Selective Fetal Reduction Multifetal pregnancies are at risk for extremely preterm birth and major neonatal complications. To prevent this, selective reduction of higher-order multiple gestations often is practiced. The largest series describes 3,513 pregnancies treated with ultrasound-guided fetal intracardiac injection of potassium chloride (0.2–0.4 mL of a 2-mmol solution in the first trimester, 0.5–3.0 mL in the second trimester). The rate of fetal loss fell as operators gained experience. Loss was greater with higher starting number of gestations (starting number greater than six, 15.4% loss, decreasing to 6.2% loss for starting number of two gestations), and greater if more fetuses were left intact (finishing number three, 18.4% loss, decreasing to 7.6% for finishing number of gestations of one) (368). Another indication for selective reduction is the presence of one anomalous fetus in a multifetal gestation. In a series of 402 patients treated for this indication, rates of pregnancy loss after the procedure by gestational age at the time of procedure were 5.4% at 9 to 12 weeks, 8.7% at 13 to 18 weeks, 6.8% at 19 to 24 weeks, and 9.1% at 25 weeks or more (369). No maternal coagulopathy occurred, and no ischemic damages or coagulopathies were seen in the surviving neonates. Maternal serum α-fetoprotein remains elevated into the second trimester after first-trimester procedures (370). Because of the possibility of embolic phenomena and infarction in the surviving twin, a different technique is needed for selective reduction of monoamniotic twins or with monochorionic twin–twin transfusion syndrome. He and colleagues describe ultrasound guided bipolar coagulation of the umbilical cord of the affected twin in such cases (371).
The Future
Spermicides Research includes efforts to develop spermicides and microbicides that prevent pregnancy and are effective against HIV and STDs. Trials of microbicides such as cellulose sulphate and surfactant were disappointing and showed no efficacy against HIV (371,372). The most promising research includes development of antiretroviral microbicides with alternative delivery systems such as rings and gels. The antiretroviral tenofovir has good safety and efficacy in animals and human tissue models and is being evaluated in human effectiveness studies (373).
Intrauterine Devices The GyneFix, a frameless copper IUD available in Europe, consists of a surgical suture with small copper cylinders crimped to it. The knot on the proximal end of the suture is pushed 1 cm into the uterine wall with a special inserter. Comparative trials found it more effective than the copper T380A and it requires fewer removals for pain and bleeding (374).
Other ongoing research of IUDs includes a smaller levonorgestrel IUD that may be more acceptable to nulliparous women and IUDs that are suitable for irregularly shaped uteri (38).