Ace Your Clinical Lab Science 2026 Parasitology Exam – Dive into Success!

Egg morphology is a key identifying feature for nematodes in fecal exams. The description of eggs that are elongated, barrel-shaped, about 50 by 22 μm, with clear polar plugs at each end is classic for Trichuris trichiura, the whipworm. The barrel shape and the distinct plugs at both ends are distinctive and closely tied to this species’ eggs, making it the best fit for the given measurements and features.

Ascaris lumbricoides eggs are typically oval or slightly round and larger, with a thick, mammillated outer shell and no polar plugs, so they don’t match the barrel-with-plug appearance. Hookworm eggs from Ancylostoma duodenale or Necator americanus are thin-shelled and oval, usually about 60 by 40 μm, and they may contain a developing embryo rather than a polar-plug, barrel form.