Embryo Reduction. Management


Antenatal management should include attention to nutrition, avoidance of strenuous physical activity, frequent prenatal visits, and counseling on symptoms of preterm labor, PROM, and hypertensive disorders of pregnancy. Ultrasound assessment of fetal growth and amniotic fluid volume should be performed every 4 weeks unless evidence of an abnormality suggests that this be done more frequently. Discordant fetal growth may be due to constitutional differences in otherwise normal twins, growth restriction of one fetus, a chromosomal or anatomic abnormality of one fetus, or the twin-twin transfusion syndrome. In situations of threatened or imminent delivery before 34 weeks, maternal antenatal steroid administration is recommended for acceleration of fetal lung maturity and prevention of intraventricular hemorrhage. If preterm labor occurs, controversy exists over the safety and efficacy of the various tocolytic drugs currently available. As indicated, fetal surveillance with an NST or BPP is recommended.

Vaginal delivery is the preferred approach when both twins are in a vertex presentation. After delivery of twin A, and with continuous surveillance of twin B with real-time ultrasonography or electronic monitoring, it is believed that the interval between delivery of the twins is not important in the presence of a reassuring FHR.

Embryo Reduction

The higher-order multiple gestations resulting from assisted reproductive technologies has resulted in an increased risk of preterm delivery, which is directly proportional to the number of fetuses developing in utero. Multifetal pregnancy reduction is a procedure designed to increase the chances of delivering closer to term by decreasing the number of fetuses in the uterus.

Multifetal pregnancy reduction is usually performed via the transabdominal or transvaginal route. A needle is guided under direct ultrasonic visualization into the fetal heart or thorax, and potassium chloride solution is injected to accomplish asystole. The procedure is usually performed late in the first trimester rather than earlier because this allows for 1) the possibility of spontaneous loss of one or more fetuses before the procedure, 2) easier accessibility to the fetuses given their increased size, and 3) greater opportunity to detect disturbances in growth or morphology.

The incidence of preterm delivery increases with increasing numbers of fetuses; the mean gestational age of delivery for singletons, twins, triplets, and quadruplets is 39, 35, 33, and 31 weeks, respectively. Multifetal pregnancy reduction increases gestational age at delivery. This clearly has had a beneficial impact on the outcome of pregnancies that begin with four or more fetuses.

The data regarding triplets, however, are not as definitive. Some studies have suggested that multifetal pregnancy reduction reduces the spontaneous loss rate in these gestations, and the rates of intraventricular hemorrhage and respiratory distress syndrome are increased in unreduced triplets compared with twins. It is not clear, however, whether these differences during the neonatal period have a meaningful impact on later cognitive, physical, and psychologic ability. Although fetal benefit can be debated, maternal advantages are obvious. Women with triplets have an increased risk of preterm labor, prolonged hospitalization, PIH, anemia, and postpartum hemorrhage compared with those carrying twins.

The antenatal care of post-multifetal pregnancy reduction twins is no different from that of spontaneous twins, except for one screening tool. Maternal serum alpha-fetoprotein levels after a reduction are consistently higher than those for non-reduced twins at comparable ages because of the retained dead fetus(es). Therefore, maternal serum alpha-fetoprotein cannot be used to screen for NTDs or other anomalies in these patients. Studies comparing the morbidity and mortality of reduced versus unreduced twins show comparable results.

Multifetal pregnancy reduction optimizes the chances of a woman successfully maintaining her pregnancy by decreasing the risks of preterm delivery. For many women, this is not a light decision. Multifetal pregnancy reduction is associated with mourning for the lost fetus(es), guilt, and sadness, but overall, it is well tolerated. One study revealed that 93% of the women who underwent multifetal pregnancy reduction did not regret their decision. Until the multifetal gestations created by modern infertility therapy can be limited to twins, multifetal pregnancy reduction will remain an option available to help couples maximize their potential for delivering healthy infants at low risk for developing the devastating sequelae that can accompany severe prematurity.

More information about Multiple Gestation

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