestational Age Success rate
TAS 10-13 WEEKS 98% to 100%
TAS AT 14 WEEKS 90%
TVS is needed

20. 10-14weeks of GA
Detection rate False+ve rate Study group
77% 5% Fetal medicine
foundation,
London
63% 5% The SURUSS
trial,UK
69% 5% The BUN trial,
US
70%-64% 5% The FASTER
trial, US

21. Nicholaides: First trimester NT =/> 3mm
Detection rate→86% of Trisomic fetus
False +ve rate→4.5%
Pandya (1995):
NT (mm) 3 4 5 >6
RISK ↑ 3 18 28 36
•TRISOMIES 13,18,21
•FETAL LOSS RATE =15% with NT of 5mm
•↑ NT → ↑ RISK OF CONGENITAL HEART DEFECT
•With Normal Karyotype & with abnormal karyotype

22. Progression from an abnormal NT to a
normal one→ not necessarily indicative of a
nomal Karyotype
So the fetus with nuchal abnormalities →
candidates for amniocentesis ,regardless of
whether the abnormality resolves
Among the women with advanced maternal
age b/w 11-14wks GA→NT can be used to
determine which patients would benefit from
an early First trimester Amniocentesis/CVS,
Vs delay of the invasive testing until 16 weeks
for the safest possible procedure.

23. MAJOR CARDIAC ANOMALIES
DIAPHRAGMATIC HERNIA
ANT. ABD.WALL DEFECT
FETAL AKINESIA/DYSKINESIA SYNDROME
OTHERS- Cornelia de lange,Noonan,Smith-lemli-
Opitz,Joubert,Apert&Fryns
SKELETALANOMALIES→
Achondrogenesis,Ectrodactyly-ectodermal
dysplasia,Multiple Pterygium syndrome,Robert syndrome

24. Localised nuchal fluid→CYSTIC HYGROMA(CH)
FETAL HYDROPS
DIFFUSE EDEMA
SEPTATED CH:
ANEUPLOIDY EUPLOID
50% 50%
50%-MAJOR structural
malformation
CARDIAC x12
SKELETAL DYSPLASIA

26. Presence of Septations within
a nuchal swelling is ominous
Non - Septate CH Septate CH
98%- transient 44%-transient
6%→ Abnormal 72%→ Abnormal
Karyotype Karyotype
Bronshtein et al.

27. NO NEED TO DELAY DECISION MAKING→
while awaiting serum marker results/using
computerized risk calculation algorithms
IMMEDIATE OPTIONS FOR CVS
IF NO FETAL ANEUPLOIDY→
A DETAILED FETAL ANATOMIC
EVALUATION
+ FETAL ECHOCARDIOGRAPHY AT 18-20
WEEKS

28. FASTER TRIAL-
>3mm NT → CVS SHOULD BE OFFERED
IMMEDIATELY,because of a minimum risk of
aneuploidy of 1 in 6.
NO ROLE FOR DELAYING DECISION
MAKING while awaiting serum marker
results,because such additional information
does not meaningfully alter the original
aneuploidy risk

29. GROWTH PATTERNS- CRL
NASAL BONE
DUCTUS VENOSUS SONOGRAPHY
TRICUSPID REGURGITATION
ANTERIOR ABDOMINAL WALL DEFECTS
ENCEPHALOCELES
LIMB DEFORMITIES
HEART DEFECTS

30. Schemmer et al;
CRL→ NOT significantly reduced
with Trisomy-21,Turner Syndrome or
Sex chromosome Trisomies
 → SIGNIFICANTLY reduced
growth rates with Trisomies 13 & 18
and Triploidy

31. ABSENCE OF NASAL BONE & DS
Cicero et al; (N= 701 fetuses with ↑NT)
ABSENCE OF NB PRESENCE OF NB
73% 0.5%
(43 OF 59) (3 OF 602)
NOT RELATED TO ↑ NT
COULD BE COMBINED INTO A SINGLE USG
SCREENING MODALITIES
PREDICTED SENSITIVITY OF 85% FOR 1% FALSE +VE
RATE.

32.  MID SAGITTAL PLANE
 FETAL PROFILE FACING
UPWARD
 ADEQUATE MAGNIFICATION
 VISUALIZATION OF TWO
PARALLEL LINES AT THE
LEVEL OF THE FETAL NOSE→
1. Superficial: fetal skin
2. Deeper: nasal bone
 NASAL BONE- MORE
ECHOLUCENT AT THE DISTAL
END.

