Diagnostic Ultrasound - Abdomen and Pelvis

Testicular Torsion/Infarction
TERMINOLOGY
Definitions
• Spontaneous or traumatic twisting of testis & spermatic
cord within scrotum, resulting in vascular
occlusion/infarction
IMAGING
General Features
• Best diagnostic clue
○ Absent or decreased abnormal testicular blood flow on
color Doppler US
• Location
○ Unilateral in 95% of patients
• Morphology
○ Complete/incomplete torsion
○ Types according to location of torsion knot
– Intravaginal torsion: Torsion knot within tunica
vaginalis
– Extravaginal torsion: Torsion knot outside tunica
vaginalis
Ultrasonographic Findings
• Grayscale ultrasound
○ Testicular torsion
– Findings vary with duration and degree of rotation of
cord
– Grayscale appearance during acute phase (critical
phase) may be normal
– Spiral twist of spermatic cord cranial to testis and
epididymis causing torsion knot or whirlpool pattern
of concentric layers
– Enlarged testis and epididymis (heterogeneous
echotexture, most often decreased echogenicity)
– Edema of scrotal wall, secondary hydrocele
– Intratesticular necrosis, hemorrhage or fragmentation
if delayed diagnosis missed torsion
– At 24 hours after onset changes like congestion,
hemorrhage, and infarction are seen
– Hypoechoic areas associated with testicular infarction
may have striated appearance (due to accentuation of
septa within the testis)
– Normal testicular echogenicity is strong predictor of
testicular viability; decreased and heterogeneous
testicular echogenicity correlates with worse
prognosis and may indicate nonviability
– Subacute phase (1-10 days): Testis echogenicity
decreases in initial 4-5 days, then may show focal or
diffuse infarction; epididymis may remain echogenic
– Chronic phase: Small atrophied homogeneously
hypoechoic testis; enlarged echogenic epididymis
○ Testicular infarction
– Diffusely hypoechoic small testis or focal wedgeshaped
hypoechoic area in infarcted testis
– Hyperechoic regions (hemorrhage/fibrosis), focal
infarctions may have striated appearance
• Color Doppler
○ Color Doppler is very useful to establish diagnosis of
testicular torsion
○ In acute torsion sensitivity, 80-90%; 10% of patients with
early or partial torsion have normal exam
– Setup optimized for detection of slow flow (low pulse
repetition frequency, low wall filter, high Doppler
gain)
○ Absent or decreased or abnormal flow
○ Comparison with contralateral spermatic cord and testis
is mandatory
○ In subacute or chronic torsion: No flow in testis and
increased flow in paratesticular tissues, including
epididymis-cord complex and dartos fascia
○ Role of spectral Doppler is limited; may be helpful to
detect partial torsion; in partial torsion of 360° or less,
spectral Doppler may show diminished diastolic arterial
flow
○ Use of intravascular ultrasound contrast agents may
improve sensitivity for detecting blood flow in testes
○ Increased flow may be seen in the affected testis in a
case of torsion-detorsion syndrome: Correlation with
clinical history of preceding intermittent ipsilateral pain is
helpful clue
Nuclear Medicine Findings
• Tc-99m pertechnetate: Dynamic flow imaging at 2-5 second
intervals for 1 minute (vascular phase); 5-minute intervals
for tissue phase; sensitivity 80-90%
○ Can detect reduced or absent testicular flow in 94-99%
○ In testicular torsion, rounded cold area and halo of
dartos perfusion is seen
Imaging Recommendations
• Best imaging tool
○ US with high-frequency linear transducer & color/power
Doppler
• Protocol advice
○ Compare grayscale, color Doppler appearances to
contralateral normal testis
DIFFERENTIAL DIAGNOSIS
Testicular Trauma
• Hematocele, irregular contours, heterogeneous
parenchymal echogenicity
• Avascular fracture plane
Testicular Abscess (Epididymoorchitis)
• Thick-walled, hypoechoic focus with low-level internal
echoes, thickened tunica albuginea
• Enlarged hypoechoic epididymis with increased flow on
color Doppler
Testicular Tumor
• Focal hypoechoic mass with heterogeneous areas
• Abnormal vascularity within mass
Torsion of Appendix Testis or Appendix Epididymis
• Presents with acute scrotum
• Small firm nodule that is palpable on superior aspect of
testis that exhibits bluish discoloration through overlying
skin, called the blue dot sign
• Hyperechoic mass with central hypoechoic area adjacent to
testis or epididymis, reactive hydrocele, skin thickening, and
peripheral hyperemia
Diagnoses: Scrotum
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