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CAP Home > CAP Reference Resources and Publications > CAP TODAY > CAP TODAY 2009 Archive > Q & A for November 2009
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  Q & A

 

 

 

 

November 2009

Editor:
Fredrick L. Kiechle, MD, PhD

Question Q. What is the standard for reporting sperm in urine? My logic says you report every element you see. Our policy is not to report sperm if we see it in the sediment of women. But what if the urine the lab is testing is that of a teenage girl from an unsuspected case of sexual abuse? If the lab has a policy of reporting sperm in the urine of young girls, at what age does it draw the line and say it is now not dealing with abuse?

A. I can sympathize with the concern about reporting sperm in the urine, especially in young women and girls. I am not aware of a specific “standard” and believe that the laboratory and the medical staff need to consider carefully what policy they feel is most appropriate. In my practice at a pediatric hospital, we concur that seeing sperm in the urine of a girl raises concerns about sexual abuse as well as the more mundane possibility of a specimen mixup. We have developed a policy to handle the observation of sperm in a girl under 16 years of age. (I previously commented on this topic in CAP TODAY in 2001. At that point we used a lower age cutoff of 10 years, but we have since reconsidered the most appropriate age to specifically communicate spermaturia to the attending physician.)

We first confirm as best we can that the urine examined is indeed from the young girl (check labeling, examine additional sediment from the correctly labeled container, and so on), and we request that an experienced observer (senior technologist/supervisor or pathologist if available) confirm the observation. When we have confirmed as best we can that there has not been a specimen mixup and that sperm is there (as raising the issue of abuse is not to be taken lightly but is not something that should ever be ignored), we treat the finding of sperm as a “critical” result and notify the ordering physician directly and document this, and we preserve the urine specimen in the event it is needed for additional studies. We know this approach may be overkill (for example, the pregnant 14-year-old in an adolescent clinic), but it was developed in conjunction with our abuse evaluation center and adolescent physicians and is well accepted. In cases where the girl/young woman is being evaluated specifically for rape, a kit provided by our state criminal investigation laboratory that is handled using chain of custody is used to provide appropriate forensic evidence. These samples go directly to the state forensic laboratory.

In males we report sperm if it is present. (As I noted in my previous response in 2001, there are circumstances in which finding sperm is clinically significant, but it is much more difficult for the laboratory to anticipate this. For example, we would not know if a patient had a vasectomy.) In the rare case of an adult female patient whose specimen is sent to our laboratory, we report sperm if we see it. In adult women it is much more difficult to infer the significance of sperm, but we feel we should report it as there are rare reports of women in institutional settings who are being abused and the urinalysis report is the way the attending physician is alerted. We would do our best to ensure there was no specimen mixup, but we would not treat sperm in the urine of an adult woman as a “critical” result.

Robert Novak, MD
Department of Pathology
Children’s Hospital
Medical Center of Akron
Akron, Ohio

Immediate past chair,
CAP Hematology/Clinical
Microscopy Resource Committee

Question Q. How is it possible to have PaO2 measurements greater than 800 mm Hg? Our blood gas analyzer (Nova Biomedical’s Critical Care Xpress) operates at atmospheric pressure with a linear range of zero to 800 mm Hg. We see cardiac bypass patients who are cooled to temperatures of 16° to 21°C presenting with PaO2 values of 750 to 850 mm Hg. Results greater than the measurement range are reported as that.

A. To interpret a value for the partial pressure of oxygen in arterial blood (PaO2), one should know the mean alveolar PO2 (PAO2) and if the results have been adjusted for the patient’s temperature.1 The PAO2 may be calculated from the partial pressure of the inspired (tracheal) O2 and the partial pressure of the arterial carbon dioxide (PaCO2). The question lacks some of this information, but I am going to assume the following: The patient is intubated and receiving 100 percent O2, the test is performed at sea level where the barometric pressure is 760 mm Hg, the inspired air has a water vapor pressure of 47 mm Hg, the PAO2–PaO2 difference is 10 mm Hg, and the patient has a normal PaCO2 of 40 mm Hg, a normal temperature of 37°C, and normal lung function. Further, I assume the blood gas analyzer is properly calibrated and in control. Given these assumptions, the maximum PaO2 for the patient would be 655 mm Hg.1 This is less than the values reported in the question.

Why are the values higher than expected for the patients described in the question? The patient’s temperature is probably the answer to this question. The patient’s temperature is directly related to the PaO2 through a rather complicated formula.2 The Critical Care Xpress instrument defaults to reporting blood gas analyses at a temperature of 37°C, unless another temperature is entered. If a different temperature is entered, the results are adjusted to that temperature. As an example of the impact of body temperature on PaO2 values, if at 37°C and an oxygen saturation of 95 percent a patient’s PaO2 is 77 mm Hg, the PaO2 would be 28 mm Hg at 22°C.2 The patient would need to be in a hyperbaric oxygen chamber to achieve the PaO2 values in this question when the results are adjusted for the patient’s temperature. Thus, I believe the patient temperatures were not entered into the blood gas analyzer and the results were reported for a patient temperature of 37°C for these values.

References

1. Martin L. All You Really Need to Know to Interpret Arterial Blood Gases. 2nd ed. Baltimore, Md: Lippincott Williams & Wilkins;1999:17.

2. Burtis CA, Ashwood ER, Bruns DE. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 4th ed. St. Louis, Mo.: Elsevier Saunders; 2006:1013–1014.

Ronald J. Elin, MD, PhD
A.J. Miller Professor and Chair
Department of Pathology and
Laboratory Medicine
University of Louisville
School of Medicine
Louisville, Ky.

Member, CAP Chemistry
Resource Committee


Dr. Kiechle is medical director of clinical pathology, Memorial Healthcare, Hollywood, Fla.
 
 
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