Embryo transfer is the final and most crucial step in IVF. Sometimes, however, the embryo transfer can be technically difficult. This article describes what we do to help tackle this problem

The Ideal Embryo Transfer catheter

Embryo transfer is the final and most crucial step in IVF. About 95% of patients undergoing IVF reach the embryo transfer stage, but less than half of these achieve a pregnancy.

The pregnancy rate after embryo transfer is dependent upon multiple factors including embryo quality, endometrial receptivity and the technique of the embryo transfer itself.

The main goal of the clinician doing the embryo transfer should be to place the embryos in the uterine cavity , without causing pain; bleeding or trauma to the endometrium or the embryos. Too much manipulation can stimulate uterine contractions, which can result in expulsion of the precious embryos from the uterine cavity ! This can reduce pregnancy rates , in spite of transferring top quality embryos into a healthy endometrial lining.

The ideal embryo transfer catheter should avoid any trauma to the endocervix and/or endometrium ; and it should be malleable enough to find its way into the uterine cavity.

What type of catheter should we use for embryo transfer to avoid any kind of trauma?

Different types of catheters should be used for different patients.
We can categorize Embryo Transfers into 2 categories. "Easy embryo transfers" and "Difficult embryo transfers"

A trial transfer (which is often done at the time of the egg collection ) is called a mock embryo transfer. In this procedure, the doctor passes an empty catheter into the uterine cavity. This allows the doctor to measure the uterine cavity depth and direction . It is beneficial , as there is great variability in cervical and uterine anatomy amongst women, and recording these details allows the doctor to be better prepared for the actual embryo transfer. This procedure also helps in the selection of the right embryo transfer catheter.

Easy Embryo Transfer

The Embryo transfer procedure is considered easy if :

• The trial embryo transfer catheter negotiates the endocervix easily.
• Patient doesn't feel any pain throughout the procedure.

A soft Catheter should be preferred for an Easy Embryo Transfer.

By using a soft catheter we can ensure less trauma, as the catheter will easily find its way into the uterine cavity. Soft catheters allow the tip to follow the contour of the cervical and uterine axis and are preferred as they minimize trauma to the endometrium

The soft Embryo transfer catheters we use in our Clinic include:

• Frydman embryo transfer catheter
• Rocket Soft embryo transfer Set
• Wallace embryo transfer catheter.

Difficult Embryo Transfer

The Embryo transfer procedure is considered difficult if :

1. The trial embryo transfer catheter doesn't go into the endocervix easily.
2. The doctor has a hard time placing the catheter into the uterus.
3. Patient feels pain throughout the procedure.
4. If the patient has an acutely anteverted or retroverted uterus or cervical stenosis, as a result of which a soft flexible catheter encounters resistance while being inserted through the endocervix.

The best catheter for a difficult embryo transfer procedure is the one which the following components:

an outer sheath with bulb;
a stopper for helping with accurate placement;
an inner catheter; and
an obturator.

OUTER SHEATH

The outer sheath is a thick hollow plastic tube(catheter ) with a bulb ; and markings at the tip of the catheter. This bulb helps the doctor to bypass the blind endocervical crypts which line the cervical canal and can cause the tip of the catheter to get trapped.

INNER SHEATH

The inner sheath is a soft tube , with markings at distal end of the tip. The embryologist loads your embryos into this sheath and then hands this to the doctor for the embryo transfer .

• In a difficult transfer, the outer sheath with its inner obturator is curved to suit the curvature of endocervix.
• The stopper is adjusted according to the uterine cavity length.

The sheath is slowly guided into the endocervix.

• The embryologist loads the embryos into the inner sheath ( under microscopic guidance) and then hands over this loaded catheter to the doctor.
• The doctor slowly withdraws the obturator out of outer sheath ; after which the inner catheter (with its embryos ) is slowly guided into the outer sheath. Once the tip of the inner catheter is beyond the other sheath ( and safely within the uterine cavity), the embryos are placed gently into the uterine cavity by pushing the plunger of the syringe.
• The doctor then removes the inner and outer sheaths which are then checked by the embryologist to confirm that no embryos have been retained within them inadvertently.
• Some doctors will use ultrasound guidance to help them during the transfer

Catheters we use for difficult embryo transfer procedures:

• Labotect Embryo transfer set
• Frydman soft 4,5 with guideli>
• Wallace Embryo transfer with stylet
• Gynetics tulips set
• Cook SIVF 7019