Chronic retention – all you need to know Chronic urinary retention is a common presentation in elderly and frail patients. Two types should be recognised - low pressure chronic retention (LPCR) and high pressure chronic retention (HPCR). Acute-on-chronic retention occurs when a person with chronic retention stops voiding completely. Box 1 in the article provides a useful list of points of assessment. The presence of nocturnal enuresis is often a strong pointer towards the presence of HPCR. In some of these cases, the cause is merely tight phimosis with pin-hole opening (which in my experience is often overlooked at initial assessment). Box 2 includes a list of drugs which can lead to retention. Investigations should include urine dipstick analysis, full blood count (FBC), urea, creatinine and estimated glomerular filtration rate (e-GFR). In LPCR, renal function is usually normal, In HPCR, renal function is impaired with elevated serum creatinine and reduced eGFR. Imaging studies should include a simple bedside bladder scan to confirm the diagnosis if unsure, and quantify the retention volume. Ultrasound of the renal tract is recommended in all patients with chronic retention. The authors provide guidance on triaging of referrals which may be immediate, urgent and outpatient. Some key points made regarding the management include the fact that not all patients with chronic retention require catheterisation, such as those without symptoms and with normal renal function. Clean intermittent self-catheterisation may be an option for those with symptoms and recurrent infections. HPCR requires catheterisation and a trial of void is contraindicated before a definitive intervention (e.g. surgery) has been undertaken.