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 (Qmax).

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 Qmax 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; Pabd: abdominal pressure; Pdet: detrusor pressure; PUV: posterior urethral valve; (N)(P)PV: (negative) (positive) predictive value; Pves: vesical pressure; Qmax: maximum urinary flow rate; UDS: urodynamic studies; UI: urinary incontinence.