Bladder pain syndrome/interstitial cystitis (BPS/IC) is a chronic disorder of unknown aetiology that has a significant negative impact on health related quality of life. It is a heterogeneous disorder with a number of possible aetiologies, including infectious, autoimmune, and neurological causes, amongst others. There is a lack of consensus worldwide on how to define the condition, the nomenclature to use, and how to optimally investigate and treat patients. This is reflected in the considerable variation in management worldwide, and the divergent recommendations in national and international guidelines. This uncertainty can lead to a considerable delay in diagnosis and therefore in initiating optimal management. It is now thought that IC with Hunner lesion represents a different disease process to BPS, requiring different management strategies, and there is debate about whether this should now be completely separated from BPS. Investigating the prevalence of different BPS phenotypes and the outcomes of phenotype-directed management would enable optimisation and standardisation of therapy, and inform future research efforts. 
The aim of this study is to describe the prevalence of IC with Hunner lesion in a contemporary cohort of patients with BPS/IC in the UK. We also aim to determine the efficacy and re-treatment rate of phenotype-directed management with transurethral Holmium laser ablation of Hunner’s lesions.

This is a retrospective analysis of all patients diagnosed with BPS/IC in a single specialist centre over almost 4 years, from Jan 2015 - Nov 2018. Patients were diagnosed with BPS/IC after exclusion of other confusable conditions with mid-stream urinalysis, post-void residual, cystoscopy, pelvic imaging, and urodynamics if indicated. Data on demographic details, self-reported duration of symptoms prior to formal diagnosis, method of investigation and treatments were collected. Outcomes of patients who underwent phenotype-directed management with laser ablation to Hunner’s lesions were collected using the Global Response Assessment (GRA) tool- a 7-point Likert scale from -3 (markedly worse) to +3 (markedly improved).

A total of 163 patients (mean age of 43 years (20 – 85)) were included in this study. The majority (78%) were female and patients had experienced symptoms for an average of 6 years prior to formal diagnosis (1 – 30 years). 83% of patients had pelvic imaging – 44% ultrasound, 42% MRI and 14% CT. Imaging was abnormal in only 5 patients (4%). 14% had Hunner’s lesions (ESSIC 3), and the mean bladder capacity under anaesthesia in this group was lower than those with a normal cystoscopy (ESSIC 1) -  373ml v 709ml. Of those with Hunner lesions 55% were moderately/markedly improved after laser ablation with a mean duration of effect of 10 months. ESSIC findings and outcomes of laser ablation are summarised in Table 1.

The majority of patients presenting with BPS/IC in contemporary UK practice are female, and patients have often suffered for many years prior to diagnosis. Pelvic imaging (with either ultrasound, CT, or MRI) rarely finds any abnormality to account for the patient’s pain symptoms, and the mainstay of investigation is a diagnostic cystodistension to accurately phenotype patients. The prevalence of Hunner’s lesions in patients presenting with BPS/IC is more common that often thought, with an overall prevalence of 14%. Holmium laser ablation to Hunner’s lesions is a minimally-invasive treatment with a success rate of 55% and a mean duration of effect of 10 months. If efficacious, patients often require repeat treatments.

The presence of Hunner’s lesions in patients with BPS/IC is not uncommon. Pelvic imaging rarely identifies any cause for pain and so patients should undergo cystoscopy under anaesthesia, with cystodistension, as a diagnostic test for accurate phenotyping. Phenotype-directed management with Holmium laser ablation to Hunner’s lesions is a minimally-invasive treatment for this difficult to treat patient population, with good short-term efficacy in improving pain. However, patients should be counselled about the likely need for repeat treatments.