Bladder anatomy physiology and pathophysiology: Elements that suit near infrared spectroscopic evaluation of voiding dysfunction

Bladder studies are the most recent biomedical application of NIRS in urology. Transcutaneous monitoring of the detrusor muscle in the bladder wall as the organ fills and empties offers new parameters for evaluation of normal and dysfunctional voiding. While established as a research entity clinical adoption requires comprehensive understanding of the attributes and limitations of the technique.

We review key anatomic and physiologic elements that suit the bladder to study using NIRS. These include the depth and consistent relationship of the anterior wall below the abdominal skin which allow transcutaneous monitoring; the unique vascular anatomy which is central to normal organ function and maintenance of perfusion during the spatial changes that occur during bladder expansion and contraction; and the known association of various pathologies with adverse effects on the microcirculation and compromise of the contractile properties of the detrusor muscle.

Such pathologies cause symptoms of voiding dysfunction which in many patients are due to disordered detrusor hemodynamics and/or an imbalance in oxygen supply and demand. Yet current clinical methodology for evaluating the underlying cause of voiding dysfunction only measures pressure and flow, and provides no information related to bladder hemodynamics or oxygenation. Monitoring data from prior studies that illustrate how NIRS of the bladder can contribute novel information related to the physiology of the bladder in health and disease are summarized.