Clinical Laboratory Science Parasitology Practice Test 2026 – The All-in-One Guide to Success!

The key idea is recognizing nematode eggs by size and surface texture. Ascaris lumbricoides eggs are among the largest seen in human stool and have a distinct rough, mammillated outer surface—little wart-like projections on the shell—measuring about 45–75 μm in length. This combination of large size and a mammillated shell is characteristic and helps distinguish them from other common nematode eggs.

For context, Enterobius vermicularis eggs are smaller and have a flattened side with a smoother surface; Trichuris trichiura eggs are barrel-shaped with bipolar plugs; Ancylostoma duodenale eggs are 60–75 μm long but possess a thin, smooth shell without mammillations.