Multiple Pregnancy Flashcards
What is the incidence of twins and triplets?
Twins = 1 in 80
Triplets = 1 in 1000
Incidence increasing due to fertility treatments
List the types of multiple pregnancy
- Dizygotic twins
2. Monozygotic twins
What are the key points about dizygotic twins?
- 2/3 of all multiple pregnancies
- Fertilisation of different oocytes by different sperm
- May be of different sex
- No more genetically similar than siblings from different pregnancies
What are the key points about monozygotic twins?
- Mitotic division of single zygote into ‘identical twins’
- Sharing of amnion or placenta depends on time of division:
- Division before day 3 = dichorionic diamniotic
- Between days 4-8 = monochorionic diamniotic
- Later division (9-13) = monochorionic monoamniotic
- Incomplete division = conjoined twins
What is the aetiology behind multiple pregnancy?
- Assisted conception
- Genetic factors
- Increasing maternal age and parity
How can we diagnose multiple pregnancy?
- Vomiting may be more marked in early pregnancy
- Uterus larger than expected for dates and palpable before 12wks
- Most diagnosed at US
List the maternal complications of multiple pregnancy
- All obstetric risk exaggerated
- GDM + pre-eclampsia more frequent
- Anaemia
List the fetal antenatal complications of all multiple pregnancies
- Greater mortality and long term handicap:
- IUGR
- Preterm delivery
- Monochorionicity - Miscarriage:
- One twin early on
- Increased late miscarriage - Preterm labour
- IUGR
- Congenital abnormalities:
- More common per baby in MC twins
List the complications of monochorionicity
- Twin-twin transfusion syndrome (TTTS)
- Twin anaemia polycythemia sequence (TAPS)
- Twin reversed arterial perfusion (TRAP)
- IUGR more common
- Co-twin death
- Monoamniotic twins - cord entanglement and in utero demise due o shunting of blood between two babies
What is twin-twin transfusion syndrome (TTTS)?
- Only in MCDA twins
- Unequal blood distribution through vascular anastomoses of the shared placenta
- Staged according to Quintero in stages 1-5
- High risk of in utero death or severely preterm delivery
What happens to the ‘donor twin’ in TTTS?
- Volume depleted
- Develops anaemia
- IUGR
- Oligohydramnios
What happens to the ‘recipient twin’ in TTTS?
- Volume overloaded
- May develop polycythemia
- Cardiac failure
- Massive polyhydramnios
Describe the Quintero Classification
Stage I:
- Significant discrepancy in amniotic fluid volume
- Bladder of donor twin visible
- Doppler studies normal
Stage II:
- Bladder of donor twin is not visible
- Doppler studies not critically abnormal
Stage III:
- Doppler studies are critically abnormal in either the donor or recipient twin
- Abnormal or reversed end-diastolic velocities of the umbilical artery in the donor
- Abnormal venous Doppler velocities in the recipient
Stage IV:
- Ascites, pericardial or pleural effusion
- Scalp oedema or overt hydrops present unusally in recipient
Stage V:
- One or both babies are dead
How is TTTS managed?
- Fetoscopic laser coagulation is the treatment of choice if diagnosed before 24wks
- Solomon technique (complete ablation along vascular equator rather than selective ablation) is preferred technique
- If complicated by this after 26wks DELIVER
- Survival of both twins = 50%; one twin = 80%
What is twin anaemia polycythemia sequence (TAPS)?
- Marked haemoglobin differences between MC twins in absence of liquor volume changes characteristic of TTTS
- Consequence of small placental anastomoses
- Can follow incomplete laser ablation for TTTS