Differential Diagnosis

The patient's complaint of semen coming out of the penis when compressing the abdomen while passing stools, especially with a history of prior surgery, suggests a possible connection between the urinary and gastrointestinal systems. Here's a structured approach to the differential diagnosis:

• Single Most Likely Diagnosis

  • Rectourinary Fistula: This condition, where there's an abnormal connection between the rectum and the urinary system, could explain the patient's symptoms. The history of prior surgery (possibly a prostatectomy, rectal surgery, or other pelvic surgeries) increases the likelihood of this diagnosis. The fistula could allow semen to escape through the rectum and then be expelled when the patient strains during bowel movements.

• Other Likely Diagnoses

  • Urethrorectal Fistula: Similar to a rectourinary fistula but specifically involves a connection between the urethra and the rectum. Symptoms could include the passage of urine or semen through the rectum.
  • Prostatic Urethral Disruption: If the patient has had recent surgery or trauma, a disruption in the prostatic urethra could potentially cause semen to leak into the urethra and then be expelled during straining.

• Do Not Miss Diagnoses

  • Testicular or Epididymal Injury: Although less likely, any condition that causes a blockage or injury to the testicles or epididymis could potentially lead to abnormal semen discharge. This would be more of a concern if there was recent trauma or surgery in these areas.
  • Infection or Abscess: An infection in the pelvic area, possibly as a complication of surgery, could lead to fistula formation or other complications that might result in the patient's symptoms.

• Rare Diagnoses

  • Congenital Anomalies: Certain congenital conditions could potentially lead to abnormal connections between the urinary and gastrointestinal systems, though these would be extremely rare in an adult presenting for the first time.
  • Malignancy: Although very rare, a tumor in the pelvic area could potentially cause erosion into adjacent structures, leading to fistula formation. This would be a consideration if there were other symptoms suggestive of cancer or if the patient had a known history of malignancy.

Given the acute onset and the patient's history of prior surgery, the most immediate step would be to consult with a urologist or a colorectal surgeon to further evaluate the patient for a possible fistula. Diagnostic tests such as a cystoscopy, retrograde urethrogram, or a colonoscopy might be necessary to confirm the diagnosis. Treatment would depend on the exact nature and location of the fistula but could involve surgical repair.