Overactive bladder with urodynamic study-induced bladder pain: An overactive bladder subtype with symptoms similar to those of interstitial cystitis/painful bladder syndrome

Overactive bladder (OAB) and interstitial cystitis/painful bladder syndrome (IC/PBS) are 2 lower urinary tract disorders with urgency and bladder pain for diagnosis and with several other shared symptoms. Because of their overlapping symptoms, precise differential diagnosis of OAB and IC/PBS remains difficult. Thus, we characterize a subgroup of OAB with bladder pain (OAB-BP) that can be differentiated from OAB alone by urodynamic study (UDS) findings. We also further examined the clinical presentations and urodynamic parameters of OAB alone, OAB-BP, and IC/PBS. Data were collected between September 2018 and April 2019. Patients were categorized into 3 groups, OAB-alone (no bladder pain during UDS, n = 39), OAB-BP (with bladder pain during UDS, n = 35), and IC/PBS (the comparator, n = 39). Chi-square tests were used to compare OAB alone, OAB-BP, and IC/PBS with respect to their clinical presentations and urodynamic parameters. Factors with P < .05 were further analyzed through post hoc comparisons with Bonferroni adjustment. An unique subgroup of OAB patients was identified (i.e., OAB-BP), bladder pain can only be induced at maximal cytometric capacity during UDS. We also identified that the case histories and UDS parameters (e.g., low first desire, normal desire, and maximum cytometric capacity) of the OAB-BP group were more similar to those of the IC/PBS group than to those of the OAB-alone group. The OAB-BP group and the IC/PBS group reported more intrusive, longer-lasting symptoms before their final diagnoses, more extensive family history of urinary tract disorder, and more associated comorbidities (e.g., irritable bowel syndrome, and myofascial pain) than the OAB-alone group. The UDS assessment induced bladder pain in the OAB-BP group to reveal their hidden symptoms. Careful attention to patient history and sophisticated UDS evaluation may help to identify this unique OAB group.