Increased size and vascularisation, plus decreased echogenicity, of foetal thyroid in two-dimensional ultrasonography caused by maternal Graves' disease.

Foetal ultrasonography monitoring is a valuable tool in assessing foetal thyroid function when pregnancy is complicated by maternal Graves' disease with accompanying high levels of TSH receptor antibodies, or when antithyroid drug therapy is instituted. Among several ultrasonographic signs of foetal thyroid disorder such as abnormalities in bone maturation and heart rhythm, cardiac failure, hydrops, intrauterine growth restriction and polyhydramnios, goitre is the most sensitive one. Here we report three cases of pregnant women with Graves' disease accompanied by very high serum levels of TSH receptor antibodies. In all three cases, as documented by foetal or neonatal serum TSH and thyroid hormones measurements, foetal thyroid dysfunction occurred. The only ultrasonographic sign of foetal involvement was a goitre with decreased echogenicity and increased vascularisation, central or peripheral. This is the first report demonstrating that a foetal thyroid gland when affected by transplacental passage of maternal TSH receptor stimulating antibodies can present exactly the same characteristic ultrasound pattern of Graves' disease as in adults.