Testicular torsion happens when the spermatic cord, which supplies blood to the testicle, twists and cuts off circulation. In most cases, it occurs because the testicle isn’t anchored securely inside the scrotum, allowing it to rotate freely. The result is sudden, severe pain and a medical emergency: without restored blood flow within about six hours, the testicle can be permanently damaged or lost.
The Anatomy Behind It
Normally, each testicle is attached to the surrounding tissue in a way that prevents it from spinning. But some males are born with what’s called a “bell clapper deformity,” where the membrane lining the scrotum wraps completely around the testicle, epididymis, and a length of the spermatic cord instead of anchoring them in place. This gives the testicle room to swing and rotate, much like the clapper inside a bell.
Autopsy studies estimate that 5 to 16 percent of males have this anatomy, and in 66 to 100 percent of those cases, it’s present on both sides. That’s why someone who experiences torsion on one side often has their other testicle surgically secured at the same time. You can have the bell clapper deformity your entire life and never know it until torsion happens, or it may never cause a problem at all.
What Triggers the Twist
The twist itself can happen during physical activity, after minor trauma, or seemingly out of nowhere. A surprisingly common trigger is sleep. During REM sleep, the cremaster muscle (the small muscle that raises and lowers the testicle in response to temperature or touch) can contract sharply. Erections during REM sleep, combined with peak testosterone levels in the early morning hours, may cause a strong enough cremasteric spasm to rotate a loosely attached testicle. This is especially relevant for newborns and adolescents, who have the highest testosterone surges during sleep.
Cold weather has also been associated with torsion, likely because the cremaster muscle contracts more vigorously in response to cold. But in many cases, there’s no identifiable trigger at all.
Who Is Most at Risk
Torsion overwhelmingly affects young males. A Japanese nationwide study found an incidence of about 15 per 100,000 males under 21, with two peak periods: infancy and adolescence. It’s rare after age 35 and, outside the newborn period, uncommon before age eight. The adolescent peak likely reflects the rapid growth of the testicles during puberty, which can increase their weight and mobility inside the scrotum before the supporting tissues fully develop.
What It Feels Like
The hallmark of torsion is sudden, severe scrotal pain. It typically comes on fast, often within seconds, and may be accompanied by nausea or vomiting. The affected testicle usually rides higher than normal in the scrotum and may sit in a horizontal rather than vertical position. Lifting the testicle tends to make the pain worse rather than better.
One of the most telling physical signs is the absence of the cremasteric reflex. Normally, stroking the inner thigh causes the testicle on that side to rise slightly. In torsion, this reflex disappears. Studies show this absent reflex is about 88 percent sensitive and 86 percent specific for torsion, with even better accuracy in boys 11 and older (100 percent sensitivity, 89 percent specificity). An ultrasound with Doppler imaging can confirm the diagnosis by showing reduced or absent blood flow to the testicle.
Intermittent Torsion
Not every episode of torsion is a one-way event. Some males experience intermittent torsion, where the cord twists and then spontaneously untwists. The pattern is distinctive: severe pain that starts suddenly and then resolves within seconds to a few minutes. About a quarter of patients with intermittent torsion also report nausea or vomiting during episodes, and nearly half have visible testicular swelling when examined during an episode.
These episodes often start during sleep or physical activity and can recur over weeks or months. A horizontal lie of the testicle on exam is a strong indicator that the bell clapper deformity is present. Intermittent torsion is worth taking seriously because each episode risks progressing to a complete torsion that doesn’t resolve on its own.
How It Differs From Other Scrotal Pain
Two conditions commonly mimic torsion: epididymitis (infection or inflammation of the coiled tube behind the testicle) and torsion of the testicular appendix (a small tissue remnant on the upper pole of the testicle).
- Epididymitis causes pain that builds gradually over hours or days rather than striking all at once. It’s often accompanied by urinary symptoms like burning, frequency, or fever. The cremasteric reflex remains intact, and lifting the testicle may relieve pain rather than worsening it. Ultrasound shows increased blood flow, the opposite of torsion.
- Torsion of the testicular appendix typically affects boys between 7 and 14 and causes localized tenderness at the top of the testicle. A classic clue is the “blue dot” sign, a small area of bluish discoloration visible through the scrotal skin, indicating the tissue has lost its blood supply. The cremasteric reflex is preserved, and the condition resolves on its own with pain management.
The key distinguishing features of true testicular torsion are acute onset, absent cremasteric reflex, a high-riding testicle, and pain that worsens with elevation. Urinary symptoms like burning or frequency are rare with torsion but common with epididymitis.
What Happens After Torsion
Surgical repair involves untwisting the cord and stitching the testicle to the scrotal wall to prevent future episodes, a procedure called orchiopexy. If the testicle has been without blood flow for too long and the tissue is no longer viable, it’s removed. The sooner surgery happens, the better the outcome. Within the first six hours, salvage rates are high. After 12 to 24 hours, the chances of saving the testicle drop significantly.
Even after successful repair, torsion can affect long-term fertility. Studies show that up to one third of patients have lower sperm counts following a torsion event. The temporary loss of blood flow can damage the sperm-producing cells, and in some cases, the immune response triggered by injured testicular tissue may affect the opposite testicle as well. Most men with one healthy testicle still produce enough sperm for fertility, but the reduction is worth knowing about if future family planning is a consideration.