PARASITES, Graff's Textbook of Urinalysis and Body Fluids, Microscopic Examination of Urinary Sediment
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PARASITES
Parasites may occasionally be found in the urine, either because they are indigenous to the urinary tract or as the result of vaginal or fecal contamination. Chemical analysis does not detect parasites in urine. Microscopic evaluation of urinary sediment is important if parasitic infections are suspected. Chemical analysis may reveal the presence of leukocytes, if present during these infections.
TRICHOMONAS VAGINALIS
Trichomonas vaginalis is the most frequently occurring parasite in the urine. It is a flagellate organism that is about the same size as a large white cell (Fig. 5-71). In the unstained wet mount, the organism should not be reported unless it is motile. Sometimes when bacteria are next to a white cell, the cell may be mistaken for Trichomonas, which is why motility is the diagnostic feature. This organism may be found in males, although it is more common in females. T. vaginalis is frequently accompanied by WBCs and epithelial cells.
Figure 5-71. Trichomonas vaginalis.Note the four flagella (1000 ).
ENTEROBIUS VERMICULARIS
Enterobius vermicularis (pinworm) ova and occasionally also the female adult may be found in the urine, perhaps even more frequently than was once believed. The ova are very characteristic in shape, having one flat and one rounded side (Fig. 5-72). The developing larva can usually be observed through the transparent shell of the egg. If the urine is found to contain many ova, examination of the original urine container may reveal the adult worm (Fig. 5-73).
Figure 5-72. Enterobius vermicularis ovum and WBCs (500x).
Figure 5-73. Head of the Enterobius vermicularis adult female worm (100x).
SCHISTOSOMA HAEMATOBIUM
Schistosoma haematobium is a blood fluke that inhabits the veins in the wall of the urinary bladder. The adult deposits eggs in the capillaries of the mucosa. Abscesses develop around the eggs, and the eggs can be found in the urine accompanied by RBCs and WBCs. This type of schistosomiasis is endemic in Africa, especially around the Nile Valley, in the Middle East, and around the Mediterranean. The S. haematobium ovum has a characteristic terminal spine and measures about 50 microns by 150 microns (Fig. 5-74).
Figure 5-74. Schistosoma haematobium ovum.
(Courtesy of Dr. Kenneth A. Borchardt, San Francisco State University, San Francisco CA.)
REFERENCES
Lillian A. Mundt and Kristy Shanahan, Graff's Textbook of Urinalysis and Body Fluids, Second Edition 2011
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