be found in the Clinical Microbiology Procedures Handbook (1).
Protocols are divided into three sections: preanalytic, analytic, and postanalytic. The preanalytic phase includes steps taken before the test is actually performed (pre-examination phase). Processes begin with the test request and its format, patient preparation, specimen collection, specimen transportation, specimen receipt in the laboratory, and specimen processing. The analytic phase contains all activities related to the performance of laboratory testing or examination of specimens. The postanalytic phase contains the steps that occur after a laboratory test has been performed. Processes include data review, report formatting, result interpretation and presentation, permission for release, result transmission, and sample storage.
Specimen Handling and Record Storage
All specimens must be recorded in an accession book, log book, worksheet, computer, or other comparable record. If specimens are not examined as fresh material, they should be preserved in appropriate fixatives for later examination. On the basis of current guidelines, it is recommended that specimen and test result records be kept for at least 2 years (longer for pathology records and those from the blood bank). Also, remember that when your laboratory is inspected, you must be able to retrieve those records within no more than a few hours; this is particularly important if the inspector is actually checking this parameter.
Test Request Requisitions
All requisitions should be designed to allow sufficient information for patient and physician identification and any clinically relevant information. Specific items should include (i) patient name, (ii) patient identification number, (iii) name of ordering physician, (iv) source of specimen, (v) specific procedure(s) ordered, (vi) time of specimen collection, and (vii) time of receipt or initial processing by the laboratory. Other helpful information, particularly in the parasitology division, is (i) suspected diagnosis, (ii) travel history, and (iii) recent medication. Since this information is often not on the original requisition, the physician may have to be contacted for clarification.
Procedure QC and Documentation
QC measures for all procedures are included in the individual protocols within this section of the book. Not only must the QC checks be performed as indicated, but also complete documentation should be generated, including specific plans for out-of-control results and problem resolution. Result expectations and normal results or values must be specifically defined and posted on any QC check sheets used in the laboratory. It is not sufficient to merely check a column that QC is within acceptable limits; you must also have on these sheets a definition of what normal or “acceptable limits” means. Dates and space for the initials or name of the person performing the QC checks must also be included. Specific procedure recommendations include the following (1, 6, 55, 56)
1. The examination of formed stools should include a concentration procedure.
2. A permanent stained smear is recommended for every stool specimen submitted for testing (liquid, soft, or formed).
3. A direct wet mount should be performed for fresh stool specimens (liquid or mushy—not semiformed or formed), in addition to the concentration and permanent stained smear. Since the direct wet mount is designed to allow the detection of organism motility, it is not necessary to perform the direct wet mount on preserved specimens or semiformed/formed stools. Consequently, if the stool specimens are received in preservative, proceed directly to the concentration and permanent stained smear.
4. Both thick and thin blood films are prepared for examination for malarial parasites.
5. Stained smears are washed with buffered distilled water (pH 6.8 to 7.2); any of the blood stains can be used (Giemsa, Wright/Giemsa, Field’s, rapid stains).
6. Adequate numbers of oil immersion fields should be examined (at least 300) on both stained blood films and permanent stained fecal smears.
Test Result Reports
With few exceptions, the following methods of reporting are acceptable.
1. All parasites should be reported, regardless of whether they are considered nonpathogenic or pathogenic. The presence of any parasites within the intestine generally confirms that the patient has acquired the organism through fecal-oral contamination.
2. Generally, protozoa and helminths are not quantitated on the laboratory slip. However, the specific stage (i.e., trophozoites, cysts, oocysts, spores, eggs, or larvae) is indicated.
3. Exceptions to quantitation would be Blastocystis spp. (there may be some association between numbers and symptoms) and Trichuris trichiura (light infections may not be treated).
4. The complete genus and species name of the organism identified should be reported.
5. Charcot-Leyden crystals should be reported and quantitated.
6. If the specimen is fresh or freshly preserved, budding yeast cells should be mentioned and quantitated (consultation with the physician recommended).
7. All quantitation should be consistent (Table 11.9).
8. Helminth eggs and larvae should be reported.
9. Special circumstances (additional specimens required to rule out this infection, etc.) require additional comments on the laboratory report.
10. Remember, the name of the laboratory actually performing the procedures must be indicated on the final report or elsewhere.
Reagents
All reagents should be properly labeled with (i) content, (ii) concentration, (iii) date prepared or received, (iv) lot number, (v) date placed in service, and (vi) expiration date. If reagents are prepared in-house, you should also have recorded (i) the name of person preparing the reagent and (ii) the date and results of the QC check.
The specific gravity of certain solutions (e.g., zinc sulfate) should be checked before use (this is particularly important if the solution is used infrequently). The hydrometer should have a scale large enough to differentiate between specific gravities of 1.18 for use with fresh specimens and 1.20 for use with formalinized specimens. This type of solution should be kept in a tightly stoppered bottle.
Stains should be routinely checked with control specimens for correct staining properties before use. Certainly, new lot numbers or new batches of stain should be checked. Also, if reagent use is infrequent, the stains should be checked before use. The same rule generally applies to fixatives.
With these basic recommendations in mind, the following specific QC methods can be used. While not every reagent used in diagnostic parasitology work is reviewed, these methods can be adapted to other reagents.
The examination of fecal material for ova and parasites may reveal, in addition to parasitic
