Patient's question:
Description of the problem: I have pain in the groin area, and the doctor performed a barium enema examination, which did not reveal any abnormalities. The doctor's report said to undergo clinical examination. What is going on?Doctor's answer:
What is Epididymitis?I. Anatomical and Physiological Structure of the Epididymis
The epididymis is a long structure attached to the posterior margin of the testis. The upper end is dilated and rounded, forming the head of the epididymis, the middle part is the body of the epididymis, and the lower end is the tail of the epididymis. The tail of the epididymis curves upward and transitions into the vas deferens. The head of the epididymis is formed by the coiling of efferent ductules from the testis. The terminal ends of these ductules merge into a single epididymal duct. The epididymal duct forms multiple loops, constituting the body and tail of the epididymis. At the end of the tail of the epididymis, the duct abruptly turns upward and transitions into the vas deferens. Therefore, the epididymis can be divided into five parts: the initial part, head, body, tail, and vas deferens, as it relates to the gross structure, physiological function, and the location of sperm maturation at different stages. For example: sperm movement can only be observed when sperm pass through the head of the epididymis; however, the acquisition of fertilization ability typically occurs when sperm pass through the body of the epididymis.
Histologically, the epididymis is composed of principal cells, basal cells, apical cells, stromal cells, clear cells, and narrow cells, and the number and size of these cells vary along the epididymal duct. In the proximal region of the epididymis, principal cells are tall, resulting in a narrow lumen of the epididymal duct. However, in the distal region of the epididymis, principal cells are short and columnar, and the lumen becomes larger. This significant change in cellular structure is mainly due to the different functions of each segment of the epididymis. In the proximal region of the epididymis, it has a strong ability to absorb water, so the cells exhibit typical features of an absorptive epithelium. The fluid microenvironment of the epididymis promotes sperm maturation. Epididymal fluid is hypotonic and greatly differs from plasma in composition. The main components of epididymal fluid are organic soluble substances. In the proximal region of the epididymis, the fluid is strongly acidic with a pH of 6.5, gradually increasing to approximately 6.8 in the distal region. The exact roles of each organic soluble substance and ion are not yet fully understood. However, research has shown that these substances play a role in the acquisition of motility in sperm, the regulation of osmotic pressure between sperm and epididymal epithelial cells, and metabolism. Proteins related to sperm have also been found in the lumen of the epididymal duct, and these proteins may play a role in sperm maturation and/or (or) sperm-egg interaction.
The epididymis actively participates in the process of sperm maturation, not only by providing a suitable environment for sperm but also by providing many molecules required for sperm to fertilize an egg. The upper end of the testis and epididymis often has a small, stalked body, respectively called the testicular appendix and the epididymal appendix, which are remnants of the pararenal ducts and nephric tubules during embryonic development. These stalked structures are prone to torsion. The blood supply of the testis and epididymis primarily comes from the left and right testicular arteries. The left and right testicular arteries arise from the anterior wall of the abdominal aorta slightly below the renal arteries. In the upper posterior part of the testis, the arteries divide into inner and outer branches, distributing blood to the testis and epididymis. The veins of the testis and epididymis merge into a pampiniform plexus within the spermatic cord and ascend to merge into a single spermatic vein at the inguinal canal. The left vein primarily drains into the left renal vein, while the right vein drains into the inferior vena cava. In the scrotum, the pampiniform plexus has rich anastomoses with the veins of the scrotum and vas deferens. The lymphatic drainage of the testis and epididymis accompanies the spermatic veins, returning to the para-aortic lymph nodes. The lymphatic vessels on both sides are richly anastomosed and also connect with the mediastinal and cervical lymph nodes. Therefore, testicular tumors can metastasize to the chest and neck.
II. Etiology and Pathology
(1) The most common pathogens causing epididymitis include Escherichia coli, Proteus, Staphylococcus, and Pseudomonas aeruginosa. Additionally, Neisseria gonorrhoeae and Chlamydia associated with sexually transmitted diseases are also common causative microorganisms. Pathogenic bacteria enter the urinary tract through the urethra, causing urethritis, cystitis, and prostatitis, and then invade the epididymis and testis through the lymphatic system or the lumen of the vas deferens, leading to epididymo-orchitis.
(2) During tonsillitis, mumps, dental infections, or systemic infections, bacteria or viruses can enter the bloodstream and cause epididymitis, often occurring when the immune system is compromised.
(3) After scrotal trauma, a hematoma may form in the scrotum, epididymis, and testis, followed by acute epididymitis, though this is uncommon. Sometimes, urethral instrumentation or prolonged indwelling catheterization can also cause epididymitis.
