NT AND ANEUPLOIDY
.
Monosomics for all human autosomes die in utero.
A sex-chromosome monosomic complement of 44
autosomes + 1 X produces the phenotype of Turner
syndrome.
The most common type of viable human aneuploid is
Down syndrome occurring at a frequency of about 0.15
percent of all live births
The only other human autosomal trisomy to survive to birth
are afflicted with either trisomy 13 (Patau syndrome) or
trisomy 18(Edwards syndrome).
Trisomies chromosome 2, 16, and 22 are relatively
common in abortuses but never survive to birth.
Trisomy of the sex chromosomes is possible, such as in
(47,XXX), (47,XXY), and (47,XYY).
NUCHAL TRANLUCENCY
USG MARKERS
NT - MOST ROBUST MARKER
NASAL BONE
TRICUSPID FLOW
DUCTUS VENOSUS FLOW
WHY FIRST TRIMESTER
COMBINED SCREENING
MA+NT+BIOCHEMICAL MARKERS
Advantages compared to second trimester biochemical screening include:
Earlier diagnosis (11-14 weeks)
Higher detection rates for fetal Down syndrome (80-90% or perhaps even higher compared to
75% for the second trimester "quad" screen and 60-70% for the older "triple" screen)
Detection of most major chromosome abnormalities other than trisomy 21
Acts as a nonspecific marker for other birth defects including some major cardiac defects and
syndromic conditions
Can detect a number of major structural birth defects associated with normal chromosomes
The primary disadvantage is
Narrow window of entry (11-14 weeks with ideal entry at 11-12 weeks).
NT AND ANEUPLODY
MATERNAL AGE + NT
M A + NT + BIOCHEMICAL MARKERS
M A + NT + B M + NB/DV FLOW/TCV FLOW.
RISK 1 TO 50
RISK UPTO 1 TO 1000
HYPOPLASTIC NB
NB –N
NO CHANGE IN RISK
NB- N
RISK REDUCED
NB-AB
RISK INCREASED
ALL OTHER MARKERS N –REPEAT SCAN
REVERSE a WAVE
RISK ALWAYS INCREASED
NT AND EUPLOID FETUS
INCREASED NT A/W INCREASED FETAL MORTALITY
INCREASED NT A/W STRUCTURAL ABNORMALITIES
MAJOR CARDIAC DEFECTS
DIAPHRAGMATIC HERNIA
EXOMPHALOS
SKELETAL DEFECTS
BODY STALK ANOMALIES
THE 11-14 WEEK SCAN
I
Fetal abnormalities
Cardiac defects
Diaphragmatic hernia
Exomphalos
Achondrogenesis type II
Achondroplasia
Asphyxiating thoracic dystrophy
Beckwith-Wiedemann syndrome
Blomstrand osteochondrodysplasia
Body Stalk anomaly
Campomelic dysplasia
EEC syndrome
Fetal akinesia deformation sequence
Fryn syndrome
GM1-gangliosidosis
Hydrolethalus syndrome
Jarcho-Levin syndrome
Joubert syndrome
Meckel-Gruber syndrome
Nance-Sweeney syndrome
Noonan syndrome
Osteogenesis imperfecta type II
Perlman syndrome
Roberts syndrome
Short-rib polydactily syndrome
Smith-Lemli-Optiz syndrome
Spinal muscular atrophy type 1
Thanatophoric dysplasia
Trigonocephaly 'C' syndrome
VACTEREL association
Zellweger syndrome
ABNORMAL NT NORMAL FETUS
Normally nuchal translucency
disappears by 14 weeks.
