Controls & Proficiency

Sperm analysis is the only lab test that attempts to quantify live and independently moving cells. This reality creates a unique problem regarding controls and proficiency.

The electro-optical system of the SQA detects only motile cells, and derives the rest of its report from statistical evaluation. Therefore, external daily controls at two levels would have to be two populations of live cells at two different levels of activity. This is impractical, and for most laboratories impossible, for two reasons.

One obstacle is that any such controls must be initially evaluated by some means that produces an incontrovertible number. Even a $50k computer-assisted-sperm-analysis (CASA) system, or exhausting microscopic evaluations by a team of highly competent laboratorians, cannot provide perfect consistency, especially after the samples have been frozen, because different thaw rates and freeze times can have a significant effect upon vitality upon thaw.

Another obstacle, which probably makes it impossible to use live controls, is that live cells are sensitive to slight variations of temperature and other environmental conditions, and their characteristics change with time.

To avoid ambiguities, all controls would have to undergo identical freezing, storage and thaw conditions, and then be tested after the same time-since-thaw and at the same ambient temperature.

Controls

Labs that use CASA (computer-assisted semen analysis) use taped or digitized video as controls, which is a valid approach suitable to the andrology laboratory.

Labs that use microscopy usually depend upon fixed and dead specimens (often stained) on slides, as controls. Obviously, this is a distant second to a live and motile population, but until the introduction of the SQA it's been a necessary compromise.

Because the SQA is operated by an internal computer, it employs a solution that was presented to and accepted by the Centers for Disease Control (administrators of CLIA), and the California Board of Health. This approach is 100% objective and computer controlled.

Optical system test

The SQA's internal computer automatically self-tests every time the instrument is turned on; that internal procedure has several steps to it, of which the first is validation of the optical system. The system tests the optical path to ensure that there is no obstruction, and that all components are properly functioning.

It does that by measuring the amount of power required by the light source to produce a required level of detected light energy. That power check is actually a comparison to a precision internal standard used throughout the industry. Such a closed-loop system represents the highest level of electronic control, and ensures that there is no fault in the light circuit, or in the optical path.

Quartz crystal frequency measurement

To simulate an active specimen, an internal circuit produces an electrical signal based upon a quartz crystal, with better accuracy than that in a typical quartz watch. Such quartz crystals are built to various tolerances. The SQA uses a quartz crystal that is accurate to 1 part in 1,000 (1,000 parts in 1,000,000, or 6.1%). Such frequency control devices are very reliable, and are used in the most delicate and precise instruments in medicine, communication, and electronic test equipment. In the SQA, the quartz signal is used to modulate the light source.

Unless a given instrument passes its self-tests, and successfully achieves its self-calibration, the internal computer will not permit further use until corrective action is taken. If the instrument passes, then the computer will permit the following two levels of control:

Control One: MIDRANGE LEVEL

That signal is measured as fluctuations in light, identical to those created by moving sperm cells as they pass between the calibrated light source and the detector. Independent circuitry ensures that the control signal is correct, and so can the operator, as follows:

By pushing the calibration button (rear panel), the frequency number (409 ±2) should be displayed. Ibis corresponds to a midrange, or "normal" sample.

Control Two: LOW LEVEL

The second control is the "LOW" test. A blank capillary is inserted into the instrument, and a normal test is performed. The displayed result must be 000 (+2, -0).

Summary

The SQA uses the most redundant and accepted self-test and selfcalibration protocols, computer operated and based upon the same high quality internal frequency and voltage standards upon which the world of technology depends.

If an SQA passes its stringent self test, and subsequently passes the MEDIUM and LOW level controls tests, it is fully functional and may be depended upon.

Proficiency

Because technical operation is governed and measured by the instrument, the operator demonstrates proficiency by following the simple protocol required to support the SQA's internal computer. There is no judgment required by the operator.

Typically, to demonstrate proficiency the operator:

• Turns on the instrument and observes the built-in test result. Checks the "LOW" range of detection using an empty capillary.
• Allows a collected sample to liquefy, and then stirs/mixes the sample to ensure homogeneity.
• Fills the capillary tube and uses the provided swab to remove any of the sample from the exterior surface of the capillary.
• Inserts the capillary into the instrument, presses the "READ" button, and records the results.

In addition, some organizations establish collateral procedures requiring checking, such as sample identification, visual checks, disposal of biohazard waste, record-keeping, etc. These may be included in the proficiency testing protocol.