Factors Associated with Embryo Transfer Success

In-vitro fertilization is a process whose success depends on several factors and characteristics that contribute to an environment that can make or break a couple’s chances at having a baby. While there have been numerous studies on improving stimulation of hormones, the current medical literature is not as comprehensive on the aspects of oocyte collection and embryo transfer.

The procedure for oocyte collection has remained relatively unchanged in the past several years, and harvest rates remain relatively high. Other studies have examined implantation of embryos as dependent on the condition of the receiving endometrium. However, the subject of embryo transfer is relatively new, and reproductive specialists and clinicians have a wide range of opinions in regards to it.

Embryo transfer was initially performed in 1973 using a plastic cannula through which the specialist would thread a polyethelene tube containing the embryo with its culture medium. Three years later, the technique evolved, using a catheter passed through a sleeve inserted into the cervix. After 1980, open catheters became instruments of choice, and subsequently, numerous different types of catheter have been produced, to varying degrees of success.

The removal of hydrosalpinges has been cited among reproductive specialists as among the most important factor in improving the success of embryo transfer. Hydrosalpinx has been found to have a negative effect on the ability of the endometrium to receive the embryo for implantation, as well as contribute to a toxic environment incompatible with development of the embryo.

Hydrosalpinx is a fallopian tube with a distal blockage, usually caused by pelvic inflammatory disease (PID). PID itself is the consequence of sexually transmitted infections such as chlamydia or gonorrhea. Some cases may be due to tuberculosis. Such infectious diseases have been seen as detrimental to IVF success in the Philippines.

Ensuring that the transfer does not result in trauma or bleeding is another important factor. Whether a transfer is difficult is almost exclusively due to the technique used by the fertility specialist, and much less the fault of any anatomical variations of the patient. The presence of blood is often indicative of a difficult transfer resulting in trauma however slight to the endometrium, embryo, or both, but whether the blood itself is a factor is still under investigation.
Avoiding contacting the fundus of the uterus is another key element of the transfer technique, an opinion popular among several fertility professionals. Any irritation or trauma of this upper region of the uterus is often an indication of difficult transfer or poor technique.

The role of ultrasound monitoring during the embryo transfer procedure is another area that warrants study, since ultrasound guidance improves the placement of the catheter tip. Visual aids to help the specialist improve placement of the transfer catheter require more study to determine their true utility in improving embryo transfer success.