Key Performance Indicators (KPI) in an embryology laboratory

Key Performance Indicators (KPI)

As your team expands and you add on more embryologists in your stand-alone centre or centres, it is very important to have benchmarks and KPIs to evaluate and standardize the performance of embryologists. Standard operating procedures along with benchmarks reduce variability in your procedure, thereby creating a robust operating system inside the laboratory. For instance, you see a dip in your pregnancy rates, but you know that there is strict adherence to SOP and all the embryologists are performing within benchmark. This will give an indication that the problem may lie in the stimulation or the cold chain of injections and so on. Remember the lesser the number of variables, the easier it is to analyse and reach the source of the problem. KPIs also help in determining whether any team member in the lab needs more training or fine-tuning in any of the procedures.

Systematic monitoring of embryology key performance indicators (KPIs) is an important component of quality management within the IVF laboratory. Embryology KPIs track performance and benchmark against industry standards(1). Key Performance Indicators (KPIs) are deemed essential for evaluating the introduction of a technique or process, establishing minimum standards for proficiency, monitoring ongoing performance, and benchmarking and quality improvement. In general, the results of a series of KPIs will provide an adequate overview of the most important steps in the IVF laboratory process(2)

Some of the important KPI are listed as follows:

  • 1. Oocyte recovery and maturity
  • 2. Sperm KPI
  • 3. Fertilization rate
  • 4. Oocyte degeneration
  • 5. Cleavage rate
  • 6. Blastulation rate
  • 7. Usable blastulation rate
  • 8.Pregnancy rate
  • 9. Implantation rate
  • 10. Live birth rate

Oocyte Recovery and Maturity

Oocyte recovery rate is defined as the likelihood of aspirating a COC from each follicle over a certain size, as measured on the day of triggering. The rationale for this is the expectation that the follicles that have achieved a certain size. The expected recovery rates, based on several studies, are generally ranging from 70 to 80% as the competence level, and 85–100% as the benchmark value.

Oocyte maturity rate, generally related to nuclear maturity, is defined as the proportion of oocytes at MII stage. Its potential value is as a marker of the efficiency of ovarian stimulation and triggering. Of the Alpha survey respondents, 80% indicated that their laboratory determined the MII rate, with median competence and benchmark values of 75% and 90%, respectively.

Sperm KPI

Andrology laboratory PIs are related to sperm recovery rate, and sperm motility post-wash. The expected proportion of motile spermatozoa in the final washed preparation showed values of 90% for competency and 95% for the benchmark.

A major issue when considering semen analysis data is that many ART laboratories do not employ methods that meet the minimum standards required by the World Health Organization (WHO). Therefore, reported values for sperm concentration and motility must be understood to have high certainty of measurement; any association between semen analysis characteristics, yield and fertility potential will remain unclear if you are using inappropriate semen analysis techniques. For that reason, it is very important for laboratories to adopt the correct method of doing semen analysis and sperm preparation. You should invest in a maklers chamber which helps in analysing the correct sperm count and motility.

Morphology is another important parameter and WHO proposes a cut -off of 4% normal should be kept in mind while reporting the percentage.

Sperm recovery rate, defined as the percentage recovery of progressively motile sperm after washing as compared to pre-washing, can be used as a laboratory KPI, providing useful information for inter-operator comparison and proficiency testing.

A laboratory should develop its own standard based on WHO guidelines. It should aim at developing a robust technique for semen analysis and preparation.

Although several potential KPIs have been identified in ICSI, the presentation focused on the four most pertinent, i.e. normal fertilization rate, oocyte degeneration rate, poor fertilization rate and failed fertilization rate.

Fertilization Rate

Fertilization is seen about 16 – 19 hours after the procedure, to determine the presence or absence of pronuclei. A normal fertilization process is defined based on the formation of two distinct pronuclei. The percentage of fertilized oocytes is used as a benchmark for the KPIs-score.

ICSI fertilization rate is a commonly reported and effective indicator that is informative of gamete quality and operator competence. ICSI 2PN rate depends on the various criteria used for performing ICSI, which can be considered a weakness of the indicator.

Benchmark for fertilization rate after ICSI sits at or above 70%.

The formula used to calculate fertilisation rate is:

ICSI Fertilisation Rate   = Number of oocytes with 2PN X 100
Number of MII injected

Oocyte Degeneration

ICSI damage rate or oocyte degeneration rate is ranked important and is based on the operator competency and oocyte quality. Oocyte damage can be observed at two time points during the ICSI process: during ICSI, or at the fertilization assessment on Day 1. Oocyte damage probably occurs most frequently during injection, but without immediate signs of damage; this is not detected until the fertilization check. Oocyte damage is more probable in oocytes which have no resistance and are termed as “fragile”. Degenerated oocytes during ICSI or on the day of fertilization check should be recorded together, as the reason for both is likely to be the same – ICSI.

There is a third instance where oocytes may be degenerated, that is, during denudation. The frequency is quite low and this can be recorded separately, as the cause is most likely the operator’s incompetency. In this case, the operator should be trained and validated again for denudation.

The benchmark for oocyte degeneration during or after ICSI should be less than 10%. In case the degeneration is more for a specific operator, their techniques should be reassessed and fine tuning should be advised, wherever necessary. If all the operators in the lab have a degeneration rate above 10%, it could be indicative of technical problems (e.g. cumulus cell removal stress, vibration), and an in depth analysis should be done.

