What is the differential diagnosis for a patient presenting with acute right testicular pain radiating to the right lower abdomen?

Differential Diagnosis for Acute Right Testicular Pain Radiating to Right Lower Abdomen

The differential diagnosis for acute right testicular pain radiating to the right lower abdomen must prioritize testicular torsion as the primary consideration requiring immediate surgical evaluation, followed by epididymitis/epididymo-orchitis, torsion of testicular appendage, incarcerated inguinal hernia with possible appendicitis, and less commonly testicular tumor or segmental testicular infarction. 1, 2

Life-Threatening Diagnoses Requiring Immediate Action

Testicular Torsion

• This is a surgical emergency requiring intervention within 6-8 hours to prevent permanent testicular loss 1, 2
• Characterized by abrupt onset of severe scrotal pain that may radiate to the lower abdomen 2, 3
• More common in adolescents with bimodal distribution (neonates and postpubertal boys), though can occur at any age 2
• Key clinical feature: negative Prehn sign (pain NOT relieved with testicular elevation) 2
• Normal urinalysis does NOT exclude testicular torsion 2
• Duplex Doppler ultrasound shows decreased or absent blood flow and the pathognomonic "whirlpool sign" of twisted spermatic cord 1, 2

Incarcerated Inguinal Hernia with Appendicitis

• Extremely rare but critical diagnosis where appendicitis occurs within an incarcerated inguinal hernia presenting as testicular pain 4, 5
• May present with systemic signs including fever, elevated white blood cell count, and elevated C-reactive protein 4
• The radiation of pain to the right lower abdomen in your patient makes this particularly relevant 4
• Requires urgent surgical exploration of both the scrotum and abdomen 4

Common Non-Emergent Diagnoses

Epididymitis/Epididymo-orchitis

• Most common cause of testicular pain in adults over 25 years, representing approximately 600,000 cases annually in the United States 2, 3
• Characterized by gradual onset of pain (contrasting with torsion's abrupt onset) 2, 3
• Positive Prehn sign (pain relief with testicular elevation) 3
• May have abnormal urinalysis, though normal urinalysis does not exclude diagnosis 2
• Duplex Doppler shows enlarged epididymis with increased blood flow 2, 3

Torsion of Testicular Appendage

• Most common cause of testicular pain in prepubertal boys 2
• The "blue dot sign" is pathognomonic but only seen in 21% of cases 2
• Generally self-limiting condition 2

Less Common but Important Diagnoses

Testicular Tumor

• Germ cell tumors constitute approximately 95% of all testicular tumors 3
• Can rarely present with acute pain mimicking torsion 6
• Typically presents as painless hard mass, but acute presentation can occur 6
• Ultrasound findings suspicious for malignancy should prompt inguinal orchidectomy 6

Segmental Testicular Infarction

• Presents with classic wedge-shaped avascular area on ultrasound 2, 7
• May also present as round lesions with variable Doppler flow 2
• Rare differential diagnosis requiring awareness 7

Critical Diagnostic Approach

Immediate Clinical Assessment

• Determine exact timing and onset of pain: abrupt onset suggests torsion, gradual onset suggests epididymitis 2, 3
• Assess Prehn sign: pain relief with elevation suggests epididymitis rather than torsion 3
• Examine for systemic signs (fever, vomiting, diarrhea) that might suggest appendicitis 4
• Palpate for inguinal hernia, especially given the radiation to right lower abdomen 4, 5

Imaging Protocol

• Duplex Doppler ultrasound of the scrotum is the first-line imaging modality with sensitivity 69-96.8% and specificity 87-100% 1, 2
• Ultrasound should include: grayscale examination for "whirlpool sign," color Doppler assessment of testicular perfusion, and power Doppler (particularly useful in prepubertal boys) 2
• If clinical suspicion for torsion is high, do NOT delay surgical exploration for imaging 1, 2
• Consider CT abdomen and pelvis if inguinal hernia with appendicitis is suspected based on systemic signs and abdominal tenderness 1, 4

Critical Clinical Pitfalls

• False-negative Doppler evaluations occur in 30% or more of cases, particularly with partial torsion or spontaneous detorsion 2
• Significant overlap exists in clinical presentation between different causes, making diagnosis challenging 2, 3
• The radiation of pain to the right lower abdomen creates diagnostic complexity, as this can occur with both testicular pathology and intra-abdominal processes like appendicitis 1, 4
• Never rely solely on imaging when clinical suspicion for torsion is high - proceed directly to surgical exploration 1, 2