(4) Pathology: In the early stages, epididymitis is a cellulitis that typically starts in the vas deferens, spreads to the tail of the epididymis, and then to the head. In the acute phase, the epididymis becomes swollen, uneven, and forms small abscesses; histologically, tissue edema and inflammatory cell infiltration are observed. In later stages, the infection may completely resolve without damage, but fibrosis around the epididymal ducts can obstruct the lumen. Chronic epididymitis is generally the irreversible terminal stage of acute epididymitis, with the epididymis becoming hard due to fibrosis. Histologically, widespread scars and obstruction of the epididymal ducts, along with lymphocytic and plasmacytic infiltration, are observed. If bilateral epididymitis occurs, it may lead to male infertility. The common routes of infection in this disease include retrograde infection along the reproductive tract, lymphatic spread, and hematogenous infection.
III. Acute Epididymitis
The epididymis is attached to the posterior side of the testis, with the upper end being the head and the lower end being the tail, while the middle part is the body. Any enlargement of the epididymis is a pathological change. During acute epididymitis, swelling and tenderness are prominent. In chronic epididymitis, only mild enlargement and slight tenderness are present. Epididymal tuberculosis is hard and painless, and may be adhered to the skin or form sinuses. After vas deferens ligation, if epididymal congestion occurs, the epididymis becomes enlarged, smooth, and uniformly hard with significant tenderness. During infertility examinations, attention should be paid to whether the tail of the epididymis is developed and whether it continues with the vas deferens. The spermatic cord should be checked for varicocele, thickening, hardening, and masses. The vas deferens should be examined for smoothness, continuity, adhesions, thickening, and nodules.
1. Diagnosis
(1) Typical symptoms: The onset is usually acute, initially presenting as localized pain in the scrotum that radiates to the inguinal region or lower abdomen. Subsequently, pain worsens, the epididymis becomes highly sensitive and rapidly enlarges, accompanied by systemic discomfort, fever, and sometimes urethral discharge. Symptoms of cystitis, urethritis, or prostatitis may also be present.
(2) Physical examination: Tenderness is present in the inguinal region or lower abdomen on the affected side, along with scrotal swelling and redness. The affected epididymis is enlarged, hardened, and tender. In the early stages, the boundary between the epididymis and testis is clear, but it becomes indistinct later. The spermatic cord is swollen and thickened. If an abscess forms, it may have a fluctuating sensation. The abscess may also rupture spontaneously, forming a fistula.
(3) Ancillary tests:
- Blood routine: Leukocyte count increases with left shift.
- Urinalysis: Presence of pus cells.
- Urine culture or urethral secretion culture: Bacterial growth is observed.
2. Treatment
- General management: Rest in bed with the affected scrotum elevated. Early use of ice packs, followed by local heat application or hot baths in later stages. Pain relief can be achieved with oral analgesics or a 1% lidocaine 10-20 mL spermatic cord block. Physical activity and sexual intercourse should be strictly avoided during the acute phase. If epididymitis is caused by a long-term indwelling catheter, the catheter should be removed to facilitate inflammation resolution.
- Antibiotic therapy: Sensitive antibiotics should be selected, typically administered intravenously for 1-2 weeks, followed by oral antibiotics for 2-4 weeks to prevent chronic inflammation. Commonly used drugs include cephalosporins, quinolones, and nitroimidazoles.
- Incision and drainage: If the inflammatory mass of the epididymis enlarges, the scrotal skin becomes red and swollen, and a fluctuating sensation is present, indicating an abscess has formed. Prompt incision and drainage should be performed, along with systemic antibiotic use.
- Surgical treatment: If testicular infarction occurs, orchiectomy should be performed.
- Prognosis: Most patients respond well to timely and effective treatment, with symptoms resolving within 1-2 weeks. However, it may take 4-6 weeks for the size and hardness of the epididymis to gradually return to normal. In some cases, inflammation may persist, leading to chronic epididymitis. Bilateral epididymitis may result in infertility.
IV. Chronic Epididymitis
Chronic epididymitis is relatively common clinically. It may result from the persistence of acute epididymitis, though most patients have no history of acute episodes.
1. Diagnosis
(1) Typical symptoms: Generally, there are no obvious symptoms, but if symptoms occur, they vary widely. Local discomfort, a sense of heaviness or fullness in the scrotum, or pain in the scrotum that radiates to the lower abdomen or inner thigh may be present. Acute episodes may also occur.
(2) Key physical signs: The affected epididymis is palpable as enlarged and hardened, or only as a hard mass in the epididymis with no or mild tenderness. The boundary between the epididymis and testis is clear. The spermatic cord and vas deferens are thickened, and the prostate is hardened.
2. Treatment
- Simple antibiotic therapy is often ineffective for chronic epididymitis.
- If chronic prostatitis is also present, it must be treated concurrently.
- If chronic epididymitis recurs and is caused by chronic prostatitis, vas deferens ligation may be considered followed by continued treatment. If recurrence persists, epididymectomy may be performed.