Reference Ranges

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Reports after the 1st October 2011 will show reference values from the updated WHO guidelines (2010). Motility will be reported as 3 categories instead of 4 and a chart showing 95th percentiles will be on the back of the reports.

Lower reference limits (5th centiles and their 95% confidence intervals) for semen characteristics :

 

Parameter Lower reference limit  Laboratory method uncertainty (95% CI)
Semen volume (ml) 1.5 (1.4-1.7)  1.4-1.7
Total sperm number (106 per ejaculate) 39 (33-46)
Sperm concentration (106 per ml) 15 (12-16)  13-16
Progressive motility (PR, %) 32 (31-34)  30-34
Sperm morphology (normal forms, %) 4 (3.0-4.0)  3.74-4.26
Vitality (live spermatozoa, %) 58 (55-63)
pH ≥ 7.2

Distribution of values for semen parameters from men whose partners became pregnant within 12 months of discontinuing contraceptive use (click on title to view table).

Measurement Uncertainty Values for Semen Analysis

Every measurement is subject to some uncertainty. Measurement uncertainty can come from the measuring instrument, from the item being measured, from the environment, from the operator, and from other sources. Measurement uncertainties can be estimated using statistical analysis of a set of measurements. The use of good practice such as traceable calibration, careful calculation, good record keeping, and checking can reduce measurement uncertainties.

In order to provide a measure of confidence in results produced by a laboratory, it is necessary to identify all factors which may contribute to variation of measurement in a process and assess the potential to influence uncertainty. Once identified these factors must be reduced or controlled to an acceptable level and a value for the range of acceptable uncertainty assigned where possible.

Andrology has determined the measurement uncertainty values for semen analysis. They are reviewed regularly and reassessed whenever a significant change in the procedure occurs, e.g. new equipment or modification of the assay. These uncertainty measurement values are available upon request.

Retrograde semen analysis

Retrograde ejaculation is a condition where semen is ejaculated backwards into the bladder. Some patients may be able to produce semen if masturbation takes place whilst the bladder is full. The urine is examined for the presence of spermatozoa if there are no spermatozoa in the semen sample or if no semen is produced.