Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a prevalent condition associated with symptoms such as genitourinary pain and lower urinary tract symptoms and affects 10–15% of the male population. The etiology and pathophysiology of CP/CPPS are still unclear but may involve a combination of neuropsychological factors, such as inflammation, anxiety, depression, and dyssynergia voiding. Empiric antibiotics, alpha-blockers, and anti-inflammatory drugs are predominantly used in clinical practice; however, they have not shown beneficial effects compared to placebos.
Recently, the therapeutic benefits of transcatheter arterial embolization (TAE) have been demonstrated in addressing inflammation and pain by occluding aberrant blood vessels that proliferate in chronic inflammatory tissues. This efficacy has been reported for conditions such as frozen shoulder and knee osteoarthritis. The mechanism is believed to involve occlusion of neovascularization resulting from inflammation, leading to a reduction in the number of inflammation-induced microvessels, infiltration of inflammatory cells, and alleviation of inflammation severity.
The aim of the present study was to evaluate the midterm results of TAE in patients with CP/CPPS refractory to non-surgical management.

This retrospective study reviewed the medical records of patients with CP/CPPS who underwent TAE between April 2022 and February 2023. The diagnosis of CP/CPPS was defined as persistent pelvic pain for at least three months within the previous six months, without evidence of infection. The lack of infection was demonstrated using a 2-glass test. We included patients with moderate-to-severe symptoms, defined as a total score of at least 15 on the NIH-Chronic Prostatitis Symptom Index (NIH-CPSI). 
Treatment was performed as an outpatient procedure under local anesthesia in all patients. A 3.3-Fr sheath was inserted through the femoral artery and an angiographic catheter was advanced into the internal iliac artery (Figure 1). Selective angiography of the bilateral prostate and the internal pudendal arteries was performed. Imipenem cilastatin sodium (IPM/CS) was used as the temporary embolic material. IPM/CS is a crystalline compound that is slightly soluble in water and forms small particles with a temporary embolic effect when suspended in contrast medium. IPM/CS was injected into the prostate artery until blood flow was completely stagnant. Figures 2 and 3 shows examples of digital subtraction angiography images obtained before and after embolization. After the IPM/CS injection, the catheter and sheath were removed, and manual compression was performed for 10 min. The patients were discharged 1 h after treatment provided that they remained at rest. 
Technical success was defined as selective administration of IPM/CS to the bilateral prostate arteries. NIH-CPSI, pain numeric rating scale (NRS), and complications were evaluated at 1, 3, and 6 months after the initial TAE and at the final follow-up. Clinical success was defined as a reduction of at least 6 points from baseline in the NIH-CPSI because 6-point decrease in the NIH-CPSI was reported as the optimal threshold to predict treatment response. We also evaluated the presence of late gadolinium enhancement (LGE) of the prostate on pre-TAE dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).
The rates of clinical success at 6 months after the initial TAE were compared using the Fisher exact test in the presence of LGE of the prostate on pre-TAE DCE-MRI. All P values were two-tailed, and P < 0.05 was considered a statistically significant difference. Statistical analyses were performed using R version 4.1.2.

A total of 48 patients with CP/CPPS who had moderate to severe symptoms were treated with TAE between April 2022 and February 2023. Four patients were excluded because of loss to follow-up, and 44 patients with a mean age of 46±12 years (range: 23-71), duration of symptoms of 59±46 months (range: 4-120), were enrolled in this study. The mean follow-up period was 16.6±3.1 months (range 12-22 months). Technical success was achieved in 42 (95 %) patients. Only unilateral prostate arteries could be embolized in two patients with technical failure. The mean procedural time, from local anesthesia to catheter removal, was 56±21 minutes (range, 15-113 minutes). The mean NIH-CPSI scores before treatment, at 1, 3, and 6 months post-treatment, and at the final follow-up were 27±6, 21±8, 20±9, 17±9, and 18±9, respectively. The pain NRS scores changed from 7.0±1.6 to 4.8±2.5, 4.1±2.6, 3.7±2.4 and 3.4±2.3 at the corresponding time points. The proportions of clinical success at 6 months after TAE and the final follow-up were 70% and 64%, respectively. Clinical success at 6 months after the initial treatment was achieved in 77% (27/35) of patients with LGE and in 20% (1/5) of patients without LGE on pre-TAE DCE-MRI. No severe procedure-related complications were noted.

In this study, selective embolization of bilateral prostate arteries was achieved in 95% of patients, and in all cases, selective embolization of at least unilateral prostate artery was achieved. Therefore, TAE for CP/CPPS is considered technically feasible.
No severe complications were noted. The temporary embolic agent used in this study, IPM/CS, may have contributed to the lower incidence of complications than permanent embolic materials. However, further research is warranted to assess the long-term outcomes. Future studies are needed to refine the patient selection criteria, investigate underlying mechanisms, and conduct prospective randomized controlled trials, including sham interventions.

TAE with IPM/CS for CP/CPPS demonstrated technical success, safety, and therapeutic efficacy in this retrospective study. The sustained improvement in symptoms over the 12-month follow-up period suggests that TAE is a viable treatment option for refractory CP/CPPS.

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