What is the initial workup for a patient presenting to the Emergency Room (ER) with urinary frequency?

Initial ER Workup for Urinary Frequency

The initial ER workup for urinary frequency should include a focused history, physical examination with digital rectal exam, urinalysis with microscopy, and consideration of post-void residual measurement if obstructive symptoms are present. 1

Essential History Components

• Document the duration, severity, and degree of bother from frequency symptoms, including number of voids per 24 hours and nighttime awakenings 2, 1
• Assess for associated symptoms including urgency, dysuria, hesitancy, weak stream, incomplete emptying, or incontinence 1, 3
• Review fluid intake patterns and timing, as excessive intake can worsen symptoms 1
• Obtain sexual history in younger patients, as sexually transmitted infections causing urethritis can present with frequency 1
• Review current medications that may affect urinary symptoms, including diuretics, anticholinergics, or alpha-agonists 2
• Screen for red flag symptoms including fever, flank pain, hematuria, or constitutional symptoms suggesting pyelonephritis or complicated infection 3, 4

Physical Examination

• Perform suprapubic examination to assess for bladder distension or tenderness 1
• Complete digital rectal exam (DRE) to evaluate prostate size, consistency, and tenderness in males 1
• Assess for costovertebral angle tenderness to evaluate for upper tract involvement 3
• Check for lower extremity edema and perform focused neurologic assessment if neurogenic bladder is suspected 1

Laboratory Testing

Urinalysis is the cornerstone of the initial workup and should include both dipstick and microscopic examination 2, 1:

• Positive leukocyte esterase or nitrite strongly suggests urinary tract infection, with nitrite having a positive likelihood ratio of 7.5-24.5 5
• Moderate pyuria (>50 WBCs/HPF) or bacteruria are accurate predictors of UTI with positive likelihood ratios of 6.4 and 15.0 respectively 5
• Negative leukocyte esterase and blood can effectively rule out UTI with negative likelihood ratios of 0.2 5
• Hematuria warrants further evaluation for malignancy, stones, or other structural abnormalities, particularly in patients over 35 years with risk factors 2

Urine culture should be obtained selectively 1, 6:

• Order culture for suspected pyelonephritis, recurrent infections, complicated UTIs, or when antibiotic resistance is suspected 3
• Culture is generally unnecessary for uncomplicated cystitis in young women with classic symptoms and positive urinalysis 6
• All UTIs in men are considered complicated and warrant urine culture 1

Post-Void Residual (PVR) Measurement

PVR measurement via bladder ultrasound is indicated when 1, 7:

• Obstructive symptoms are present including hesitancy, weak stream, or sensation of incomplete emptying 1
• History of urinary retention, prior prostatic surgery, or neurologic disease exists 1
• Elevated PVR (>100-150 mL) suggests incomplete emptying from obstruction, stricture, or neurogenic bladder 7

When to Obtain Additional Testing in the ER

Imaging is generally not part of the initial ER workup unless specific indications exist 2:

• Renal ultrasound if concern for hydronephrosis, obstruction, or urinary retention with elevated PVR 2
• CT abdomen/pelvis without contrast if nephrolithiasis is suspected based on flank pain and hematuria 4
• Avoid CT with IV contrast in patients with renal insufficiency or when unenhanced imaging is adequate 2

Critical Pitfalls to Avoid

• Do not rely on history and physical examination alone to diagnose or exclude UTI, as no single finding has sufficient accuracy (likelihood ratios 0.8-2.2) 5
• Do not assume frequency equals infection - overactive bladder, polyuria, and behavioral factors are common non-infectious causes 2
• Do not miss urinary retention presenting as frequency from overflow incontinence - always consider PVR in appropriate patients 1, 4
• Do not overlook red flags requiring urgent urology consultation: acute urinary retention, suspected Fournier gangrene, or obstructing stone with infection 4

Disposition and Follow-Up

Most patients with uncomplicated frequency can be discharged with appropriate treatment or referral 1:

• Initiate empiric antibiotics for suspected UTI based on local resistance patterns 1
• Arrange outpatient urology referral for persistent symptoms, abnormal findings, hematuria, or elevated PVR requiring further evaluation 1, 7
• Immediate urology consultation for acute retention, severe obstruction, or suspected malignancy 1