Noteworthy are cases with abnormal NT that resolve spontaneously
around 14 weeks and show healthy outcome
Chromosomally and structurally normal fetuses with history of
thickened NT with no evidence of nuchal fold thickening or nonimmune hydrops, at 20 weeks -- no increased risk for perinatal or longterm morbidity and mortality
PATHOPHSIOLOGY OF NT
Chromosomally and structurally normal fetuses with
Altered dermal collagen composition (eg, Down syndrome)
Abnormal nuchal lymphogenesis (eg, Turner syndrome)
Hemodynamic alterations and cardiac dysfunction( heartdefects)
Abnormal endothelial cell differentiation
NASAL BONE
ABSENT
PRESENT
MAXILLO FACIAL ANGLE
NORMAL
REDUCED
INCREASED TRISOMY 21
DUCTUS VENOSUS FLOW
reverse a wave a/w chromosomal defects
cardiac defects and adverse fetal outcome
TRICUSPID FLOW
Prevalence of TCV regurgitation in fetuses with trisomy 21 is about 74% whereas
only 7% of chromosomally normal fetuses have this finding There is an increased
prevalence of cardiac defects with TC regurgitation, irrespective of the presence or
absence of aneuploidy
FETAL MEASUREMENTS AS MARKERS
FETAL GROWTH/ CRL - REDUCED GROWTH CAN BE SEEN IN TRISOMY 13
,18, TURNERS SYNDROME HOWEVER NOT IN TRISOMY 21
FETAL HEART RATE -BRADYCARDIA SEEN IN TRISOMY 18 AND TRIPLOIDY
AND TACYCARDIA IN TRISOMY 13 AND TURNER SYNDROME
FETAL STRUCTURAL DEFECTS AS MARKERS
SINGLE UMBILICAL ARTERY/ TWO VESSEL CORD
SEVEN FOLD INCRESED RISK FOR TRISOMY 18
MEGACYSTIS
MEGACYSTIS LONG. BLADDER OF >7MM
7-15 MM A/W INCREASED RISK OF TRISOMY 13 AND 18
EUPLOID FETUSES –SPONTANEOUS RESOLUTION
>15 MM LESS LIKELY CHROMOSOMAL ANOMALIES MORE
LIKELY TO CAUSE OBSTRUTIVE UROPATHY
OMPHALOCOELE
HIGH ASSOCIATION WITH TRISOMY 18
ONE OF THE REASONS TO PERFORM NT SCREENING AT 11WEEKS NO
PHSIOLOGICAL BOWEL HERNIATION
OMPHALOCOELES WITH ONLY BOWEL HERNIATION STRONGER ASSO. WITH
ANEUPLOIDY
Aneuploid fetuses with omphalocoeles containing only bowel show
resolution in significant no of fetuses, most likely developmental delay.
HOLOPROSENCEPHALY
EXTREME FORM ALOBAR HOLOPROSENCEPHALY CAN BE DETECTED IN
FIRST TRIMESTER
INCREASED RISK OF ANEUPLOIDY MOSTLY TRISOMY 13
THE FIRST TRIMESTER ANOMALY SCAN
DETECTABLE ABNORMALITIES
THE FIRST TRIMESTER SCAN IS NO
LONGER A NT SCAN BUT A FETAL
ANATOMY SCAN
INTRACRANIALTRANSLUCENCY
IN OPEN NEURAL TUBE DEFECTS
The fourth ventricle presents as an intracranial
translucency (IT)
between the brain stem and the choroid plexus.
a case of open spina bifid demonstrating
compression of the fourth ventricle with
no visible translucency.
ARNOLD CHIARI 2
Lemon sign: Scalloping of frontal bones
Banana sign: Caudal displacement of cerebellum , obliteration of CM
Not consistently seen in first trimester.
POSTERIOR FOSSA AT 11 TO 13.6 WEEKS
NORMAL
POST FOSSA CYST
OPEN SPINA B
NEURAL TUBE DEFECTS
Meningoenc
Occipital (MC) – A/w skull defect (cf D/D Nuchal cystic hygrom
Parietal
Frontoethmoidal
A/w Microcephaly, Hydrocephalus, Spina bifida,
Meckel Gruber Syn.
