In this randomized controlled trial, we intend to determine whether electrical pudendal nerve stimulation is more effective than intravesical instillation in urethral pain syndrome.

According to the 2017 edition of European Association of Urology Guideline, there is no specific treatment for urethral pain syndrome (UPS), and it is recommended this type of patients should be treated in a multi-disciplinary and multi-modal program. Since some mechanisms for the development of UPS suggest it may be a form of bladder pain syndrome (BPS) due to the intimate relation of the urethra with the bladder (both covered with urothelium), a combination of intravesical hyaluronic acid and lidocaine plus sodium bicarbonate, the more widely used regimen for BPS in China, is also applied to UPS here in China. However, the symptom relief of the intravesical irrigation won't last long and patients usually report recurrence in 2-3 weeks. Hence, the purpose of this study is to explore whether the electrical pudendal nerve stimulation（EPNS）, which has been proven effective in treating BPS, is more effective than intravesical instillation (intravesical hyaluronic acid and lidocaine plus sodium bicarbonate) in patients with UPS.

Inclusion Criteria:

1. male or female patients aged 18 - 75
2. Occurrence of chronic or recurrent episodic pain perceived in the urethra, especially related to micturition, for more than 3 months; accompanied by other symptoms such as increased daytime and night-time frequency, in the absence of proven infection or other obvious urethral pathology such as urethral diverticulum.
3. Negative in urine routine test or urine cultivation.
4. agreement to sign the written informed consent.

Exclusion Criteria:

1. Symptoms relieved by anti-inflammatory drugs, α-blockers, muscle relaxants.
2. A diagnosis of bacterial cystitis or prostatitis within a 3-month period; bladder or ureteral calculi; active genital herpes; any type of cystitis; vaginitis.
3. life threatening complication such as uterine, cervical, vaginal, or urethral cancer, bladder tumor, heart failure, cardiovascular disease, hemorrhagic disease, uncontrolled diabetes, and/or factors that can affect hemostasis.
4. Female patients with pregnancy or lactation.
5. Serious mental disorders.