Noiw it’s time for a history lesson.
The first successful IVF birth occurred in 1978. The specialty has made remarkable advances since then helping to make IVF a very successful procedure. Ovarian stimulation to produce a number of eggs, ICSI to make it possible for men with the most severe male factor issues capable of creating a healthy pregnancy and preimplantation genetic screening (PGS) to help select chromosomally normal embryos for transfer are just a few of the major advances.
One advance that is not heralded is change in transfer technique. In the old days the transfers were done with firm catheters and guided by measurements determined by a so-called trial transfer done sometime before the actual IVF cycle. Since we could not see that the catheter was not touching the uterine wall, the firm catheters could scratch the endometrial surface and cause bleeding. Over the years the catheters improved, the major improvement was the use of ultrasound to guide that catheter in real time in the axis of the uterus to 1.5 to 2 cm. from the top of the uterus. There was much less chance of causing bleeding or disturbing the endometrium or having a difficult embryo transfer using additional maneuvers.
In a study published in 2017, researchers from Barcelona analyzed 7,714 embryo transfers to determine the impact of maneuvers during embryo transfers on the pregnancy rate. Using the direct embryo transfer as a reference, each instrumentation needed to successfully deposit the embryos in the ideal locatioon at the top of the uterus served as an index of the difficulty of transfer. A difficult transfer occurred in 7.7% of cycles, and the researchers found that the clinical pregnancy rate decreased progressively with the use of additional maneuvers during embryo transfer. Specifically, the clinical pregnancy rate was 39.4% when no additional maneuvers were required, 36.9% when an outer catheter sheath was used, 31.7% when a Wallace stylet was used, and 26.1% when a tenaculum was used.
The use of ultrasound reduces the need for additional maneuvers. Many published studies have found that significantly higher pregnancy rates occur with routine bladder distension prior to embryo transfer to help ultrasound visualization, probably because of the smooth and easy insertion of the embryo transfer. A Scandinavian meta-analysis found that the odds ratio (OR) favoring ultrasound guidance and a full bladder for ongoing pregnancy was 1.44 (1.44 times the chance without it) and clinical pregnancy was 1.55, which is similar to that seen during an earlier review from The Cochrane Collaborative, with an OR of 1.47 for ongoing pregnancy and OR 1.53 for live birth.
So make sure your embryo transfer is done with a full bladder and ultrasound guidance.