Answering your questions

Wet mount bacteria reporting, venipunctures on children,
Miller disk use and arterial blood for tests

Wet mount bacteria reporting

Q: We need information about
reporting wet mounts. Should we report bacteria? Although bacteria are normally present in the vaginal area, some of us think that it would be diagnostically important. If we do report it, do we indicate as few, moderate, etc., or 1+, 2+, etc.? We all need to report the same elements. Also, should clue cells be reported in urine? By reporting clue cells in the urinalysis, would this help the health practitioner rule out a urinary tract condition vs. a vaginal condition?

A: Reporting the presence of bacteria
in a wet mount is not diagnostically helpful or standard procedure. As you stated, bacteria will normally be present on a wet mount. The more important question to answer is, What kind of bacteria is present? A gram stain provides a superior answer since this will differentiate between normal and abnormal vaginal flora. Additionally, the wet preparation should be examined for trichomonas, yeast/hyphae and clue cells (vaginal epithelial cells covered with gram variable rods).

Normal vaginal specimens show predominantly Lactobacillus. The most common organism found in vaginal infections is Gardnerella vaginalis. Infection with this organism is also termed bacterial vaginosis. Additionally, Mobiluncus and Bacteroides spp. are usually present and increased in bacterial
vaginosis.

Reporting clue cells in the urine provides one piece of information to the clinician, but is not a definitive clinical finding to diagnose a urinary tract infection or a vaginal condition. For a clinician assessing a patient with symptoms of abnormal vaginal discharge, the diagnosis of bacterial vaginosis can be made fairly easily by the presence of clue cells. On a wet mount, they have a granular appearance, and the borders are obscured. A gram-stained smear will show an altered vaginal flora, one filled with pleomorphic gram-negative to gram-variable rods and lacking in the normally present gram-positive lactobacilli. A positive whiff test (mixing vaginal secretions with a 10 percent KOH solution and noting a fishy smell) and a pH > 4.5 on the vaginal secretion lead to a fairly definitive diagnosis of bacterial vaginosis. Culture is usually not indicated.^1,2

Bacteria in the urine are not necessarily indicative of a urinary tract infection. We know that specimens can easily be contaminated and show clinically insignificant elements. Some laboratories only report bacteria when observed in fresh specimens in conjunction with white blood cells. However, since the laboratorian does not have a complete clinical history, it is prudent to report the findings and let the provider determine the diagnostic significance. Bacteria in the urine are significant when culture results show the presence of >105 CFU/mL. Counts between 103 and 105 may indicate an incipient urinary tract infection. Collecting another clean-voided midstream urine specimen is recommended.³

Small numbers of epithelial cells and bacteria may be found in urine, but generally are of little significance. Contamination or prolonged storage before examination contributes to an increase in bacteria; however, the presence of any bacteria should be reported in a urine sample.⁴

How do you report these elements? Your procedure must clearly spell out your reporting format and standards. In our laboratory, we report bacteria and cellular findings as few, moderate and many, per high power field, and quantify these ranges. The presence of clue cells could be reported in the comment field.

You may want to consider soliciting input from medical staff who frequently order microscopic urinalysis, consulting with your pathologist and checking the NCCLS guideline on urinalysis reporting.⁵ Your ultimate goal is to provide consistent, relevant diagnostic reporting that allows the providers to make the appropriate diagnosis and prescribe effective therapy.

Juanita Petersen, MT(ASCP), MBA
Manager, Core Laboratory
Oregon Health and Science University
Portland, OR

References

1. Wilson J, Braunwald E, et al. Harrisons Principles of Internal Medicine. 12th Edition. McGraw- Hill, Inc.; 1991.
2. Delost M. Introduction to Diagnostic Microbiology. Mosby, Inc.; 1997; 487-488.
3. Modern Urine Chemistry. Tarrytown, NY: Miles Inc.; 1991;63.
4. Tips of Urinalysis.
   MLO. 2000; 16-17.
5. NCCLS. Routine Urinalysis and Collection, Transportation, and Preservation of Urine
   Specimens. Approved Guideline GP 16-A2. Wayne, PA: NCCLS; 2001.

Venipunctures on children

Q: We have a doctor in our emergency department who insists on venous draws on all children for CBCs. Do you know of any benefit to venous draws vs. good capillary draws? The techs feel as though we are ruining the childrens veins and traumatizing them. Any recommendations?

A: Although capillary specimens
differ from venous specimens in glucose, potassium, total protein and calcium levels, venous blood for CBCs should correlate highly with blood from good capillary draws.¹ The operative word here, though, is good. When improperly performed, CBC results from skin punctures can vary significantly. Results can be altered by tissue fluid, hemolysis and platelet clumping if the puncture is traumatic or if excessive squeezing is required. Therefore, it is not unreasonable for one to consider blood obtained by venipuncture to be the gold standard. It is clear that your ED physician questions the integrity of the specimens collected by skin puncture and has concerns that not all skin punctures are good skin punctures. Perhaps a discussion on the skills of your phlebotomists would reassure him/her. At the same time, a skills assessment of your phlebotomists may be necessary for your own reassurance.