Maximal urethral closure pressure < 20 cm H ₂O: Does it predict intrinsic sphincteric deficiency?

OBJECTIVE: To assess whether the large discrepancy in the literature in the incidence of intrinsic sphincteric deficiency (ISD) is due to different methods by which maximal urethral closure pressure (MUCP) is measured. STUDY DESIGN: We compared the measurement of MUCP in the supine position with 300 mL saline in the bladder, according to International Continence Society guidelines, to that in the sitting position (full bladder) in 54 consecutive patients who were diagnosed as having stress urinary incontinence. RESULTS: In the supine position the mean MUCP was 38.4 ± 2.85 cm H ₂O as compared to 22.80 ± 3.22 cm H ₂O in the sitting position (p < 0.0001). The mean difference was 15.65 ± 2.11 cm H ₂O. MUCP ≤ 20 cm H ₂O was observed in 14 of 54 (25.9%) patients in the sitting position as compared to 1 of 54 (1.8%) in the supine position. CONCLUSION: When MUCP is measured in the supine position, according to International Continence Society guidelines, the cutoff point for diagnosis of ISD should be 35 rather than 20 cm H ₂O.