RAUL M. QUILLAMOR, MD FPOGS, FPSMFM, FPSUOG UERM College of Medicine MULTIFETAL PREGNANCY

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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