ULTRASOUND EVALUATION OF CHROMOSOMAL ABNORMALITIES HOLDORF

~DOWN SYNDROME IS THE MOST COMMON CHROMOSOMAL ABNORMALITY AMONG LIVE BORNS. OCCURING AMONG THE YOUNGER AGE GROUPS AND ALSO CHANGING ACCORDING TO GESTATIONAL AGE DUE TO FETAL LOSSES OF CHROMOSOMALLY ABNORMAL CONCEPTIONS. ~FEATURES: FLAT FACIAL PROFILE, SHORT STATURE, EPICANTHAL FOLDS, MUSCLE HYPOTONIA, SIMIAN CREASE OF THE PALM, EXCESS SKIN AT THE BACK OF THE NECK, HYPOPLASTIC MIDDLE PHALANX OF THE 5TH DIGIT, DUODENAL ATRESIA, HEART DEFECTS AND ABNORMAL ILIAC B ONE ANGLES.

Nuchal Translucency ABNORMAL MEASUREMENT OF THE NT CAN EVOLVE INTO LARGE CYSTIC HYGROMAS WITH OR W/PUT HYDROPS. ITS NORMAL MEASUREMENT IS 3MM BUT CAN INCREASE WITH GESTATIONAL AGE, (FIRST TRIMESTER) TURNER SYNDROME HAS ALSO BEEN LINKED TO SEVERE LYMPHANGIECTASIA AND ANBORMAL MEASUREMENT OF NT. ANOTHER ABNORMALITIES ASSOCIATED WITH NT IS CYSTIC HYGROMA. THESE CYSTS ARE ALSO INDICATIONS OF DEVELOPMENTAL FETAL HYDROPS AND DIFFUSE EDEMA. CHROMOSOMALLY NORMAL FETUSES WITH THICKENED NT HAVE AN INCREASED RISK OF CARDIAC ANOMALIES, DIAGPHRAGMATIC HERNIA, ANTERIOR WALL DEFECTS.

2nd TRIMESTER IN THE 2ND TRIMESTER FETAL ANATOMY IS EVALUATED WITH MORE DETAIL, EVALUATING MORE INTO DEPTH THE FEMUR AND HUMERUS. FETUSES WITH TRISOMY 21 HAVE SHORT FEMURS AND HUMERI OTHER ANOMALIES ASSOCIATED WITH DOWN SYNDROME: PYELECTASIS IS ALSO ASSOCIATED WITH DOWN SYNDROME, WHERE THE RENAL PELVIS MEASURES GREATER THAN OR EQUAL TO 4MM, HYPER ECHOIC BOWEL , USED FOR DETECTION OF ANEUPLOIDY, THIS CAN ALSO LEAD TO INFECTION, PRENATAL VAGINAL BLEEDING, POOR PRENATAL OUTCOME, PREMATURITY, INTRAUTERINE GROWTH RESTRICTION, AND FETAL DEMISE. ECHOGENIC INTRACARDIAC FOCUS: ASSOCIATED WITH TRISOMY 13 AND 21. 90% OF ECHOGENIC INTRACARDIAC FOCI ARE LOCATED IN THE LEFT VENTRICLE, WHEN BOTH VENTRICLES ARE INVOLVED THERE IS MORE INCIDENCE OF CHROMOSOMAL ABNORMALITIES

MINOR MARKERS ANOMALIES OF THE PELVIC BONES SUCH AS ILIAC WINGS, (WIDER AND MORE LATERAL SPAN OF THE ILIAC BONES), (ANYTHING GREATER THAN 90% IS SAID TO BE ABNORMAL) PROFILE: HAVING A SMALLER NOSE AND LARGE LIPS IS CONSIDERED TO BE A MINOR MARKER AS WELL. SMALL EARS , SIMIAN CREASE OF THE PALM, CLINODACTYLY AND SANDAL GAP OF THE GREAT TOE.

TRISOMY 13 OCCURING IN 1/5000 BIRTHS MOST SEVERE OF THE THREE AUTOSOMAL TRISOMIES. THIS ANOMALY INCLUDES ABNORMALITIES OF THE FACE, BRAIN, EXTREMETIES AND HEART. ALOBAR HOLOPROSENCEPHALY IS ALSO ASSOCIATED WITH THIS TRISOMY. (INCLUDING= CYCLOPIA, MIDLINE CLEFTS, HYPOTELORISM, ABSENCE OF THE NOSE AND MICROPHTHALMIA). NEONATES WITH TRISOMY 13 USUALLY DIE WITHIN THE FIRST FEW HOURS OF DAYS OR LIFE. RARE SURVIVORS HAVE SEVERE MENTAL RETARDATION AND SEIZURES.

