raul m. quillamor, md fpogs, fpsmfm, fpsuog uerm college of medicine multifetal pregnancy
TRANSCRIPT
RAUL M. QUILLAMOR, MDFPOGS, FPSMFM, FPSUOG
UERM College of Medicine
MULTIFETAL PREGNANCY
Epidemiology
INFERTILITY THERAPY
1980s onwards - increase in number of deliveries:
Increasing incidence of twins and higher-order pregnancies
Increasing incidence of multiple births: A public health concern
Higher rate of preterm delivery
Compromised chances of neonatal survival
Increased risk of lifelong disability
Increased vulnerability to malformations and twin-to-twin transfusion syndrome
Increased incidence of maternal complications:
PreeclampsiaPostpartum
hemorrhageMaternal deaths
Superfetation vs Superfecundation
Superfetation SuperfecundationA long interval
intervenes between fertilizations
Requires ovulation & fertilization during the course of an established pregnancy
Unproven to occur in humans
Fertilization of 2 ova within the same menstrual cycle but not at the same coitus, nor necessarily by sperm from the same male
Etiology
FraternalFertilization of
two (or more) separate ova
- Double-ovum
- dizygotic
Dizygotic Twinning
Variable incidenceSame or different
fetal sexDichorionic,
diamnionicTwo separate or
one fused placenta
2 sperm cells, 2 eggs
Dizygotic Twinning
2 sperm cells, 2 eggs
Etiology
IdenticalSingle fertilized ovumSubsequently divides
into two (or more) similar structures with a potential to develop into separate individuals
- Single-ovum
- monozygotic
Monozygotic Twinning
1 sperm cell, 1 egg
Placenta & Membranes
Placenta & Membranes
Monozygotic Twinning: Conjoined twins
Anterior
- thoracopagus
Posterior
- pygopagus
Cephalic
- craniopagus
Caudal
- ischiopagus
Monozygotic Twinning: Siamese twins
CHANG and ENG BUNKER: 1811 - 1874Conjoined twins:1:50,000 t0 1:200,000
birthsHigher incidence in
Southwest Asia & Africa
Approx 25% survival rate
3:1, females
Monozygotic Twinning: Conjoined twins
1. Fission –
fertilized egg splits partially
2. Fusion-
fertilized egg splits completely but stem cells find like-stem cells on the other twin & fuse the twins together
Conflicting theories:
Monozygotic Twinning
Dicephalic parapagus tetrabrachius
Monozygotic Twinning
Diprosoic parapagus
Twins with one trunk, one head with two faces
Monozygotic Twinning
Dicephalic parapagusTwins with one
trunk & two heads
May be:Dibrachius
(2 arms)Tribrachiustetrabrachius
Monozygotic Twinning
Dicephalic parapagus
Monozygotic Twinning: Conjoined twins
XiphopagusTwo bodies fused
in xiphoid cartilage (from navel to lower ribs).
Twins almost never share any vital organs, except the liver
Monozygotic Twinning: Siamese twins
Thoraco-omphalopagus
Approx 28% of cases Two bodies fused from the
upper chest to the lower chest
Twins usually share a heart, liver, & part of the GIT
Monozygotic Twinning
IschiopagusTwo bodies fused at
the lower halfSpines conjoined end-
to-end at a 180-degree angle
4 arms; 2,3, or 4 legsTypically one external
set of genitalia and anus
Monozygotic Twinning
Parasitic twinAsymetrically
conjoined twins
One twin is small, less formed, dependent on the other twin for survival
Monozygotic Twinning
Parasitic twin
Monozygotic Twinning
Omphalopagus
Two bodies fused at the lower chest
Heart is never involved
Twins share a liver, digestive system, diaphragm & other organs
Monozygotic Twinning
CraniopagusFused skulls, separate
bodiesMay be conjoined at
the back, front, or side of the head, but not on the face & base of the skull
Monozygotic Twinning
Parapagus Dithoracic parapagus
Fused side-by-side with a shared pelvis
Fused at the abdomen & pelvis but not the thorax
Monozygotic Twinning
Craniopagus
parasiticusPyopagus
Like craniopagus, but with a 2nd bodiless head attached to the dominant head
Iliopagus
