Objective: Hysterosalpingography (HSG) to assess patency of the Fallopian tubes with the use of iodinated (oil- or water-based) contrast media is a standard test during fertility work-up. An observational study found an increased risk of congenital hypothyroidism in neonates whose mothers were exposed to high amounts of oil-based contrast during HSG. Oil-based contrast contains more iodine (480mg Iodine/ml) than water-based contrast (250mg Iodine/ml). We investigated whether preconceptional HSG with oil- or water-based contrast affects neonatal thyroid function.
Design: Retrospective data-analysis of an RCT (H2Oil trial) (Dreyer et al.,2017).
Materials and Methods: In the H2Oil trial, 1,119 women were randomized to receive HSG with oil-based contrast (Lipiodol®) (n=557) or water-based contrast (Telebrix Hystero®) (n=562). Of the 369 women who gave birth to a liveborn infant, 208 consented to be approached for future research. Thyroid function tests of their children were retrieved from the Dutch neonatal screening program, which includes the assessment of T4 in all newborns, followed by TSH only in those with a T4 level ≤-0.8SD score. Furthermore, amount of used contrast and time between HSG and conception were compared between the groups.
Results: Data were collected on 140 neonates conceived after HSG with oil-based (n=76) or water-based contrast (n=64). T4 SD score was -0.05 (IQR-0.5-0.5) in the oil-group versus 0.2 (IQR-0.3-0.9) in the water-group (p-value 0.12). None of the neonates had a positive screening result for congenital hypothyroidism.
The median amount of used contrast did not differ between the oil-group (9.0ml (IQR6.0-11.8)) and water-group (10.0ml (IQR7.5-14.0)) (p-value 0.43). Time between HSG and conception was comparable between the oil- and water-group (respectively, 2.3 months (IQR1.1-4.3) versus 2.1 months (IQR1.1-4.0), p-value 0.83).
There were 13 children with a T4 ≤-0.8SD score in the oil-group versus 7 in the water-group (RR, 1.5; 95%CI 0.7-3.6, p-value 0.32). All had a normal TSH value. The amount of contrast or duration between HSG and conception between neonates with a T4 ≤-0.8SD and ≥-0.8SD score in either group did not differ.
Conclusions: This study showed that preconceptional HSG with oil-based and water-based contrast did not affect thyroid function in newborns. Although our results suggest that the use of iodinated contrast for HSG is safe for the offspring, we advise to keep the amount of contrast as low as possible. Since data on maternal thyroid function was lacking, while the fetal brain relies on the mother during neurodevelopment, no inferences regarding neurodevelopment could be made.
19 - 21 Sep 2019
European Society for Paediatric Endocrinology