Researchers in a 2023 study report the results of an Italian consensus of clinicians and embryologists on key performance indicators (KPIs) to assess IVF clinic quality. This includes KPIs like rates for egg maturity, fertilization, blastocyst formation, thaw survival, clinical pregnancy, and more.
This consensus is based on the collaboration between the Italian Society of Fertility, Sterility and Reproductive Medicine (SIFES-MR) and the Italian Society of Embryology, Reproduction and Research (SIERR).
The groups added to existing consensuses on KPIs in IVF, in particular the Vienna Consensus of 2017 and the Maribor Consensus of 2021.
The experts suggested different indicators to assess clinical and lab quality. Each indicator was given a value for minimum competence (what the lab should be able to achieve) and benchmark values (what they should strive for). They also included the suggested frequency the IVF clinic should evaluate these indicators, to ensure that high quality is maintained.
Where appropriate, the indicators were stratified based on female age (≤34 years, 35–39 years,≥40 years) and ovarian response (poor, normal, and high responders). Poor responders are women who collect less than 4 eggs during a cycle, and high responders collected more than 15.
The panel of experts didn’t fully agree on all of the indicators, so they organized them based on their level of agreement:
- KPIs with high agreement (>80%).
- Performance indicators with medium agreement (40-80%).
- Recommended indicators with poor agreement (<40%).
🔗 Original studies are referenced in this post or within the linked Remembryo posts.
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Highly agreed upon key performance indicators for IVF
The highly agreed KPIs are listed below (>80% of participants agreed). Following the chart, I’ll provide the definitions for each KPI and the formula used to calculate it, as indicated by the authors, along with any other select additional information that was provided.
IVF cycle cancellation rate:
- Definition: IVF treatment discontinuation before retrieval.
- Formula: Number of cancelled cycles before retrieval / Number of cycles started.
Late follicle-to-oocyte index (FOI):
- Definition: The FOI assesses the number of late follicles (antral follicles up to the 5th day of stimulation) to the number of retrieved eggs.
- Formula: Number of eggs retrieved / Number of antral follicles at the beginning of ovarian stimulation.
- Additional information: “Comparing the number of oocytes retrieved to the cohort of follicles matured during ovarian stimulation is valuable to understand if starting dose, triggering and oocyte retrieval were properly defined and conducted.” Besides technical issues, low responses may be due to genetic or environmental factors.
Mature eggs at ICSI:
- Definition: Proportion of mature eggs available for ICSI.
- Formula: Number of mature (MII) eggs at ICSI / Number of eggs retrieved.
- Additional information: Low egg maturity rates may be due to 1) low levels of hCG in the follicle (due to high BMI, injection errors), 2) <35 h between injection and retrieval, 3) follicles < 14 mm, 4) LH receptor deficiency. “Values outside the normal range must prompt a review of any changes in ovarian stimulation, triggering, or follicle aspiration practices.”
Complication rate after retrieval:
- Definition: Complications include bleeding, infection, severe pain or injury of pelvic structures. Excluding OHSS.
- Formula: Number of complications / Number of retrievals.
ICSI fertilization rate:
- Definition: The proportion of injected mature eggs with 2 pronuclei (2 PN) and 2 polar bodies (2 PB) the day after injection.
- Formula: Number of fertilized eggs with 2 PN and 2 PB / Number of mature eggs injected.
- Additional information: This is an important KPI that is informative of both sperm and egg quality, as well as the competency of the embryologist.
Embryos with ≥8 cells on day 3:
- Definition: The proportion of embryos with at least 8 cells on day 3 (around 68 h after insemination).
- Formula: Number of embryos on day 3 with 8 or more cells / Number of fertilized eggs.
- Additional information: This KPI informs on the quality of the lab’s culturing system. This KPI is also dependent on egg and sperm quality (not mentioned by the authors).
Blastocyst formation rate:
- Definition: The total number of blastocysts that develop up to 168 h post insemination (day 7).
- Formula: Number of blastocysts / Number of normally fertilized eggs.
- Additional information. This KPI only considers whether or not a blastocyst formed, and doesn’t consider its quality or how fast the embryo became a blastocyst. This KPI reports on the quality of the IVF lab’s culturing system. This KPI is also dependent on egg and sperm quality (not mentioned by the authors).
Clinical pregnancy rate:
- Definition: Pregnancy confirmed by clinical means (ultrasound visualization of the gestational sac, heart beat, etc.).
- Formula: Number of clinical pregnancies / Number of first embryo transfers (first transfers tend to use the best quality embryos).
- Additional information: This KPI is an indicator of how well a lab selects an embryo for transfer and the transfer procedure itself. It isn’t representative of the overall performance of an IVF center (which is better represented by cumulative live birth rate – listed as a performance indicator in the next section). This KPI is also dependent on egg and sperm quality (not mentioned by the authors).
Multiple pregnancy rate:
- Definition: A pregnancy with one or more fetuses.
