A critical review of bi-dimensional and three-dimensional ultrasound techniques to monitor follicle growth: do they help improving IVF outcome?

Abstract

BackgroundThis review focuses on the possibility of improving the outcome of human IVF by studying the follicles where oocytes grow by ultrasound techniques. A comprehensive analysis of bi-dimensional (2D) and three-dimensional (3D) ultrasound (US) assessment of the follicle size and volume is presented.MethodsPublished reports from the year 1999 to 2014 analyzing the relationship between oocyte competence, IVF outcome and ultrasound assessment of the follicle size and volume have been critically analyzed.ResultsUS assessment of growing follicles has been performed mainly by 2D-US, and while overall very useful, it has been found to be of limited usefulness in predicting oocyte competence, recognize which follicles will release a mature metaphase II oocytes and decide the ideal time to trigger ovulation. In fact, a quite wide follicle size range (16–22 mm) has been reported to be associated with mature oocytes with good competence toward fertilization and embryo development. It has been also shown that smaller follicles sometimes contain mature, fertilizable oocytes. However, embryos derived from smaller follicles have probably a lower implantation potential, while follicles larger than 22 mm often contain post-mature eggs.ConclusionsThe study of follicular size by 2D-US is of limited usefulness in helping in the identification of follicles containing the best oocytes and in choosing the best moment to trigger ovulation. Possibly the value of US in this area will be improved by large prospective studies in which automated 3D-US will be used.

Relationship between follicular volume and oocyte competence, blastocyst development and live‐birth rate: optimal follicle size for oocyte retrieval

“…Calculation of the follicular volume (V f = 4/3 × r 3 × π) with conventional two‐dimensional TVS bears the risk of false estimation, possibly contributing to the controversial publications on this topic in the past. In contrast, the 3D ultrasound technique, as applied in our study, allows a more accurate volume calculation.…”

Three-dimensional sonography-based automated volume calculation (SonoAVC) versus two-dimensional manual follicular tracking in in vitro fertilization

“…The present results, along with those of previous studies, indicate that SonoAVC shows great promise as a follicular tracking method. The advantages of this technique include saving time for the busy practitioner [4,8–10], objectivity and reproducibility compared with manual measurements [11], and low training requirements, which would allow senior consultants to delegate the task of follicular tracking to juniors or residents. Further, subjective errors—such as double inclusion or omission of a follicle—are greatly reduced.…”

“…Post‐processing is therefore required to add, remove, or merge follicles, or to adjust the settings of follicular growth or separation, making it a time‐consuming process. Another important disadvantage is the high cost of the machine [8,11].…”

Does large (>24mm) follicle yield a competent oocyte/embryo?

“…Data exist, both in human and animals models, on the optimal follicular size on the day of oocyte retrieval, that are most likely to yield a mature oocyte (5). Follicles of 16-22 mm are more likely to yield mature oocytes than smaller follicles, while larger follicles would more likely yield "post-mature" oocytes that are not competent for fertilization (6).…”