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Urethroscrotal Fistula: A Rare Cause of Scrotal Swelling

Summary Background Urethroscrotal fistula (USF) is an abnormal communication between the urethra and the scrotum. This rare abnormality may be iatrogenic or secondary to perforation of the urethra by a stone. After the passage of urine to the scrotum through the fistula, painless scrotal swelling develops, which disappears completely with manual compression, and voiding can be maintained in this way. Retrograde urethrography (RU) and voiding cystourethrography (VCU) are traditional diagnostic methods, but they have limitations, such as technical difficulties and inability to evaluate the surrounding tissues. Multidetector CT (MDCT), together with reformatted images, can provide valuable information about the surrounding tissues and associated pathologies. Case Report We present a case of a 36-year-old male patient who had painless scrotal swelling after cystolithotomy and urethral stone surgery. The patient indicated that the swelling disappeared after manual compression. A fistula between the bulbous urethra and the scrotum was discovered by MDCT. In our case, we believe that the fistula developed iatrogenically during stone excision or secondary to perforation of the urethra by a stone. Conclusions As a rare pathology, urethroscrotal fistula should be considered in men with a history of urethral stone surgery and symptoms, including painless scrotal swelling, which can be manually compressed after voiding.


Background
Urethroscrotal fistula is a rarely-seen pathology in men [1]. It is frequently iatrogenic or secondary to urethral stones [2]. These causes lead to the perforation of the urethra and fistula formation between the urethra and the scrotum [1,2].

Case Report
A 36-year-old male patient underwent bladder calculi surgery in 2003. The patient was followed for urinary incontinence as a result of congenital lumbosacral meningocele. Bladder and urethra calculi occurred over time. The patient underwent cystolithotomy and urethral stone excision in 2013. Six months later, he returned to hospital with painless scrotal swelling, which he indicated had disappeared after manual compression. Urinary leakage had also been seen. Ultrasonography showed a huge fluid-filled sac with multiple calculi inside (no figure available). The patient was referred to the MDCT unit. On unenhanced sections, stones in the fluid-filled scrotal sac were observed ( Figure 1). The late pyelogram phases showed that contrast media filled the scrotal sac and the contrast leakage arose through a thin fistula from the bulbous urethra (Figures 2, 3). An operation was recommended but the patient refused it and left hospital with normal vital signs.

Discussion
Genitourinary tract fistulas may develop between the urethra and the rectum, perineum, bladder, and genital structures. They may be congenital or acquired, and possible causes include infection, inflammatory disease, neoplasms, congenital conditions, trauma, and iatrogenic injury. There may be an anomalous communication between the urethra Authors' Contribution: and the scrotum in males iatrogenically [1]. Although it is a very rare, urethral stones may move to the scrotum, perforating the urethra [2]. In our case, we believe that the fistula could have developed iatrogenically during stone excision or secondary to perforation of the urethra by a stone, as described above.
There are many case reports on urethral diverticulum (UD), which involves sac-like dilatations of the urethra, in the literature [3][4][5]. UD is a very rare condition in men and in 90% acquired in origin. Trauma, infection, stricture, urethral surgery, and iatrogenic wounds are among the causes [3,4]. Urethral stones can also be added to the etiopathogenesis [5,6]. Paraplegic patients have a higher risk of UD due to long-term urethral catheterizations [3]. UDs may be complicated by stone formation [7]. Stricture of the anterior urethra and chronic voiding symptoms cause the development of a diverticulum, in which stones may occur [8]. Urine stasis predisposes patients to infection and formation of calculi within the diverticulum [6]. Urethral diverticulum is a condition similar to USF; however, there is a fistulous tract between the urethra and urine-filled scrotal sac in USF.
Urinary incontinence, obstructive flow pattern and scrotal swelling are significant clinical symptoms. Scrotal mass and urinary leakage after manual compression are the findings in physical examination [4,9].
Retrograde urethrography and voiding cystourethrography are considered the standard radiologic techniques for the morphology of the urethra. We can visualize the fistula, accompanying cavities, and passage of the contrast agent into the neighboring organs by retrograde urethrography. But there are some limitations to this technique as it can only visualize the urethral lumen similar to urethroscopy. It is possible for MRI, CT, and US to evaluate periurethral tissues and adjacent anatomic structures that cannot be assessed with VCU, RU, and urethroscopy [10]. MDCT is an important diagnostic tool that can be used as an alternative to traditional radiographic methods. It has many advantages: only one position is enough for the examination, no distortion, 3D images can be created, and associated pathologies can be diagnosed [11].
Diverticulectomy with urethrotomy and end-to-end anastomosis are the surgical procedures most commonly used for treatment [4]. As non-operative management, manual compression is adequate in patients who can empty the scrotal swelling [12].

Conclusions
Not all scrotal swellings are secondary to hydrocele, epididymal cyst, or hernia. Urethroscrotal fistula, a very rare cause of scrotal swelling, is a distinctive abnormality with its etiology and clinical findings. Therefore, MRI and CT play an important role in delineating the anatomy and extent of the fistulous tract.