Testicular Torsion

• Peak incidence is bimodal: the neonatal period and, far more commonly, puberty to the early twenties.
• The anatomic substrate is the bell-clapper deformity — failure of the tunica vaginalis to anchor the testis posteriorly, leaving it free to rotate. It is usually bilateral, which is why the contralateral testis is fixed at the same operation.
• Salvage is time-dependent: near-universal within about 6 hours of onset, falling steeply thereafter and approaching zero beyond roughly 24 hours.
• Classic findings are sudden severe pain with nausea and vomiting, a high-riding testis with a transverse lie, and an absent cremasteric reflex — the most useful single sign.
• Prehn sign (relief on elevation) suggests epididymitis rather than torsion, but is unreliable and must not be used to exclude it.
• Colour Doppler ultrasound shows absent or reduced flow, but surgical exploration should not be delayed for imaging when suspicion is high.

Anatomic mechanisms

• Intravaginal torsion (the adolescent form): the bell-clapper deformity leaves the tunica vaginalis inserting high on the cord so the testis hangs free like a clapper in a bell and rotates within the tunica. Usually bilateral, which drives contralateral fixation at surgery.
• Extravaginal torsion (the neonatal form): the tunica vaginalis itself has not yet fused to the dartos, so testis, tunica, and cord rotate as a unit. Often occurs in utero or perinatally and presents as a firm, discoloured, characteristically painless hemiscrotal mass.

Triggers that convert anatomy into an event

• Cremasteric contraction: cold exposure, trauma, or vigorous activity produces a spiral pull on a mobile testis. Onset during sleep is classic, attributed to nocturnal cremasteric activity.
• Rapid pubertal testicular growth: increased testicular mass and weight on an unanchored cord raises torsional torque — the reason incidence peaks around ages 12–18.

Non-modifiable risk factors (what the stem plants)

• Age: bimodal, neonatal and peripubertal/early twenties.
• Bell-clapper deformity and a horizontally lying testis on the contralateral side.
• Cryptorchidism / undescended or retractile testis: substantially increased risk, and the stem may describe an empty scrotum with inguinal pain.
• Prior intermittent torsion: recurrent self-resolving episodes of severe unilateral pain — an indication for elective bilateral orchiopexy.
• Family history of torsion or bell-clapper deformity.
• Testicular tumour or enlarged testis, which adds mass to the cord.

Modifiable/iatrogenic factors

• Blunt scrotal trauma and contact sports — the only meaningfully avoidable precipitants; trauma is a trigger, not an alternative diagnosis, and does not exclude torsion.
• Failure to fix the contralateral testis at prior surgery, or fixation with absorbable suture, permits later metachronous torsion.

• The twist is of the spermatic cord, not the testis alone: rotation about the cord's long axis kinks the testicular artery, the deferential and cremasteric arteries, and — because they are thin-walled and low-pressure — the pampiniform venous plexus first.
• Venous outflow fails before arterial inflow: continued arterial delivery into an obstructed venous bed produces progressive interstitial oedema and haemorrhagic engorgement. This is why the testis becomes swollen, exquisitely tender, and firm early, while Doppler may still show some arterial signal in partial torsion — a dangerous false reassurance.
• Rising intratesticular pressure within the non-distensible tunica albuginea creates a compartment effect that finally overcomes arterial pressure, producing haemorrhagic infarction rather than bland pallor.
• Degree of rotation determines speed: incomplete twists (roughly 180°) may leave residual flow and a subacute course, whereas 360° or greater produces complete ischaemia and a short salvage window — the basis for the steep, hour-by-hour fall in viability described earlier.
• Cord shortening from the twist retracts the testis toward the external ring, giving the high-riding testis, and the rotation reorients it, giving the transverse (horizontal) lie.
• The cremasteric reflex is lost because the twisted cord carries the genital branch of the genitofemoral nerve; distortion and oedema abolish the efferent limb, so stroking the medial thigh no longer elevates the testis.
• Visceral afferent innervation of the testis travels with T10 sympathetics, so pain is poorly localised, referred to the lower abdomen or flank, and accompanied by autonomic nausea and vomiting — a boy may present as an "abdominal pain" stem with a scrotum no one examined.
• After reperfusion, ischaemia–reperfusion injury with reactive oxygen species and neutrophil influx can damage the seminiferous epithelium even in a testis that looks viable, and exposure of sequestered germ-cell antigens across a breached blood–testis barrier is the proposed basis for antisperm antibodies and contralateral subfertility.

