Prostatitis: This is often considered the most common cause of hematospermia, especially in younger men. Prostatitis, which is inflammation of the prostate gland, can lead to bleeding into the semen.

Benign Prostatic Hyperplasia (BPH): Enlargement of the prostate can cause bleeding into the semen due to increased vascularity and potential for minor trauma during ejaculation.
Urethritis: Inflammation of the urethra can cause bleeding, which may then appear in the semen.
Seminal Vesiculitis: Inflammation of the seminal vesicles can lead to hematospermia due to the direct involvement of these structures in semen production.

Prostate Cancer: Although less common, prostate cancer can cause hematospermia. Given the potential severity of this diagnosis, it is crucial not to miss it, even if it is less likely in a younger patient.
Genitourinary Trauma: Any form of trauma to the genital or urinary tract area can cause bleeding into the semen and should be considered, especially if there is a history of recent injury.
Infections (e.g., Tuberculosis, Schistosomiasis): Certain infections can involve the genitourinary tract and cause hematospermia. These conditions are important to identify due to their potential for serious complications if left untreated.

Vascular Malformations or Aneurysms: Abnormalities in blood vessels within the pelvic area can potentially cause bleeding into the semen, although this is a rare occurrence.
Amyloidosis: A condition characterized by the deposition of amyloid (a particular type of protein) in various tissues, which can rarely affect the prostate or seminal vesicles and cause hematospermia.
Systemic Bleeding Disorders: Conditions like hemophilia can increase the risk of bleeding, including into the semen, though this would typically be associated with other bleeding symptoms.