Thyroid Dysfunction in Neonates Born to Mothers Who Have Undergone Hysterosalpingography Involving an Oil-Soluble Iodinated Contrast Medium

BACKGROUND/AIMS: Patients developing neonatal thyroid dysfunction following maternal hysterosalpingography (HSG) involving the use of oil-soluble iodinated contrast medium (ethiodized oil) have been reported. The present study aimed to investigate the frequency and risk factors for neonatal thyroid dysfunction following HSG. METHODS: We studied 212 infants born to mothers who had become pregnant after undergoing HSG involving the use of ethiodized oil. RESULTS: Five of the 212 infants tested positive during congenital hypothyroidism screening; this frequency (2.4%) was higher than the recall rate among first congenital hypothyroidism screening results (0.7%) in Tokyo, Japan. Two of the 5 screening-positive infants showed hypothyroidism, and 3 showed hyperthyrotropinemia. The urinary iodine concentrations in 4 out of the 5 screening-positive infants were 1,150, 940, 1,570, and 319 μg/l. The subjects were divided into thyroid dysfunction (n = 5) and normal thyroid function (n = 207) groups. The median dosage of ethiodized oil in the thyroid dysfunction group was significantly higher than in the normal thyroid function group (20 vs. 8 ml, p = 0.033). CONCLUSION: When infertile women undergo HSG, the dosage of oil-soluble iodinated contrast medium should be as low as possible to minimize the risk of fetal or neonatal thyroid dysfunction.