Obstetrics - Multiple pregnancies Flashcards
Multiple pregnancy
Definitiuon
Depidemiology
Risk factors for dizygotic and monozygotic twin
Types of multiple pregnancies
Classification:
number of fetuses: twins, triplets, quadruplets…
number of fertilized eggs: zygosity
number of placentae: chorionicity (絨毛膜)
number of amniotic cavities: amnionicity (羊膜)
Cause of monzygotic multiple pregnancies
Assessment of chorioamnionicity
Complications of multiple pregnancies
(Unrelated to amniochorionicity)
- Increase incidence and risk of minor ailments of pregnancy: e.g. early onset N/V, anemia, Pre-eclampsia, APH, AFLP…
- Miscarriage and severe pre-term delivery
- Single fetal demise: Vanishing twin syndrome, 2nd and 3rd trimester intrauterine death
- IUGR due to anomalous umbilical cord insertion, placental crowding, unequal placental sharing
- Fetal anomalies: most commonly cardiac anomalies
IUGR in multiple pregnancies
Growth rate
Cause of growth restriction
Management
Fetal anomalies in multiple pregnancies
Risk of anomalies
Types
Management option
Specific complications to monochorionic twins
Higher rates of congenital abnormalities, preterm delivery
Twin-to-twin transfusion syndrome (TTTS) (雙胎輸血綜合症): 10-15% of all MCDA twin
Other variants of TTTS:
Twin anemia-polycythemia sequence (TAPS) (雙胎貧血紅細胞增多症): one twin anemic, other twin polycythemic, but w/o amniotic fluid volume discordance
Twin-to-twin transfusion syndrome
Pathogenesis
S/S
Staging
Outcome
Management
Complications specific to mono-amniotic twins
Antenatal management of multiple pregnancies
Antenatal management:
- Routine iron and folate supplementation for increased fetoplacental demand
- Determination of chorionicity by US: important for risk stratification and subsequent Mx
Screening and diagnosis of fetal abnormality:
- nuchal translucency: test of choice for DS screening as biochemical test unreliable
- CVS: care to ensure that both fetuses are sampled as the placentae may be fused together
- amniocentesis: require direct puncturing of inter-twin membrane to ensure that both sacs are sampled
Monitoring of fetal growth and well-being should be by US as SFH and fetal movement (FM) unreliable
- Fetal measurements, activity, lie, amniotic fluid volume
- Growth scan Q4w
- Monochorionic twin: Screen for TTTS Q2-3w from 16w onwards, fetal echocardiogram in 22-24w
Timing of delivery for multiple pregnancies
Mode of delivery for cephalic-cephalic presentation twins
Mode of delivery for cephalic- non-cephalic presentation twins
Mode of delivery for non-vertex presenting twins
Locked twin: very rare, occur in breech/cephalic (usu C/I to vaginal delivery)
when first twin descend during delivery, the twins lock chin-to-chin
usu not recognized until delivery of part of 1st twin has occurred
survival unlikely unless urgent C/S
Compare pros and cons between vaginal and C/S delivery of twins
Higher multiple pregnancies
- Risks
- Mode of delivery
- Multifetal reduction method
- Outcome for triplet
