Acute Scrotum Pain

Etiology

The causative etiologies of acute scrotum pain are broad. These include ischemic, traumatic, infectious, inflammatory, referred pain, acute or chronic, or idiopathic. Given the nature of these, an acute scrotum should be considered analogous to patients presenting with an acute abdomen.

It is difficult to describe the causes of acute scrotum pain in subgroups, as many conditions are chronic but have an acute presentation. For example, inguinal hernias remain asymptomatic but when obstructed or strangulated present acutely.

Ischemic/traumatic

• Torsion of testes
• Torsion of testicular appendages
• Testicular hematoma
• Thrombosed varicocele
• Inguinoscrotal hernia (obstructed/strangulated)

Infective/inflammatory

• Epididymitis
• Epididymo-orchitis

Neuropathic/referred pain

• Mid urethral stone
• Inguinal hernias (obstructed/strangulated)
• Aortic/common iliac artery aneurysm
• Nerve entrapment
• Diabetic neuropathy (chronic presentation is more common)
• Sexual abuse

By far the most common causes are epididymitis/epididymo-orchitis, testicular appendage torsion, spermatic cord torsion (commonly referred to as testicular torsion), varicoceles, and obstructed or strangulated inguinal hernias. The incidence and frequency of these etiologies are highly variable by age groups. Acute scrotal pain in children is much more likely to represent torsion of the spermatic cord or testicular appendages whereas patients older than 25 are much more likely to have epididymitis. A complete list of differential diagnoses is discussed later.[5][6][7][8]

Epidemiology

There is little data that specifically reports the incidence of the acute scrotum as a presenting complaint, but male genitourinary complaints are estimated at between 0.5% and 2.5% of all emergency department visits. The annual incidence of testicular torsion, however, is estimated at 1 in 4000. This means that an estimated 1 in every 160 men will experience spermatic cord torsion within their first 25 years of life. Although it is possible to occur at any age, the incidence drops off dramatically in the adult years. Even among children, however, the most common cause of acute scrotal pain is torsion of the appendix testis rather than that of the spermatic cord.

Epididymitis is the most common cause of acute scrotal pain in adults. It is estimated that over 600,000 cases are diagnosed in United States (US) emergency departments each year, and this condition was responsible for 1 out of every 144 outpatient visits for men between 18 and 50 years of age. The condition tends to have a bimodal age incidence due to differing microbiological etiologies and risk factors.[9][10][11][12]

Pathophysiology

Spermatic cord torsion may be intravaginal or extravaginal. Extravaginal torsion is seen almost exclusively in neonates. It occurs due to the increased mobility of the testicle before the descent into the scrotum when attached to the scrotal wall via the tunica vaginalis. During intravaginal torsion, frequently associated with the bell clapper deformity, the spermatic cord twists on itself, ultimately pinching off arterial blood supply to the testicle leading to ischemia and infarction. The degree of torsion may be variable, usually causing venous occlusion and congestion first. Most cases of spermatic cord torsion leading to infarction are twisted to at least 720 degrees.

Epididymitis is a genitourinary tract infection that is usually due to continuous spread from pathogens affecting the bladder of the urethra. In men less than 35 years old, this is most commonly associated with sexually transmitted organisms such as Chlamydia trachomatis and, less commonly, Neisseria gonorrhea. Men older than 35 years or those without sexual partners usually present with gram-negative urinary pathogens, which are also responsible for cystitis and prostatitis, predominantly Escherichia coli. Other urinary pathogens such as Klebsiella pneumoniae, Proteus mirabilis, and Ureaplasma urealyticum, may be seen. Rare organisms can occur, such as cytomegalovirus, Mycobacterium, and other fungal causes that may be seen in immunocompromised hosts such as those with HIV.[13]

When inguinal or inguinoscrotal hernias can not be reduced, venous and arterial flow is impeded. This results in ischemia.[14][15]

History and Physical

A focused history and physical examination are essential in the evaluation of the acute scrotum. A patient should be interviewed and asked about the onset and duration of symptoms as well as whether they have been continuous or intermittent. The clinician should ask about the history of increased activity, physical exertion, heavy lifting, or direct trauma as well as any objective external signs such as swelling, urethral discharge, erythema, rash, or skin color changes. Associated symptoms such as fevers, dysuria, frequency, urgency, hematospermia, abdominal pain, back pain, or weight loss should be required. It is also important to ask about relevant comorbid conditions including diabetes, congestive heart failure, or any immunocompromised state. A sexual history should also be reviewed including the number and gender of sexual partners, use of barrier contraceptives (condoms), and history of diagnosis of or treatment for sexually transmitted illnesses.

Physical examination should include a visual inspection of the fully exposed abdomen, groin, penis, and scrotum. Care should be taken to note any rashes, ulcers, abnormal scrotal asymmetry (it is normal for the left hemiscrotum to hang slightly lower), or horizontal position of a testicle. The scrotum, perineum, and thighs should be palpated to feel for the presence of crepitance or subcutaneous emphysema. The scrotal contents should be palpated to compare the relative size of the testes, detect any obvious intratesticular masses, or other scrotal contents such as hernias. The urethra should be inspected for discharge. Finally, the clinician should investigate bilaterally for the presence of a cremasteric reflex.

