What are normal findings for hematuria on a catheterized urinalysis?

From the Guidelines

Normal findings for blood on a catheterized urinalysis should show no blood or minimal blood presence, with a normal catheterized urine sample typically containing 0-3 red blood cells (RBCs) per high-power field (HPF). The presence of more than 3 RBCs/HPF is considered abnormal and may indicate conditions such as urinary tract infection, trauma from catheterization, kidney stones, or other urological issues 1. When examining a catheterized sample, healthcare providers should expect to see clear urine without visible blood (no hematuria). The absence of blood is important because catheterization bypasses the urethra, reducing contamination from external sources. If blood is detected in a catheterized sample, it suggests the bleeding source is within the bladder, ureters, or kidneys rather than the urethra or external genitalia. This distinction helps clinicians better localize potential pathology. It's worth noting that even proper catheterization technique can sometimes cause minor trauma resulting in microscopic hematuria, but this should be minimal and transient. Key points to consider when evaluating hematuria include:

• The definition of microscopic hematuria as three or more red blood cells per high-power field on microscopic evaluation of urinary sediment from two of three properly collected urinalysis specimens 1
• The importance of a thorough history, physical examination, urinalysis, and serologic testing prior to any initial imaging 1
• The use of ultrasound, CT, and MRI as common imaging modalities to evaluate hematuria 1
• The consideration of risk factors, such as age, gender, and smoking history, when evaluating hematuria 1

From the Research

Normal Findings for Hematuria on a Catheterized Urinalysis

• A properly collected catheterized urine sample is essential for accurate evaluation of microscopic hematuria 2
• Normal findings for hematuria on a catheterized urinalysis include:
  • Fewer than 3 red blood cells per high-power field 3, 2
  • Fewer than 2 squamous epithelial cells per high-power field 2
• Catheterized urinalyses have significantly fewer red blood and squamous epithelial cells compared to voided urinalyses 2
• The presence of more than 2 squamous epithelial cells per high-power field may indicate a poorly collected specimen 2
• The evaluation of hematuria should include renal function testing, urinary tract imaging, and cystoscopy in the absence of obvious causes 4
• Computed tomography urography is a useful technique for evaluating hematuria, especially for detecting small tumors and calculi 5, 3