MULTIPLE PREGNANCY

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MULTIPLE PREGNANCY Powered By Docstoc
					MULTIPLE PREGNANCY

       BY

PROF. O.B. FASUBAA
INTRODUCTION AND INCIDENCE
• Occurrence of 2 or more fetuses
  in the uterine gestational sac.
• Accompanied with increase
  obstetric complicetry.
• PNM and morbidity are increased
  several times over that of
  singleton pregnancies.
•  Increase incidence of fetal
  wastage and       abortion  e.g.
  occasional retention of a dead
  twin as a fetal papyraceus while
  gestation continues as a single
  pregnancy. USS evidence of twin
  disappearance syndrome attest to
  this.
• Usually regarded as a very high risk
  pregnancy whenever it occurs
• Considerable ethnic and geographic
  variations in the frequency of multiple
  pregnancy
• The highest rates occurs in Africa
  with up to 45 twin/1000 births Ijesha
  and Igboora in Oyo North have the
  highest incidence in the whole world
  with incidence varying between 1 in
  18 to 1 in 25 births
• The yam food in these areas seem to
  contain HCG like substance
• In far Eastern Europe – rate of 5
  /1000    birth   and   among    the
  caucasians 10-12/1000 births
• Variations in frequency are almost
  entirely due to different rates of
  dizogotic twins
Dz twins in Europe    = 70%
Dz twin in Africa     = 90%
• Incidence of Mz twin is constant
  throughout the world.
  TWINS       - Dz
              - Mz
MECHANISM OF TWINNING
Dz – represents duplication of the normal
 process of conception, implantation and
 further development of the embryo arising
 from fertilization of two ova from the same
 or opposite ovaries
• Each fetus will have its own
  membranes, (both chorion and
  amnion) and its own placenta
• Duplication of the membrane is
  described as dichrononic diamniotic.
• The fetuses may be like or unlike in
  sex
• Fetus will have differences in genetic
  constitution
Possibilities:*Super fecundation
              *Super fetation
Mz       Unlike DZ is a gross departure
  from the normal process
• Its several varieties are determined
  by the time (days after fertilization)
  when splitting occurs in the embryo,
  giving rise to different structural
  arrangements of the membranes.
A. If division occurs within the
  first 3days after fertilization at the 8
  cell stage while cells remain
  unspecialized; two separate normal
  blastocysts form and if both implant
  succesfully a twin pregnancy results
• There will be separate implantation
  sites which may or may not be close
  together
• Structural   arrangements      of      the
 membrane and placenta (dichorionic
 diamniotic) are exactly the same as
 Dz twins
• Unlike DZ, fetuses will be identical
• This early splitting accounts for 1/3 of
 Mz
B. If splitting is delayed until
  the inner cell mass is formed
  (4-7day); a single blastocyst will
  implant with a single chorion
  giving rise to one placenta in
  which there are anastomosis
  between he two fetal circulations
• Each embryo develop its own
  amniotic membrane and cavity
• Monochronic diamniotic
• Offspring are identical
• Accounts for 2/3 of Mz twin
C. If division occurs 8-12 day after
  formation of inner cell mass;
• Two identical fetuses will develop with
  single amniotic cavity sharing a single
  chorion and placenta with
  communication between the 2
  circulations (Monochorionic
  monoamniotic)
D. If division occurs from 13th day
  upwards after the primitive streak
  has appeared. The incomplete
  splitting of the germinal disk will result
  in cojoined twins.
Types of cojoined twins
• Cranio pagus
• Thoraco pagus
• Visceropagus
• Pyopagus etc
DETERMINATION OF ZYGOSITY AT
 BIRTH
• Twins of unlike sex are DZ
• Careful examination of the placenta
  and membranes will identify the
  majority (2/3) of Mz twin pairs that
  share a single chorionic membrane
• Dichorionic twins of like sex may be
  DZ or MZ due to early splitting and
  tests of genetic markers in the blood
  and placenta are required to
  determine if the twins have an
  identical genetic constitution
• Demonstration of only one genetic
  difference between co-twin suffices to
  establish dizygositing
• These can be achieved by red cell
  antigen testing (blood group) and
  genotyping, HLA, red cell enzymes,
  serum    proteins   and   placenta
  enzymes.
Factors influencing twinning rates
1. Ethnic and geographic variations
2. Maternal age: Dz  with ing
   maternal age
3. Increasing parity
4. Women conceiving early within 3
   months of marriage
5. Nutritional influences
6. Tall women
7. Previous twin delivery
8. Family Hx of twin (Maternal and
   paternal)
9. Ovulation       inducing drugs:
   Clomiphene, pergonal etc
10.Assisted conception (IVF-ET)
Maternal physiological changes
• Considerable maternal physiological
   changes take place in women with
   multiple pregnancy.
1.  pressure effects from excessive uterine
   enlargement gives rise to varicos veins,
   haemorrhoids, dependent oedema
2. Cardiovascular changes:
  •   co
  •   plasma vol 
  •    total circulating red cell mass
  •   haematocrit and Hb than in singleton
Complications of multiple pregnancy
Maternal and fetal
Maternal
1. Hyperemesis 
2. Anaemia
3. Polyhydramnios
4. APH
5. Hypertensive complications
Fetal
Fetal abnormalities
• Fetal malformations are confined to
  MZ and rates of concordance (both
  twins affected) may be up to 30% e.g
  in congenital dislocation of the hip
• Malformation of the heart and CNS
  e.g. cushions defects, hydrocephaly
  and neural tube defect, acardiac
  monstars, cojoined twins
Twin to twin transfusion syndrome
• Result from presence of anastomosis between
  the 2 placental circulation giving rise to
  discordant twins.
• Dono fetus is pale and the recipient twin is
  plethoric wit no inequality in development
     Abortion/fetal wastage
     UGR/Low birth weight
     Prematurity
Antenatal management
Diagnosis: Depends on high degree of
  clinical suspicion e.g. Hyperemesis early 
  BP in preg
• Family Hx, and Hx of risk factors
• Careful abdominal palpation
• Routine USS in early preg
Routine care
• ANC based on more frequent
  attendances to pick complications
  early
• Shared responsibility between
  obstetrician and GP
• Bed rest at home, good diet
  haematinics and prophylaxis against
  endemic disease e.g. Malaria
• Prenatal diagnosis of fetal
  abnormality
• Prevention of preterm labour
    • Hospitalization
    • Tocolysis
    • Cervical suture
Labour in multiple pregnancy
• Should be conducted in a well
  equipped hospital with experienced
  obstetrician and neonatologist with
  anaesthetist
• PCV, GrP x Xr match
• Intravenous infusion in early labour
• Continous fetal heart rate monitoring
  of both twins, the first by scalp
  electrode, the 2nd by external
  recording
• 1st stage shouldn’t be prolonged.
• Indication for oxytoxic stimulation
  are same for singletion and
  recourse for C/S is done for
  obstetric indication
• Epidural analgesia is ideal but
• Pudendal block and perineal
  infiltration are okay for delivery
Mode of delivery
Depends on presentation and GA
Vx Vx -     40%          -   SVD
VxB     -   2%           -   SVD
BVx     -   10%          -   C/S
Bx Bx -     10%          -   C/S
Bx Tx -      5%          -   C/S
TxTx    -   5%           -   C/S
Labour complications in multiple preg
Fetal                    Maternal
• Fetal distress         Obstructed labour
• Malpresentation/       PPH
  malposition
• Mechanical obstruction
• Conjoined twin
• Coalition
• Locking
• Interlocking

				
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posted:10/2/2012
language:English
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