Do patient factors influence embryologists’ decisions to freeze borderline blastocysts?

Abstract

Research question

To investigate whether patient factors influence the decision to freeze a blastocyst with low implantation potential.

Design

This experimental study assessed 170 practicing embryologists from a variety of countries who were recruited via an online survey. Participants were currently practicing embryologists, who grade blastocysts as part of this role. The survey presented decision-making ‘vignettes’ to participants. These included specific patient information, as well as an image of an expanded blastocyst that was of borderline quality for inner cell mass and trophectoderm, for which the embryologist selected whether or not to freeze. High/low maternal age, the presence/absence of other top quality blastocysts, and the presence/absence of previously unsuccessful IVF cycles were systematically varied within the patient information in a 2 × 2 × 2 design. Participants reported how likely they would be to freeze a particular blastocyst on a scale of 1 (Extremely Unlikely) to 7 (Extremely Likely), and whether or not they would ultimately freeze each blastocyst (Yes or No).

Results

Lower maternal age, no other high-quality blastocysts within the cohort, and multiple unsuccessful IVF cycles were associated with greater likelihood of recommending to freeze (P < .001). Furthermore, significant interactions among all three patient factors were noted.

Conclusion

This study provides evidence suggesting that when faced with an uncertain blastocyst, factors pertaining to the patient (maternal age, the presence/absence of other top quality blastocysts, and the presence/absence of previously unsuccessful IVF cycles) influence the decision to freeze.

Appendix. Survey vignettes and images presented to embryologists for decision making

You have been assigned to grade and freeze blastocysts for the day. You have a reasonable number of cases to check, and systematically work your way through the case load before you start performing ICSI later in the day. The following cases are presented. All couples have been previously unsuccessful at achieving a live birth following either natural cycles or treatment and have no children. For various reasons, all cases presented here are ‘freeze all’ cycles, but none are undergoing either pre-implantation genetic screening (PGS) or pre-implantation genetic diagnosis (PGD). Each vignette outlines the relevant medical history of each couple and focuses on blastocyst development during the current cycle. Each vignette asks whether each embryo presented should be frozen given its morphological appearance on the last day of culture (day 6).

Vignette 1

Laura, aged 35 years, has recently been diagnosed with tubal infertility after a hysterosalpingography (HSG) showed occlusion of both fallopian tubes. Laura also undergoes high-intensity exercise 4–5 times per week but has maintained a body mass index (BMI) of 21. Laura’s partner David, who is 38 years, presented with a normal semen analysis. The total number of motile sperm seen in David’s ejaculate was 94 million, and overall, a high percentage of rapidly moving sperm were recorded (34%). Following Laura’s diagnosis, Laura and David came through for their first cycle of IVF. Laura showed a normal ovarian response to her stimulation regimen and was triggered when her three largest follicles were ≥ 18 mm. The pick-up procedure was straightforward, and a final number of 10 eggs were collected. The couple had good fertilization where all but two eggs fertilized. Following 5 days of culture, the embryos were checked for development to the blastocyst stage. Although there were 3 expanding morulas, no embryo had reached a suitable stage for freezing on day 5. Following 6 days of culture, the embryos are checked for development to the blastocyst stage. Five blastocysts are suitable for freezing, where these have all expanded and have a high grade for their inner cell mass (ICM) and trophectoderm (TE). Would you freeze the remaining embryo indicated here?

