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Summary Table

Domain	Detail
Risk Factors	Neonates and adolescents (bimodal peak), "bell clapper" deformity (horizontal lie of testis due to high attachment of tunica vaginalis), history of prior torsion or intermittent torsion, cold weather, recent trauma or vigorous activity, undescended testis
Etiology	Twisting of the spermatic cord along its longitudinal axis, leading to venous congestion followed by arterial compromise and ischemic necrosis of the testis
Patient Presentation	Sudden onset of severe, unilateral scrotal pain, often waking the patient from sleep; associated nausea and vomiting; no urinary symptoms (no dysuria, no discharge)
Classic Physical Exam	High-riding testis with transverse (horizontal) lie, absent cremasteric reflex on the affected side, diffuse testicular tenderness, negative Prehn sign (pain NOT relieved by scrotal elevation), possible blue dot sign if torsion of the appendix testis instead
Key Diagnostic Results	Color Doppler ultrasound shows decreased or absent blood flow to the affected testis; whirlpool sign of the twisted spermatic cord; no role for urinalysis in confirming the diagnosis (UA is typically normal)
Management	Emergent surgical exploration and detorsion with bilateral orchiopexy; if the testis is nonviable, orchiectomy with contralateral orchiopexy; manual detorsion ("open the book" technique) is a temporizing bridge, not definitive treatment
Keywords	"Sudden scrotal pain," "absent cremasteric reflex," "high-riding testis," "horizontal lie," "bell clapper deformity," "adolescent male," "awakened from sleep by pain," "nausea and vomiting with scrotal pain"

1. Pathophysiology

Testicular torsion occurs when the testis rotates on the spermatic cord, twisting the vascular pedicle and obstructing blood flow. The underlying anatomical predisposition is the "bell clapper" deformity, in which the tunica vaginalis attaches abnormally high on the spermatic cord rather than along the posterior aspect of the testis. This gives the testis excessive mobility within the tunica, allowing it to swing freely and twist, much like the clapper inside a bell. This deformity is bilateral in the majority of cases, which is why prophylactic fixation of the contralateral testis is always performed during surgical repair.

The vascular compromise follows a predictable sequence. Because venous pressure is lower than arterial pressure, the thin-walled veins are compressed first. This leads to venous congestion, edema, and hemorrhagic infarction of the testis. As the degree of torsion increases (often 360 degrees or more), arterial inflow is eventually occluded as well, resulting in complete ischemia. This explains why the testis becomes swollen, firm, and exquisitely tender on examination. The cremasteric reflex is lost because the twisted cord disrupts the normal reflex arc carried by the genitofemoral nerve (L1-L2). The testis rides high in the scrotum because the twisting of the cord effectively shortens its length, pulling the testis superiorly, and the abnormal suspension causes it to assume a transverse (horizontal) lie rather than the normal vertical orientation.

The time-to-ischemia relationship is the single most important concept for exam purposes. Testicular salvage rates exceed 90% if detorsion occurs within 6 hours of symptom onset. Between 6 and 12 hours, salvage drops to approximately 50%. Beyond 24 hours, the testis is almost certainly nonviable. This is why testicular torsion is a true surgical emergency and why the diagnosis should never be delayed by imaging when clinical suspicion is high.

Nausea and vomiting accompany testicular torsion because of the visceral afferent innervation of the testis via the T10 sympathetic fibers, which overlap with gastrointestinal innervation. This referred visceral pain response is a hallmark feature that helps distinguish torsion from more superficial causes of scrotal pain.

2. Classification and Clinical Manifestation

Type	Age Group	Mechanism	Clinical Features
Intravaginal torsion	Adolescents (peak 12 to 18 years)	Twisting of the spermatic cord within the tunica vaginalis; associated with bell clapper deformity	Sudden severe unilateral scrotal pain, high-riding testis, absent cremasteric reflex, horizontal lie, nausea/vomiting; most common type overall
Extravaginal torsion	Neonates (prenatal or perinatal)	Entire testis, cord, and tunica vaginalis twist together because the tunica is not yet fixed to the scrotal wall	Painless, firm, discolored (dark or blue) scrotal mass in a newborn; often presents at birth as an already-infarcted testis; contralateral orchiopexy is performed to protect the other side
Torsion of the testicular appendage (appendix testis or appendix epididymis)	Prepubertal boys (peak 7 to 14 years)	Torsion of a vestigial embryologic remnant (Mullerian duct remnant for appendix testis, Wolffian duct remnant for appendix epididymis)	Gradual onset of pain, often localized to the upper pole of the testis; "blue dot sign" (a small blue/black discoloration visible through the scrotal skin at the upper pole); cremasteric reflex is typically preserved; self-limiting and managed conservatively with NSAIDs
Intermittent torsion	Adolescents	Repeated episodes of partial torsion that spontaneously resolve	Recurrent episodes of sudden scrotal pain lasting minutes to hours, then resolving completely; history of multiple ER visits for scrotal pain; warrants elective bilateral orchiopexy to prevent a complete torsion event

