NEW YORK (Reuters Health) – A slight modification to the embryo transfer (ET) technique leads to significantly better pregnancy rates, according to researchers in Iran. They use an insulin syringe to push air into the catheter immediately after ET.

The point of the intervention is to lower the risk of embryo expulsion from the uterine cavity. “It has been reported that 15% of the transferred embryos are pushed out after ET and can be seen in the catheter tip, cervix, and on the vaginal speculum,” according to lead author Dr. Tahereh Madani, of the Royan Institute, Tehran, and colleagues.

In their randomized trial, reported online May 7th in Fertility and Sterility, 110 women aged 40 or younger underwent in vitro fertilization (IVF) or intracytoplasmic sperm injection with (n = 55) or without (n = 55) 0.2 mL of air pushed into the catheter after ET.

Both groups were well matched in terms of basic clinical characteristics and factors that might have influenced outcome such as basal follicle-stimulating hormone levels, type of gonadotropin used, number of retrieval oocytes, fertilization rate, and number and quality of transferred embryos or ET procedures.

The implantation rate was 19.5% in the air-intervention arm, compared to 7% in the control arm (p = 0.002). The clinical pregnancy rate was also higher in the intervention group (40% vs 16.4%; p = 0.006).

“By pushing air gently into the catheter after driving the embryos into the uterine cavity, we generate positive air pressure to stop embryos from back-tracking when the catheter is pulled out,” the authors said. “This also creates a force against the waves generated by uterine contractions, thus reducing the rate of embryo expulsion.”

“Our method…is an easy, efficient, low-cost addition…to the standard ET techniques,” Dr. Madani and colleagues conclude.

References:

Fertil Steril 2010.