Weakness of the Pelvic Floor Muscle and Bladder Neck Is Predicted by a Slight Rise in Abdominal Pressure During Bladder Filling: A Video Urodynamic Study in Children

PURPOSE: To investigate the significance of slowly rising abdominal pressure (SRAP), which is often observed in nonneurogenic children during bladder filling in video urodynamic studies (VUDSs). METHODS: The records of patients who underwent VUDS from July 2011 to June 2013 were reviewed. SRAP was defined as a rising curve over 5 cm H2O from the baseline abdominal pressure during the filling phase in VUDS. Bladder descent was defined when the base of the bladder was below the upper line of the pubic symphysis. An open bladder neck was defined as the opening of the bladder neck during the filling phase. RESULTS: Of the 488 patients, 285 were male patients. The mean age at VUDS was 3.7 years (range, 0.2–17.6 years). The VUDS findings were as follows: SRAP, 20.7% (101 of 488); descending bladder, 14.8% (72 of 488); and bladder neck opening, 4.3% (21 of 488). Of the 72 patients with a descending bladder, 84.7% had SRAP. A significant difference in the presence of SRAP was found between the descending bladder and the normal bladder (P<0.001). Of the 101 patients with SRAP, 40 (39.6%) did not have a descending bladder. Of the 40 patients, 14 (35.0%) had a bladder neck opening, which was a high incidence compared with the 4.3% in all subjects (P<0.001). CONCLUSIONS: SRAP was associated with a descending bladder or a bladder neck opening, suggesting that SRAP is a compensatory response to urinary incontinence. SRAP may also predict decreased function of the bladder neck or pelvic floor muscle.