Affiliations: Near Infrared Study Group, University of British Columbia, UBC Hospital Bladder Care Centre, Vancouver, BC, Canada | Stellenbosch Institute for Advanced Study, Wallenberg Research Centre, Stellenbosch, South Africa
Note:  Corresponding author: Dr. Andrew Macnab, Bladder Care Centre, Unit 1B – Room F329, UBC Hospital, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5. Tel.: +1 604 822 7616; Fax: +1 604 822 7591; E-mail: firstname.lastname@example.org.
Abstract: Near Infrared Spectroscopy (NIRS) has recently been applied to evaluation of bladder function during voiding by transcutaneously monitoring changes in the concentration of oxygenated (O2Hb) and de-oxygenated (HHb) haemoglobin within the detrusor muscle during voiding. This prospective cohort study evaluated the consistency of bladder anatomy relative to the suprapubic location of the NIRS sensor patch during simultaneous invasive urodynamic pressure flow studies (UDS) and non-invasive NIRS monitoring in female subjects evaluated for lower urinary tract symptoms (LUTS). Pelvic ultrasound measurements of the bladder were performed after bladder emptying, at 150 ml, 300 ml and maximum capacity in supine, sitting and upright positions; simultaneous NIRS data at 10 Hz were collected during UDS. Ultrasound measurements in 24 subjects (14 with and 14 without hysterectomy) showed that a NIRS sensor patch positioned on the abdomen 2 cm superior to the symphysis remained directly over the anterior wall of the bladder throughout the voiding cycle, with no significant difference in bladder measurements relative to the abdominal wall with or without hysterectomy. At higher bladder volumes the majority of bladder expansion appeared to involve the dome. Conclusions: With bladder volumes of 150 cc or greater the anterior wall is within the field of view of a NIRS sensor on the abdominal skin, and prior hysterectomy does not compromise NIRS monitoring of the detrusor.