Torsion of the Testis

Definition

• Incidence: 3.8-4.5 per 100,000 males under 18 years annually
• Accounts for 10-15% of acute scrotal disease in children
• Most common between ages 10 and 25 years

Pathophysiology

Types of Torsion

• Seen almost exclusively in neonates
• Occurs due to increased mobility of the testicle before it descends into the scrotum and becomes attached to the scrotal wall via the tunica vaginalis
• The entire spermatic cord, including the tunica vaginalis, twists

• The predominant type beyond the neonatal period
• Results from one or more anatomical predispositions:

Figure: (a) Normal attachment, (b) Abnormally high attachment (bell-clapper deformity) - the tunica vaginalis investment is too high, allowing free rotation, (c) Separation of testis from epididymis - torsion about the pedicle between them - Bailey & Love, 28th Ed.

Precipitating Factors

• Physical activity (straining, lifting, sport)
• Sexual activity
• Thermal stimulation
• Occasionally occurs during sleep (cremasteric reflex while waking)

Degree of Torsion and Ischaemia

• Twists of 720° cause more rapid ischaemia than twists of 360° or less
• Duration-dependent damage: venous outflow obstructed first, then arterial inflow
• Contralateral testicular biopsy findings are abnormal in 57-88% of males when torsion occurs, suggesting underlying bilateral spermatogenic dysfunction

Consequence of Torsion

• Up to 50% of men develop adverse spermatogenic effects after torsion
• 36-39% will have sperm concentrations below 20 million/mL
• Up to 11% develop antisperm antibodies due to disruption of the blood-testis barrier (tight junctions between Sertoli cells)

Clinical Features

Differential Diagnosis

Investigations

Clinical Priority First

1. Doppler Ultrasound (most commonly used)

• Can confirm absence of blood flow to the affected testis
• Sensitivity 92-100% for confirming epididymitis
• Absence of blood flow = torsion until proven otherwise
• Caveat: False-positive results (apparent flow) can occur, so it is not routinely recommended as a reason to withhold surgery. A positive Doppler (flow present) does not absolutely exclude torsion.

2. Radionuclide Scanning (Technetium-99m scan)

• Uptake of tracer into the centre of the testis rules out torsion
• Less available, rarely used in acute setting

3. Urinalysis

• Normal in testicular torsion (WBCs and bacteria suggest epididymo-orchitis)

4. FBC/Bloods

• Leukocytosis suggests infection rather than torsion
• No specific blood test for torsion

Key principle from Smith & Tanagho's General Urology:

"The presence of blood flow in the testis on Doppler ultrasonography or uptake of tracers into the center of the testis on radionuclide scanning rules out torsion."

Management

Time is Testis - Salvage Rates by Duration

Step 1: Immediate Urological Consultation

Step 2: Manual Detorsion (can be attempted in ED)

• Testis usually rotates medially (inward), so manual detorsion involves rotating it outward (laterally), like opening a book
• If successful, pain relief is immediate and vascular flow restored
• This is a temporising measure only - does not negate need for surgical fixation

Step 3: Emergency Surgical Exploration

• Fix with 3 non-absorbable sutures between the tunica albuginea and the scrotal raphe (orchiopexy)
• Absorbable sutures must NOT be used (risk of recurrent torsion as suture dissolves)
• Fix the contralateral testis as well - the anatomical predisposition is bilateral

• Wrap the testis in a warm swab and observe for several minutes
• Make a small incision in the tunica albuginea - if bright red arterial bleeding is seen, the testis may survive
• Fix as above if viable

• Orchiectomy is performed - the dead testis must be removed
• Counsel the patient about testicular prosthesis later
• Still fix the contralateral testis to prevent future torsion

Step 4: Contralateral Orchiopexy

Step 5: Cases With Prolonged History (Several Days)

• The affected testis will already be infarcted
• Little can be gained (other than pain relief) by immediate exploration of the affected side
• However, urgent contralateral fixation is still necessary

Orchiopexy Techniques (for intermittent/elective cases)

1. Suture fixation - 3-0 non-absorbable sutures fixing tunica albuginea to dartos muscle or scrotal raphe
2. Dartos pouch procedure - testis placed in a subcutaneous pouch between dartos and external spermatic fascia, secured by purse-string suture; preferred by some as it avoids intratesticular vessel injury

Summary Algorithm

Acute Scrotal Pain
      ↓
High clinical suspicion for torsion?
      ↓
YES → Emergency surgical exploration (do not delay)
      ↓
Viable testis? → Bilateral orchiopexy (non-absorbable sutures)
Infarcted?    → Orchiectomy + contralateral orchiopexy

NO / Uncertain → Doppler ultrasound
      ↓
No flow → Emergency exploration
Flow present + confident alternative diagnosis → Treat accordingly

