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Updated: Mar 6, 2026

Comparative Analysis of Automatic Fecal Analyzer versus Direct Wet Smear Microscopy for Detecting Parasitic Infections in Stool Samples
Published on: April 25, 2025
Undigested Pills in Stool Mimicking Parasitic Infection
Fazia Mir1, Ilyas Achakzai2, Jamal A Ibdah1
1Division of Gastroenterology and Hepatology, University of Missouri, Columbia, 1 Hospital Drive, Columbia, MO 65212, USA.
Undigested controlled-release pills in stool can mimic parasitic infections, causing patient and physician concern. Reviewing medication lists for extended-release formulations is crucial to avoid unnecessary diagnostic workups.
Area of Science:
- Gastroenterology
- Pharmacology
Background:
- Oral medications exist in immediate and controlled-release (CR) formulations.
- CR preparations aim to enhance patient compliance and reduce dosing frequency.
Observation:
- A 67-year-old obese male reported chronic abdominal pain and observed undigested, pearly oval structures in his stool.
- These symptoms coincided with the initiation of nifedipine for hypertension.
Findings:
- The observed structures were identified as undigested nifedipine CR pills excreted whole.
- This phenomenon can be mistaken for a parasitic infection.
Implications:
- Undigested CR pills in stool can lead to misdiagnosis and unnecessary investigations.
- Physicians should consider extended-release formulations when patients report seeing pills in their stool.
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