3. Diagnostic Workup

Test	Role	Key Findings
Clinical examination	Best initial assessment; sufficient to proceed to surgery if suspicion is high	Absent cremasteric reflex (sensitivity >95%), high-riding testis, horizontal lie, diffuse tenderness, negative Prehn sign
Color Doppler ultrasonography	Best initial imaging test when diagnosis is uncertain	Decreased or absent intratesticular blood flow on the affected side compared to the normal side; "whirlpool sign" of the twisted cord; testicular swelling and heterogeneity in late cases
Nuclear scintigraphy (technetium-99m pertechnetate scan)	Most accurate test (historically); rarely used in practice due to time constraints	"Cold" or photopenic area over the affected testis surrounded by a rim of increased uptake ("rim sign") from reactive hyperemia of the surrounding dartos
Urinalysis	Used to evaluate for alternative diagnoses	Normal in torsion; pyuria and bacteriuria suggest epididymitis or UTI instead
Surgical exploration	Gold standard for definitive diagnosis and simultaneous treatment	Direct visualization of the twisted cord and assessment of testicular viability

The most important principle to understand is that testicular torsion is a clinical diagnosis, and imaging should never delay surgical exploration when clinical suspicion is high. If a teenage boy presents with sudden-onset scrotal pain, absent cremasteric reflex, and a high-riding testis, the correct next step is emergent surgical exploration, not an ultrasound.

Color Doppler ultrasound is ordered when the presentation is ambiguous or atypical, for example when the history is vague, the cremasteric reflex is equivocal, or the physician needs to distinguish between torsion and epididymitis. The key finding is absent or markedly reduced arterial flow within the affected testis compared to the contralateral side. A secondary finding is the whirlpool sign, which represents the spiraling of the twisted spermatic cord visualized on grayscale or color Doppler imaging.

Urinalysis is not a diagnostic test for torsion but serves as a discriminator. A normal urinalysis in a patient with acute scrotal pain supports torsion, whereas pyuria with or without bacteriuria redirects the diagnosis toward epididymitis or urinary tract infection.

The cremasteric reflex is elicited by stroking or pinching the inner thigh and observing for ipsilateral testicular retraction. Its absence is the single most sensitive physical exam finding for testicular torsion (reported sensitivity of 96% to 99% in pediatric studies). On exam questions, the phrase "absent cremasteric reflex" is virtually diagnostic of torsion and should trigger immediate recognition.

4. Management and Treatment

Phase	Intervention	Details
Immediate temporizing measure	Manual detorsion	"Open the book" technique: rotate the affected testis medially to laterally (toward the thigh on each side); for the left testis, rotate clockwise from the patient's perspective; for the right, rotate counterclockwise; successful detorsion is signaled by immediate pain relief and restoration of normal lie; this is a bridge to surgery, not definitive treatment
Definitive treatment	Emergent surgical exploration	Untwist the spermatic cord under direct visualization; assess viability of the testis (color return, bleeding from tunica after detorsion); perform bilateral orchiopexy (fixation of both testes to the dartos fascia using nonabsorbable sutures) to prevent recurrence on either side
Nonviable testis	Orchiectomy + contralateral orchiopexy	If the testis does not recover after detorsion (dark, nonbleeding, necrotic), perform orchiectomy; always fix the contralateral testis because the bell clapper deformity is bilateral
Torsion of appendix testis	Conservative management	NSAIDs for pain control, scrotal support, activity restriction; condition is self-limiting within 1 to 2 weeks; surgery only if pain is severe and refractory
Intermittent torsion	Elective bilateral orchiopexy	Prevents future complete torsion; indicated after recurrent episodes of self-resolving scrotal pain

Step 1: Recognize the emergency. The moment a patient presents with sudden scrotal pain, absent cremasteric reflex, and a high-riding testis, the clock starts. Do not delay for imaging. The next best step is emergent surgical consultation.

Step 2: Attempt manual detorsion while awaiting surgery. If the operating room is not immediately available, attempt bedside manual detorsion using the "open the book" technique. Most torsions occur in a medial (inward) direction, so the correction involves rotating the testis laterally (outward), as if opening the cover of a book toward the patient's thigh. The degree of rotation needed is often 360 to 720 degrees. Success is confirmed by sudden relief of pain, return of the testis to its normal vertical lie, and restoration of Doppler flow on repeat ultrasound if available. Even after successful manual detorsion, surgery is still required because the anatomical predisposition (bell clapper deformity) persists.

