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MS WordPerinatologist Corner - C.E.U/C.M.E. Modules
Twins: Antepartum assessment and Intrapartum management
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10 Twin Pregnancy: Double Trouble?
Step 10. Labor Management
CASE STUDY (continued)
Mrs. BP’s preterm labor was arrested at 28 weeks and she now returns at 36 weeks with recurrence of uterine contractions. They are stronger and are occurring every 3-5 minutes. On exam her vital signs are normal. Her cervix is 4-5 cm dilated, 90% effaced, with bulging membranes and bloody show. You are not sure of the presentation, which is at a -3 station. A bedside ultrasound reveals that the A twin is presenting as a cephalic, and the B twin as a breech.
- How will you accomplish the delivery?
- Should the delivery take place at your level II facility?
As noted above, because there are two fetuses, the incidence of malpresentation is higher in twins than in singletons. Is your institution comfortable with 35-36 week infants? Do you have emergency surgical facilities available? If one of the twins is in a non-cephalic presentation (over half of them), should they be delivered by cesarean?
What is the optimal length of twin gestation?
A retrospective study comparing PNM among 89,000 infants born of multifetal pregnancies to PNM in six million singleton infants reported that PNM in twin gestations reached a nadir at 37 to 38 weeks of gestation then increased, while the lowest PNM in singleton pregnancies was at 39 weeks.
Data from the United States National Center for Health Statistics, including over 11 million singleton and almost 300,000 twin births, showed the lowest mortality for singletons was at 39 to 41 weeks (approximately 1 fetal and 1 neonatal death per 1000 deliveries) and at 37 to 39 weeks for twins (3 to 4 fetal and 2 neonatal deaths per 1000 deliveries). Moreover, as of 39 weeks gestation, the prospective risk of fetal death in an ongoing twin pregnancy exceeded the risk of neonatal death.
Other smaller series have confirmed these findings. The lowest perinatal mortality for twin pregnancy appears to be at 36 to 38 weeks of gestation.The only randomized trial that tried to determine whether delivery at 37 weeks resulted in better outcomes than later delivery had too few patients (n = 36) to detect significant differences.
Mode of delivery
| Twin A | Twin B | Prevalence |
|---|---|---|
| Cephalic | Cephalic | 42.5% |
| Cephalic | Non-Cephalic | 38.4% |
| Non-Cephalic | Either | 19.1% |
Most authorities feel that if the twins are “cephalic - cephalic”, they can be safely delivered vaginally
if there are no other obstetric contraindications. (Ayers) The A twin in this situation will usually have a pretty standard birth. The B twin may be at a high station, but gentle oxytocin augmentation, and perhaps needling the membranes, will usually result in its coming down safely in cephalic presentation. (Barret) The B twin should be monitored electronically, or with ultrasound, after A delivers.
If the B twin experiences a non-reassuring heart rate pattern, cord prolapse, or if heavy bleeding develops suggesting placental disruption, its birth should be expedited by either instrumental delivery if feasible, or by cesarean (“the ultimate birth experience”, see vagominal delivery)
If the twins are thought to be monochorionic, theoretically you should not collect blood from A’s cord until B is delivered, because of the risk of hemorrhaging B. (Healy)
Monoamniotic twins should all be delivered early by cesarean delivery because of the cord problems inherent in this situation. If the A twin is presenting as anything other than a cephalic (approximately 19% of all twins), it is also the standard of care to deliver the pair by cesarean delivery regardless of the presentation of B. Triplets and other higher order multiples are also recommended to be delivered by cesarean delivery because of the risks of interlocking.
