Fetal abnormalities » Multiple pregnancies
Management options at 11-13 weeks:
- In triplet pregnancies diagnosed during the first trimester management options include continuing with the whole pregnancy or embryo reduction (ER) to twins or singletons.
- The consequence of ER is decrease in the rate of early preterm birth, but increase in the rate of miscarriage at <24 weeks (Table below).
- Trichorionic (TC) triplets: ER is achieved by fetal intracardiac injection of potassium chloride (KCl).
- Dichorionic (DC) triplets: ER by KCl involves either the separate fetus or both monochorionic (MC) twins; the injected KCl to only one of the MC twins could be transferred to the co-twin through the inter-twin placental vascular anastomoses or death of one fetus could lead to hemorrhage from the co-twin into the dead fetoplacental unit with consequent death or neurodevelopmental impairment in the survivor.
- In DC, compared to TC triplets, there is a higher rate of miscarriage both with expectant management, and after ER to MC twins, which could, at least in part, be attributed to subsequent development of sFGR or TTTS.
- Another option for DC triplet pregnancies is ER to DC twins by ultrasound-guided laser ablation of the pelvic vessels of one of the MC twins. The risks of miscarriage and early preterm birth are lower with this method than with other options. However, with intrafetal laser half of the pregnancies will result in the birth of one rather than two babies, because the other MC twin dies within 2 weeks of the procedure.
at 11-13 weeks
12+0 to 23+6 weeks
24+0 to 32+6 weeks
|- Expectant management||3%||35%|
|- Reduction to DC twins by KCL||7%||13%|
|- Reduction to singleton by KCL||10%||8%|
|- Expectant management||9%||38%|
|- Reduction to MC twins by KCL||13%||23%|
|- Reduction to singleton by KCL||18%||9%|
|- Reduction to DC twins by laser||3%||7%|
Feto-fetal transfusion syndrome (FFTS):
- In triplet pregnancies complicated by severe FFTS, the best management option is endoscopic laser ablation of communicating placental vessels.
- DC triplets: the separate fetus can pose some technical problems in selecting the appropriate site of entry of the fetoscope but in general these problems can easily be overcome. Consequently, the outcome of affected pregnancies is similar to that in MC twins but with an inevitable higher incidence of early preterm birth.
- Survival: overall 75%, at least one baby 95%. Birth at <32 weeks: 55%.
- MC triplets: endoscopic laser surgery can be technically difficult because of the necessity to ablate the communicating placental vessels between all three fetuses. The fetoscope is introduced into the sac of the recipient fetus and laser was used to coagulate the vessels between this fetus and each of the other two fetuses. Subsequently, the fetoscope is advanced through the inter-twin membrane into the sac of one of the other fetuses to coagulate the vascular connections between them. As a result of such technical problems or the inability to achieve the objective of complete separation between all fetuses the outcome is poorer than in DC triplets.
- Survival: overall 55%, at least one twin 80%. Birth at <32 weeks: 65%.