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.