d/d : Cystic Hygroma
ACRANIA–EXENCEPHALY-ANENCEPHALY
SKULL OSSIFICATION AT 11 WEEKS OF
OCCIPITAL BONE
Varying degrees of distortion of brain
MECKEL GRUBER SYNDROME
Encephalocoele
Polycystic kidneys
Polydactyly
DANDY WALKER COMPLEX
Complete or partial absence of cerebellar vermis
4th Ventricle Dilatation
End point of chromosomal abn. , Genetic Syndromes ,
congenital infection or Isolated abn
HYDRANENCEPHALY
Total absence of cerebral hemispheres
Large head
Small hemispheres
Fluid-filled intracranial cavity with no
midline echoes
HOLOPROSENCEPHALY
Alobar and
Semilobar a/w facial abnormalities
Lobar
INIENCEPHALY
Rare
Cervical dysraphism with occipital(inion) defect
+ encephalocoele
Persistently extended fetal head -clue
CARDIAC ANOMALIES
Fetal 4 chamber view can be demonstrated at 11to 14 weeks scan
RAISED NT
PERSISTENT BRADYCARDIA (60BPM)
COMPLETE AV CANAL DEFECT
A 14 WEEK SPECIALIST SCAN CAN REVEAL MAJOR ABN OR RAISE SUSPICION
FOR LATER DETAILED SCAN
4 CHAMBER VIEW
AV CANAL DEFECTS
VSD
MUSCULOSKELETAL ABN.
CAUDAL REGRESSION SYNDROME
DEGREES OF VERTEBRAL ANOMALIES FROM PERTIAL SACRAL AGENESIS TO
ABCENCE OF LUMBAR SPINE.
250 TIMES MORE COMMON IN POORLY CONTROLLED DIABETIC MOTHERS
ABSENT LIMBS
BODY WALL ANOMALIES
PHSIOLOGIC BOWEL HERNIATION AT 9 TO
11 WEEKS
EXOMPHALOS - a/w
CHROMOSOMAL DEFECTS .CORD
INSERTION AT APEX OF SAC VS
GASTROCHISIS PARA MIDLINE
HERNIA SAC
URINARY ANOMALIES
PYELECTASIS
MEGACYSTIS
CYSTIC DYSPLASTIC KIDNEY
RENAL AGENESIS
POLYCYSTIC KIDNEYS
RANGE
SECOND TRIMESTER FETAL ANOMALY
CARDIOVASCULAR ANOMALY
Fetal cardiac examinations optimally performed between 1822 weeks.
Some anomalies may be identified in late first and early
second trimester especially when increased nuchal
translucency is identified.
4 chamber view, 3 vessel view and outflow tracts can detect
80% -85% of cardiac anomalies
BASIC VIEW
four chamber view
EXTENDED BASIC
VIEWS
Right ventricular outflow Left ventricular outflow
tract(LVOT)
tract(RVOT)
VSD
•
•
•
One of the most common congenital cardiac anomaly
VSD is easily diagnosed on the four-chamber view alone.
However, color Doppler US may be needed to demonstrate
smaller defects and some may not be detected until after
birth.
Small VSD (MUSCULAR)show spontaneous closure
ENDOCARDIAL CUSHION DEFECT
When the endocardial cushions fail to fuse, a wide
range of atrioventricular septal defects occur.
(four-chamber view)
shows absence of the
interventricular and
interatrial
septa, thus producing
connections
between the ventricles and
between the atria.
PERSISTENT TRUNCUS ARTERIOSUS
The undivided truncus receives blood from both
ventricles.
A VSD is almost always present
a.(four-chamber view) shows a VSD (arrow). Dao
descending aorta. b.(base view)
shows a single trunk (arrow) overriding both
ventricles.
HYPOLPASTIC LEFT HEART SYNDROME
Small left ventricle, which is associated with aortic
atresia.
Atretic or hypoplastic mitral valve.
Hypoplastic left heart
syndrome in a fetus
(four-chamber view) shows
that the left ventricle is
small relative to the right
ventricle and the left atrium is
small relative to the right
atrium.
EBSTEIN ANOMALY
CAUDALLY PLACED TRICUSPID VALVE /OFFSET BETWEEN MITRAL AND TRICUSPID
VALVE /ENLARGED RT VENTRICLE /TRICUSPID REGURGITATION
DOUBLE OUTLET RIGHT VENTRICLE
PARALLEL OUTFLOW TRACTS , LARGE RT VENTRICLE ,SMALL LT VENTRICLE
RHYTHM AMNORMALITIES OF HEART
NORMAL HEART RATE 2ND IS 120BPM TO 160BPM
FETAL ARRYTHMIAS can now be defined precisely for mechanism-specific therapy
and for subsequent monitoring of response.
