TWIN PREGNANCY

K.VINEELA,2K8

DEFINITION: SIMULTANEOUS DEVELOPMENT OF TWO FETUSES IN THE UTERUS

TYPES: MONOZYGOTIC DIZYGOTIC

INCIDENCE:HELLIN’S RULE:MATHEMATICAL FREQUENCY OF MULTIPLE BIRTH IS TWINS

1 IN 80 PREGNENCIES,TRIPLETS 1 IN 80,QUADRUPLETS 1 IN 80

GENESIS OF TWINS• DIZYGOTIC TWINS: FERTILIZATION OF TWO OVA MOST LIKELY

RUPTURED FROM TWO DISTINCT GRAAFIAN FOLLICLES BY TWO SPERMS IN A SINGLE OVTARIAN CYLCE.

• MONOZYGOTIC TWINS: TWINNING MAY OCCUR AT DIFFERENT PERIODS

AFTER FERTILIZATION

DIAMNIOTIC DICHORIONIC DIAMNIOTIC MONOCHORIONIC MONOAMNIOTIC MONOCHORIONIC

DETERMINATION OF ZYGOSITYPLACENTA COMMUNIC

ATING VESSELS

INTERVENING MEMBRANES

SEX GENETIC FEATURES (DOMINANT BLOOD GROUP)DNA FINGERPRINTING

SKIN GRAFTING(RECIPROCAL)

FOLLOW UP

MONOZYGOTIC

ONE PRESENT TWO(AMNIONS)

ALWAYS IDENTICAL

SAME ACCEPTANCE

USUALLY IDENTICAL

DIZYGOTIC

TWO(MOST OFTEN FUSED)

ABSENT FOUR(TWO AMNIONS TWO CHORIONS)

MAY DIFFER DIFFER REJECTION NOT IDENTICAL

ETIOLOGY:

MONOZYGOTIC: MATERNAL ENVIRONMENTAL FACTORS

DIZYGOTIC: RACE HERIDITY ADVANCING AGE OF MOTHER INFLUENCE OF PARITY IATROGENIC

SUPER FECUNDATIONSUPERFETAIONFETUS PAPYRACEOUS OR

COMPRESSUSFETUS ACARDIACUSHYDATIDIFORM MOLEVANISHING TWIN

MATERNAL PHYSIOLOGICAL CHANGES IN TWIN PREGNANCY:

o THERE IS INCREASE IN WEIGHT GAIN AND CARDIAC OUTPUT

o PLASMA VOLUME IS INCREASED BY 500ML,BUT THERE IS NO CORRESPONDING INCREASE IN RED CELL VOLUME RESULTING IN EXAGGERATED HEMODILUTION AND ANEMIA

o THERE IS INCREASE IN AFP LEVELS,TIDAL VOLUME AND GFR

LIE AND PRESENTATION:COMMENEST IS LONGITUDINAL

COMBINATION OF PRESENTATION OF FETUSES ARE:

BOTH VERTEX---60%FIRST VERTEX AND SECOND BREECH—20%FIRST BREECH AND SECOND VERTEX---10%BOTH BREECH---10%FIRST VERTEX AND SECOND TRANSVERSEBOTH BEING TRANSVERSE--POSSIBILITY OF CONJOINT TWINS SHUD BE RULED OUT

DIAGNOSISHISTORY:o HISTORY OF OVULATION INDUCING DRUGS LIKE

GONADOTROPHINS,FOR INFERTILITY OR USE OF ARTo FAMILY HISTORY OF TWINNING,MORE OFTEN IN THE

MATERNAL SIDE

SYMPTOMS: INCREASED NAUSEA AND VOMITING IN THE EARLY

MONTHS CARDIORESPIRATORY EMBARASSMENT IN THE LATER

MONTHS LIKE PALPITATIONS,BREATHLESSNESS TENDENCY OF SWELLING OF THE LEGS,VARICOSE

VEINS AND HEMORRHOIDS IS GREATER UNUSUAL RATE OF ABDOMINAL ENLARGEMENT AND

EXCESSIVE FETAL MOVEMENTS

GENERAL EXAMINATION: PREVELENCE OF ANAEMIA IS MORE

UNUSUAL WEIGHT GAIN NOT EXPLAINED BY PREECLAMSIA OR OBESITY

EVIDENCE OF PREECLAMSIA IS COMMON

ABDOMINAL EXAMINATION:INSPECTION: BARREL SHAPED AND UNDULY ENLARGED ABDOMEN

PALPATION: HEIGHT OF UTERUS IS MORE THAN THE PERIOD OF

AMENORRHOEA GIRTH OF THE ABDOMEN AT THE LEVEL OF UMBILICUS

IS MORE THAN NORMAL FETAL BULK SEEMS DISPROPORTIONATELY LARGER IN

RELATION TO THE SIZE OF THE FETAL HEAD FINDING OF TWO FETAL HEADS OR THREE FETAL

POLES

AUSCULTATION: SIMULTANEOUS HEARING OF TWO DISTINCT FETAL

HEART SOUNDS LOCATED AT SEPARATE SPOTS WITH A SILENT AREA IN BETWEEN BY TWO OBSERVERS WITH A DIFFERNCE IN HEART RATE ATLEAST 10BPM

INTERNAL EXAMINATION: IN SOME CASES ONE HEAD IS FELT DEEP IN THE

PELVIS,WHILE THE OTHER IS LOCATED BY ABDOMINAL EXAMINATION

INVESTIGATIONSSONOGRAPHY:

CONFIRMATION OF DIAGNOSIS AS EARLY AS 10TH WEEK OF PREGNANCY

VIABIALITY OF FETUSES,VANISHING TWIN IN THE 2ND TRIMISTER,

CHORIONICITY (LAMBDA OR TWIN PEAK SIGN) PREGNANCY DATING FETAL ANOMALIES FETAL GROWTH MONITORING FOR IUGR PRESENTATION AND LIE OF THE FETUSES TWIN TRANFUSION (DOPPLER STUDIES) PLACENTAL LOCALISATION AMNIOTIC FLUID VOLUME

CHORIONICITY OF PLACENTA:

IT IS BEST DIAGNOSED BY USG AT 6 TO 9 WKS OF GESTATION.

IN DICHORIONIC TWINS THERE IS A THICK SEPTUM BETWEEN THE CHORIONIC SACS,WHICH IS BEST IDENTIFIED AT THE BASE OF THE MEMBRANE,WHERE A TRIANGULAR PROJECTION IS SEEN.THIS IS KNOWN AS “LAMBDA OR TWIN PEAK SIGN”. IT INDICATES DICHORIONIC PLACENTA.

Dichorionic Diamniotic twins at 13 weeks gestation. Axial transabdominal US image of the uterus shows the twin peak sign (arrow). P = single placental mass due to contiguous

or fused placentas.

RADIOGRAPHYBIOCHEMICAL TESTS

DIFFERNTIAL DIAGNOSIS:

HYDRAMNIOS BIG BABY FIBROID OR OVARIAN TUMOUR WITH PREGNANCY ASCITES WITH PREGNANCY