Enterobius vermicularisOva in a Vaginal Smear

Enterobius vermicularis is one of the most common parasites found in the intestine of humans. The gravid female worms migrate outside the anus to release eggs on the perianal skin. Rarely, they migrate to the genitourinary tract in female patients. We present a case in which pinworm eggs were found in a cervicovaginal smear of a 37-year-old woman. The eggs were elongated oval shaped and flattened on one side. The thick, double contoured birefringent shell stained bright yellow or orange. Some coarsely granular embryos or curved larvae were enclosed in the refractile shell. Empty eggs or wrinkled shells with clumped granular material were also present. Although pinworm eggs are easily identified because of their characteristic morphologic appearance, careful screening is needed due to the frequent masking by inflammatory cells.