Reduced bladder capacity without daytime voiding symptoms with nocturnal enuresis

Background This study aimed to evaluate the prevalence of monosymotomatic nocturnal enuresis (MSNE) with reduced bladder capacity in children with primary nocturnal enuresis (NE) and to suggest treatment outcomes. Methods This study retrospectively evaluated 54 children (30 males, 24 females; median age: 8; range: 5-14) who were newly diagnosed with primary NE from November 2017 to October 2019. Reduced bladder capacity in MSNE was defined when a patient's maximal voided volume (MVV) from his or her voiding diary was 75% or less than estimated functional bladder capacity ([age + 1] x 30 mL) for his or her age and there were no daytime lower urinary tract symptoms (LUTS) as assessed using history taking and questionnaires. Results Nineteen (35.2%) of 54 children with newly diagnosed primary NE did not report daytime LUTS. Fifteen children (27.8%) had a reduced bladder capacity and were prescribed anticholinergic or beta-3 agonist. After three months of medication, MVV significantly increased from 117.5 mL to 183.3 mL (P = 0.010), but frequency showed no significant change from 5.7 to 4.9 times a day. Improvement in enuresis occurred completely and partially in 41.7% and 25% of participants, respectively. Conclusions The prevalence of reduced bladder capacity without daytime voiding symptoms was relatively high as 27.8% in children newly diagnosed with primary NE. In primary MSNE, reduced bladder capacity should be investigated using a frequency-volume chart in addition to thorough history taking or questionnaires. Anticholinergics or beta-3 agonists for MSNE with reduced bladder capacity are effective at increasing the bladder capacity of these patients.