Hysterosalpingography with oil-based contrast boosts pregnancy rates: A landmark study

Infertile women undergoing Hysterosalpingography (HSG) with an oil based contrast have a 10% higher chances of getting pregnant and continue the pregnancy as compared to women who have HSG with a water based medium reports results of a multicentric, randomized trial from Netherlands.

The study was published online May 18 in the New England Journal of Medicine and presented at the 13th World Congress on Endometriosis in Vancouver, Canada.

Looking back, the debate about superiority of one medium over other has been going on for 50 years. It is known that flushing of the fallopian tube enhances fertility, but controversy about the type of medium continues.

First HSG was carried out by Carey in 1914 and he used collergol. Lipiodol was introduced by Sicard and Forestier in 1924 and remained a popular contrast medium for many decades. Later, water-soluble contrast material was generally preferred as it avoided the possible complication of oil embolism.

A 2007 update of Cochrane review concluded that “Flushing of the tubes with oil-soluble media increases subsequent pregnancy rates in infertility patients. Clinicians should consider flushing the tubes with OSCM before contemplating more invasive therapies.”

While other smaller studies have reported that contrast does not affect the cumulative pregnancy rate.

The current study called the The H2Oil study was conducted by Professor Ben W.J. Mol along with Dr. Kim Dreyer & Dr. Velja Mijatovic from the Department of Reproductive Medicine, VU University Medical Centre, Amsterdam, and their multi-center research team from 27 hospitals in the Netherlands.

The study recruited 1,119 women who were undergoing fertility treatment and were advised hysterosalpingography (HSG). The women were randomized to a standard HSG with water-soluble contrast medium (WSCM)(Hystero) or another group which used an oil-based contrast with Lipiodol Ultra-Fluide. (LIPIODOL Ultra-Fluid 480 Injection 10 mL, GUERBET). (Ethiodol in the United States). Then couples received expectant management or the women underwent intrauterine insemination.

All women were between 18 and 39 years of age, with regular menstrual cycles, and were undergoing treatment for infertility for at least 1 year.

The primary outcome measure was positive fetal heart rate by USG at 12 weeks of pregnancy within 6 months of the HSG test. Multiple secondary outcomes were tested like positive pregnancy test by USG, live birth, ectopic pregnancy, miscarriage and pain scores by the Visual-Analogue Scale for Pain.

After statistical analysis at 6 months, it was seen that 220(39.7%) in oil-based group had an ongoing pregnancy versus 161(29.1%) in water based group (P <.001). The oil based group also had considerable more live birth rates, 38.8% versus 28.1% (P <.001).   

Professor Mol said “This means that for every ten women undergoing an HSG to test their fallopian tubes, if Lipiodol® is used for that test, there will be one more pregnancy six months later and, consequently, one more baby nine months after that.”

The groups were comparable to each other in terms of bilateral tubal patency, pain score, miscarriage rates, ectopic pregnancy, twins, stillbirth rates and median duration of pregnancy.  

“If we move to the use of Lipiodol® Ultra-Fluid for routine diagnostic tubal patency testing, more women will have a successful fertility outcome and will avoid the need for other expensive fertility treatments such as IVF. I believe that is justifiable at this point,” he further added.

Professor Mol has a personal connection with the study which came to light only when he started researching about HSG. He himself was born, after his mother underwent HSG using Lipiodol after being infertile for 9 years.  

Professor Neil Johnson, President of the World Endometriosis Society concluded “This new study from our Dutch colleagues confirms beyond doubt the fertility value of Lipiodol® Ultra-Fluid.”