Direct and transplacental intrauterine fetal therapy

Several approaches for an intrauterine fetal therapy have been reported in recent years for different congenital diseases. This article concentrates e specially on the treatment of the congenital adrenal hyperplasia and other rare enzymatic defects, on abnormal fetal thyroid function and fetal tachya rrhythmia. Results of intrauterine treatment of congenital adrenal hyperpla sia are optimal, when maternal dexamethason therapy is started very early i n pregnancy, preferable at 6 weeks of gestation. Other rare congenital defe cts are methylmalonic acidemia, a functional vitamin B-12 deficiency, and b iotin-responsive multiple carboxylase deficiency. Transplacentar treatment was reported by administration of cyanocobalamin and biotin, respectively. Sonographic prenatal diagnosis of a goiter in fetuses with intrauterine hyp othyreosis has been described previously. Treatment by injection of thyroxi ne into the amniotic fluid was successful and size of the fetal thyroid dec reased. Fetuses are at risk of hyperthyreosis, if maternal thyroid stimulat ing antibodies cross the placenta. Presenting symptoms might be fetal tachy cardia, general hydrops or even intrauterine fetal death. Initiation of pre natal therapy with propylthiouracil is recommended in these cases. Successf ul intrauterine therapy of fetal tachyarrhythmia has been reported using di goxin alone or in combination with flecainide. In most cases fetal hydrops resolved and therapy via cordocentesis was not necessary. However in fetuse s with complete AV-block and general hydrops there is no standardised proto col for the intrauterine treatment in the literature.