Retention
Retention is failure to empty the bladder completely. The acute form characteristically affects men, presents urgently and requires immediate catheterisation or hospitalisation. Chronic retention may produce few symptoms and may only be discovered during palpation of the abdomen.
Differential diagnosis
Common Diagnoses
- Prostatic Hypertrophy: Benign, Rarely Carcinoma
- Anticholinergic Drugs: Bladder Stabilisers and Tricyclic Antidepressants
- Constipation
- Bladder Neck Obstruction/Urethral Stricture
- UTI (Including Prostatitis and Prostatic Abscess)
Occasional Diagnoses
- Urethral Calculus
- ‘Holding on’ (Leads to Prostatic Congestion)
- Pelvic Mass: Retroverted, Gravid Uterus or Fibroid Uterus
- Acute Genital Herpes (Via Local Inflammation and Interference with Neurological Control of Detrusor Reflex Arc)
- Clot Retention (e.g. After Bleed from Tumour or Post-Turp Bleed)
- Balanoposthitis in Children (If Very Painful)
Rare Diagnoses
- Neurological: MS, Syphilis, Spinal Cord Compression
- Pedunculated Bladder Tumour
- Traumatic Rupture of Urethra
- Foreign Body Inserted into Anterior Urethra
- Phimosis
- Psychological
Ready reckoner
Key distinguishing features of the most common diagnoses
| Prostatic Hypertrophy | Drugs | Constipation | Bladder Neck | UTI | |
|---|---|---|---|---|---|
| Enlarged Prostate PR | Yes | No | No | No | Possible |
| Acute | Possible | Yes | Possible | No | Yes |
| Young Patient | No | Possible | No | Possible | Possible |
| Abnormal Urinalysis | Possible | No | No | No | Yes |
| Palpable Colon | No | No | Yes | No | No |
Possible investigations
Likely: Urinalysis, MSU.
Possible: U&E, PSA, ultrasound, cystoscopy
Small Print: Neurological investigations, prostatic biopsy, urethrography (all hospital-based investigations).
- Urinalysis of any urine available may confirm a UTI as the cause; may also reveal microscopic haematuria if a stone or bladder tumour.
- MSU: Will confirm infective agent in UTI.
- U&E: Renal failure may follow chronic retention
- PSA may be worth considering if preceding symptoms of prostatism or abnormal prostate on examination.
- Specialist tests may include: Renal ultrasound (reveals obstruction and pelvic masses), cystoscopy (may be diagnostic and therapeutic for stones, stricture, bladder outflow obstruction and bladder tumour), neurological investigations (e.g. spinal cord imaging if cord lesion suspected), prostatic biopsy (if suspicious area of prostate palpable) and urethrography (for stricture).
Top Tips
- Do not overlook faecal impaction in the elderly patient as a cause of urinary retention.
- ‘First-aid’ relief of retention when the cause is a painful perineal condition (e.g. balanoposthitis, herpes simplex or UTI) may be achieved by encouraging the patient to urinate while immersed in a warm bath.
- Anuria can be mistaken for retention. A straightforward clinical assessment should differentiate the two conditions.
Red Flags
- A history suggesting a disc prolapse with urinary retention indicates possible cord compression – admit immediately.
- Sudden stoppage of urine with a pain like a blow to the bladder and passage of a few drops of blood is pathognomic of urethral calculus.
- Beware of any drugs with anticholinergic side effects in patients with a history of outflow obstruction – they may precipitate acute retention.
- Avoid catheterisation when sepsis is likely (e.g. possible UTI) – instrumentation may result in septicaemia. Instead, admit to hospital for catheterisation under appropriate antibiotic cover.
- Do not catheterise the patient with chronic retention; admit for controlled drainage. Sudden decompression can result in haematuria and renal complications.