Can rectal catheters be avoided during paediatric urodynamic studies?

Objective: To determine if the interpretation of urodynamic studies (UDS) in children without a rectal catheter may be similar to multi-channel studies, as UDS in children are challenging and can sometimes be difficult to interpret. Patients and methods: In this retrospective pilot study, 115 paediatric pressure-flow studies were included. A blinded investigator was given two sets of UDS traces. The first set had the vesical trace of all children and the second set had the multi-channel trace. The agreement between the interpretations of both the sets was tested by Cohen's κ, and sensitivity, specificity, and predictive values were expressed with 95% confidence intervals (CIs). The voiding pattern was compared and Pearson's correlation coefficient was used to analyse the pressure at maximum urinary flow (Q_max). Results: The most common indications for UDS were neurogenic bladder and posterior urethral valves. The interpretation of compliance and detrusor overactivity by single-channel analysis had a positive predictive value of 92.1% (95% CI 84.7-96.1%) and 89.4% (95% CI 78.3-95.6%), respectively, and a negative predictive value of 100% and 97.1% (95% CI 89.5-99.2%) respectively, in comparison to multi-channel analysis. Children with underactive detrusor were identified reliably by analysing the straining pressure pattern and flow curve. Amongst children who voided, the pressure at Q_max showed a moderate correlation (Pearson's coefficient = 0.53) between the two groups. Conclusion: Rectal catheters may be avoided in a carefully selected group of children undergoing UDS who only need filling phase assessment. Abbreviations: DO: detrusor overactivity; EBC: expected bladder capacity; P_abd: abdominal pressure; P_det: detrusor pressure; PUV: posterior urethral valve; (N)(P)PV: (negative) (positive) predictive value; P_ves: vesical pressure; Q_max: maximum urinary flow rate; UDS: urodynamic studies; UI: urinary incontinence.