Differential Diagnosis for the Patient

The patient's symptoms of inability to urinate, presence of blood at the tip of the penis, and severe pain, combined with a history of prostate cancer, suggest several potential diagnoses. These can be categorized as follows:

• Single Most Likely Diagnosis

  • Urinary Retention with Hematuria due to Prostate Enlargement or Prostate Cancer: Given the patient's history of prostate cancer and symptoms of urinary retention, this is a highly plausible diagnosis. Prostate enlargement or recurrence of prostate cancer could be obstructing the urethra, leading to urinary retention and bleeding.

• Other Likely Diagnoses

  • Urethral Stricture: This condition, characterized by a narrowing of the urethra, could cause obstructive urinary symptoms and bleeding, especially if there is a history of trauma, infection, or previous surgeries.
  • Bladder Outlet Obstruction (BOO): BOO can be due to various causes including benign prostatic hyperplasia (BPH), prostate cancer, or bladder neck contracture, leading to urinary retention and potentially hematuria.
  • Kidney Stones: Although less likely given the specific symptoms of blood at the tip of the penis, kidney stones could cause severe pain and urinary retention, especially if a stone is obstructing the ureter or bladder outlet.

• Do Not Miss Diagnoses

  • Septic Prostatitis or Epididymitis: Infection of the prostate or epididymis could present with severe pain and urinary retention. Missing this diagnosis could lead to severe consequences, including sepsis.
  • Ruptured Bladder or Urethral Injury: Although less common, especially without a history of trauma, these conditions are emergencies that require immediate intervention to prevent further complications.
  • Metastatic Disease Causing Ureteral Obstruction: Given the patient's history of prostate cancer, metastatic disease causing ureteral obstruction is a critical diagnosis not to miss, as it can lead to renal failure if not promptly addressed.

• Rare Diagnoses

  • Malignant Urethral Stricture: A rare condition where a urethral stricture is caused by a malignancy, which could explain the patient's symptoms of urinary retention and bleeding.
  • Penile or Urethral Cancer: Although rare, these cancers could present with bleeding and obstructive urinary symptoms, especially in the context of a history of prostate cancer, which might increase the risk of other urological malignancies.

Workup

The workup for this patient should include:

• Imaging: Ultrasound of the bladder and kidneys to assess for obstruction, kidney stones, or other abnormalities. A CT scan of the abdomen and pelvis may also be necessary, especially to evaluate for metastatic disease or ureteral obstruction.
• Laboratory Tests: Urinalysis to check for infection or blood, complete blood count (CBC) to assess for signs of infection or bleeding, and blood urea nitrogen (BUN) and creatinine to evaluate renal function.
• Urodynamic Studies: May be considered to assess bladder function and obstruction.
• Cystoscopy: To directly visualize the bladder and urethra for any abnormalities, including tumors, strictures, or stones.
• Prostate-Specific Antigen (PSA) Level: To monitor for potential recurrence of prostate cancer.

Given the complexity and severity of the patient's symptoms, a thorough and prompt evaluation is crucial to establish an accurate diagnosis and initiate appropriate treatment.