Multiple pregnancy Flashcards
Definition of multiple pregnancy
Occurs when more than one fetus develops simultaneously in the uterus
Risk factors of multiple pregnancy
- Family history of multiple pregnancy, genetics
- Advanced maternal age
- Assisted reproductive technique – ovulation induction, IVF
- Multiparity
- Ethnicity i.e., African American
Types of twins
- Dizygotic twins (80%)
- Non-identical/ fraternal
- Fertilization of 2 separate eggs by different
sperm
- Can be same sex or different sex pairings
- Dichorionic - Monozygotic twins (20%)
- Identical
- Arise from fertilization of a single egg by 1
sperm then split into 2
- Often same sex
- Monochorionic/ dichorionic
Etiology of twin formation
Type of twins depend on how long after
conception the split of ovum occurs
The earlier the splitting of the zygote, the more
independent these twins will develop
- Within 3 days: DCDA (most common)
- Between D4 and D8: MCDA
- Between D8 and D12: MCMA
- If splitting delayed beyond D12: Conjoined twins
Symptoms of multiple pregnancy
Normal symptoms of pregnancy are often exaggerated
* Severe morning sickness/ hyperemesis gravidarum
* More weight gain, bloated
* Breast tenderness
* Palpitations, breathless
* Varicose veins, leg swelling, piles
* Incidental!
Ultrasound features for multiple pregnancy
Date, label twins, determine chorionicity & amnionicity
DCDA – lambda sign “twin peak”
- Best seen at 10-14w, becomes less prominent after 20w
MCDA – T sign
- Thin inter twin membrane comprising of 2 amnions
Changes to mom with multiple pregnancy
In a normal pregnancy, there are physiological changes in the
mother.
These hemodynamic changes are exaggerated in multiple gestations due to greater stressors on maternal reserves/ physiology
- Worsened in women with pre existing health issues e.g. women with cardiac disease, autoimmune issues, renal disease
- Gestational diabetes
- Hypertensive disorders (pregnancy induced hypertension, pre-
eclampsia) - Anaemia, venous thromboembolic disease
- Others:
- Intra-hepatic cholestasis of pregnancy, placental
abruption
Fetal complications in multiple pregnancy
a. Miscarriage, vanishing twin, in utero demise
b. Preterm delivery -> NICU admissions, risks of prematurity
- 50% of twins deliver before 37w GA
- 20% deliver before 34w
- 10% deliver before 32w
c. Increased perinatal mortality
d. Congenital anomalies – MCDA > 3x fetal anomalies compared to DCDA
e. Chromosomal defects
f. Intrauterine growth restriction
g. Cerebral palsy
Monochorionic twins
Develop from a single fertilized egg, share same placenta
- Occur in 1:300 pregnancies
- Higher risk pregnancy compared to DC twins
- Connected by their blood circulation systems and these can lead to
complications
Complications in MC twins
- Twin to twin transfusion syndrome (TTTS)
- Twin anemia polycythemia sequence (TAPS)
- Selective intrauterine groth restriction
- Twin reversed arterial perfusion sequence (TRAP)
Twin to twin transfusion syndrome
Disease of the placenta
- Communicating vessels within placenta leads to UNEQUAL sharing of blood
between twin fetuses
- Donor: Oliguria, oligohydramnios, fetal
growth restricted, doppler changes
- Recipient: Polyhydramnios, hydrops with cardiac failure, PPROM, preterm labour
- Majority between 16-26w GA
- Can be fatal for 1 or both twins
Staging criteria used for twin to twin transfusion syndrome
Quintero staging
Management of twin to twin transfusion syndrome
- Expectant management
- Risks: Preterm delivery, in-utero death of 1 twin (up to 80%) - Amnioreduction
- Removal of amniotic fluid from recipient twin to reduce risk of PPROM, preterm labour
- Does not treat the underlying cause and allows disease process to continue, may need to be repeated - Selective termination
- Can be via radiofrequency ablation or bipolar cord occlusion
- Sacrifice twin with poor chance of survival in order to improve the chance of
other
- Spontaneous death of ill fetus causes risks to remaining twin – 15% of IUD, 35% risk of neurological impairment of the latter - Selective fetoscopic laser photocoagulation (SFLP)
- Terminate whole pregnancy
Selective fetoscopic laser photocoagulation (TTTS)
- Minimally invasive procedure, done under GA
- Aim to dichorionize the placenta and ablate
the connecting vessels - Laser inserted through fetoscope
- Superficial vessels on surface of placenta that
cross the inter twin membrane ablated - 16 to 26w GA
- Curative for Stage 2 and 3 TTTS
- Increases survival to 75% for both twins
Risks:
PPROM
Iatrogenic rupture (MCMA)
Abruption
TAPS (15%)
Persistent TTTS
- Weekly MCA PSV after SFLP done
Twin anemia polycythemia sequence
Rare condition that occurs with unequal blood counts between the twins (discordant inter-twin Hb difference)
- Can be spontaneous (2%) vs post SFLP for tx of TTTS (15%)
- Donor MCA PSV >1.5 MOM (fetus anaemic), recipient MCA PSV <1.5 MOM (fetus polycythemic)
Treatment
- Expectant
- Selective fetocide
- Intra uterine transfusion
- SFLP