MSK ANOMALIES
FETAL SKELETAL STRUCTURES TO BE SEEN:
FETAL CRANIUM(BPD, HC)
ABDOMINAL CIRCUMFERENCE(AC)
MANDIBLE
CLAVICLE
SCAPULA
CHEST CIRCUMFERENCE
ALL FETAL LONG BONES( RHIZOMELIA, MESOMELIA, MICROMELIA)
FETAL FACIAL PROFILE(GLABELLAR BOSSING, FLATTENED NASAL
BRIDGE, MICROGNATHIA)
VERTEBRAL BODIES
HAND AND FEET( EXTRA/MISSING/MALFORMED DIGITS)
MINERALISATION PATTERN.
CHEST:ABDOMEN CIRCUMFERENCE( <0.6 ABNORMAL)
FL:AC RATIO(<0.16 ABNORMAL)
FL: FOOT LENGTH RATIO(<1 ABNORMAL)
CONTD..
FETAL LONG BONES:
PRESENCE/CURVATURE/MINERALISATION/FRACTURES
The femur length–abdominal circumference ratio (<0.16 suggests lung
hypoplasia)
femur length–foot length ratio(normal = 1, <1 suggests skeletal dysplasia)
THORAX: CHEST CIRCUMFERENCE/ CT RATIO MEASURED AT THE LEVEL OF
FOUR CHAMBER VIEW OF HEART.
HAND AND FEET: PRE AND POSTAXIAL
POLYDACTYLY/SYNDACTYLY/CLINODACTYLY/OTHER DEFORMITIES
SKULL:HC/BPD/SHAPE/MINERALISATION/OSSIFICATION.
FACIAL STRUCTURES:MICROGNATHIA/ SHORT UPPER LIP/ABNORMALLY
SHAPED EAR/FRONTAL BOSSING/CLOVERLEAF SKULL.
PELVIS: HYPOPLASTIC ACETABULAE/FLAT ILIAC BONES.
FETAL SKELETAL DYSPLASIA
LIMB DEFICIENCY: complete absence –amelia,
incomplete absence-meromelia.
lack of a normal hand and the abnormal soft
tissue at the distal end of the
forearm
THANATOPHORIC DYSPLASIA
Disproportionate dwarfism with very short extremities,which are
bowed in type 1 and may be straight in type 2.
Thorax is narrow.
Cloverleaf skull deformity is generally seen in type 2.
Polyhydramnios is present in almost 50% of cases.
Pulmonary hypoplasia.
hypoplastic thorax
telephone receiver–shaped
femur
OSTEOGENESIS IMPERFECTA
Rib fractures
Thin cortex in tubular bones, and, in more severe cases
thin shafts with fractures and bowing deformities.
The skull may be thinner than usual and the weight of the
US probe may deform the head quite easily. In severe
cases, the cranial vault has a wavy outline and is easily
compressed.
OSTEOGENESIS IMPERFECTA
bone fractures and
deformities.
irregular
shape of the ribs
a finding that also suggests
fractures.
decreased skull
ossification
CHONDRODYSPLASIA PUNCTATA
Craniofacial dysmorphism
Very short humeri and relatively short femora
Punctate calcification of epiphyses may be seen prenatally
multiple contractures
DIASTROPHIC DYSPLASIA
• diastrophic” implies twisting and describes the twisted
habitus in diastrophic dysplasia
short broad long bones
bilateral clubfeet with limb
bilateral clubfeet with shortening (arrowheads)
limb shortening
and bilateral hitchhiker’s
thumb (arrow)
?RACIAL VARIATION
UNIFORMLY SMALL LONG BONES
CASE OF SHORTENING OF LONG BONES MANIFESTED AFTER 20 WEEKS
FEMUR FOOT RATIO .9
THORACIC CIRCUMFERENCE /AC AND CARDIAC THORAX RATIOS
CONT
THORAX ABNORMALITIES
Diaphragmatic herniaAbdominal organs will be in the chest.
