by Michael Daignault, MD
Approximately 0.5% of all patient visits to the Emergency Departent (ED) are acute scrotal pain. The differential is long, and includes epidiymitis, orchitis, testicular torsion, torsion of the testicular appendage, testicular trauma, and herniation of abdominal contents into scrotum. In the ED, we are most concerned with testicular torsion, testicular trauma, and herniation. As they say in CVA, time is brain. In this case, TIME IS TESTICLE. This article focuses on evaluation of acute scrotal pain for torsion, as well as the application of bedside ultrasound to evaluate for testicular torsion.
Torsion occurs when the spermatic cord twists around its axis, cutting off vascular flow to the testicle and surrounding structures in the scrotum. Bedside testicular ultrasound can be a very useful adjunct to the history and physical exam in evaluating a patient for torsion. First, IV access should be obtained for laboratory analysis and most importantly to provide analgesia. A urinalysis should also be obtained if possible. Once analgesia is achieved, the patient should be in the supine position with legs spread apart. Ideally the scrotum should be supported with a sling fashioned from a towel and the penis should be covered with a towel that is taped to the abdominal wall (or the patient can be asked to support his penis in a cephalad position). A high-frequency linear ultrasound probe is then applied perpendicular to the penile shaft to obtain transverse view of the scrotum.
In this “saddle view,” both testicles can be viewed in the same window, as in the following picture:
The definitive treatment for torsion is surgery, so in the ED, we are concerned solely with identifying patients who are immediate candidates to go to the OR. As such, on bedside ultrasound, we want to identify patients with a testicle that has decreased or absent blood flow. Change the settings on your ultrasound machine to “doppler” or “color doppler” and first slide the probe while staying in transverse view to the unaffected testicle. You should see multiple pulsations in both red and blue color throughout the testicle signifying vascular flow. It doesn’t matter whether you have more red or more blue. The key is to have a baseline of “normal” vascular flow in your patient so as to compare to the affected testicle.
Next, gently slide the probe (again while staying in transverse view) to the testicle in question. You are looking for a demonstrable reduction or absence in vascular flow compared to the unaffected testicle. In the following image, there is clearly a reduced flow to the right testicle in this patient compared to the left.
Again, bedside ultrasound for testicular torsion should be used as an adjunct to the physical exam and a good history taking. Absence of cremaster reflex remains the most sensitive sign (90-100%) in diagnosing torsion. Complete ultrasound evaluation of the acute scrotum is obviously much more comprehensive than what I have outlined above, but is beyond the scope of both this article and the purview of the emergency physician. However, visualized absence of vascular flow on bedside ultrasound should prompt immediate urology consult and preparation for the OR.
For more info on scrotal ultrasound: http://www.sonoguide.com/smparts_testicular.html