Do Busier IVF Days From Grouped Cycles Impact Pregnancy Rates and Embryo Development?

L. S. Morrison, S. M. Carney, M. P. Portmann, B. A. McGuirk, M. J. Tucker, R. F. Feinberg

Reproductive Associates of Delaware, Newark, DE

Objective:

To determine if days of higher IVF volume due to patient grouping for controlled ovarian hyperstimulation influences implantation rates, ongoing pregnancy rates, and blastocyst formation.

Design:

Outcomes of 561 fresh non-donor cycles from patients of all ages during a 5 year period were analyzed based on the daily number of retrievals performed: Low Intensity (1–3 retrievals/day), Moderate Intensity (4–6 retrievals/day) and High Intensity (7-8 retrievals/day). The parameters analyzed for each group were implantation rate, spare embryo blastocyst formation, and ongoing pregnancy rate per retrieval.

Materials and Methods:

Oocytes were retrieved in HTF (InVitrocare – IVC, Frederick, MD) or Fertilization Media (Sage, Cooper Surgical Inc. – Trumbull, CT) hyaluronidased after 2 to 3 hours incubation and ICSI’ed 1 to 3 hours following cumulus-corona removal. Oocytes were placed in IVC-1 (IVC) or Cleavage Media (Sage) after ICSI and cultured individually in this media until Day 3. Embryos were placed into CCM (Vitrolife, Denver, CO) or Blastocyst Media (Sage) on the morning of Day 3 for extended culture. The best embryos were identified and laser hatched prior to transfer using the Zilos laser system from Hamilton Thorne (settings: one pulse; 0.500 milliseconds duration). Morphologic assessment occurred on Day 2, 3, 5, 6 and 7. Blastocysts were cryopreserved on Day 5, 6 or 7. All transfers occurred on Day 3 or Day 5 using a Wallace 23cm stylet (Irvine Scientific, Irvine, CA) and Cook Echotip Catheter (Cook OB/GYN, Spencer, IN) under abdominal ultrasound guidance and were performed by the same physician (RF). Three Thermo-Forma water-jacketed CO₂ incubators were used for embryo culture by 2.5 (FTEs) embryologists. Oil overlay was utilized exclusively throughout the study period.

Results:

	Group A Low Intensity (1-3)	Group B Moderate Intensity (4-6)	Group C High Intensity (7-8)
# of Occurrences	220	35	6
# Patients	358	159	44
Mean Embryos Transferred	2.7	2.4	2.6
Implantation Rate	29.2%^*	28.8%^*	29.2%^*
Spare Blast Formation	22.2% ^1,3	25.1% ^1,2	16.2% ^2, 3
Ongoing Pregnancy Rate/Retrieval	44.4%^*	42.1%^*	45.5%^*
			^*p = N.S.
			^1Group A vs. Group B
			P = 0.03063
			^2Group B vs. Group C
			P = 0.00007
			^3Group A vs. Group C
			P = 0.00327

There were no statistically significant differences between groups A, B and C with regard to implantation rate and ongoing pregnancy rate using Chi Square Analysis. However, Group C resulted in significantly lower blastocyst formation rates when compared with Groups A and B, based on the total number of embryos.

Conclusions:

Grouping of IVF patients for controlled ovarian stimulation has numerous logistical and economic advantages for smaller clinics, as long as outcomes are not being compromised. As our facility has grown, so has the volume of IVF clinical and lab procedures during specific days. Although embryo implantation and ongoing pregnancy rates appear to be remarkably similar between lower and higher intensity work days, there may be other factors that are exerting a negative impact on blastocyst formation rates. One important factor in the lab may be repeated incubator openings, causing subtle but significant fluctuations in culture temperature and pH. In this study, our facility had a limited number of Group C (“high intensity” days). However, as IVF utilization increases, we will continue to evaluate this work volume factor prospectively, and will preemptively enhance workflow efficiency through additional sterile hoods, incubators, and professional personnel.