Fluid filled mass just behind the left atrium and ventricle.
Suspicious if stomach not visualized in abdomen.
.
shift in the mediastinum
Small abdominal .circumference
Polyhydramnios
Peristalsis of bowel in fetal chest.
CCAM/ CPAM
SOLID /CYSTIC/ MIXED MASS
CAM can displace mediastinal structures with compression of the heart and
IVC.
Generally unilateral involving a single lobe.
Associated with Hydrops,polyhydramnios,
and pulmonary hypoplasia.
Many times small with little mass effect
PULMONARY SEQUESTRIAN
Well circumscribed,uniformly echogenic mass in the fetal thorax.
May be associated with fetal hydrops and maternal
polyhydramnios. Color-Doppler to
detect the arterial supply
from the descending aorta
to the mass.d/d CCAM
TRACHEAL/ LARENGEAL ATRESIA
If trachea or larnx is partially or completely obstructed, fluid is
secreted by the lungs cannot be expelled. So distended lung,
appears hyperechogenic and bronchi become dilated. Associated
with fetal ascites.
Echogenic Bowel
ECHOGENIC BOWEL
To call it echogenic bowel the echogenicity should be equal to bone.
IN THIRD TRIMESTER ECHOGENIC IS NORMAL AS MECONIUM IS ECHOGENIC
50% CASES OF ISOLATED ECHOGENIC BOWEL RESOLVE OVER TIME
Truly echogenic bowel in a second-trimester fetus, differential diagnostic
considerations include Cystic fibrosis
Chromosomal abnormalities-look for morphological anomalies ,congenital infection
and intraamniotic bleeding,
a/w IUGR
MECONIUM PERITONITIS
ECHOGENIC GASTRIC DUPLICATION CYST
1/3RD CASES A/W OTHER ABNORMALITIES GI and SPINAL
FETAL MASSES
NEUROBLASTOMA
Associated malformations are unusual. Neuroblastoma is characteristically
a heterogeneous solid mass with cystic components that displaces the
adjacent kidney inferiorly and
laterally.
. Spontaneous regression
occurs in up to 40% of cases.
SUBDIAPHRAGMATIC EXTRALOBAR
PULMONARY SEQUESTRATION
MESOBLASTIC NEPHROMA
Arteriovenous shunting, Heart failure and Polyhydramnios are common.
Mesoblastic nephroma is benign, and postnatal nephrectomy is curative
CARDIAC MASSES
MC RHABDOMYOMA
A/W TUBEROUS SCLEROSIS
TERATOMAS
SACROCOCCYGEAL TERATOMAS – MC .HIGHLY VASCULAR RESULTANT
VASCULAR STEAL CAUSES HYDROPS/ POLYHYDAMNIOS AND PRE MATURE
DELIVERY
NECK TERATOMAS
FETAL GENITOURINARY ABN
ABNORMALITIES PRESENTING IN THIRD
TRIMESTER
OESOPHAGEAL ATRESIA
Prenatally, the diagnosis of esophageal atresia is suspected when, in the
presence of polyhydramnios (usually after 25 weeks), repeated
ultrasonographic examinations fail to demonstrate the fetal stomach.
SMALL BOWEL OBSTRUCTION
The lumens of the small bowel and colon do not normally exceed 7 mm and
20 mm, respectively. Diagnosis of obstruction is usually made quite late in
pregnancy (after 25 weeks), as dilatation of the intestinal lumen is slow and
progressive. Jejunal and ileal obstructions are imaged as multiple fluid-filled
loops of bowel in the abdomen.
OVARIAN CYSTS
Fetal ovarian cysts are hormone-sensitive (human chorionic gonadotropin
from the pLacenta) and tend to occur after 25 weeks of gestation
cysts are benign and resolve spontaneously in the neonatal period
FUTURE DIRECTIONS
SCREENING AT 6 TO 10 WEEKS
CRL
GSD
YSD
FHR
RECENT PAPER BY FMF HAS SHOWN A sonographically detectable
differences between euploid and trisomic embryos.
