[A case of urinary retention caused by true phimosis].

We report a case of urinary retention caused by true phimosis in a 67-year-old man with untreated diabetes mellitus. The patient could not void in a stream, and urine dropped out of the external urethral orifice with manual compression of the penis. Subsequently, he visited our hospital due to urinary retention. Ultrasonography revealed right hydronephrosis and ballooning of the foreskin. An emergency dorsal slit was performed, and hydronephrosis showed immediate improvement. Histopathologically, fibrosis and inflammation of the foreskin were observed. The mechanisms responsible for urinary retention in this case are discussed.