Stool microscopy in a child with rectal prolapse shows barrel-shaped eggs with mucous plugs at both poles. The most likely causative organism and its diagnostic characteristic are:

• A Ascaris lumbricoides; mammillated outer coat
• B Enterobius vermicularis; D-shaped eggs on cellophane tape
• C Necator americanus; ovoid thin-shelled eggs with blastomeres
• D Trichuris trichiura; barrel-shaped eggs with bipolar mucoid plugs ✓

Explanation

Trichuris trichiura (whipworm) causes heavy infection leading to rectal prolapse in children; the eggs are barrel-shaped (resembling lemons) with characteristic translucent mucous plugs at both poles. Ascaris eggs have a mammillated (knobby) outer coat. Enterobius eggs are D-shaped and collected by perianal tape, not stool microscopy. Necator eggs are oval with blastomeres and thin shell.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.