Andrology

Information for healthcare professionals

The following information is intended for healthcare professionals and laboratory users.

Measurement uncertainty

Measurement uncertainty is the range within which the true value of a test result is expected to lie. It is a recognised part of all laboratory testing and is monitored as part of the laboratory's quality management system.

Diagnostic semen analysis

The laboratory has calculated the coefficient of variation (CV) for each diagnostic semen analysis parameter and uses this as the measurement uncertainty associated with that parameter.

Clinical interpretation

When results are close to established clinical decision limits, measurement uncertainty should be considered during interpretation. The associated uncertainty may influence the clinical pathway for patients whose results lie near the decision thresholds for a specific parameter.

Examples include:

• Motility: a reported result of 30% with an expanded uncertainty of ±5.1% gives a reportable range of 24.9%–35.1%
• Concentration: a reported result of 16 × 10⁶/ml with an expanded uncertainty of ±5.8 × 10⁶/ml gives a reportable range of 10.2–21.8 × 10⁶/ml
• Morphology: a reported result of 4% with an expanded uncertainty of ±1.8% gives a reportable range of 2.2%–5.8%
• Vitality: a reported result of 54% with an expanded uncertainty of ±13.9% gives a reportable range of 40.1%–67.9%

Understanding and communicating measurement uncertainty is particularly important when results are close to diagnostic decision limits, as the uncertainty interval may cross clinically significant thresholds and therefore influence patient management within the fertility pathway.

The potential clinical impact of measurement uncertainty will be communicated to service users through annual updates published on the departmental website.

Post Vasectomy Semen Analysis

To ensure compliance with the clearance levels of the 2016 post vasectomy guidelines (<100, 000 sperm/ml) the laboratory have ensured that sperm can be detected in samples that contain 1,753.8 sperm/ml (as ascertained through multiple dilutions).

Retrograde Analysis

Retrograde samples have multiple factors that can influence the uncertainty of the results. The laboratory has established a limit of detection for sperm of 18.8 sperm/ml.

Clinical impact

Measurement uncertainty, either for one reported parameter or as a combination of multiple reported parameters could have a clinical impact. For example, if a concentration of 15 x 10⁶/ml is reported (oligozoospermia), given a UoM of 1.4 x 10⁶/ml, this sample could have a concentration of 16 x 10⁶/ml (normozoospermia).

For some users, a diagnosis of oligozoospermia, even at the borderline level of 15 x 10⁶/ml, could lead to the recommendation of an assisted reproductive technology such as intracytoplasmic sperm injection (ICSI) to promote the chance of fertilisation, when conventional IVF, or even natural conception, might be possible.

We inform our users of this uncertainty and emphasize that the reports can be used to guide clinicians to determine how to proceed with further investigation and management of a subfertile couple. We stress that all reported parameters should be considered holistically.

Furthermore, as per WHO 2021 guidance, we inform users that many known and unknown female factors hamper the value of using only semen examination parameters to predict the prognosis for the couple of spontaneous or assisted fertilization.

The decision limits that we provide on our reports are derived from WHO 2021 and are derived from data characterizing the semen characteristics of a reference population (men whose partners had a time to pregnancy of 12 months or less). The data uses a diverse international populations, noting that the percentiles used do not represent distinct limits between fertile and subfertile men.

We highlight that a semen analysis is never prognostic of fertility, as it is the fertility potential of the couple that defines them as fertile or subfertile.