Prenatal diagnosis and early in utero management of fetal dyshormonogenetic goiter.

We present a case of a fetal dyshormonogenetic goiter diagnosed by ultrasound examination at 24 weeks of gestation, in a woman with no past history of thyroid disease or goitrogen treatment and with normal thyroid tests, including absence of auto-antibodies. In this situation, fetal goiter may only be associated with fetal hypothyroidism, therefore cord blood sampling was not performed but early treatment was initiated. Amniotic fluid instillation of thyroid hormone led to a rapid decrease in amniotic fluid volume and a clear reduction in thyroid goiter. However, fetal thyroid volume did not totally normalise, and cord blood analysis at birth showed elevated fetal TSH level. As prenatal treatment of fetal hypothyroidism remains controversial in euthyroid mothers, the main objective is to prevent obstetrical complications of large goiters. Therefore, in some selected cases with no maternal history of thyroid disease and normal thyroid function tests, cordocentesis is not necessary to confirm fetal thyroid status or to adjust fetal treatment.