Two bodies joined back-to-back at the buttocks
Monozygotic Twinning
Cephalo
thoracopagusSynecephalus
Fused head & thorax
Two faces facing in opposite directions
Sometimes a single face and an enlarged skull
One head with a single face but four ears & two bodies
Determinants of Twinning
HeredityMaternal age &
parityNutritional factors
Pituitary gonadotropins: FSH
Infertility therapyAssisted
reproductive technology
Diagnosis
HistoryPhysical
examinationSerial fundal
height evaluation
Differential diagnoses:Distended bladderInaccurate menstrual
historyPolyhydramniosHydatidiform moleUterine tumorsAdnexal tumorsLarge baby/
macrosomia
Diagnosis
Diagnosis
Diagnosis
Diagnosis
Vanishing Twin One fetus dies or
vanishes before the 2nd trimester; the remaining fetus delivers as a singleton
DiagnosisVanishing TwinMay cause elevations
in:
- maternal serum & amniotic fluid AFP levels
- amniotic fluid acetylcholinesterase assay
GENDER
Male-Female Male-MaleFemale-FemaleUndetermined
DIZYGOTIC
Dichorionic-Diamniotic
2 Placentas 1 Placenta
Determination of Zygosity
SINGLE PLACENTA
(+) Chorionic peak(-) Chorionic peak
DichorionicDiamniotic
Evaluate inter-twin membrane
(-) (+)
Mono-monoMono-di
Stuck twin
Thick Thin
Di-di Mono-di
Determination of Zygosity
Pregnancy Outcome
Congenital malformations from:
- Twinning itself
- Vascular interchange between
monochorionic twins
- Fetal crowding
AbortionPreterm labor &
deliveryLow birth weight
Pregnancy Outcome
Normal donor twin with heart failure
Recipient twin with NO heart (acardius) & other various structures
With artery-to-artery & vein-to-vein shunt
ACARDIAC TWIN:
twin reversed-arterial-perfusion sequence
(TRAP)
Acardiac twin
Pregnancy Outcome
Perfusion pressure of donor twin greater than recipient twin
Arterial blood from donor twin preferentially goes to the iliac vessels of recipient, perfusing only the lower part of the body
ACARDIAC TWIN:
Mx: Ligation of umbilical cord of acardiac twin by transabdominal fetoscopy
Pregnancy Outcome
Twin-to-Twin Transfusion Syndrome
DONOR TWIN RECIPIENT TWIN
AnemicGrowth-restricted
PhletoricHydrops (circulatory overload)
One portion of placenta paleSolitary, deep A-V channels w/in capillary beds of villous tissue
TTTS
Pregnancy Outcome
Inequality in size of twin fetuses
Pathological growth restriction in one twin
Cause unclear: but may be due to vascular anastomoses resulting in hemodynamic imbalance between the twins
DISCORDANT TWINS:
Mx:
Utz monitoring of growth parameters in both twins
Principles of Management
3. Avoidance of fetal trauma during labor and delivery
4. Availability of expert neonatal care
1. Prevention of preterm delivery
2. Identification and prompt delivery of growth restricted fetuses
Management
DIET ANTEPARTUM SURVEILLANCE
Additional 300 kcal/day on top of 300 kcal/day required for uncomplicated pregnancy
Weight gain of at least 50 lbs
60 – 100 mg/day of iron 1 mg/day of folic acid
Non-stress test Biophysical profile Monitoring of fetal growth
parameters Doppler velocimetry
Management
PREVENTION of PRETERM DELIVERY
Bed rest, limited physical activity, early work leave?
Tocolytic therapy?Corticosteroids for pulmonary maturation?Prophylactic cervical cerclage ?
Management
LABOR
Presence of skilled obstetrician & pediatrician, appropriately trained attendant, & experienced anesthesiologist
Availability of ultrasound machine & blood transfusion products
Establishment of intravenous infusion system
Management
DELIVERY : Vaginal or Abdominal?
Problems encountered when presenting twin is breech:
- Aftercoming head is large for the passageway (big baby)
- Delivery of extremities & trunk through an inadequately dilated cervix (small baby, small head)
- Risk of umbilical cord prolapse
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