Use of Nomogram to Predict Acute Urinary Retention

Abstract

We agree with the authors, that male patients over 70 years of age undergoing lower limb arthroplasty under spinal anaesthesia are at high risk of developing acute urinary retention (AUR). This is due to a combination of benign prostatic hyperplasia, immobility, spinal anaesthesia and postoperative analgesia. The use of IPSS/AUA-SI score is a useful means of assessing prostate symptoms and there is evidence to indicate patients with moderate-to-severe symptoms have a higher risk of developing AUR in the community.1 However, using this score alone is not a significant predictor of AUR,2 so it is not surprising it lacks accuracy in this series. Slawin et al.2 suggested using a nomogram with a combination of parameters including IPSS/AUA-SI, PSA, prostate size and flow rate – a simple noninvasive test, providing a much more accurate prediction of the likelihood of AUR. Studies are currently underway to assess the value of the newer generation of α-blockers in preventing postoperative AUR. Indiscriminate catheterisations of all male patients over 70 years old run the risks of urethral trauma and subsequently urethral stricture as well as urinary sepsis. Until the results of these studies are available, it may be useful to use a nomogram to predict outcome and catheterise only the high-risk group.