TRISOMY 13

TRIPLOIDY OCCURS IN 3 SETS OF CHROMOSOMES RATHER THAN TWO YIELDING IN 69 CHROMOSOMES, RESULTING FROM AN EXTRA PATERNAL SET OF CHROMOSOMES. MOST ENDING IN SPONTANEOUS ABORTION, ANOMALIES INCLUDE: INTRAUTERINE GROWTH RESTRICTION, FACIAL ANOMALIES SUCH AS HYPERTELORISM, MICROGNATHIA, AND MICROPHTHALMIA, AND BRAIN ANOMALIES SUCH AS VENTRICULOMEGALY, DANDY WALKER, AGENESIS OF THE CORPUS CALLOSUM, HOLOPROSENCEPHALY, AND MENINGEOLCELE. FETUSES WITH TRIPLOIDY ALSO HAVE THICKENED LUCENCY, CYSTIC HYGROMAS, HEART DEFECTS, RENAL ANOMALIES, CLUBBED FEET, SINGLE UMBILICAL ARTERIES, AND OLIGOHYDRAMNIOS. TRIPLOIDY RESULTS IN MOST SEVERE GROWTH RESTRICTION.

TURNER SYNDROME CHROMOSOMAL ANOMALY DUE TO THE LOSS OF ONE SEX CHROMOSOME, RESULTING IN A 45X KARYOTYPE. CONCEPTIONS WITH THIS SYNDROME ARE SPONTANEOUSLY ABORTED, SOME FETUSES GO INTO THE 2ND TRIMESTER WITH SEVERE LYMPHATIC ANOMALIES. THEY HAVE LARGE CYSTIC HYGROMAS THAT ARE SEPTATED BUT CLEAR. SONOGRAPHICALLY, THE ENTIRE FETAL BODY IS SEEN SWOLLEN, RESEMBLING A SPACE SUIT. THERE IS ALSO EVIDENCE OF HYDROPS, PLEURAL EFFUSION, ASCITES AND EDEMA IN ALL BODY PARTS. TS IS ALSO ASSOCIATED WITH HEART DEFECTS , LEFT SIDE ANOMALIES SUCH AS COARCTATION OF THE AORTA AND AORTIC VALVE ANOMALIES.

TRISOMY 18 (EDWARD SYNDROME) HAS AN INCIDENCE OF 3/10,000 LIVE BIRTHS AND IS ASSOCIATED WITH MULTIPLE SEVERE STRUCTURAL ABNORMALITIES THAT MOSTLY INVOLVE THE HEART , EXTREMETIES, FACE AND BRAIN. AFFECTED FETUSES ARE OFTEN MISCARRIED OR DIE IN UTERO. 90 % OF LIVE BORNS DIE DURING THE 1ST YEAR OF LIFE SURVIVORS ARE USUALLY MENTALLY RETARTED THIS IS DETECETED WHEN ALPHA FETO-PROTEIN , UNCONJUGATED ESTRIOL, AND HUMAN CHORIONIC GONAGOTROPIN ARE ALL LOW. LIMB ABNORMALITIES ALSO INCLUDE PREAXIAL UPPER LIMB REDUCTION AND CLENCHED HANDS W/ OVERLAPPING INDEX FINGER, FETUSES MAY ALSO PRESENT WITH STRAWBERRY SHAPED SKULLS, ROCKER BOTTOM FEET, CLUBBED FEET, AND HYDRONEPHROSIS.

CHOROID PLEXUS CYSTS PRESENT IN 1/3 OF FETUSES W/ TRISOMY 18 AND ONLY 1-2% OF NORMAL FETUSES. IT IS CONCLUDED THAT THE PRESENCE OF THESE CYTS DO NOT INCREASE THE RISK OF DOWN SYNDROME, THEY USUALLY GO AWAY ON THEIR OWN. THEY ARE MONITORED WITH FUTHER FOLLOW UP EXAMS