Not a worm: a case report of a 20 cm worm-like structure in a urine sample

Background Large worm-like structures recovered from urine are rare and may mimic urinary helminth infections, creating significant diagnostic uncertainty. Reports of urinary pseudoparasites remain limited in the literature.Case presentation A 72-year-old Belgian man presented with urinary retention, hematuria, and obstruction of a urinary catheter. During catheter replacement, a 20-cm worm-like structure was recovered from the urine, initially raising suspicion of urinary helminthiasis caused by Dioctophyme renale. Microscopic examination revealed no characteristic parasitic structures, and further parasitological investigations, including schistosomiasis serology and expert review at the national reference laboratory, were negative. The specimen was ultimately identified as a non-parasitic artifact, most likely an elongated blood clot. The patient’s symptoms resolved after restoration of urinary drainage without specific antiparasitic treatment.Conclusion This case highlights the diagnostic challenges posed by urinary pseudoparasites and emphasizes the importance of integrating morphological, laboratory, and epidemiological data when evaluating unusual urinary findings. Increased awareness may help prevent misdiagnosis, unnecessary investigations, and avoidable healthcare costs.