What is the likely diagnosis for a patient presenting with acute onset of groin pain, left testicle (testis) larger and more painful than the right, with symptoms starting yesterday?

Acute Testicular Pain with Unilateral Enlargement

This is testicular torsion until proven otherwise—a surgical emergency requiring immediate urological consultation and surgical exploration within 6-8 hours to prevent testicular loss. 1

Why Testicular Torsion is the Primary Diagnosis

The clinical presentation of acute onset (yesterday) with unilateral testicular enlargement and severe pain in a young patient is classic for testicular torsion. 1 Key features that point to torsion include:

• Abrupt onset of severe scrotal pain rather than gradual progression 1
• Unilateral testicular enlargement with associated pain 1
• Time-sensitive nature of symptoms (started yesterday means you're approaching the critical 24-hour mark) 1

The critical window for testicular salvage is 6-8 hours from symptom onset, with surgical outcomes significantly better when intervention occurs within 12 hours. 1 Since symptoms began yesterday, immediate action is essential.

Physical Examination Findings to Confirm Suspicion

Look for these specific clinical signs:

• High-riding testicle on the affected side 2, 3
• Absent cremasteric reflex (highly suggestive of torsion) 4
• Negative Prehn sign (pain NOT relieved when elevating the testicle) 1
• Firm, swollen, tender testis 2
• Associated nausea and vomiting (present in up to 50% of cases) 2, 3, 4

Up to half of patients report previous similar episodes of pain that resolved spontaneously, suggesting intermittent torsion. 2

Immediate Diagnostic Approach

Do NOT delay surgical exploration if clinical suspicion is high—imaging should never postpone definitive treatment. 1, 4 However, if there is intermediate clinical suspicion:

• Duplex Doppler ultrasound is the first-line imaging modality with 69-96.8% sensitivity and 87-100% specificity 1
• Key ultrasound findings include:
  • Decreased or absent blood flow to the affected testicle 1
  • "Whirlpool sign" of the twisted spermatic cord (96% sensitivity, most specific finding) 1, 5
  • Enlarged heterogeneous testis appearing hypoechoic 1
  • Ipsilateral hydrocele and scrotal wall thickening 1

Critical pitfall: False-negative Doppler studies occur in up to 30% of cases, particularly with partial torsion or early presentation. 1 Normal ultrasound does NOT exclude torsion if clinical suspicion remains high.

Differential Diagnosis (Less Likely but Consider)

While torsion is the primary concern, other possibilities include:

Epididymitis/Epididymo-orchitis

• Gradual onset of pain (not abrupt like this case) 1
• More common in adults over 25 years 1
• Ultrasound shows increased blood flow (hyperemia) rather than decreased flow 1
• May have abnormal urinalysis, though normal urinalysis doesn't exclude it 1

Important caveat: Epididymitis can rarely precipitate testicular torsion due to testicular enlargement, so even if infection is present, torsion must still be excluded. 6

Torsion of Testicular Appendage

• Most common cause of testicular pain in prepubertal boys (less likely in adults) 1
• "Blue dot sign" is pathognomonic but only seen in 21% of cases 1
• Normal testicular perfusion on Doppler with localized hyperemia 1

Management Algorithm

If high clinical suspicion for torsion:

1. Immediate urological consultation 1, 4
2. Urgent surgical exploration without waiting for imaging 1, 4
3. Bilateral orchiopexy during surgery to prevent contralateral torsion (82% have "bell-clapper" deformity predisposing both sides) 1, 2

If intermediate suspicion:

1. Urgent Duplex Doppler ultrasound 1
2. If ultrasound confirms torsion or remains equivocal with high clinical suspicion: immediate surgical exploration 1
3. If ultrasound clearly demonstrates alternative diagnosis (e.g., epididymitis with increased flow): treat accordingly but maintain close follow-up 1

Critical Time-Dependent Prognosis

• Within 6 hours: High testicular salvage rate 1, 5, 4
• 6-8 hours: Critical window closing, permanent ischemic damage begins 1, 4
• Beyond 12 hours: Significantly decreased salvage rates 1
• Beyond 24 hours: High likelihood of testicular loss requiring orchiectomy 4

Since this patient's symptoms started yesterday, you are already at or beyond the optimal intervention window, making immediate action even more critical.

Post-Treatment Considerations

Even with successful detorsion, long-term complications include:

• Abnormal exocrine function on semen analysis 2
• Decreased fertility potential 4
• Risk of testicular atrophy despite successful detorsion 3

Bottom line: Treat this as testicular torsion, obtain immediate urological consultation, and proceed to surgical exploration urgently. The testicle's viability depends on how quickly you act. 1, 4