Testicular torsion is the sudden twisting of the spermatic cord within the scrotum. It most commonly affects neonates and young men. Because of the risk of ischemia and possible infarction of the testis, it is considered a urological emergency. Testicular torsion is characterized by sudden-onset unilateral testicular pain, which may radiate to the lower abdomen, with nausea and vomiting. Clinical findings include a high-riding testis with an absent cremasteric reflex. Imaging with duplex ultrasound of the scrotum may be required if the clinical diagnosis is in doubt. If testicular torsion is suspected, prompt surgical exploration within six hours of symptom onset is essential to salvage the testis. Important differential diagnoses, e.g., orchitis and epididymitis, should be ruled out before initiating treatment.
- Peak incidence: neonatal period (first 30 days of life) and during puberty (10–14 years) 
- 3.8 per 100,000 male individuals under the age of 18 (two-thirds of cases occur between 12 and 18 years of age) 
- Accounts for 10–15% of acute scrotal illness in children within the United States 
Epidemiological data refers to the US, unless otherwise specified.
- Idiopathic 
- Occurs as a result of vigorous physical activity or trauma in very rare cases 
- Predisposing factors, especially in adults: testicular malignancy
- Testicular torsion is a sudden twisting of the spermatic cord (and vascular pedicle) associated with a poorly secured testis.
- Three mechanisms of testicular torsion may be identified:
- Intravaginal torsion: hypotheses suggest this occurs because of a congenital abnormality in which the tunica vaginalis attaches to the superior pole of the testis (bell-clapper deformity) → increased mobility of testis within tunica vaginalis, with possible abnormal transverse lie of testis → torsion of the testis (along the spermatic cord) 
- Extravaginal torsion: lack of fixation of the tunica vaginalis to the gubernaculum → concomitant torsion of the testis and tunica vaginalis (along the spermatic cord) 
- Long mesorchium : elongated mesorchium (thick band of connective tissue between the efferent ductules of the epididymis and the posterior surface of the testis) → torsion of the testis along the mesorchium 
- Torsion results in venous engorgement with consequent arterial compromise, tissue ischemia, and possible infarction.
- Irreversible damage occurs after 6–12 hours of torsion. 
- Abrupt onset of severe testicular pain and/or pain in the lower abdomen
- Typically swollen and tender testis and/or lower abdominal tenderness 
- Nausea and vomiting
- Abnormal position of the testis
- Absent cremasteric reflex
- Negative Prehn sign
- In neonates
Management of testicular torsion is time-sensitive.
- Perform rapid clinical evaluation of patients with acute scrotal pain as soon as possible.
- Record time from symptom onset.
- Consider .
- Consider using the to supplement clinical judgment.
- Urgently refer the patient to urology as soon as torsion is suspected (e.g., high clinical likelihood, TWIST score ≥ 6–7). 
- Consider imaging for patients with uncertain diagnoses, if this does not delay definitive treatment (see “Diagnostics”). 
- Obtain IV access and start ; consider a spermatic cord block.
- If surgery is not immediately available, consider performing a .
- Reassess pain frequently until the patient has been taken for exploratory surgery (see “Treatment).
Do not delay urological referral in order to perform imaging or manual detorsion, especially if clinical suspicion is high, as there is a significant risk of infertility and/or testicular loss if definitive surgical management is delayed > 6 hours from symptom onset.
Clinical decision score 
The TWIST score may be used to help guide decisions on imaging prior to surgical exploration.
- High-risk patients with a score of ≥ 6: extremely high likelihood of torsion
- Low-risk patients (especially those with a score of 0): very low risk of torsion (ultrasound may not be required, however, this controversial) 
- Medium-risk patients or clinical uncertainty: Obtain a scrotal ultrasound to help confirm diagnosis.
|Testicular workup for ischemia and suspected torsion score (TWIST score) |
|Clinical feature||Score if present|
|Swelling of the scrotum|| |
|Testis firm to palpation|| |
|Cremasteric reflex absent|| |
|Scrotal elevation (high-riding testis)|| |
|Nausea or vomiting|| |
RIsk categories (from original derivation and validation cohort)
Testicular torsion is typically a clinical diagnosis. Do not delay definitive treatment for diagnostic workup if clinical suspicion is high.
Imaging is not routinely indicated in patients in which there is high clinical suspicion but should be considered in patients with atypical clinical features.
Duplex ultrasound of the scrotum 
- Indication: inconclusive clinical findings 
- Characteristic findings 
Other imaging modalities
These are typically time-consuming studies and may not be readily available in emergency situations.
Radionuclide imaging 
- Inconclusive clinical findings
- Evaluate for epididymitis
- Characteristic findings
- MRI with IV contrast: may be used as an alternative to radionuclide imaging 
Surgical intervention is recommended for suspected testicular torsion, regardless of radiological findings.
|Differential diagnosis of scrotal pain |
|Testicular torsion|| |
|Testicular tumor|| |
|Torsion of testicular appendage (hydatid of Morgagni)|| || |
Torsion of testicular appendage (hydatid of Morgagni) 
- Description: an embryological remnant on the upper pole of the testes or at the epididymis (the remnant of the Mullerian duct) that has the potential to rotate
- Clinical features: Symptoms resemble acute testicular torsion.
- Imaging: Doppler ultrasound may show an enlarged testicular appendix and/or mild hydrocele with preserved testicular blood flow.
The differential diagnoses listed here are not exhaustive.
Testicular torsion is a medical emergency and should ideally be treated within 6 hours of the onset of symptoms for the best chance of testicular salvage. Manual detorsion in the emergency department may be attempted prior to surgery for immediate pain relief, but should not delay transferring the patient to the operating room.
Manual testicular detorsion 
- Indication: : may be attempted prior to surgery for immediate pain relief or if surgery is not immediately available
- Consider performing under ultrasound guidance to increase the likelihood of success.
- Rotate the testis laterally toward the thigh ; two-thirds of torsions occur toward the midline.
- If lateral rotation does not provide symptom relief, rotate the testis toward the midline; one-third of torsions occur laterally. 
- Surgery should still be performed in all patients to resolve any possible degree of remaining torsion and to prevent recurrence. 
Exploratory surgery 
- Indication: suspected testicular torsion
- Timing: ideally, within 6 hours of symptom onset 
- Immediate surgical exploration of the scrotum with reduction (untwisting) and of the affected testis
- Orchiopexy of the contralateral testis is recommended because the risk of testicular torsion on the contralateral side increases with previous or current testicular torsion. 
- Orchiectomy if the testis is grossly necrotic or nonviable
- Examine the patient and consider using the TWIST score to help guide further management.
- High likelihood of torsion: urgent urology referral without prior imaging
- Intermediate or low risk: Consider imaging (provided it can be performed rapidly) prior to urology consult.
- Start pain management with parenteral analgesics.
- If pain persists and surgery is not immediately available, consider .
- Urgent transfer to the OR for surgical exploration of the scrotal sac
- Testicular salvage rates depend on the interval of time between symptom onset and restoration of testicular blood flow. 
- Within 6 hours: 90–100% 
- > 12 hours: 20–60%
- > 24 hours: up to 20%
- Late or absent surgical intervention → testicular ischemia (with/without necrosis) → disruption of the blood-testis barrier → formation of antisperm antibodies → infertility