Vignette 2

Luke (35 years) has congenital bilateral absence of the vas deferens (CBAVD) due to a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, resulting in obstructive azoospermia. Stacey, also 35 years, has been tested and is not a carrier of the mutation. Stacey has a family history of polycystic ovarian syndrome (PCOS) but has no symptoms herself. She has a normal AMH for her age and has regular cycles. Following Luke’s diagnosis, he had a testicular sperm extraction (TESE) procedure, resulting in motile sperm being frozen. Altogether, Luke and Stacey have had 4 previous cycles of ICSI using the frozen TESE sperm. During each cycle, Stacy had a good response to ovarian stimulation, but so far no transfer has resulted in a live birth. This current cycle resulted in 11 eggs being collected; however, 2 of the eggs had not fully matured to metaphase II by the time the eggs were injected using ICSI. Eight of the 9 mature eggs fertilized normally following ICSI. After 5 days of culture the embryos were checked for their development, where there was one morula, one expanding morula, and one very early blastocyst present, all of which did not reach the criteria for freezing following observation. Following 6 days of culture, the embryos are checked for development to the blastocyst stage. Five top quality blastocysts are ready to be frozen. Would you freeze the remaining embryo indicated here?

Vignette 3

Mike, 34 years, was recently diagnosed with azoospermia after his first semen analysis. He subsequently had a second semen analysis, confirming that no motile sperm could be found following ejaculation. Six months after the initial diagnosis, Mike had a testicular sperm extraction, but motile sperm could not be found in the extracted tissue. This was confirmed following histology on a section of the tubule tissue. Two years after the diagnosis Mike, now 36, and his partner Lucy, 35 years, are coming through for their first cycle of ICSI using Mike’s younger brother Sam (33 years) as a personal sperm donor. Lucy is fit and healthy and has regular cycles. Lucy showed an adequate response to her stimulation protocol, producing a cohort of 13 eggs ≥ 14 mm at the time of trigger. Of the 11 eggs collected at pick-up, 9 were injected, and 8 fertilized successfully using the donor sperm. On day 5 of embryo development, it was noted that there was one very early blastocyst, but none were ready to be frozen on this day. Following 6 days of culture, the embryos are checked for development to the blastocyst stage. From the cohort of embryos, 7 have not passed the cleavage stage and are therefore not suitable for freezing. Would you freeze the remaining embryo indicated here?

Vignette 4

Andrew (age 35) has male factor infertility, characterized by low sperm concentration (3 million sperm per ml), and reduced motility (22%). Of note, Andrew also has few rapidly motile sperm (2%). Andrew’s partner Marlena (age 40) has a normal ovarian reserve, but due to her maternal age is expected to have a high rate of aneuploidy in her eggs. Marlena and Andrew have elected not to undergo PGS testing on their embryos but may consider noninvasive prenatal testing (NIPT) during a pregnancy. Andrew and Marlena are currently undergoing their first cycle of ICSI treatment. Marlena experienced steady follicle growth following 9 days of follicle stimulating hormone (FSH) stimulation and was triggered when her 4 largest follicles were ≥ 18 mm. At pick-up, 9 mature eggs were collected, and one empty zona pellucida was noted at the time of hyase denudation. Following ICSI of the 9 mature eggs, 8 fertilized following ICSI. The embryos were checked for their development on day 5; two embryos remained at the cleavage stage of development, but the remaining embryos had shown some progression on from the cleavage stage, with 3 morulas, one expanding morula, and two low grade blastocysts (low number of cells in the ICM and TE), which were not suitable for freezing after assessment. Following 6 days of culture, further blastocyst development had been observed, and 5 blastocysts were suitable for freezing. Would you freeze the remaining embryo indicated here?

Vignette 5

Thomas (age 44) has retrograde ejaculation. Following processing of a retrograde sample, an adequate number of sperm were frozen for use during ICSI (1 million motile sperm per straw). Kelly (age 40) has a BMI of 27, mild submucosal fibroids, and an adequate ovarian reserve for her age. During Thomas and Kelly’s first cycle of ICSI, Kelly had a poor response to stimulation, with slow follicle growth, and only 3 mature eggs collected. Following a change in stimulation regimen in her second cycle, Kelly’s response to stimulation was improved and 10 mature eggs were collected. In total, Thomas and Kelly have now had 4 previous ICSI cycles, each resulting in a fresh blastocyst transfer, but without success. In the current cycle, there were 11 mature eggs collected, and 8 of these fertilized following ICSI. The 3 eggs that did not fertilize all contained only 1 pro-nuclei (1PN). On day 5, 4 of the embryos showed early signs of blastocyst development, but no embryo had reached a suitable level of expansion for adequate assessment of the ICM and TE. Following 6 days of culture, the embryos are checked for development to the blastocyst stage. Five good quality blastocysts are suitable for freezing. Would you freeze the remaining embryo indicated here?

