OB Final Exam - Multiples

Multiples are at greater risk of...

Premature delivery

Low birth weight/FGR

Congenital anomalies

Fetal death

Placental abruption or placental previa

Vasa previa

Cord knotting

Maternal HTN with preeclampsia

3rd trimester maternal bleeding and/or postpartum hemorrhage

Dizygotic Twins

Always dichorionic diamniotic

Fraternal - can be same or different sexes

2 placentas

2 amniotic sacs

Thick membrane

Lambda sign - means 2 placentas

Monoamniotic Twins

Must be monozygotic & monochorionic

Associated with cord knots & conjoined twins

Monochorionic Twins

Must be monozygotic, but can be mono or diamniotic

Thin membrane

Associated with TTTS, TRAP, FGR

Monochorionic Diamniotic Twins

1 placenta

2 amniotic sacs

Monochorionic Monoamniotic Twins

1 placenta

1 amniotic sac

High risk for conjoined twins

Twins Assessment Protocol

Number of sacs & fetal poles

Number & location of placentas

Membrane - thickness and movement

Gender of each baby

Biometry comparison

Umbilical cord Doppler

Fluid assessment

Normal screening anatomy

Presence of anomalies

Assign a letter to each baby (A & B)

Stage 1 TTTS

Amniotic fluid discrepancy

Stage 2 TTTS

Amniotic fluid discrepancy

Absent bladder in donor twin

Stage 3 TTTS

Amniotic fluid discrepancy

Absent bladder in donor twin

ABNL umbilical artery S/D ratio in donor twin

Ductus venosus flow reversal in recipient twin

Stage 4 TTTS

Amniotic fluid discrepancy

Absent bladder in donor twin

ABNL umbilical artery S/D ratio in donor twin

Ductus venosus flow reversal in recipient twin

Hydrops in recipient twin

Stage 5 TTTS

Death of at least 1 twin

TRAP Sequence

Occurs in monochorionic twins

Artery-to-artery connection

TRAP Twin

No heart

Absent upper body

Reversal of flow in umbilical artery

Stuck Twin Syndrome

Seen in monochorionic diamniotic twins with TTTS

Severe polyhydramnios of 1 twin, and oligohydranmios of the other

Little/no movement of babies

Cord Entanglement

Occurs only in monochorionic monoamniotic twins

50% compromise blood flow - end in fetal demise

Growth Discordance

>20% overall difference between the twins

AC difference of 20mm

BPD difference of 6mm

Femur length difference of 5mm

Conjoined Twins

Incomplete division of embryo - division after 13 days

Occurs in monochorionic monoamniotic twins

TERM

Thoracopagus Twins

DEFINITION

Conjoined at thorax

TERM

Omphalopagus Twins

DEFINITION

Conjoined at anterior wall

TERM

Craniopagus Twins

DEFINITION

Conjoined at cranium

TERM

Pygopagus Twins

DEFINITION

Conjoined at buttocks

TERM

Ischiopagus Twins

DEFINITION

Conjoined at ischial region

TERM

Cephalopagus Twins

DEFINITION

Conjoined at back of head

Fused in the upper portion of the body

TERM

Rachipagus Twins

DEFINITION

Conjoined at the vertebral column

TERM

Parapagus Twins

DEFINITION

Conjoined at the abdomen and pelvis