2022 Volume 71 Issue 4 Pages 743-747
Hematoidin crystals are hemoglobin degradation products that form in the obstructed body cavity under a low-oxygen-tension environment. The presence of hematoidin crystals in urinary sediments has been increasingly observed in recent years. Because of the special environment required for the formation of hematoidin crystals, they rarely appear continuously in urinary sediments. We encountered a case in which hematoidin crystals were continuously observed in the urinary sediment. The patient was a man in his 70s on chemotherapy for prostate cancer. Urinary sediment examination was performed owing to repeated gross hematuria and urinary retention, and hematoidin crystals showing various morphologies were continuously observed. It was presumed that their continuous presence was due to an obstruction inside the bladder caused by urinary retention and repeated bleeding from the bladder tumor. Subsequently, clean intermittent self-catheterization (CIC) was introduced to improve the symptoms, and no hematoidin crystals were observed in the subsequent urinary sediment examination. After the introduction of CIC, urinary retention was reduced, and it was considered that the environment inside the bladder was no longer conducive to the formation of hematoidin crystals. Therefore, it is highly possible that no new hematoidin crystals were formed, and preexisting crystals disappeared. Hematoidin crystals are considered to have clinical significance in the sense that they result from bleeding. From the clinical course of this patient, we infer that if there is persistent bleeding in the bladder, the presence or absence of hematoidin crystals may be a practical index for objectively evaluating if CIC is performed correctly.
