RCGP SCA Algorithm — UK Primary Care
Frequency is a symptom with two quite different mechanisms: passing large volumes (polyuria — diabetes, hypercalcaemia, drugs, fluid intake, nocturnal polyuria) or passing small volumes often (bladder or outlet problem). Screen for the dangerous causes first.
Chronic retention is often painless and presents as frequency, nocturia or "incontinence"; a palpable bladder with renal impairment is high-pressure retention that threatens the kidneys. New bladder symptoms with back pain or neurological symptoms must prompt questions about saddle sensation and leg weakness.
NICE NG12 (updated April 2026) uses visible haematuria at 45 or over (unexplained, or persisting after UTI treatment) and non-visible haematuria at 60 or over with dysuria or a raised white cell count as suspected cancer pathway criteria; a hard, irregular prostate needs referral regardless of the PSA; and persistent urinary urgency or frequency is one of the ovarian cancer symptoms that should prompt a CA125 in women aged 40 or over.
The first question — "large or small amounts?" — divides the differential in half. A 3-day frequency-volume chart answers it objectively and also shows total intake, functional bladder capacity and the proportion of urine passed at night. In men, splitting voiding from storage symptoms decides whether an alpha-blocker or an OAB treatment is likely to help (NICE CG97).
NICE CG97 asks for an examination of the abdomen, external genitalia and a digital rectal examination in men with LUTS; NG123 asks for a pelvic examination in women with urinary symptoms to look for prolapse, atrophy and pelvic floor function. A palpable bladder after voiding changes the whole plan.
The bladder diary is the most informative free test in this presentation (NICE NG123 and CG97): it separates high intake, global polyuria and nocturnal polyuria from OAB, which need completely different treatments. PSA testing in men with LUTS is offered after a balanced discussion of false positives and negatives; a hard or irregular prostate needs referral whatever the PSA.
Persistent irritative symptoms with sterile pyuria or non-visible haematuria in a smoker should make you think of bladder carcinoma in situ, which mimics OAB. In older adults nocturia is commonly multifactorial: nocturnal polyuria, reduced bladder capacity, prostate disease and sleep disturbance all contribute, so the diary guides which factor to treat first.
Most frequency and nocturia is managed in primary care after excluding infection, polyuria and red flags. Specialist referral is for retention, suspected cancer, persistent or recurrent infection in men, refractory OAB and women with significant prolapse or voiding problems.
Next steps: see Female urinary incontinence · Male LUTS · Benign prostate enlargement · UTI in women · UTI in men · Recurrent UTI · Pelvic organ prolapse · Prostatitis
Bladder training is first-line for OAB in women and men and works for many without medication (NICE NG123, CG97). Antimuscarinics add a cumulative anticholinergic load that is linked with cognitive impairment, falls and constipation in older people; NICE NG123 asks clinicians to consider the anticholinergic burden and not to offer immediate-release oxybutynin to frail older women. Mirabegron avoids the anticholinergic effect but can raise BP, hence the MHRA advice to measure it before and during treatment.
Nocturia is often nocturnal polyuria, which an antimuscarinic will not fix; desmopressin causes hyponatraemia, particularly in older people.
Conservative measures are first-line in both NICE NG123 and CG97 and should be tried properly, with a review, before drug treatment unless symptoms are severe. Many people restrict fluids to control frequency, which concentrates the urine and can worsen urgency.
Antimuscarinics and alpha-blockers both show their effect within a month, so an early review finds non-responders and side effects. Haematuria that persists after a treated UTI is one of the NG12 triggers and is easily lost if the dipstick is not repeated.