33. INCIDENCE OF ABSENT NASAL BONE
GENERAL HIGH RISK
POPULATION POPULATION
17%-29% 48%
LIMITED ROLE AS A SCREENING TOOL FOR
GENERAL POPULATION

34. FORWARD TRIPHASIC
PULSATILE FLOW→
NORMAL
REVERSED FLOW AT THE
TIME OF ATRIAL
CONTRACTION
→ANEUPLOIDY/FETAL
CARDIAC MALFORMATION
WITH NT → ↑ THE DETECTION RATE/↓ THE FALSE +VE
RATE

35. PITFALLS
The ductus venosus vessel- as small as
2mm at 10-14weeks
Very difficult to get proper image
SECONDARY SCREENING TEST IN
THE HANDS OF EXPERIENCED
SONOLOGIST

36. CHEST WALL-ANTERIOR
THE FETAL HEART SHOULD
BE ISONATED PARALLEL TO
THE VENTRICULAR SEPTUM
HIGH RISK PREGNANCIES
AT 11-13 WEEKS
Significant TR INCIDENCE
NORMAL FETUS 4%
DS Fetus 68%
TRISOMY- 18 33%
SECOND LINE TEST

37. AT 10-14 WEEKS
Normal parameters
GA(weeks) FHR (beats/min)
10 171
14 156
Higher than normal rate- TRISOMY-21
Lower than normal rates- TRIPLOIDY & TRISOMY-18

38. SENSITIVITY
ABNORHAL FHR- 26%
NT- 72%
MATERNAL AGE- 48%
MATERNAL AGE+ NT + FHR- 83% of
detection rate at 5% false +ve rate

39. Authors Parameter Sensitivity False +ve rate
Orlandi et al. NT alone 57% 5.8%
NT + 87% 5.8%
biochemistry &
maternal age
Noble et al; NT + 80-85%
Biochemistry &
maternal age
BEST DETECTION RATE IN 1ST TRIMESTER-
Urine free β- hCG , beta core & Oestriol + NT

40. 10-14 WEEKS
NT SONOGRAPHY
CYSTIC HYGROMA NO CYSTIC HYGROMA
CVS
SINGLETONE MULTIFETAL
EUPLOID ANEUPLOID GESTATION GESTATION
18-20 WKS COUNCEL
ANATOMY
SCAN &
FETAL ECHO

41. NT + NO CYSTIC HYGROMA
SINGLETONE GESTATION MULTIFETAL GESTATION
NT + SERUM MARKERS NT INTERPRETED WITH
PAPP-A & β- hCG MATERNAL AGE ONLY
RISK ↑ RISK ↑
RISK NOT↑
CVS EUPLOID CVS
EUPLOID
ANEUPLOID ANEUPLOID
18-20 WKS
COUNCEL ANATOMY SCAN & COUNCEL
FETAL ECHO

42. MOST COMMON SONOGRAPHIC MARKERS
NUCHAL FOLD THICKENING
ECHOGENIC INTRACARDIAC FOCUS
SHORTENED LONG BONES
HYPERECHOIC BOWEL
RENAL PYELECTASIS
CHOROID PLEXUS CYST
CLINODACTYLY
HYPOPLASTIC OR ABSENT NASAL BONE

43. EXCESS SOFT TISSUE IN THE POSTERIOR NECK AREA
Measurement
TS OF FETAL HEAD
ANGLED POSTERIORLY
TO INCLUDE THE
CEREBELLUM & THE OCCIPITAL N T
BONE
OUTSIDE OF THE OCCIPITAL BONE
OUTER SKIN EDGE

44. THE NUCHAL SKIN FOLD MEASUREMENT THRESHOLD
AUTHORS Gestational Threshold
Age
Gray & Crane 14-17 wks 5mm
18-20 wks 6mm
Wilson < 17wks 5mm

45. SENSITIVITY
AUTHORS CUT OFF VALUE SENSITIVITY FALSE +VE
Crane & >/= 5 mm 75%
Gray
Borrell & >/= 6 mm 33% 0.1%
Colleagues
Borrell & >/= 5mm 77.8% 2%
Colleagues

46. May persists throughout the 2nd trimester
Or regression may occur

47. ONCE AN ABNORMAL NUCHAL SKIN
MEASUREMENT IS OBTAINED,THEREFORE ,AN
AMNIOCENTESIS IS INDICATED, REGARDLESS
OF WHETHER THE NUCHAL SKIN THICKNESS
RESOLVES

