Diagnostic Ultrasound - Abdomen and Pelvis

Testes
○ Internal oblique muscle → cremasteric muscle and fascia
○ External oblique muscle → external spermatic fascia
○ Dartos muscle and fascia embedded in loose areolar
tissue below skin
○ Processus vaginalis closes and forms tunica vaginalis
– Mesothelial-lined sac around anterior and lateral sides
of testis
– Visceral layer of tunica vaginalis blends imperceptibly
with tunica albuginea
ANATOMY-BASED IMAGING ISSUES
Imaging Recommendations
• Palpation of scrotal contents and taking history prior to US
examination
• High-frequency (10-15 MHz) linear transducer
• Patient in supine position
○ Penis lies on anterior abdominal wall
○ Towel draped over thighs to elevate scrotum
○ Additional positions with patient upright or with patient
performing Valsalva maneuver
IMAGING ANATOMY
Sonographic Anatomy
• Testes
○ Ovoid, homogeneous, medium-level, granular
echotexture
○ Mediastinum testis may appear as prominent echogenic
line emanating from posterior testis
○ Blood flow
– Testicular artery pierces tunica albuginea and
arborizes over periphery of testis
– Multiple, radially arranged vessels travel along septa
– May have prominent transmediastinal artery
– Low-velocity, low-resistance waveform on Doppler
imaging, with continuous forward flow in diastole
• Epididymis
○ Isoechoic to slightly hyperechoic compared with testis
○ Best seen in longitudinal plane
○ Head has rounded or triangular configuration
○ Head 10-12 mm, body and tail often difficult to visualize
– May be helpful to follow course of epididymis in
transverse plane if difficult to visualize in longitudinal
plane
• Spermatic cord
○ May be difficult to differentiate from surrounding soft
tissues
○ Evaluate for varicocele with color Doppler
○ Risk of carcinoma is increased for both testes, even if
other side is normally descended
Varicocele
• Idiopathic or secondary to abdominal mass
○ Idiopathic more common on left
• Vessel diameter > 3 mm abnormal
• Always evaluate with provocative maneuvers, such as
Valsalva
Dilated Rete Testes
• Clusters of dilated tubules in mediastinum testis
• Empty into epididymis
• Often associated with epididymal cysts
Torsion
• Occurs most commonly when tunica vaginalis completely
surrounds testis and epididymis
○ Testis is suspended from spermatic cord (like bellclapper)
rather than being anchored posteriorly
• Normal grayscale appearance with early torsion
○ Becomes heterogeneous and enlarged with infarction
• Color and spectral Doppler required for diagnosis
○ Some flow may be seen even if torsed but will be
decreased compared to normal side
○ Venous flow compromised 1st, then diastolic flow, and
finally systolic flow
Testicular Microlithiasis
• Calcifications in testicular parenchyma
• Association with testicular carcinoma
○ Controversial whether risk factor
Testicular Carcinoma
• Most common malignancy in young men
○ 95% are germ cell tumors
– Seminoma (most common pure tumor), embryonal,
yolk sac tumor, choriocarcinoma, teratoma
– Mixed germ cell tumor (components of 2 or more cell
lines) most common overall
○ Remainder of primary tumors are sex cord (Sertoli cells)
or stromal (Leydig cells)
○ Lymphoma, leukemia, and metastases more common in
older men
• Most metastasize via lymphatics in predictable fashion
○ Right-sided 1st echelon nodes: Interaortocaval chain at
2nd vertebral body
○ Left-sided 1st echelon nodes: Left paraaortic nodes in
area bounded by renal vein, aorta, ureter, and inferior
mesenteric artery
Anatomy: Pelvis
CLINICAL IMPLICATIONS
Hydrocele
• Fluid between visceral and parietal layers of tunica vaginalis
• Small amount of fluid is normal
• Larger hydroceles may be either congenital (patent
processus vaginalis) or acquired
Cryptorchidism
• Failure of testes to descend completely into scrotum
• Most lie near external inguinal ring
• Associated with decreased fertility and testicular carcinoma
SELECTED REFERENCES
1. Appelbaum L et al: Scrotal ultrasound in adults. Semin Ultrasound CT MR.
34(3):257-73, 2013
2. American Institute of Ultrasound in Medicine et al: AIUM practice guideline
for the performance of scrotal ultrasound examinations. J Ultrasound Med.
30(1):151-5, 2011
3. Dogra V et al: Acute painful scrotum. Radiol Clin North Am. 42 (2): 349-63,
2004
4. Dogra VS et al: Sonography of the scrotum. Radiology. 227(1):18-36, 2003
5. Dogra V et al: Ultrasonography of the scrotum. J Ultrasound Med. 21(8):848,
2002
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