ICSI Fertilisation and Oocyte Degeneration Rates: KPIs and Troubleshooting

ICSI is a skilled technique, and its results vary between operators and laboratories. Measuring the right key performance indicators (KPIs) helps embryologists track their own competence and lets laboratories detect problems early. This guide explains the main ICSI KPIs and how to troubleshoot poor results.

The main ICSI KPIs

The ESHRE and ALPHA Vienna consensus (2017) proposed reference indicators for IVF laboratories. For ICSI, the most relevant are:

• ICSI damage (degeneration) rate: the proportion of injected oocytes that degenerate. The consensus suggests a competency value of 10% or less and a benchmark of 5% or less
• ICSI normal fertilisation rate: the proportion of injected mature (MII) oocytes with two pronuclei (2PN). The consensus suggests a competency value of 65% or more and a benchmark of 80% or more
• Failed fertilisation rate: cycles in which no oocyte fertilises after ICSI should be rare

Each laboratory should calculate these regularly, per embryologist as well as for the lab as a whole, and compare them with its own historical results.

Causes of oocyte degeneration after ICSI

Operator technique

• Using an injection pipette that is too wide, blunt or poorly angled
• Excessive aspiration of cytoplasm, or failing to break the oolemma cleanly
• Injecting too much PVP or medium
• Holding the oocyte with too much suction
• Positioning the polar body incorrectly, increasing the risk of damaging the spindle

Equipment and conditions

• Temperature drift on the heated stage
• Poorly aligned optics or micromanipulator, causing uneven movements
• Unstable pH while the dish is outside the incubator for too long

Oocyte factors

• Fragile oolemma or abnormal oocyte morphology, sometimes linked to the stimulation response
• Damage during denudation. See our guide to oocyte denudation and maturity assessment

Causes of low fertilisation after ICSI

• Injecting immature (MI or GV) oocytes by mistake
• Not immobilising sperm properly before injection
• Sperm-related factors such as globozoospermia or severe DNA damage
• Oocyte activation failure, which is a cause of repeated total fertilisation failure in some couples
• Assessing fertilisation too early or too late. Fertilisation checks are usually performed about 16 to 18 hours after injection

A troubleshooting approach

1. Look at the data. Is the problem limited to one operator, one day, one batch of consumables, or the whole lab?
2. Check equipment. Verify stage temperature, micromanipulator alignment and pipette quality
3. Review technique. Observe or record injections; peer review is very effective
4. Review the patient factors. One cycle with poor results may reflect the patient's oocytes rather than the lab
5. Act and remeasure. Document corrective actions and track KPIs to confirm improvement

Our article on IVF lab KPIs explains how to set up continuous monitoring.

Competence and supervised training

ICSI skills develop through supervised practice. Trainees typically begin by practising on discarded or donated material where permitted and consented, before performing ICSI on patient oocytes under close supervision until their KPIs consistently meet the laboratory's standards. Under India's ART (Regulation) Act, 2021, ICSI may be performed only in registered Level 2 ART clinics, by appropriately qualified staff. See how long it takes to learn ICSI.

Frequently asked questions

What is an acceptable degeneration rate after ICSI?

The Vienna consensus suggests a competency value of 10% or less and a benchmark of 5% or less for oocytes damaged by injection.

What is a good ICSI fertilisation rate?

The Vienna consensus suggests a normal fertilisation rate (2PN) of at least 65% of injected mature oocytes as a competency value, and 80% as a benchmark.

When should fertilisation be checked after ICSI?

Usually about 16 to 18 hours after injection, when the two pronuclei are visible.

Train in micromanipulation and ICSI

ReproNest's Masterclass in Micromanipulation & Advanced ICSI / Laser Assisted Hatching covers micromanipulator setup, micro-tools, sperm processing and injection technique. Read what hands-on ICSI training should cover, or contact our team.

This article is educational content for healthcare professionals and trainees. It is not medical advice and does not replace clinical judgement, current guidelines or the ART (Regulation) Act 2021 and Rules 2022.