Assisted reproductive therapies have been established as mainstay treatment for fertility caused by many clinical conditions. However, the rate of implantation of a transferred embryo during in-vitro fertilization (IVF) or intracytosplasmic sperm injection (ICSI) is low. Since embryo transfer is crucial for implantation, the technique used in this procedure is vital for IVF success.
Studies have also shown that a significant proportion of women undergoing embryo transfer after IVF or ICSI have had embryos transferred to a location within their uterus that was less than ideal. Therefore, solving this issue often calls for a trial transfer before the actual embryo transfer procedure.
The purpose of the trial embryo transfer is to determine the measurement of the uterus as well the presence of any features or characteristics that would suggest the need for special instruments or procedural modifications. For most patients, this outpatient procedure is brief, simple and painless, and is done simply as a precautionary measure. For women who have a history of a previous pregnancy, there may be a discrepancy between the perceived and actual size of the uterine cavity.
The trial transfer technique is performed on day 12 of the patient’s menstrual cycle. The woman is placed in the dorsal lithotomy position, and a speculum is used to allow visualization of the cervix. Then the cervix is prepared for the procedure using gauze soaked in Betadine. A semi-rigid catheter is inserted through the cervix into the uterus and navigated until the tip is perceived to make contact with the uterine fundus, or the topmost area. This determines not only the depth of the uterine cavity, but also its orientation. Then the catheter is removed, and the length of the catheter that was actually within the uterine cavity is measured. During actual embryo placement, the implantation site is 1 to 2 cm below the fundus. Note that the length of the uterus is done by tactile perception and feel, and the resulting measurements may vary between clinicians examining the same patient.
The procedure of trial embryo transfer can also be performed with ultrasound guidance. This increases the accuracy of determining the length of the uterine cavity, as studies between ultrasound-guided vs non-guided trial transfers have revealed that longer or larger uterine cavities can be underestimated when ultrasound is not used.
The placement of the embryo at the ideal uterine depth can mean the difference between successful or failed implantation. In the Philippines, infertility treatments benefit from the use of procedures that can accurately diagnose and measure. As a safe and painless procedure, the trial transfer also gives valuable information, leaving very little to chance on the day of actual embryo transfer.