48. TRISOMY-21 oSHORT STATURED
oSHORT FEMURS
oSHORT HUMERI
RATIOS OF THE MEASURED - TO - EXPECTED FL OF
</= 0.91, BPD.
EXPECTED FL = - 9.3105 + 0.9028 x BPD

49. SENSITIVITY
STUDY SENSITIVITY FALSE +VE RATE
LOCKWOOD 50% 7%
CALLEN 68%
GRIST 50% 6.5%

50. Study Parameter Sensitivity False +ve Anomalies
rate
Brumfield BPD: FL 40% 2.2% TRISOMY-
et al; >/= 1.8 18 & 21
Ginsberg -do- 53% 7% - do-
et al;
Ginsberg + NT 81% 7% - do-
et al;
NOT A HELPFUL TOOL FOR SCREENING OF DS
USEFUL IN COMBINATIONS WITH OTHER SONOGRAPHIC MARKER
Eg: HUMERUS LENGTH & PYELECTASIS

51. THE MEASURED- TO – EXPECTED HUMERUS LENGTH
= - 7.9404 + 0.8492 x BPD
< 0.90 as a cut - off
STUDY METHODS SENSITIVITY FALSE +VE
Callen HL 50% 6.25%
Rodis et al; HL 54%
FL 18%
Biagiotti FL + HL ↑ ↓↓
Periti
Cariati

52. Nyberg et al; Short FL + HL 11 fold ↑ risk of
DS
Johnsons et al; FL+ HL 53% - sensitivity
Foot Length 7% - false +ve
rate

54. An antero-posterior diameter of the renal pelvis
>/=4 mm

55. STUDY METHOD SENSITIVITY FALSE +VE
Callen PYELECTAS 25%
IS
Crane & -do- 18.7%
Gray
Corteville , -do- 17% 2%
Dicks &
Crane
ISOLATED PYELECTASIS- ↑risk
NOT SUFFICIENT TO INDICATE AMNIOCENTESIS
USED IN COMBINATION WITH OTHER

56. THE BOWEL IS AS ECHOGENIC AS BONE
0.6% OF ALL 2ND -
TRIMESTER FETUSES
BE AWARE:
High frequency transducer
may tend to accentuate the
echogenicity of the fetal
bowel in NORMAL fetus

57. ↑ RISK OF
IUGR
PREMATURITY
FETAL DEMISE
POOR PERINAL OUTCOME
APH
 CYSTIC FIBROSIS - Parental allele testing for CF
carrier status is recommended
 IN-UTERO CMV INFECTION

58. MINERALIZATION IN THE PAPILLARY MUSCLE
UNILATERAL BILATERAL

59. 90% in the left ventricles
When the Right ventricle or both ventricles
are involved ↑ risk of Chromosomal anomalies
FETAL STATUS EIF in Left EIF in Right / B/L
Ventricle
Normal 88% 12%
Down Syndrome 78% 22%

60. STUDY NORMAL TRISOMY- 21 TRISOMY- 13
Brown,Roberts 2% 16% 39%
& Miller
Callen 4.7% 18%
Association of EIF & Chromosomal anomalies is low
in low risk patient
NO AMNIOCENTESIS
Not associated with cardiac anomalies in low risk
patient

61.  NORMAL FETUSES - 0.3% TO 3.6%
 1/3RD OF FETUSES WITH TRISOMY - 18
•16-21 WEEKS → TRANSIENT
•BY 23RD WEEKS → USUALLY REGRESS
•25-26 WEEKS → UNCOMMON

62. U/L SINGLE SMALL
B/L MULTIPLE LARGE
SIZE = 0.5 cm – 2cm
Very large CPC → Fill almost the entire
lateral ventricle & expands its walls →
FALSE VENTRICULOMEGALY

63. + OTHER ISOLATED CPC
SONOGRAPHIC
FINDINGS
CONSERVATIVE
INVASIVE TESTING With detailed fetal
sonographic anatomic
survey by experts

64. EXAMINING THE UA TRANSVERSE VIEW OF A FREE
RUNNING ALONGSIDE & LOOP OF CORD
AROUND THE BLADDER
Transverse view of the pelvis

65. 17% - CYTOGENETIC ABNORMALITY
TRISOMY- 18 ( Most Common )
TRISOMY- 13
TURNERS SYNDROME (45X)
TRIPLOIDY
Commonly seen in normal fetuses
It is non-specific
The most common organ system
involved – HEART , GI SYSTEM & CNS

66. A targeted & detailed fetal ISOLATED SUA –
anatomic survey should be No ↑ incidence for a
done with detailed chromosome
evaluation of the heart abnormality

