A prospective crossover study comparing ICCS-recommended and Palmer-adjusted filling rates in children with spina bifida.
OBJECTIVE: This study aimed to investigate whether the maximal cystometric capacity (MCC) in children with spina bifida (SB) is indeed lower, as predicted by the Palmer formula, and to evaluate the impact of different bladder filling rates on urodynamic parameters. MATERIALS AND METHODS: This prospective, randomized, two-sequence crossover-controlled study included 70 children aged 3-18 years with spina bifida under regular follow-up. In Group 1, the first two bladder fillings were performed at the ICCS-recommended rate, and the third at 75% of that rate (Palmer formula). In Group 2, the sequence was reversed. Urodynamic parameters, including maximal cystometric capacity (MCC), bladder compliance, detrusor activity, filling pressures, and detrusor leak point pressure (DLPP), were analyzed across fillings. RESULTS: Cystometric bladder capacity was lower during fillings performed at the Palmer-adjusted rate compared with those at the ICCS-recommended rate. The proportion of reduced compliance significantly decreased in Group 1 (p = 0.046) but remained unchanged in Group 2. A significant positive correlation was observed between expected bladder capacity (EBC) and measured MCC in both groups (ρ ≈ 0.5-0.6). The highest correlation and agreement were found in Group 1 during the third filling at the Palmer rate (ICC = 0.606). No significant intra- or intergroup differences were observed in detrusor pressure, end-filling pressure, DLPP, or overactive bladder prevalence. CONCLUSION: Bladder filling rate was associated with differences in both cystometric capacity and bladder compliance in children with spina bifida. Fillings performed according to the Palmer formula (approximately 75% of the ICCS-recommended rate) were associated with capacities that more closely approximated age-expected values and with modest differences in bladder compliance. Conversely, faster filling rates did not produce similar benefits. These findings suggest that slower filling strategies may improve measurement consistency and agreement with expected bladder capacity estimates. However, the magnitude and direct clinical impact of these differences should be interpreted cautiously, particularly in light of the potential influence of sequence-related effects.