A “high-riding” asymmetrical testicle with an abnormal lay and loss of ipsilateral cremasteric reflex is historically described as the classic presentation of acute testicular torsion. If there is pain relief on lifting the affected testicle, this is suggestive of epididymitis, but if there is no pain relief then this suggests testicular torsion. This is called Prehn's sign. However, this dogmatic description of the classic presentation is not universally observed in all cases and may lead to misdiagnosis or delay in definitive treatment. The cremasteric reflex is fickle and may be absent in up to 30% of normal males without any pathology. Conversely, several case series report patients with surgically confirmed testicular torsion may still have preserved cremasteric reflexes anywhere from 8% to 30% of the time. Other scrotal pathology such as epididymo-orchitis may also result in the loss of a normal reflex.[16][17][18][19][8]

Evaluation

Evaluation first begins with a detailed history and physical examination. If the diagnosis of spermatic cord torsion is strongly suspected, then an emergency surgical consultation is warranted without further delay. The “classic” cutoff for salvage of testicular torsion is surgical exploration and detorsion within six hours of the onset of symptoms. This does not mean however that prompt evaluation and definitive surgical exploration be delayed for patients in whom symptoms have been present for greater than six hours. The salvage rates do drop to between 80% to 88% at 12 hours, 31% at 24 hours, and only 2.6% at 48 hours. This may be due to variable degrees or torsion (incomplete torsion) or torsion-detorsion phenomena.[20]

Provided it does not delay definitive surgical consultation, additional studies that may be useful include complete blood counts, urinalysis with microscopy, urine culture, and urethral swabs for gonorrhea and chlamydia. For systemically ill patients or those presenting with sepsis, blood cultures, inflammatory markers, and cross-sectional imaging of the pelvis through the mid-thighs may be considered.

Doppler ultrasonography is the most appropriate imaging modality for evaluation of the acute scrotum when it does not delay definitive surgical consultation in cases of presumed torsion. The sensitivity of color Doppler ultrasound is reported to range between 96% to 100% with a specificity of between 84% to 95%. A body of literature exists which also supports the role of point-of-care ultrasound by the treatment provider for the evaluation of the acute scrotum. A detailed review of this technique is beyond the scope of this article, but findings on ultrasound suggestive of testicular torsion include an enlarged, homogenous, hypoechoic testicle with the absent color flow or spectral Doppler waveforms suggesting increased vascular resistive index. The spermatic cord torsion may also be directly observed with ultrasound; a finding described as the “whirlpool” or “snail” sign.[21][22][23]

Conversely, infectious etiologies of the acute scrotum cause an increase in blood flow to the testicle or epididymis, which is apparent in Doppler imaging. Resistive indices of the testicle may be abnormally low, and the testicle or epididymis will again be larger than the asymmetry side. Abscesses may also be identified, as well as the presence of subcutaneous gas within the scrotal wall.

Other imaging modalities are also available. Radionuclide scrotal imaging (RNSI) was at one point the primary modality since its implementation in the 1970s. In the differentiation of testicular torsion and epididymo-orchitis, there is a reported sensitivity range of 89% to 98% and specificity of 90% to 100%. However, this modality is prone to false positives particularly in cases of spermatocele, hydrocele, and inguinal hernias, and may lead to unnecessary surgical exploration when compared to modern ultrasonography. MRI had 93% sensitivity and 100% specificity for diagnosing torsion; however, availability and length of time required to complete may limit its appropriateness. CT imaging is useful when there is a concern for necrotizing skin and soft tissue infections and Fournier gangrene.[11][24][25]

Treatment / Management

The definitive treatment of testicular torsion is surgical exploration and detorsion, usually followed by orchiopexy to prevent recurrent torsion. Manual detorsion can and often should be attempted at the bedside although its success rate is widely variable and has been reported to range from 25% to 80%. In patients with testicular torsion, the affected testicle is rotated medially. Therefore, manual detorsion should be attempted first from a medial-to-lateral direction (“opening of the book”) and may require 180 to 720 more degrees. Specifically, this requires counterclockwise rotation of the patient's right testicle or clockwise rotation of the patient's left testicle, similar to the action of opening the spine of a book. Manual detorsion is contraindicated if pain and/or suspected torsion have been present for longer than 6 hours. Point-of-care ultrasound may be useful in evaluating the direction and effectiveness of this maneuver. Successful manual detorsion should result in near-immediate relief of pain. Surgical exploration is still mandated even in the event manual detorsion is successful.[26](B2)

Treatment of epididymitis is discussed in detail in its respective article with antimicrobial therapy directed toward the most likely causative organism.[27][25]

Differential Diagnosis

The differential diagnoses include the following:

• Acute epididymitis/epididymo-orchitis
• Testicular appendage torsion
• Spermatic cord torsion
• Henoch-Schonlein purpura
• Strangulated/incarcerated inguinal hernia
• Varicocele
• Scrotal cellulitis
• Fournier gangrene
• Idiopathic scrotal edema
• Intratesticular hematoma
• Scrotal or testicular abscess
• Testicular infarction
• Testicular neoplasm
• Testicular rupture

Prognosis

The prognosis of acute scrotal pain depends on the cause. In patients with epididymitis, pain improves within several days of treatment, but the induration may last weeks or months. Some people with diabetes may develop an abscess leading to sepsis, which is a potential consequence. In patients who developed epididymitis secondary to sexual activity, the partner needs to be referred and treated to stop the cycle of transmission. For patients with a diagnosis of testicular torsion, the diagnosis depends on early diagnosis and treatment. If the treatment is delayed by 12-24 hours, the risk of losing testis and infertility is high.[28][29][30]

Complications

Delay in diagnosis and prompt treatment can result in various complications. If a severely damaged testicle is not removed, gangrene may occur. Infection can spread to the bloodstream, causing septicemia. Damage to both testes results in infertility.

Testicular prostheses may be used as cosmetic deformity occurs after orchidectomy.[31][32]