Tubal pregnancy and IVF

Tubal pregnancy (or ectopic pregnancy) can occur in approximately 2% of in vitro fertilization (IVF) cycles. This is despite the fact that most embryo transfers are conducted under ultrasound guidance confirming that they are deposited in the uterine cavity. Subsequent uterine contractions are believed to squeeze the embryos back into the tubes with a resultant tubal pregnancy.

Risk factors for tubal pregnancy and IVF include:

• history of tubal disease
• history of a tubal pregnancy
• high embryo transfer (near the top, or fundus, of the uterine cavity)
• transfer of multiple embryos

Interestingly, tubal pregnancy can still occur on the side where the tube has been surgically removed. This is because there is a portion of the tube that is within the uterine wall that cannot be removed (interstitial portion) and can be the site of a tubal pregnancy.

Is there a difference in the incidence of tubal pregnancy in fresh vs. frozen IVF cycles?

This very issue was recently addressed by Dr. Laura Londra and colleagues from the John’s Hopkins University in Baltimore, Maryland (Fertil Steril2015;104:110-118). They analyzed the Society for Assisted Reproductive Technologies (SART) database for pregnancies that resulted from fresh and frozen IVF cycles from 2008 to 2011. This is what they found:

Among 103,070 cycles that resulted in a clinical pregnancy, 1.38% were tubal pregnancies. The odds of a tubal pregnancy were 65% lower in women who had a frozen compared with a fresh embryo transfer. Donor egg transfers had lower odds of tubal pregnancy compared with cycles when women used their own eggs, with no difference between fresh and frozen donor transfers. Women who had both a fresh and a frozen transfer with their own eggs had a higher risk of EP in their fresh cycles compared with their frozen cycles.

The authors postulate that a difference in the tubal-uterine environment contributes to abnormal implantation after IVF. In fresh IVF cycles, the ovaries are stimulated with resultant high hormonal levels. These could affect uterine contractility as well as endometrial receptivity.

In a previous blog we have discussed a study that showed higher pregnancy rates with frozen embryos than with fresh embryos. Reducing the chances of a tubal pregnancy could be another reason to freeze all embryos and then doing a transfer in a subsequent cycle.

To work with a fertility team that uses state-of-the-art technology to help patients get pregnant, make an appointment at one of InVia’s four Chicago area fertility clinics.