Residual urine volume after total mesorectal excision: an indicator of pelvic autonomic nerve preservation? Results of a case‐control study

Abstract

The rate of bladder dysfunctions after total mesorectal excision (TME) for rectal cancer can be decreased by bilateral pelvic autonomic nerve preservation (PANP). However, it is not clear yet, how often partial nerve impairment may lead to bladder dysfunction. It was the aim of a case-control study, to examine the residual urine volume in patients before and after TME with and without complete PANP, in order to clarify, whether this parameter allows conclusions on the quality of PANP. Regarding bladder function, a case group (n = 26) without complete PANP was compared with a control group (n = 26) with complete identification and nerve preservation according to standadized intra-operative documentation. Twenty-six match pairs were established, identical regarding gender, wall infiltration depth, tumour site, operation procedure and operation extent. Rates of neoadjuvant therapy, R0-classification, anastomotic leakage, wound and urinary tract infection were equally distributed for both the case- and control group (P > 0.05). Residual urine volume was pre- and post-operatively determined by sonography. Pre-operatively, residual urine volumes differed neither between the pairs nor between both groups with and without nerve preservation. In the case group with incomplete PANP there was a difference between pre- and post-operative residual urine volume (median; quartil: 2.5 ml; 0.0-32.5 ml vs 130 ml; 0.0-317 ml; P = 0.001). In the control group there was no difference (median; quartile: 0.0 ml; 0.0-20 ml vs 15.5 ml; 0.0-62.0 ml; P = 0.07). The difference between the postoperatively measured volumes of the case and control group were significant (P = 0.001). With residual urine volume = 100 ml, the risk of incomplete PANP was 14 times higher (odds ratio). Residual urine volume is an indicator of the completeness of PANP during TME. It should be determined pre- and post-operatively, and besides the recording of the neurogenic bladder, serve as a quality control.