Parasites that may be found in urinary sediments include Trichomonas vaginalis, Enterobius vermicularis, and Schistosoma haematobium. Parasites and parasitic ova are usually present in urine sediment as a result of vaginal or fecal contamination.
The arrows in the top image on the right point to Trichomonas vaginalis. Trichomonas is usually a contaminant from vaginal infection and is often accompanied by an increased number of WBCs. Trichomonas is highly motile due to an undulating membrane and multiple anterior flagella; however, movement may deteriorate after 30 minutes. Confirmation of motility is essential for positive identification of Trichomonas vaginalis. Non-motile organisms can resemble WBCs, transitional, or renal epithelial cells. For this reason, it is essential to examine a freshly collected urine sample.
Enterobius vermicularis (pinworm) is not a primary urine parasite. E. vermicularis ova (eggs) are usually present in the urine sediment as a fecal contaminant. The ova are ovoid in shape and smooth with one side flattened. Embryos (larvae) may be visible within the ova. The bottom image on the right is an example of an E. vermicularis egg (400X magnification) with an embryo (larva) visible within the thick hyaline shell.
Schistosoma haematobium ova may rarely be seen in urine sediment. This parasite is considered an important factor in the etiology of carcinoma of the bladder. The ova are elongated and are 60 X 160 microns. They are slightly transparent and possess a delicate terminal spine. An example of an S. haematobium ovum is shown below.