The effect of BPH on detrusor function and structure is multidimensional, inducing molecular and morphological alterations in the urothelium, detrusor smooth muscle cells (SMCs), extracellular matrix, and bladder innervating neurons. It is hypothesized that BOO-induced bladder dysfunction follows a three-stage model initially characterized by hypertrophy, followed by compensation and, ultimately, by decompensation.222 Work has been done examining the compensatory phase of the detrusor following BOO. Hypoxia-inducible factor (HIF)‐1α and vascular endothelial growth factor (VEGF) were shown to be significantly upregulated in a time-dependent manner in cultured detrusor SMCs when exposed to hypoxia.223 The expression of HIF-1α was further investigated in obstructed human detrusor specimens showing that the urothelium and detrusor may be more resistant to hypoxic stress compared to stromal cells.224 VEGF, in addition to collagen types I, III, and nerve growth factors (NGF) are all upregulated in obstructed human bladder specimens taken during TURP. With persistent obstruction, the adaptive response of the bladder continues to diminish and eventually there is permanent damage to elasticity and contractility of the bladder until the bladder fully decompensates.225   The goal for urologists should be to try and prevent these end-organ changes in bladder function with the hope of regaining completely normal functioning of the bladder. OAB and BOO may exist separately or together, and in those men who present with both BOO and OAB, there may be a coupling of these disease processes. UDS has shown that nearly half of patients with LUTS diagnosed with BOO had concurrent DO.226, 227 Interestingly, in these men diagnosed with BOO and concurrent DO, a systematic review showed that 57.1-83.3% of patients had resolution of their DO 2-12 months after treatment of their outlet obstruction.228 Regarding treatment choice, very little comparative data is known with multiple procedures showing improvement in OAB symptoms and DO following surgery.229-232 Not all men diagnosed with OAB/DO warrant treatment for BOO, but in men diagnosed with OAB/DO, considerations should be taken to rule out obstruction as a potential etiology, as early medical or procedural interventions may help improve or correct these symptoms. Following persistent obstruction, the bladder undergoes decompensation and patients may have DU, acontractile detrusor, and urinary retention. There is significant heterogeneity in these study populations, as many authors use a bladder contractility index (BCI) <100 as a surrogate for DU, whereas DU likely exists as a spectrum between a completely acontractile bladder and those with varying levels of retained contractility. There are growing efforts to properly stratify these patients and to include other metrics such as the Watts factor into clinical practice.233 Since medical treatments for underactive bladder are extremely limited, the mainstays of treatment for underactive bladder are either catheterization or surgical interventions with the hope of retaining spontaneous voiding. Studies have shown that >80% of patients with DU or acontractile detrusor had an improvement in quality of life and a voiding efficiency >50% following a TURP.234 Additional literature has shown that following HoLEP, 78% of patients experience improvements in their bladder contractility at 6 months with 94.7% of patients able to void spontaneously following their procedure.235 In a systematic review of the literature, men with DU/acontractile detrusor who underwent an outlet operation noted an improvement in their IPSS of 3-19.5 points, an improvement in their Qmax of 1.4-11.7 mL/s, and an improvement in their PVR of 16.5-736 mL. There is literature showing that men who undergo HoLEP have better outcomes compared to PVP and TURP.236-239 In a systematic review, older age, lack of obstruction, concomitant DO, and a lower BCI were predictive of poorer outcomes following outlet procedures.228 Given the heterogeneity of data and lack of controlled trials, men with DU or acontractile bladders should undergo shared decision-making considering patient factors, weighing the risks and benefits of watchful waiting, intermittent or indwelling catheterization, or procedural interventions. In men who desire procedural interventions, they should be counseled that they may be best served with maximally debulking operations, with very limited data on the utilization of non-resective technologies.