Step 3: Surgical exploration and bilateral orchiopexy. At surgery, the spermatic cord is untwisted and the testis is inspected for viability. If the testis reperfuses (pink color, active bleeding from incised tunica albuginea), it is preserved and fixed to the scrotal wall (orchiopexy). The contralateral testis is always explored and fixed during the same operation, given the high likelihood of bilateral bell clapper deformity.

Step 4: Orchiectomy if the testis is nonviable. A testis that remains dark, nonbleeding, and necrotic after detorsion and a warm saline observation period is removed. Contralateral orchiopexy is still performed. Loss of one testis does not typically impair fertility or testosterone production significantly if the other testis is healthy.

Contraindication note: There are no absolute contraindications to surgical exploration for suspected testicular torsion. The risk of an unnecessary scrotal exploration (in the case of a misdiagnosis) is far lower than the risk of losing a testis due to delayed surgery.

5. Differential Diagnosis and Distractors

Differential	Why It Is Similar	Key Discriminator
Epididymitis / Epididymo-orchitis	Also causes acute scrotal pain and swelling; most common mimic of torsion in older adolescents and young adults	Gradual onset (hours to days) rather than sudden; positive Prehn sign (pain relieved by scrotal elevation); cremasteric reflex is present; urinalysis shows pyuria or bacteriuria; Doppler ultrasound shows increased blood flow (not decreased); associated urethral discharge or history of STI in sexually active males; associated UTI symptoms in older men
Torsion of the appendix testis	Acute scrotal pain in a similar age group (prepubertal boys); can be confused with true testicular torsion	Pain is localized to the upper pole of the testis rather than diffuse; "blue dot sign" at the superior pole; cremasteric reflex is preserved; Doppler shows normal or increased testicular flow; managed conservatively
Inguinal hernia (incarcerated)	Can present with acute inguinoscrotal pain and swelling, especially in infants	Palpable inguinal mass that does not transilluminate; swelling extends into the inguinal canal; may have associated bowel obstruction symptoms (vomiting, distension, absent bowel sounds); testis itself is usually normal in lie and position
Testicular tumor	Can present as scrotal swelling or heaviness; sometimes discovered after minor trauma	Painless scrotal mass; firm, hard, irregular testis; does not transilluminate; elevated tumor markers (AFP, beta-hCG, LDH); ultrasound shows solid intratesticular mass
Henoch-Schonlein Purpura (IgA Vasculitis)	Can cause scrotal pain and swelling in children due to vasculitis of the scrotal vessels	Associated palpable purpura on the lower extremities and buttocks; abdominal pain and arthralgia are present; scrotal involvement is part of a systemic vasculitis, not an isolated event
Fournier gangrene	Scrotal pain and swelling with rapid deterioration	Patient is typically older, diabetic, or immunocompromised; scrotal skin shows crepitus, erythema, and necrosis; systemic toxicity with fever and sepsis; imaging shows subcutaneous gas
Hydrocele	Scrotal swelling that may cause concern	Painless, slowly enlarging scrotal swelling; transilluminates (light passes through the fluid); nontender; testis is palpable and normal within the fluid collection

6. Traps and High-Yield Pearls

The most common way students get questions about testicular torsion wrong is by ordering an ultrasound instead of proceeding directly to surgery. When the vignette describes a classic presentation (adolescent male, sudden onset, absent cremasteric reflex, high-riding testis), the correct answer is emergent surgical exploration. Choosing "Doppler ultrasound" as the next step is the designed trap answer. Imaging is appropriate only when the clinical picture is ambiguous.

A second common trap involves confusing torsion with epididymitis. The vignette will use discriminating clues: epididymitis is gradual in onset, has a positive Prehn sign, shows an abnormal urinalysis, and occurs in sexually active males with risk factors for STIs or in older men with urinary obstruction. Torsion is sudden, has no urinary symptoms, and has a normal urinalysis. If the vignette mentions "absent cremasteric reflex," the answer is torsion regardless of other details.

A third trap is the torsion of the appendix testis, which presents in a slightly younger age group and has a localized upper pole tenderness with the blue dot sign. Students who do not know about this entity may incorrectly select surgical exploration for what should be conservative management.

Finally, remember these three non-negotiable facts: (1) bilateral orchiopexy is always performed because the bell clapper deformity is bilateral, (2) manual detorsion is a temporizing measure and never replaces surgery, and (3) the 6-hour window is the critical time point beyond which testicular salvage rates drop dramatically. The core competency being tested is the ability to recognize a surgical emergency, resist the urge to order unnecessary tests, and act decisively within a narrow time window.

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