67. ILIAC WING ANGLE
ILIAC LENGTH
FRONTOTHALAMIC DISTANCE (BRACHYCEPHALY)
SHORTENED FRONTAL LOBE
ABNORMAL FHR
ABNORMALLY SHORTENED EAR LENGTH
FLAT FACIES
CLINODACTYLY(with hypoplasia of the middle
phalanx of the fifth digit)
SANDAL GAP GREAT TOE
SIMIAN CREASE OF THE PALM
EAR LENGTH & WIDTH

68. LOW RISK NO further Testing
Normal USG
No markers present
HIGH RISK DS risk adjustment
LOW RISK NO further Testing
1-ISOLATED MARKER
(Except-Nuchal fold/
Absent Nasal Bone Genetic Amniocentesis
HIGH RISK
>/=2 MARKERS/Thick LOW RISK Genetic Amniocentesis
Nuchal Fold/ Absent
Nasal Bone/Structural
Anomaly HIGH RISK Genetic Amniocentesis

69. STRUCTURAL ABNORMALITIES ANEUPLOIDY MARKERS
oCardiac defects Clinodactyly
oCystic hygroma EIF
oVentriculomegaly/hydrocephalus Hyperechoic bowel
oEsophageal atresia Nuchal fold thickening
/Tracheo-esophagial fistula Pyelectasis
oDuodenal atresia Sandal gap
oOmphalocele Short long bones
Wide iliac angle
OTHER FINDINGS
SUA
Brachycephaly
Short ear length
Flat facial profile
Absent / hypoplastic
Protruding tongue
nasal bone
Hydrops
Hydrothorax
Pericardial effusion
Unfused amnion & chorion after 14 weeks

70. STRUCTURAL ABNORMALITY
Cardiac defect
Cystic hygroma
Diaphragmatic hernia
Omphalocele
Esophageal atresia+/- TOF
CNS-agenesis of
corpuscallosum,ventriculomegaly,hydrocephalus,large
cisterna magna,Dandy-Walker Malformation,cerebellar
dysgenesis,neural tube defect
CRANIOFACIAL- Strawberry-shaped skull,prominent
occiput,dolichocephaly,ocular anomalies,micrognathia,cleft
lip/palata,small,low set ears
GENITO-URINARY- Hydronephrosis,horseshoe
kidney,BOO,duplication abnormality,genital abnormality

71. EXTREMITY-
Limb reduction abnormality,Radial
aplasia,Clenched hands/Overlapping
digits,Club feet,Rocker-bottom feet,Lower
extremity/feet
abnormality,Contracture/arthrogryposis/flexion
deformity,movement disorders
ANEUPLOIDY MARKERS- OTHER FINDINGS-
 Choroid plexus cyst IUGR,Amniotic fluid
Strawberry-shaped skull abnormality,Umbilical
Nuchal thickening cord cyst,Non immune
hydrops
Single Umbilical artery
Shortened limbs

72. STRUCTURAL ABNORMALITIES-
Cardiac defects,Cystic hygroma,Nuchal
thickening,Omphalocele
CNS- Holoprosencephaly,Agenesis of corpus callosum,
Ventriculomegaly,Enlarged cisterna magna,Abnormal posterior
fossa,Neural tube defects
CRANIO-FACIAL- Microcephaly,Micrognathia,Cleft
lip/palate,Facial defects,Ocular anomalies ,Sloping
forehead,Small ears
EXTREMITIES- Postaxial polydactyly,Overlapping
digits,Camptodactyly,Radial aplasia,Rocker-bottom feet,Club feet
UROGENITAL- Hydronephrosis,Cortical cysts,Horseshoe
kidney,Echogenic kidney,Polycystic kidneys

73. ANEUPLOIDY MARKERS
Echogenic Intracardiac Focus
Pyelectasis
Single Umbilical Artery
OTHER FINDINGS
Microcephaly
IUGR
Polyhydramnios

99. PAST
Over the past decade & a half, AMNIOCENTESIS was reserved
for woman of advanced maternal age
PRESENT
In the new millenium- major changes in the indications for
INVASIVE GENETIC TESTING- such that advance maternal
age alone will no longer be an indication
FUTURE
Whether a patient is at risk for fetal Aneuploidy will be based on
the combination MATERNAL AGE,MULTIPLE BIOCHEMICAL
SERUM MARKERS & perhaps a dozen SONOGRAPHIC MARKERS
+ a complete USG evaluation of the fetus.