Clinical exam · Kidney, genitourinary, breast and obstetric exam

Male genital exam: transillumination, cremasteric reflex, Prehn sign !

Exam technique

A respectful check of the penis, scrotum and testes, with consent and a chaperone, to find lumps, hernias or a twisted testis.

Updated 2026-11-01

See it in 3D: Scrotum · Epididymis · Ductus deferens · Testes · Spermatic cord · Inguinal canal · Testicular veins and pampiniform plexus

What it is

The male genital exam covers inspection and palpation of the penis, scrotum, testes, epididymis and spermatic cord, plus a check for inguinal hernias. Three tests help with a scrotal mass or scrotal pain: transillumination (separates fluid from solid), the cremasteric reflex (almost always absent in testicular torsion) and the Prehn sign (unreliable). Torsion is an emergency: recognising it on examination saves the testis.

Landmark anatomy

The testis is wrapped in the tunica vaginalis; fluid collecting in it is a hydrocele, which is why it surrounds and hides the testis.
The epididymis lies along the back and top of the testis; the vas deferens leaves it and runs up the spermatic cord to the inguinal canal.
The cremasteric reflex uses the genitofemoral nerve (segments L1 and L2): stroking the thigh contracts the cremaster muscle and lifts the testis.
The left testicular vein drains into the left renal vein at a right angle, which is why varicocele is far more common on the left.

Technique, step by step

Explain what will be done and why, obtain verbal consent, offer a chaperone, protect privacy and wear gloves.
Examine standing first (hernias, varicocele), then lying down; uncover only the area needed.
Inspect the penis, skin, hair and the position of the urethral opening; if there is a foreskin, retract it gently and always return it at the end.
Inspect the scrotum: symmetry, colour, swelling; the left testis normally hangs a little lower.
Palpate each testis between the thumb and the index and middle fingers: size, consistency, surface, tenderness; then the epididymis, behind and above.
Palpate the spermatic cord up to the inguinal ring; the vas deferens feels like a firm, smooth cord. Standing, with Valsalva, look for a varicocele.
Transillumination: in a dark room, hold a penlight behind the scrotal mass; clear fluid glows, solid tissue does not.
Cremasteric reflex: lightly stroke the upper inner thigh; normally the testis on that side rises.
Prehn sign: gently lift the painful testis and ask whether the pain eases.
Hernia: invaginate the scrotal skin with a finger up to the external inguinal ring and ask the patient to cough.

Abnormal findings

Testicular torsion: sudden severe pain, a high testis, sometimes lying horizontally, very tender, with an absent cremasteric reflex. It is a surgical emergency; tests must not delay urology review.
Epididymitis: more gradual pain, a thick, tender epididymis, sometimes with fever or urinary symptoms; the cremasteric reflex is usually present.
Hydrocele: painless, smooth swelling that transilluminates; the testis is hard to make out through the fluid.
Varicocele: a soft 'bag of worms' above the testis, mostly on the left, that grows on standing and with Valsalva and does not transilluminate.
Testicular tumour: a hard, painless lump that is part of the testis and does not transilluminate; the most common solid tumour in young men.
Inguinoscrotal hernia: a mass that reduces or bulges with a cough; if it holds bowel it may have bowel sounds and does not transilluminate.

Common errors

Relying on the Prehn sign: its value in separating torsion from epididymitis is low.
A present cremasteric reflex does not fully rule out torsion; with clinical suspicion, urgent assessment still follows.
Some solid masses let a little light through and some thick-walled hydroceles do not; scrotal Doppler ultrasound confirms.
Forgetting to return the foreskin, with a risk of paraphimosis.
Skipping consent, the chaperone or the explanation of each step.

Test yourself

Think of the answer, then tap the question to see it.

What does it mean when a scrotal mass glows with a penlight held behind it?

That it contains clear fluid, such as a hydrocele or a spermatocele.

Which nerve and spinal segments carry the cremasteric reflex?

The genitofemoral nerve, segments L1 and L2.

Which exam findings suggest testicular torsion?

A very tender testis lying high and sometimes horizontal, with an absent cremasteric reflex.

Why is varicocele more common on the left?

Because the left testicular vein drains at a right angle into the left renal vein, with higher pressure and poorer drainage.

What limits the value of the Prehn sign?

Relief on lifting the testis can be missing in epididymitis and present in torsion, so it does not separate them reliably.

Add to my cards (5)

See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Testicular torsion: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2024); Hydrocele: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2024); Testicular self-exam: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2024); Testicle pain: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2024).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.