Background: The present communication reports intravesical semen coagulation and formation of a larger precipitate in two Cynomolgus monkeys.
Methods: Ultrasound of the urinary bladder and light microscopy of intravesical coagulates.
Results: These monkeys suffered from complete blockage of urine output and surgery was required to remove the sperm mass. Microscopic examination of the urine revealed millions of sperm as a cause of the mass and the blockage of urine output.
Conclusions: Retrograde ejaculation of sperm may cause coagulation of ejaculates in the bladder of the cynomolgus monkey Macaca fascicularis. However, involvement of sperm mass in blockage of urine passage has not been described in this species.