Investigations
1st investigations to order
Testicular Workup for Ischaemia and Suspected Torsion (TWIST) score
Test
A clinical risk score that can be used to support the assessment and management of a child or young person with testicular pain.
It is a 7-point score generated from five parameters: testicular swelling (2 points), hard testis (2 points), high-riding testis (1 point), nausea or vomiting (1 point), absent cremasteric reflex (1 point).[25][26]
Sensitivity 98.4% in low-risk patients and specificity 97.5% in high-risk patients.[27]
Emergency scrotal exploration is recommended if the TWIST score ≥5 in a child or young person with <48 hours of pain.[21] However, a score ≤4 does not completely exclude testicular torsion.
The TWIST score has also been validated for the diagnosis of testicular torsion in adults.[28]
Result
low risk (score 0 to 2), intermediate risk (3 to 4), or high risk (5 to 7)
ultrasound with Doppler flow imaging
Test
Ultrasound assessment can rapidly and accurately determine the presence of testicular torsion or identify other aetiologies for testicular pain.[29][30] Although not usually required, it may be indicated in the following scenarios: pain present for ≥48 hours; strong suspicion of an alternative diagnosis that would significantly change management; newborns with a suspected antenatal torsion (to exclude alternative diagnoses).[21]
If ultrasound can be performed without delaying treatment, it may be considered to confirm diagnosis of torsion in children and young people with pain for <48 hours.[21]
Grey-scale ultrasound can identify the whirlpool sign (swirling appearance of the spermatic cord), which is specific to partial or complete testicular torsion.[31][32][33] However, the whirlpool sign is of limited utility in neonates, and the sensitivity of detection varies with ultrasonographer experience.[34]
Colour Doppler and/or power Doppler studies are also needed to establish the presence or absence of blood flow to the testicles.[29][32] Power Doppler is more sensitive to low blood flow than regular colour Doppler.[32] Spectral analysis can be used in combination with colour and power Doppler ultrasound to determine pulsatile flow, arterial or venous.[32][33]
Normal or increased intra-testicular blood flow (i.e., hyperaemia) may suggest an inflammatory diagnosis or successful de-torsion.[29] However, blood flow does not exclude a diagnosis of testicular torsion because arterial flow may be present in early phases of torsion, or in partial or intermittent torsion. Comparison with the contralateral testicle should be carried out to identify differences in flow.[24][33] Spectral analysis may also be helpful in these cases.[33]
Result
presence of fluid and the whirlpool sign (the swirling appearance of the spermatic cord); absent or decreased blood flow in the affected testicle; decreased flow velocity in the intra-testicular arteries, increased resistive indices in the intra-testicular arteries; non-homogeneous and/or asymmetrical vascular perfusion compared with the unaffected testis on spectral analysis
Investigations to consider
urinalysis
Test
If abnormal, usually suggests alternate diagnosis (e.g., epididymitis or orchitis). However, it is important to note that the urinalysis may be negative in cases of epididymitis or orchitis and positive in the setting of testicular torsion.[35]
Result
usually normal, but can be abnormal in some cases
scintigraphy
Test
Scintigraphy has almost 100% sensitivity for identifying patients with torsion; however, it takes longer and is less readily available than Doppler ultrasound.[5][36] Scintigraphy provides information about anatomy and vascular perfusion that can be used to distinguish testicular torsion from other non-surgical causes of an acute scrotum, preventing unnecessary surgery.
Result
decreased uptake of radioactive technetium-99m to the affected testicle in patients with testicular torsion.
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