What is the workup for a patient with incomplete emptying of the bladder?

Workup for Incomplete Bladder Emptying

Measure post-void residual (PVR) urine volume immediately using ultrasound or catheterization, with intermittent catheterization indicated if PVR >100 mL. 1, 2

Initial Diagnostic Assessment

Measure Post-Void Residual Volume

• Obtain PVR measurement using bladder ultrasound or catheterization as the first diagnostic step, with PVR >100 mL confirming incomplete emptying and requiring further evaluation 1, 2
• PVR >50 mL is associated with increased dependency and poor prognosis in elderly patients, though the clinical threshold for intervention is typically >100 mL 3
• Ultrasound is preferred over catheterization when possible to reduce infection risk 2

Assess for Neurological Causes

• Evaluate for spinal cord lesions, multiple sclerosis, diabetes with autonomic neuropathy, or stroke affecting the frontal lobe or pons, as these commonly cause incomplete bladder emptying 4, 1, 2
• Assess perineal sensation, sphincter tone, and bulbo-cavernosus reflex to identify peripheral neuropathy consistent with diabetes 4
• In stroke patients, incomplete bladder emptying occurs in 30.5% and is significantly associated with aphasia and urinary tract infection 5
• Check for spasticity of the stroke-affected lower limb, as this is associated with detrusor-external sphincter dyssynergia (DESD) 5

Evaluate for Obstructive Causes

• In men, assess for benign prostatic hyperplasia (BPH) through digital rectal examination and consider prostate-specific antigen (PSA) testing 1, 6
• In women, perform complete urogynaecologic examination to exclude pelvic organ prolapse (stage 3 or higher) or prior anti-incontinence surgery 4, 1, 2
• Straining, intermittency, postvoid dribbling, and weak stream may result from urethral obstruction in men but can also indicate bladder dysfunction from denervation and poor detrusor contractility 4

Rule Out Constipation

• Assess and treat constipation, as 66% of patients with incomplete emptying improve after treating constipation alone, with 89% resolution of daytime wetting and 63% resolution of nighttime wetting 1, 2

Obtain Urinalysis and Culture

• Perform microscopic urinalysis and urine culture to exclude bacterial cystitis, as diabetic patients and those with incomplete emptying are at increased risk of urinary tract infections 4, 2
• Use a bacteriuria threshold of ≥10² CFU/mL for catheterized specimens 1, 2

Advanced Diagnostic Testing

Uroflowmetry with EMG

• Perform uroflowmetry with EMG to identify detrusor underactivity, characterized by interrupted flow pattern, low maximum flow rate, large voided volumes, and prolonged voiding time 1, 2
• This non-invasive test helps differentiate between obstructive and non-obstructive causes 1

Complete Urodynamic Studies

• Obtain complete urodynamic testing when initial management is unsuccessful or there is doubt about the diagnosis, including cystometry, uroflow, simultaneous pressure/flow studies, sphincter electromyography, and urethral pressure profilometry 4
• Urodynamic studies in stroke patients with incomplete emptying reveal acontractile detrusor in 36%, detrusor underactivity in 14%, and DESD in 50% of cases 5
• Target detrusor leak point pressure <40 cm H₂O to prevent upper tract damage 1
• Diabetes mellitus is associated with acontractile detrusor or detrusor underactivity 5

Imaging Studies

• Obtain renal ultrasound to detect hydronephrosis, parenchymal scarring, and stones, as serum creatinine is an insensitive marker for early renal damage in neurogenic bladder 7
• Never rely on serum creatinine alone to assess renal status, as GFR can decline significantly (from 90 to 60 mL/min/1.73 m²) with minimal creatinine change 7

Symptom Assessment Using Validated Questionnaires

Standardized Symptom Evaluation

• Use validated questionnaires such as the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS) to systematically assess symptoms 6
• Common symptoms include dysuria, frequency, urgency, nocturia, incomplete bladder emptying, infrequent voiding, poor stream, hesitancy in initiating micturition, and recurrent cystitis 4
• Assess quality of life impact using specific QoL questionnaires, as a feeling of incomplete emptying significantly affects patient well-being even with low PVR 4, 6
• The score for feeling of incomplete emptying is positively correlated with all IPSS-related scores and often occurs with co-occurring voiding and storage symptoms 6

Clinical Pitfalls to Avoid

Common Diagnostic Errors

• Do not assume normal creatinine means normal kidney function—patients with neurogenic bladder require regular ultrasound surveillance regardless of creatinine values 7
• Approximately 26% of patients with neurogenic bladder from spina bifida will eventually develop renal failure, but this can be prevented with proper management 7
• Recognize that a feeling of incomplete emptying can occur with little or no PVR (<50 mL), particularly in patients with co-occurring voiding and storage symptoms 6
• Incomplete bladder emptying in elderly patients is associated with greater dependency and death as the final outcome in 36% of cases 3
• Avoid anticholinergic medications in patients with incomplete emptying, as they impair detrusor contractility and worsen retention 1, 2

Special Considerations

• In stroke patients, DESD is associated with longer onset-to-evaluation interval and spasticity of the stroke-affected lower limb 5
• The bladder urothelium plays an important role as a sensor controlling bladder function, and diabetes affects urothelial receptors and signaling mechanisms 4
• Urge incontinence is very frequent in women with diabetes, while there is no increased risk of stress incontinence 4