- Formula: Number of pregnancies with more than one fetus / Number of pregnancies.
- Additional information: Women with twin pregnancies are at higher risk of complications, especially among those who are older, therefore single blastocyst transfers are often recommended. The risk of multiple pregnancies after a single embryo transfer is about 1-2%. For the recommended number of embryos to transfer by age see my post How many embryos to transfer? 2021 ASRM recommendations.
Miscarriage rate:
- Definition: The number of spontaneous losses of an IVF pregnancy.
- Formula: Number of miscarriages / Number of clinical pregnancies.
- Additional information: Pregnancy loss after IVF is about 13-32%, but can be higher in women of advanced age.
Cycles with ovarian hyperstimulation syndrome (OHSS):
- Definition: OHSS is a complication of fertility treatment, characterized by vomiting, abdominal pain, and a variety of clinical factors.
- Formula: Number of cycles with moderate or severe OHSS / Number of started cycles.
- Additional information: The incidence of severe OHSS ranges from 2-9%.
Performance indicators for IVF with medium agreement
The performance indicators with medium agreement (40-80% or participants agreed) are listed below. Following the chart, I’ll provide the definitions for each KPI and the formula used to calculate it, as indicated by the authors, along with any other select additional information that was provided.
IVF fertilization rate:
- Definition: The proportion of injected mature eggs with 2 pronuclei (2 PN) and 2 polar bodies (2 PB) the day after conventional IVF.
- Formula: Number of eggs with 2 PN and 2 PB / Number of eggs retrieved.
- Additional information: Conventional IVF isn’t dependent on the embryologist’s skill as much as ICSI.
Egg thaw survival rate:
- Definition: The proportion of living and intact eggs after thawing.
- Formula: Number of eggs that survived / Number thawed eggs.
Day 3 embryo survival
- Definition: The proportion of day 3 embryos that have at least 50% of cells surviving, or all cells surviving.
- Formula: Number of thawed day 3 embryos with at least 50% of surviving cells, or all cells surviving / Number of thawed embryos.
Blastocyst thaw survival
- Definition: The proportion of blastocysts thawed that have at least 75% of cells intact.
- Formula: Number of blastocysts that survived / Number of blastocysts thawed.
Successful biopsy rate:
- Definition: Proportion of biopsied samples where DNA is detected (ie. no “no result” or inconclusive results).
- Number of biopsies with DNA detected / Number of biopsies performed.
- Additional information: The rate of inconclusive results ranges from 3-7%.
Follicular output rate
- Definition: A measure of the pool of antral follicles at the beginning of ovarian stimulation that become pre-ovulatory follicles at the end.
- Formula: Number of pre-ovulatory follicles / Late antral follicle count.
- Additional information: This metric could help in assessing the quality of ovarian stimulation, with a low FORT (ie. 30%) indicating a hypo-response.
- Definition: Started cycles that result in the live birth of at least one baby (after multiple transfers of embryos from that cycle).
- Formula: The number of live births from one started cycle / All cycles in which all embryos are transferred until a live birth occurs, or until all embryos are used (including all cycles without transferable embryos obtained also), whichever occurs first.
- Additional information: The authors note that this metric is the most important indicator for an IVF clinic. However, it requires at least a year of follow-up to be accurate, which many clinics do not do, which is why this was ranked as a performance indicator and not a KPI.
Recommended indicators for IVF with low agreement
A number of other indicators were listed, but I’ll just address the prevalence of failed cycles indicator, which has to do with how often an ovarian stimulation cycle results in no eggs. This can be due to empty follicle syndrome. The competence for this metric was proposed as 7% or less, and 0.5% or less as the best practice goal.
Another indicator worth mentioning is treatment discontinuation, which is when patients stop treatment without becoming pregnant. For this indicator, the IVF clinic should have 50% or less for competency and 25% or less for a best practice goal. They note that it’s “very difficult and inappropriate” to compare discontinuation rates between clinics and countries because of differences in access to treatment, cost, etc. IVF discontinuation rates range from 20-60%.
Conclusions
This Italian consensus presented here gives different values for a number of IVF clinical and lab indicators.
Based on the suggested KPIs, the authors also presented a scoring system to generate a “comprehensive center performance score,” as a self-assessment tool. I’m not detailing that information here, since it’s not usable by patients. This is something that is calculated by the clinic using data from all of the patients they treat, which is information that generally isn’t available to the public.
You can access their formula by going to the publication itself (search “comprehensive center performance score”).
The authors state that “a comprehensive and accurate comparison between different clinics can be hardly conducted” using this tool, and that the cumulative live birth rate represents “the main clinical measure of success in IVF.”
Still, the values for the different indicators presented here give insight into what represents minimum competence, and what IVF labs should be striving for. I think this is crucial information for patients to have, but it’s important to recognize that these values are based on averages among a large number of patients and individual results may be very different, due to differences in egg or sperm quality, genetics, etc.
Reference
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About Embryoman
Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.
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