The scrotum and its contents have a complicated nerve supply.
(1) Sympathetic fibers from T1-L1 supply the testis, vas, and epididymis.
(2) Somatic fibers from L1-L2 supply the outer surface of the testis, the tunica vaginalis, and the anterior scrotal skin.
(3) Somatic fibers from S2-S3 supply the rest of the scrotal skin.
Scrotal pain may therefore be caused by intrascrotal pathology or result from referred pain from visceral or somatic structures. Causes of referred pain include the following:
(1) Impacted stone in the lower ureter (splanchnic L1)
(2) Small inguinal hernia compressing the genitofemoral nerve
(3) Degenerative lesions of the lower thoracic and upper lumbar spine
(4) Tendonitis at the insertion of the inguinal ligament into the pubis
(5) Disease of the genital viscera (e.g. prostate, seminal vesicles)
(6) Benign sacral meningeal cysts (see also vulvodynia p. 45)
(7) Aneurysm of the internal iliac artery.
15.1 INTRASCROTAL PATHOLOGY
The commonest cause of acute scrotal pain in the adult is acute epididymitis. In sexually active men under the age of about 35 years, this is usually caused by C. trachomatis. The patient presents with "pain in the scrotum," but there is often an associated urethritis, which may be asymptomatic. In men over the age of 35 years, the commonest causes of epididymitis are the more standard urinary tract pathogens such as E. coli, Pseudomonas spp., Klebsiella spp., and Proteus spp.
The sexual history may give a clue as to whether the condition is more likely to be sexually or non-sexually transmitted.
In the younger, sexually active single male, the initial investigations should include the following (see also chapter 13-page 74):
- urethral swab for Gram stain (to look for evidence of urethritis)
- urethral swabs for detection of Chlamydia (urine test preferred by patient but not currently routinely available in the UK) and possibly gonorrhea culture
- two-glass urine test
- MSU or send off the first glass of the two-glass urine for culture.
In the "older" age groups, culture of an MSU may be sufficient.
The "young" sexually active male with epididymitis should ideally be referred to a GU medicine clinic for urgent investigation. If evidence of urethritis is found or a sexually transmitted cause considered likely then treat with an antibiotic active against Chlamydia, such as a tetracycline (e.g. doxycycline 100 mg bd). The patient should be reviewed in 1 week or sooner if symptoms worsen. If there is clinical improvement, the treatment should be continued for at least 6 weeks. Sexual contacts must be assessed, in particular for evidence of chlamydial infection.
If a urinary tract pathogen is considered a more likely cause, treatment with, for example, trimethoprim, norfloxacin, or ofloxacin should be started while awaiting the results of MSU culture and sensitivity tests.
Many patients find a scrotal support helpful in addition to simple analgesia.
If there is any doubt about the diagnosis, an urgent urological opinion should be requested to exclude torsion of the testis.
15.1.2 Testicular (Spermatic Cord) Torsion
Just under 50% of men with testicular torsion give a history of previous brief episodes of scrotal discomfort. The pain is usually of sudden onset and severe. Torsion is more common in young men (late teens) and should be considered in this age group if tests for urethritis and upper urinary tract infection prove negative. All patients with a suspected torsion should be referred urgently for a urological opinion with the view to emergency exploration of the scrotum.
This may affect one or both testes and in the UK it is most commonly associated with mumps. Testicular atrophy develops in approximately 15% of adults following severe mumps orchitis. More unusual causes of orchitis include infectious mononucleosis, coxsackie B virus infection, and dengue fever.
Approximately 10% of testicular tumors present as a painful swelling and may be initially misdiagnosed as epididymitis. More commonly, however, tumors are painless or may be detected as a firmness or asymmetry of the testis, sometimes associated with aching or discomfort. Ultrasound scanning helps distinguish between masses in the body of the testis and other intrascrotal swellings and should also be considered in patients with possible epididymo-orchitis that fails to resolve within a couple of weeks.
This presents as a tender nodule on the surface of the testis and results from inflammation in the tunica vaginalis. Symptoms usually improve with time without the need for surgery.
15.1.6 Cremasteric Spasm
This may cause pain or discomfort, particularly during intercourse, and is associated with the testis being drawn up to the external inguinal ring. This may be relieved by circumcision of the cremaster which divides the genitofemoral nerve.
15.1.7 Epididymal Cysts
These are common and usually painless. Pain or discomfort may result from bleeding within a cyst. Referral is not required for asymptomatic cysts.
15.1.8 After Vasectomy
Scrotal discomfort after vasectomy may be caused by obstruction and distension of the epididymal duct. This is usually relieved by using a scrotal support and treatment with NSAIDs.
A small, tender swelling at the site of the vasectomy is frequently a sperm granuloma and may appear months or years after the procedure. If the pain fails to settle with a scrotal support and NSAIDs, a surgical excision or epididymectomy may be required.
Varicoceles may cause aching within the scrotum which becomes worse toward the end of the day. Thrombosis within a varicocele has been reported as a cause of scrotal pain.
In many young men with scrotal pain, the only abnormality found is a rather sensitive epididymis. This may result from "seminal congestion" and is best treated by reassurance.
15.2 IMPORTANT MANAGEMENT POINTS
(1) Consider referral to GU medicine if you think there is evidence of epididymitis.
(2) Consider urgent referral to urology if there is a possibility of torsion.
(3) Scrotal ultrasound is a useful non-invasive procedure that may help to determine the nature of intrascrotal pathology. It may also help to reassure both patient and doctor that no serious pathology is present.