Torsion of the testes is a surgical emergency, since it causes strangulation of gonadal blood supply with subsequent testicular necrosis and atrophy. [1, 2] Acute scrotal swelling in children indicates torsion of the testes until proven otherwise.
Testicular torsion is a true urologic emergency; a delay in diagnosis and management can lead to loss of the testicle. In approximately two thirds of patients, history and physical examination are sufficient to make an accurate diagnosis. If testicular torsion is suspected, notify a surgeon, urologist or pediatric surgeon and arrange for diagnostic imaging to make a definitive diagnosis as soon as possible. In adolescent males, testicular torsion is the most frequent cause of testicle loss.
Testicular torsion occurs more commonly in patients who have an inappropriately high attachment of the tunica vaginalis. This allows the testicle to rotate freely on the spermatic cord within the tunica vaginalis (intravaginal testicular torsion). This congenital anomaly is called the bell clapper deformity and results in the long axis of the testicle becoming oriented transversely rather than cephalocaudal, as shown in the image below. The bell clapper deformity is present in approximately 12% of males; 40% of them are affected in both testicles.
Extravaginal testicular torsion that occurs in newborns cannot be treated by manual detorsion.
Testicular torsion is commonly observed in males younger than 30 years, with a peak at 12-18 years. The incidence of torsion in males younger than 25 years is approximately 1 in 4000.  Torsion more often involves the left testicle. The etiologic factors involved in intravaginal testicular torsion include congenital anomaly, bell clapper deformity, undescended testicle, sexual arousal or activity, exercise, active cremasteric reflex, and cold weather.
Testicular torsion typically presents with a history of sudden onset of severe, unilateral scrotal pain. Most patients have a history of previous episodes of intermittent testicular pain that resolved (detorsion) spontaneously. Torsion can occur with activity or may develop during sleep. The main signs at presentation are 1) scrotal erythema and swelling, and 2) nausea, vomiting, or both.
Other causes of acute scrotal pain that should be ruled out before manual detorsion is considered include the following:
Torsion of the testicular or epididymal appendages
Idiopathic scrotal edema
In older boys, the classic presentation of testicular torsion is the sudden onset of severe testicular pain followed by inguinal and/or scrotal swelling. Pain may lessen as the necrosis becomes more complete.
In cases of reduced pain or resolution of the episode at presentation without manual detorsion, necrosis should be suspected. A surgical evaluation should be performed, and detorsion applied as indicated.
Testicular salvage is most likely if the duration of torsion is less than 6-8 hours. If 24 hours or more elapse, testicular necrosis develops in most patients. Manual detorsion is contraindicated if the duration of torsion is more than 6 hours.
Manual detorsion is performed without local or general anesthesia.
Mild analgesic medications may be administered when testicular torsion has been diagnosed. However, most practitioners prefer that no analgesics are administered so that the examination is not biased.
No special equipment is required for manual detorsion of the testes.
The patient should be standing or supine.
The practitioner should be positioned in front of the patient.
In patients with testicular torsion, the affected testis generally is twisted inward (medially). Although generally considered uncommon, torsion resulting from lateral rotation of the testicle has been reported in up to one third of cases. 
With torsion of the left testis, hold the testicle with the right thumb and forefinger and then rotate the testicle clockwise 180 degrees. This manipulation may need to be repeated 2-3 times, because testicular torsion may involve rotations of 180-720 degrees. These repeated attempts should be guided by resolution of pain and return to normal anatomy.
For torsion of the right testicle, the procedure is similar except that the testicle is held using the left thumb and forefinger and the testicle is rotated in a counterclockwise direction.
Manual detorsion is successful in 30-70% of patients and is evident by the immediate relief experienced by the patient. Owing to this large range in the success of manual detorsion, it is recommended to use Doppler ultrasound after the manipulation is complete to confirm the state of testicular vascularization. After successful manual detorsion, surgical exploration remains a necessity because residual torsion poses a continued risk to testicular viability. 
In patients with testicular torsion, the affected testis generally is twisted inward (medially). The clinician can easily recall which direction to rotate a torsed testicle (depending on which side is affected) by comparing the action to opening the spine of a book.
Manual testicular detorsion has no complications.
Manual detorsion of the testes is usually difficult because of acute pain during manipulation. Nonoperative manual detorsion is not a substitute for surgical exploration.