An 18 year-old female presents with dysuria and frothy discharge. Which of the following results would be expected?

The presence of dysuria and a frothy discharge in an 18-year-old female suggests a possible infection with Trichomonas vaginalis, a flagellated protozoan. When examining a sample under a microscope using normal saline preparation, one would expect to see mobile flagellated protozoa, which is characteristic of this condition.

Trichomoniasis is often associated with symptoms such as dysuria and abnormal vaginal discharge, which can be frothy and have a yellow-green color. The motility of the flagellated protozoa during microscopic examination makes it a key finding in diagnosing this infection.

In contrast, other options present different findings that are not consistent with Trichomonas vaginalis infection. Clue cells would typically indicate bacterial vaginosis, hyphae and budding yeast would suggest a Candida infection, and intracellular gram-negative diplococci would indicate a Neisseria gonorrhoeae infection. While these other conditions may cause dysuria or discharge, the specific symptoms and expected microscopy findings in this case align most closely with Trichomonas vaginalis, thus supporting the presence of mobile flagellated protozoa as the expected result.