SELFI Study

Lipiodol is the iodine-rich contrast agent that is commonly used in infertility assessments such as the hysterosalpingogram (HSG) test for blocked Fallopian tubes. This study investigated whether iodine affects the thyroid function of mothers, and thyroid development of the baby. SELFI stands for Safety and Efficacy of Lipiodol in Fertility Investigations.

A hysterosalpingograms (HSG) test is a routine infertility assessment used to detect blocks in the fallopian tubes. Lipiodol is an oil-soluble contrast agent that has been used in these assessments since the 1920s. Recent trials in the past two decades, such as the FLUSH trial and H2O oil trial, showed an increased pregnancy rate of 30-40% in women with endometriosis and unexplained infertility. These studies made Lipiodol HSGs more popular.

However, Lipiodol has high iodine content and takes a long time to leave a woman’s body due to its long half-life of 50 days. An excess of iodine could possibly affect thyroid function of women who undergo the procedure, as well as thyroid development of the foetus - in the case of a successful pregnancy within few months of Lipiodol HSG.

We recruited 200 women who planned to undergo Lipiodol HSG to learn more. We monitored their iodine levels and thyroid function before the procedure and periodically for six months afterwards.

For women who became pregnant within six months of the HSG, once the baby was born, we followed up the routine thyroid test that was done when the baby was two days old and did a repeat thyroid test of the baby at seven days old. Thyroid function is assessed with a simple heel prick test.  

Lipiodol HSG is a routine infertility assessment that is frequently carried out due to the enhanced fertility benefits. However, it is essential to ensure the treatment is safe for both mum and baby. No prior large-scale studies assessed the correlation between lipiodol retention, iodine excess and thyroid function following Lipiodol HSG. This research will help us establish protocols for thyroid monitoring and treatment after Lipiodol HSG at a national and international level.

We invited women who planned to undergo a Lipiodol procedure as part of their infertility assessment to take part in this study.

Those who took part provided an early morning urine and blood test at their nearest collection centre in Auckland. After the HSG, they had eight blood tests and five urine tests over the following six months to check iodine levels and thyroid function.

Participants benefited from early detection of any thyroid problems and - in consultation with the reproductive endocrinologist and respective fertility specialist - received expert advice on their treatment options.

If you participated in the SELFI Study and have questions, please email Paul Hofman at p.hofman@auckland.ac.nz.

Iodine and other factors associated with fertility outcome following oil-soluble contrast medium hysterosalpingography: a prospective cohort study, Divya M Mathews, Jane M Peart, Robert G Sim, Neil P Johnson, Susannah O'Sullivan, José G B Derraik, Paul L Hofman. Front Endocrinol (Lausanne). 2024 Jun 20:15:1257888. doi: 10.3389/fendo.2024.1257888. eCollection 2024.

The impact of prolonged, maternal iodine exposure in early gestation on neonatal thyroid function, Divya M Mathews, Jane M Peart, Robert G Sim, Susannah O'Sullivan, José G B Derraik, Natasha L Heather, Dianne Webster, Neil P Johnson, Paul L Hofman. Front Endocrinol (Lausanne) . 2023 Jan 31:14:1080330. doi: 10.3389/fendo.2023.1080330. eCollection 2023.

Hysterosalpingography with Oil-Soluble Contrast Medium Does Not Increase Newborn Hypothyroidism, Divya M Mathews, Jane M Peart, Neil P Johnson, Robert G Sim, Natasha L Heather, Dianne Webster Susannah O'Sullivan, Paul L Hofman. Int J Endocrinol. 2022 Feb 22:2022:4532714. doi: 10.1155/2022/4532714. eCollection 2022.

Iodine and fertility: do we know enough? Divya M Mathews, Neil P Johnson, Robert G Sim, Susannah O'Sullivan, Jane M Peart, Paul L Hofman, Hum Reprod. 2021 Jan 25;36(2):265-274. doi: 10.1093/humrep/deaa312.

The SELFI Study: Iodine Excess and Thyroid Dysfunction in Women Undergoing Oil-Soluble Contrast Hysterosalpingography, Divya M Mathews, Jane M Peart, Robert G Sim, Neil P Johnson, Susannah O'Sullivan, José G B Derraik, Paul L Hofman. J Clin Endocrinol Metab. 2022 Nov 25;107(12):3252-3260. doi: 10.1210/clinem/dgac546.