Intra-operative Urodynamics: Is the Test an Accurate Representation of the Lower Urinary Tract in Children?

To compare intraoperative UDS results with UDS in the postoperative care unit (PACU) to assess the accuracy and efficacy of intraoperative UDS in children who cannot tolerate ambulatory urodynamic evaluation.

Pediatric patients undergoing intraoperative UDS at a single institution were enrolled over a 5-year time period (1/2013-8/2018). Urodynamics were performed in the operating room under general anesthesia, then in the PACU after recovery from anesthesia. Electromyographic (EMG) activity during filling, bladder compliance, cystometric bladder capacity (CBC), detrusor overactivity, presence of urinary leak, leak point pressure (LPP), and pressure specific volumes (PSV) at 10, 20, 30, and 40 cm water were compared between studies.

Nineteen patients underwent urodynamic evaluation under general anesthesia and met inclusion criteria. Ten patients (52.6%) underwent 2 filling cycles while awake in PACU, resulting in a total of 48 urodynamic studies available for subsequent analysis. Intraoperative urodynamic studies were more likely to have decreased EMG activity during filling (P=<.01), normal compliance (P <.01), and a lower detrusor LPP (P = .03) compared to UDS performed after recovery from anesthesia. Detrusor overactivity was less frequently observed intraoperatively (P <.001) and involuntary detrusor contractions were lower in magnitude than those observed in the PACU. Twelve of the 19 (63%) children had detrusor overactivity that was present only on the UDS in PACU and not intra-operatively.

The results of urodynamic testing performed under general anesthesia should be interpreted with caution, as pediatric patients appear to have improved bladder compliance, lower detrusor LPP and decreased detrusor overactivity when under anesthesia. For this reason, it is preferable to utilize ambulatory urodynamic evaluation to guide patient management and treatment.