To evaluate the clinical efficacy of standardized intravesical Huoxue Jiedu formula instillation combined with bladder hydrodistension in patients with bladder pain syndrome/interstitial cystitis (BPS/IC), and to compare its short-term outcomes with those of bladder hydrodistension alone.

This was a prospective cohort study. Patients diagnosed with BPS/IC between March 2024 and January 2025 were consecutively enrolled and allocated to either a combination group or a control group according to whether they received postoperative intravesical therapy. The combination group underwent bladder hydrodistension followed by regular intravesical instillation of Huoxue Jiedu formula, whereas the control group underwent bladder hydrodistension alone. All patients received standardized cystoscopic evaluation, bladder hydrodistension, and bladder biopsy. The Huoxue Jiedu formula is a traditional Chinese medicine empirical prescription that was prepared under standardized pharmaceutical quality control and sterilization procedures for intravesical administration. The combination group received 8 scheduled intravesical instillations after hydrodistension. Follow-up assessments were performed before treatment and at 1 month and 3 months after treatment. The primary outcomes were Pelvic Pain and Urgency/Frequency (PUF) score and maximum voided volume, and post-treatment outcomes were compared between groups.

A total of 55 patients were included, including 25 in the combination group and 30 in the control group. Most patients were female, with a relatively long disease duration and substantial baseline symptom burden. At 1 month after treatment, the combination group showed significant improvement in maximum voided volume, PUF, and other core symptom measures including ICSI and ICPI (all P<0.001), while the control group also improved but to a lesser extent (P<0.05). At 3 months, improvement in the combination group was sustained and further enhanced (P<0.001), whereas no significant further improvement was observed in the control group for most outcome measures (P>0.05). After adjustment using a propensity score matching model incorporating baseline maximum voided volume and total PUF score, no significant between-group difference was found in daytime frequency at 1 month (P=0.152), whereas the remaining efficacy outcomes favored the combination group. At 3 months, all efficacy outcomes were significantly better in the combination group than in the control group (all P<0.001).

These findings suggest that standardized intravesical Huoxue Jiedu formula instillation combined with bladder hydrodistension may provide greater symptom relief and improvement in bladder storage function than bladder hydrodistension alone in patients with BPS/IC. The treatment benefit remained evident at 3 months after treatment. The persistence of between-group differences after adjustment for baseline factors suggests that the combined treatment may offer additional clinical benefit. From a therapeutic perspective, intravesical delivery of a standardized traditional Chinese medicine formula may offer a locally administered multimodal adjunct to hydrodistension, while avoiding reliance on systemic exposure. However, the findings should be interpreted with caution because of the single-center, non-randomized design and limited sample size.

Standardized intravesical Huoxue Jiedu formula instillation combined with bladder hydrodistension showed favorable short-term clinical outcomes in patients with BPS/IC, including improvement in symptom scores and maximum voided volume. Compared with bladder hydrodistension alone, the combined treatment may provide superior efficacy. This intravesical traditional Chinese medicine approach may represent a promising adjunctive treatment strategy for BPS/IC. Further large-scale, rigorously designed randomized controlled studies are needed to confirm these findings.