Prostatitis: This is the most common cause of hemospermia in young men, often due to chronic prostatitis or prostatodynia. The absence of pain, fever, or other symptoms does not rule out this diagnosis, as it can be asymptomatic or have minimal symptoms.

Ejaculatory duct obstruction: This condition can cause hemospermia due to the rupture of small vessels in the ejaculatory ducts. It may be associated with other symptoms like decreased ejaculate volume or post-ejaculatory pain, but these are not always present.
Seminal vesicle cysts or stones: These can cause hemospermia by obstructing the seminal vesicles or ejaculatory ducts, leading to inflammation or rupture of small vessels.
Urethral stricture or trauma: Although the patient denies dysuria or pain, a urethral stricture or previous trauma could potentially cause hemospermia, especially if there is associated urethral inflammation or scarring.

Testicular or prostate cancer: Although rare in young men, testicular or prostate cancer can cause hemospermia. It is crucial to rule out these conditions with appropriate imaging and diagnostic tests.
Genitourinary tuberculosis: This is a rare condition in many parts of the world but can cause hemospermia among other symptoms like frequency, urgency, or pain. It's essential to consider this diagnosis, especially in endemic areas or in patients with risk factors.

Amyloidosis: This condition can cause hemospermia due to the deposition of amyloid proteins in the seminal vesicles or other parts of the genitourinary system.
Vascular malformations or arteriovenous fistulas: Rarely, vascular anomalies in the pelvic area can cause hemospermia by creating abnormal connections between arteries and veins, leading to vessel rupture.
Inflammatory bowel disease (IBD) with genitourinary involvement: Conditions like Crohn's disease or ulcerative colitis can rarely involve the genitourinary system, causing symptoms including hemospermia.