Formula to calculate the oocyte degeneration rate is:

Oocyte degeneration rate = Number of degenerated oocytes X 100
Number of MII injected 

Cleavage rate

The morphological quality of the embryonic lot is evaluated routinely from 48 to 72 hours after injection at the cleavage stage, depending on Day 2 or Day 3. The embryos are broadly graded based on the cell number, symmetry and fragmentation. It is important to assess the embryos according to the timeline so as to assign them an accurate grade.

Cleavage rate reflects the ability of the culture system to support cellular division of fertilized oocytes. It is an indicator of embryo viability and has the ability to detect culture media contaminants. The presence of non-cleaved embryos or arrested zygotes on Day 3 is associated with a decrease in quality of the remaining cohort, but without a negative impact on the clinical outcome.

Cleavage rate, defined as the proportion of zygotes which cleave to become embryos on Day 2, is considered important and is widely monitored.

The benchmark for Cleavage rate should be > 95%

Formula for Cleavage rate is = Number of embryos cleaved X 100
Fertilized oocytes

Another important parameter to be considered during the cleavage stage is the rate of good quality embryos, defined as the proportion of Days 2 and 3 embryos with high score or grade. Many different scoring systems exist but for your internal scoring you should adopt one grading system and base your calculation and analysis on it. A good cleavage rate along with good A+B grade embryos on Day 2 and Day 3 are a positive indicator of your culturing system and lab parameters.

Blastulation rate

The blastocyst development rate, defined as the proportion of 2PN zygotes (not just of cleaved zygotes) at the blastocyst-stage on Day 5 (116 ± 2 h post-insemination), is rated important because it reflects the efficiency of the whole culture system. Blastocyst development rates can be calculated on Day 5, 6 or Days 5/6 combined.

The blastocyst development rate, though an objective parameter, is dependent on the assessment of blastocyst morphology, which is straightforward in case of good quality blastocysts, but can be challenging for embryos showing an attempt of cavitation. Various factors that can affect the blastulation rate are timing of laboratory observation, culture medium and culture conditions.

Blastocyst quality should be based on three factors, namely,  blastocoel expansion, appearance of trophectoderm (TE) and appearance of inner cell mass (ICM), although all three parameters have shown to be significantly correlated with pregnancy and LBR.

The benchmark for blastulation is highly variable. According to the alpha survey, there is huge variation ranging from 40% to 100%. However in our opinion, a good blastulation rate would be 45% and upwards.

Formula for calculating blastulation rate:

Blastulation rate = Number of blastocyst X 100

Usable blastulation rate:

Your laboratory forming blastocyst is one thing, but the number of usable blastocysts is equally important. Usable blastocyst is the number that is as the name suggests – Usable, either for embryo transfer or Vitrification.

Your laboratory may form blastocysts, but unless they are of good quality, their pregnancy and implantation potential will be low.

There is no definite benchmark for the number of usable blastocysts, as this parameter is variable and will depend largely on your grading protocol and the level of strictness. Some laboratories may transfer a C/D grade blastocyst, while the others may restrict it to only A/B and maybe C in case of no option. This variation will lead to a skewed usable blastocyst rate from laboratory to laboratory.

According to us a good usable grade benchmark should sit at 80% and above, which means that out of blastocysts formed on Day 5 and Day 6, there will be 80% blastocyst that may be transferred or vitrified.

Formula for usable blastocysts:
Usable blastulation =      Usable blastulation     X 100
Total blastocyst formed

Pregnancy rate

Pregnancy rate is calculated based on Beta HCG positive after 14 days of cleavage embryo transfer and 10 days after blastocyst transfer.

Pregnancy rate is not an accurate indicator of the efficiency and culture system of your clinic. A patient can be Beta HCG positive by transferring one or four embryos since this parameter is based on just being positive and not on how many embryos it takes to achieve the pregnancy.

Pregnancy rate will also vary across self, ovum donation and embryo donation cycles. Pregnancy rate will again be variable but according to us the pregnancy rate should be 60% for ovum and embryo donation cycles and 50% for self cycles.

Formula for calculating pregnancy rate

Pregnancy rate =     No of Beta HCG positives   X 100
Number of embryo transfers

Implantation rate

Implantation rate is an important indicator that reflects the overall performance of the laboratory; an overall low implantation rate is a serious alert. Implantation rate is defined as the number of gestational sacs observed, divided by the number of embryos. Implantation rate reflects the efficiency of the whole culture system, but it can be influenced by uterine receptivity, and by different policies for embryo transfer in different centers. A good clinic should transfer a maximum of two embryos and this will be reflected in the implantation rate.

Example: If you have transferred four embryos and got only one gestational sac, the implantation potential is ¼ = 25% which is low and indicates that you need four embryos to achieve one pregnancy. This also indicates that your embryo selection method is not robust. You are said to have a good embryology program if you are able to select the best embryos for transfer and achieve pregnancy with the lowest number of transferred embryos. This will ensure not only conception but a safe pregnancy term.

Implantation rate is lesser than pregnancy rate as after Beta HCG positive, some patients may see a drop in beta hcg which is termed as biochemical loss.

Benchmark for implantation rate is again a variable parameter and will have variance across self, ovum donation and embryo donation.

However, in our experience benchmark for implantation for ovum/embryo donations is at 40-45% and for self-cycles is 35%

Formula for implantation

Implantation rate =        Number of gestational sac     X 100
Number of embryo transferred

Live birth rate

LBR may be considered as the ultimate KPI for checking IVF clinic performance and is defined as the likelihood of a baby to be born per embryo transferred. LBR is largely affected by a series of clinical maternal factors pertaining to post-implantation development, rather than reflecting laboratory performance. This parameter can be calculated annually, but it is often difficult to collect the data.

Thereby, implantation rate is a good parameter to assess the performance of the lab and clinic.

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