Symptoms

• Sudden, severe, unilateral scrotal pain, constant and unrelenting — abrupt onset reflects an acute vascular occlusion rather than the crescendo course of infection.
• Nausea and vomiting in a large proportion — T10 visceral afferents produce an autonomic response; their presence in a boy with scrotal pain argues strongly for torsion over epididymitis.
• Referred lower abdominal, inguinal, or flank pain, sometimes the only complaint. Any boy with abdominal pain needs a genital examination.
• Absence of urinary symptoms: no dysuria, frequency, or urethral discharge — their presence points toward epididymitis or urethritis.
• Prior self-limited identical episodes suggest intermittent torsion.

Signs

• Absent cremasteric reflex on the affected side — the single most useful physical finding; its presence makes torsion less likely but does not exclude it.
• High-riding testis with a transverse (horizontal) lie from cord shortening and rotation.
• Diffuse testicular tenderness and firm swelling, in contrast to the localised epididymal tenderness of epididymitis.
• Negative Prehn sign: elevation does not relieve pain. Unreliable in isolation.
• Scrotal erythema and oedema develop later, as does a reactive hydrocele; a normal-looking scrotum early does not reassure.
• Neonatal torsion: a painless, firm, non-transilluminating scrotal mass with skin discolouration in the first days of life, often already infarcted.

Testicular torsion is a clinical diagnosis. High suspicion mandates urgent urologic consultation and scrotal exploration — imaging must not delay the operating room.

Initial assessment

• Focused history and examination: time of onset (starts the salvage clock), cremasteric reflex, testicular lie and height, site of maximal tenderness.
• Urinalysis: normal in torsion; pyuria and bacteriuria suggest epididymitis. A normal urinalysis does not exclude infection and an abnormal one does not exclude torsion.
• TWIST score (Testicular Workup for Ischemia and Suspected Torsion), a named bedside tool: testicular swelling and hard testis (2 points each), absent cremasteric reflex, nausea/vomiting, and high-riding testis (1 point each). Low scores support ruling torsion out and permit imaging; high scores support proceeding directly to exploration without ultrasound.

Confirmatory imaging (when the diagnosis is genuinely equivocal or suspicion is low)

• Colour Doppler ultrasonography of the scrotum is the test of choice, with high sensitivity and specificity in experienced hands. Always compare with the contralateral testis.
• Absent or asymmetrically reduced intratesticular arterial flow is the key finding.
• Whirlpool sign: spiral twist of the spermatic cord at the external ring — the most specific sign and present even in partial torsion.
• Enlarged, heterogeneous, hypoechoic testis indicates infarction and a low probability of salvage.
• Preserved or increased flow is seen in epididymitis (hyperaemia) and in torsion of the appendix testis (a small avascular upper-pole nodule with surrounding hyperaemia).
• Pitfall: early or intermittent/partial torsion may show preserved arterial flow. A reassuring Doppler in a convincing clinical picture does not overrule the examination.

Immediate measures

• Nil per os, IV access, analgesia, and emergent urology consultation the moment torsion is suspected. Opioid analgesia does not obscure the diagnosis and should not be withheld.
• Do not delay surgery for ultrasound, laboratory studies, or transfer imaging when suspicion is high — the AUA Core Curriculum and EAU paediatric urology guidance both frame torsion as a time-critical surgical emergency.

Temporising manoeuvre

• Manual detorsion at the bedside, under procedural sedation or cord block, if operative care will be delayed. The testis usually twists medially, so detorsion is classically performed laterally, "opening a book" — from medial to lateral for the physician's view. Relief of pain, descent of the testis, and return of Doppler flow indicate success.
• Detorsion is never definitive: residual twist is common and the underlying bell-clapper deformity persists. Surgery still follows urgently.
• If pain worsens, rotate the opposite direction — roughly a third of cases torse laterally.