Vignette 6

Alice is a single 40-year-old women with mild endometriosis and a normal ovarian reserve for her age. Alice has always wanted to have children and has decided to use a sperm donor as she is not in a long-term relationship and is concerned about her ticking biological clock. Alice initially enrolled a personal friend to be her sperm donor, but his first semen analysis showed azoospermia, and he was therefore unsuitable for further testing. She has now chosen a clinic sperm donor and is coming through for her first cycle of ICSI. Alice had a good response to her stimulation regimen, with 14 follicles seen on her first scan. Alice was triggered after all 14 follicles showed optimal growth. In total, 12 eggs were collected, and 9 of these were mature. Following ICSI with the donor sperm, 1 of the eggs lysed, but the remaining 8 fertilized successfully. When the embryos were checked on day 5, there were 7 that had not developed past the 12-cell stage indicating that they had arrested, but one remaining embryo was still showing signs of development, although it was not at a suitable stage for freezing. Following 6 days of culture, the embryos are checked again for development to the blastocyst stage. There is no developmental change for the 7 arrested embryos, and they are therefore not suitable for freezing. Would you freeze the remaining embryo indicated here?

Vignette 7

Nicole and Brian are both 40 years old and have unexplained infertility. Nicole has ovulatory cycles, tubal patency, an AMH of 16, and a BMI of 23. Brian’s initial semen analysis showed a good number of motile sperm (44 million motile) and IVF insemination was indicated. Their first cycle of IVF however resulted in fertilization failure, with sperm bound to the zona, and adequate sperm motility at the time of the fertilization check. All eggs were mature, so the cause of the fertilization failure was unknown. Their subsequent 3 cycles of ICSI gave successful fertilization, but no pregnancy. In their most recent cycle, Nicole and Brian requested to have two blastocysts replaced, but this did not result in a live birth. In the current cycle, Nicole had a good response to stimulation, and 11 eggs collected, which was similar to her previous cycles. Following ICSI, 8 eggs fertilized normally out of the 9 mature, where the remaining egg was noted to contain 3 pro-nuclei (3PN). No embryos could be frozen when they were checked for blastocysts development on the morning of day 5 (116 h of development), where it was recorded that 7 embryos had only developed to the day 3 stage, and the remaining embryo had begun the process of compaction. Following 6 days of culture, the embryos are checked for development to the blastocyst stage. There is no developmental change for the 7 arrested embryos, and they are therefore not able to be frozen. Would you freeze the remaining embryo indicated here?

Vignette 8

Hannah, 35 years, has Asherman’s syndrome and requires a surrogate. Hannah’s partner Harry, 41 years, has semen parameters which are below the normal range, and poor morphology was noted on his most recent semen analysis. Specifically, a high number of sperm with elongated heads were recorded. Hannah’s sister Penny, 33 years, with two children of her own, has been a surrogate for Hannah and Harry during their past 4 cycles of ICSI. Hannah’s first cycle was characterized by a high number of immature eggs, but her subsequent cycles resulted in up to 10 mature eggs each time. Penny had a fresh blastocyst transfer, but no live birth, following Hannah and Harry’s last three cycles. In the current cycle, Hannah had 13 eggs collected, and 5 of these were immature. All of the mature 8 eggs fertilized following ICSI. After being checked on day 5, it was noted that 7 embryos had stopped developing at the cleavage stage and there was one blastocyst, but it was too early to tell whether it had a suitable ICM and trophectoderm, and this was therefore not frozen. Following 6 days of culture, the embryos are checked for development to the blastocyst stage. All 7 arrested embryos show no further progression and are not suitable for freezing. Would you freeze the remaining embryo indicated here?