Scrotum

NORMAL ANATOMY AND SONOGRAPHIC APPEARANCE

Testis

Symmetrical ovoid structure; homogeneous echotexture (Figure 42.1).

Length—3–5 centimeters; width 2–4 centimeters; anteroposterior (AP) diameter 3 centimeters.

Surrounded by dense white fibrous capsule (Tunica albuginea).

Epididymis

Elongated crescent-shaped structure.

Length—6–7 centimeters; has head, body, and tail.

Located superolaterally over posterior aspect of testis, iso/hypoechoic relative to testicle.

Tunica vaginalis

Parietal layer → Lines the scrotal wall.

Visceral layer → Envelopes the testis, epididymis, and proximal spermatic cord. Covers the entire testis except small area posteriorly called mediastinum testis (where spermatic cord and its contents join the testicle and seen as a linear echogenic band).

Blood supply

Arterial

•  Testicular artery

•  Deferential artery

•  Cremasteric artery

Venous

Pampiniform plexus—Testicular vein drains into the inferior vena cava (IVC) on the right side and left renal vein on the left side.

USG TECHNIQUE

Supine position with patient’s scrotum supported by towels/sheet.

High frequency (7.5–15 MHz) linear array transducer used.

Scanning—Transverse and sagittal planes.

Valsalva maneuver—For evaluation of varicocele.

Indications for Scrotal USG

1.    Evaluation of acute scrotal disorder—Torsion, Inflammation, and trauma

2.    Evaluation of scrotal fluid collection

•  Hydrocele

•  Pyocele/Hematocele

3.    Evaluation of scrotal mass

•  Extratesticular

•  Intratesticular

4.    Evaluation of metastatic disease

•  Retroperitoneal lymphadenopathy

•  Testicular involvement—Lymphoma, leukemia

5.    Evaluation of varicocele in infertile men

6.    Evaluation of undescended testis

BENIGN CONDITIONS

Discovered incidentally

Cyst of Tunica albuginea—Mean age 40 years. Usually solitary and unilocular

Cyst of Tunica vaginalis—Rare; anechoic ± septations. Echoes d/t. Hemorrhage may be seen

Intratesticular cyst—Simple, well-defined cyst with posterior acoustic enhancement

1.    Tubular ectasia of rete testis:

Idiopathic, benign condition

Partial/complete obstruction of efferent ductules leading to cystic dilation

B/L and asymmetrical

USG findings:

Peripheral elongated structure containing multiple small cystic structures. No calcification, no solid component, and no flow on color Doppler.

2.    Epidermoid cysts

Benign, well circumscribed.

Second to fourth decade.

USG findings:

Alternating rings of hyperechogenicity and hypoechogenicity leading to characteristic ONION RING SIGN (Whorled appearance)

No flow on Doppler imaging (c.f. testicular masses)

3.    Abscess—Complication of epididymo-orchitis usually

Infectious causes → Mumps, small pox, influenza, and typhoid.

Noninfectious → Testicular torsion, infected tumor

USG findings:

Enlarged testicle containing cystic mass with hypoechoic/mixed echogenic areas

4.    Scrotal tuberculosis:

On USG:

Enlarged hypoechoic, heterogeneous epididymis with or without calcifications.

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