Definitive surgical management

• Scrotal exploration with detorsion and assessment of viability: warm the testis, wrap in saline gauze, and observe for return of colour and bleeding on tunica incision.
• Bilateral orchiopexy — three-point fixation of the tunica albuginea to the dartos with non-absorbable suture. The contralateral testis is fixed at the same operation because the bell-clapper deformity is bilateral.
• Orchiectomy if the testis is frankly necrotic, to avoid abscess and putative immunologic injury to the remaining testis; contralateral orchiopexy is still performed. A prosthesis can be placed later.
• Elective bilateral orchiopexy is indicated for a history of intermittent torsion.
• Neonatal torsion: usually extravaginal and already infarcted; urgent exploration is still generally recommended to address the salvage chance and, importantly, to fix the contralateral testis, since asynchronous bilateral neonatal torsion is anorchia.

Contraindicated / wrong answers

• Antibiotics alone treating presumed epididymitis in an adolescent with an absent cremasteric reflex.
• Observation, scrotal support, or outpatient follow-up imaging.
• Relying on a negative Prehn sign or preserved Doppler flow to send a patient home.

Of the disease

• Testicular infarction and loss — the defining complication. Driven by duration of ischaemia and degree of rotation; signalled by a swollen, heterogeneous, avascular testis on ultrasound or a black, non-bleeding testis at exploration. A missed or delayed torsion is the emergency, and delay is the most litigated and most commonly tested error.
• Testicular atrophy despite apparently successful detorsion, from reperfusion injury to the seminiferous epithelium; detected as a progressively smaller testis on follow-up examination or ultrasound months later.
• Subfertility and abnormal semen analysis, from loss of one testis plus possible injury to the contralateral gonad; the proposed mechanism is breach of the blood–testis barrier with antisperm antibody formation.
• Hypogonadism is uncommon after unilateral loss because Leydig cell reserve in the remaining testis is usually sufficient; bilateral or asynchronous neonatal torsion causing anorchia requires lifelong testosterone replacement and is an endocrine emergency in terms of long-term consequences.
• Infarcted testis left in situ: abscess formation, fever, and scrotal cellulitis.
• Recurrent intermittent torsion in an unfixed testis — repeated episodes of severe self-resolving pain, each one a chance at permanent loss.
• Chronic scrotal pain and psychological/body-image sequelae, particularly in adolescents.

Of treatment

• Recurrent torsion after orchiopexy, rare but reported, typically when absorbable suture was used or fixation was inadequate — recurrence of classic symptoms in a previously fixed testis warrants re-exploration, not reassurance.
• Wound infection, scrotal haematoma, and hydrocele after exploration.
• Testicular injury or atrophy from the fixation sutures themselves, from puncture of the tunica albuginea.
• Negative exploration: an accepted cost of an aggressive approach, not a complication to be avoided at the expense of a delayed diagnosis.
• Incomplete manual detorsion producing partial symptomatic relief that falsely reassures the team — ongoing ischaemia beneath a comfortable patient.

• The single best next step in a boy with acute scrotal pain and an absent cremasteric reflex is emergent urologic consultation for scrotal exploration — not ultrasound. "Order Doppler" is the most attractive wrong answer on Step 2 CK.
• **The absent cremasteric reflex is the highest-yield sign**; the mechanism is involvement of the genital branch of the genitofemoral nerve in the twisted cord. Its presence lowers but does not eliminate the probability of torsion.
• Nausea and vomiting with sudden scrotal pain = torsion until proven otherwise — T10 visceral afferents. Epididymitis rarely vomits.
• **The association examiners love: bell-clapper deformity is bilateral, hence bilateral orchiopexy with non-absorbable suture** even though only one side torsed.
• Cryptorchidism markedly raises torsion risk — a boy with an empty hemiscrotum and acute groin pain is torting an undescended testis.
• Distinguish the mimics: blue dot sign with focal upper-pole tenderness and a preserved cremasteric reflex = torsion of the appendix testis (supportive care only); gradual pain, dysuria, pyuria, fever, and relief on elevation (positive Prehn sign) = epididymitis (in sexually active young men, treat empirically for Chlamydia trachomatis and Neisseria gonorrhoeae per CDC STI treatment guidelines).
• Prehn sign and colour Doppler can both be falsely reassuring — partial or early torsion may retain arterial flow. The whirlpool sign of the twisted cord is the most specific sonographic finding.
• Salvage is a stopwatch: near-universal within about six hours of onset, falling steeply thereafter. Always anchor the answer to the time of pain onset, not the time of arrival.
• Neonatal torsion is extravaginal and painless — a firm, discoloured, non-transilluminating scrotal mass in a newborn.