• Bailey and Love's Short Practice of Surgery, 28th Ed., pp. 1582-1584 (Torsion of the Testis)
• Campbell-Walsh-Wein Urology, 3-Volume Set, pp. 1612-1614; 1180-1184 (Testis Torsion; Intermittent Torsion)
• Smith and Tanagho's General Urology, 19th Ed., p. 787 (Distinguishing Torsion)
• Rosen's Emergency Medicine: Concepts and Clinical Practice, p. 1595 (Disposition and Management)

Laplace's Law - Physics, Physiology, and Surgical Significance

The Formula

T = P × r / w

P = 2HT / r (rearranged: T = P × r / 2w)

• T = Wall tension (force per unit length of wall)
• P = Transmural pressure (internal minus external pressure)
• r = Radius of the hollow structure
• w / H = Wall thickness

Core Concepts

Surgical Applications - Organ by Organ

1. Aortic and Arterial Aneurysms (Most Direct Surgical Application)

"Aneurysmal dilation accelerates, increasing the risk of rupture as diameter increases, as described by Laplace's law: tension in the wall of a hollow viscus varies directly with its radius."

• A normal aorta (radius ~1 cm) generates ~170,000 dynes/cm of wall tension
• As the aorta dilates to 5-6 cm (AAA), wall tension rises proportionally - and each millimetre of further growth disproportionately increases rupture risk
• This explains why the 5.5 cm threshold for elective AAA repair is used clinically: beyond this, annual rupture risk (~10-20%) overtakes operative mortality
• A dilating aneurysm is a self-reinforcing cycle: dilation → increased tension → further dilation - a vicious positive feedback loop
• The same principle applies to popliteal, splenic, and visceral artery aneurysms

2. Bowel Obstruction and Cecal Perforation

• The cecum has the largest diameter in the colon (~9 cm normal, can reach 12-15 cm in obstruction)
• Under the same intraluminal pressure as the sigmoid colon, the cecum generates far greater wall tension
• This is why the cecum perforates first in large bowel obstruction, even when the obstructing lesion is in the left colon
• The "safe" radiological threshold is cecal diameter > 12 cm (increasing perforation risk)

3. The Heart in Cardiac Failure and Hypertrophy

• In systemic hypertension: elevated aortic pressure → left ventricle compensates by wall hypertrophy (increasing H/thickness) → this reduces wall tension for any given pressure, protecting the myocardium
• In dilated cardiomyopathy (increased radius r): the ventricle must generate more wall tension to produce the same ejection pressure → increases myocardial O₂ consumption, accelerates decompensation
• Ganong: "When the radius of a cardiac chamber is increased, a greater tension must be developed in the myocardium to produce any given pressure; consequently, a dilated heart must do more work than a nondilated heart"
• This explains why afterload reduction (ACE inhibitors, ARBs) is so beneficial in dilated cardiomyopathy - reducing wall tension reduces myocardial work

4. The Urinary Bladder

• Normal bladder wall compliance maintains low intravesical pressure despite increasing volume (large radius, but thin compliant wall compensated by accommodation)
• In chronic urinary retention with a massively distended bladder: Laplace's Law predicts enormous wall tension - predisposing to:
  • Ischaemia of the detrusor muscle
  • Loss of contractility (overflow incontinence)
  • Risk of bladder rupture (rare, but seen with trauma on a full bladder)
• Rapid decompression of an acutely distended bladder (>1 litre) should be done carefully to avoid haematuria from sudden drop in transmural pressure

5. Alveoli and Respiratory Surgery

Effect of alveolar size and surfactant on collapsing pressure. Large alveolus = low collapsing pressure; small alveolus = high collapsing pressure; surfactant reduces collapsing pressure in small alveoli - Costanzo Physiology, 7th Ed.

• Small alveoli have high collapsing pressure - they tend to collapse (atelectasis)
• Surfactant reduces surface tension (T), lowering collapsing pressure - this is the biological solution
• In neonatal respiratory distress syndrome (surfactant deficiency), small stiff alveoli collapse
• Surgically: post-operative atelectasis occurs in collapsed, surfactant-depleted small alveoli - managed with PEEP (positive end-expiratory pressure), deep breathing, and physiotherapy
• After pneumonectomy or lung resection, the remaining lung must expand: larger radius → lower wall tension per Laplace, which is actually beneficial

6. Capillaries - Why They Don't Burst

Summary Table: Surgical Implications at a Glance

• Ganong's Review of Medical Physiology, 26th Ed., p. 576 (Law of Laplace - capillaries and vessels)
• Costanzo Physiology, 7th Ed., pp. 159, 210 (Heart, alveoli)
• Fischer's Mastery of Surgery, 8th Ed., p. 3603 (Cecal perforation and Laplace)
• Rosen's Emergency Medicine, p. 1178 (Aneurysmal dilation)
• Tintinalli's Emergency Medicine, p. 3104 (Aortic aneurysm)