The Acute Scrotum

The “acute scrotum” is a condition characterized by the recent onset of scrotal pain with or without redness or swelling. A good history and physical examination are all that is needed to make an accurate diagnosis in the majority of cases.

The 3 main causes of acute scrotum are:

  1. Testicular torsion
  2. Torsion of the appendix testis or epididymis.
  3. Infection

Blue-dot sign

Rare causes of acute scrotum include mumps orchitis, referred pain from renal colic (due to an obstructing stone), muscle sprain, tuberculosis, and the list could go on and on.

Key elements of the history and exam:

  1. Pubertal status
  2. How did the pain start
  3. Duration of pain
  4. Physical exam:
    1. Redness
    2. Swelling
    3. The position of the testis
    4. Cremasteric reflex.

Pubertal status

The frequency of the 3 main diagnoses is very different before and after puberty:

Before puberty: Torsion of appendix testis >> Torsion of Testis >>>> Infection

After Puberty: Torsion of the testis > Torsion of the appendix testis >> Infection


How did the pain start

The pain from testicular torsion is sudden and intense. Patients remember exactly what they were doing when the pain started. Compare that to the gradual onset of pain from torsion of the appendix testis, where patients don’t quite remember when things got worse.


Duration of the pain

Testicular torsion needs to be treated in the first 6 hours to avoid testicular loss. After 6 hrs, the chances of saving the testis decrease rapidly, and by 24 hrs almost all testis will be completely necrotic with no chance of recovery.


Physical exam

A high riding, mildly swollen and tender testicle, is typical of testicular torsion presenting early. Late torsions are associated with large, tender, and red scrotums. The cremasteric reflex is absent in cases of testicular torsion.

Torsion of any of the testicular appendages will cause variable swelling and redness. In several years of practice, I have only seen one patient with the “blue dot” sign (see picture above) — which is the textbook sign of a torsed appendix testis. The cremasteric reflex is present in cases of a torsed appendage.


TWIST score

Researchers developed and validated a scoring system to aid with the diagnosis of testicular torsion in children:

TWIST score

Scores of 5-7 are highly predictive of torsion; these cases need to go to surgery without stopping for an ultrasound. Intermediate scores of 3-4 are best evaluated first with a doppler ultrasound. Low scores of 0-2 are very unlikely to be torsed testis.



Infection is rare but is commonly misdiagnosed on the scrotal Doppler ultrasound when the radiologist reports “epididymitis”. Both torsed testis and torsed appendages will create the appearance of “infection” on ultrasound. A good ultrasonographer can usually separate the inflamed epididymis from the actual torsed appendix as shown on this picture:

True infections occur in sexually active teenagers with fever, dysuria and positive urine analysis.


Intermittent torsion

Intermittent torsion is a somewhat nebulous diagnosis that has to be considered when discharging patients home with the diagnosis of a torsed appendage, or a muscle sprain. Intermittent torsion refers to a torsed testis that fixed itself spontaneously. If the patient is evaluated after the testis detorsed itself, the physical exam and ultrasound will be more consistent with a torsed appendix: increase flow, mild pain, mild swelling, etc. After the patient is discharged back home, the testis can torse again and this time stay torsed with the subsequent testicular loss if the family does not return for care.


When to order an ultrasound

For teenagers presenting with <6 hours of acute severe pain associated with nausea and or vomiting, elevated testicle, and no cremasteric reflex, an ultrasound will only delay the management of these patients and can potentially increase the chance of testicular loss. It would be best to take these patients directly to the operating room.

On the other hand, patients with less straightforward presentation would benefit from ultrasound to avoid unnecessary surgical exploration.



For cases of the acute scrotum, the first question should be whether the patient is pre or postpubertal. Postpubertal patients with <6 hours of pain should be evaluated and treated rapidly to avoid testicular loss. Prepubertal patients with classic torsion history — rarer– should also be evaluated and treated promptly. All other patients would benefit from a scrotal doppler ultrasound.


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