Kidney Week

Abstract: SA-PO1035

Findings in Urinary Sediment Inspected by Microscopy Several Days After Collection

Session Information

• Pathology and Lab Medicine - II
  November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

• 1800 Pathology and Lab Medicine

Authors

• Velez, Serenella A., Ochsner Health, New Orleans, Louisiana, United States

Serenella A. Velez,

• Cohen, Lauren, Ochsner Health, New Orleans, Louisiana, United States

Lauren Cohen,

• Seltzer, Jay R., Missouri Baptist Medical Center, Saint Louis, Missouri, United States

Jay R. Seltzer,

• Velez, Juan Carlos Q., Ochsner Health, New Orleans, Louisiana, United States

Juan Carlos Q. Velez,

Background

Textbooks and clinical practice manuals recommend inspection of urinary sediment specimens immediately or within < 2 hours of collection because of presumed loss of specimen quality over time. However, there is no conclusive evidence supporting that recommendation. Based on anecdotal observations, we hypothesized that adequacy of urinary sediments can be maintained way beyond the 2-hour limit.

Methods

An experimental study was conducted utilizing urinary sediment specimens obtained from patients seen by the nephrology inpatient consultation service due to acute kidney injury. Aliquots of the specimens were stored at both room temperature (RT) and at 4^oC. Urine microscopy was performed at the time of collection, 24 hours, 48 hours, and 1 week post collection, and assessed for presence of granular casts (GC), waxy casts (WxC), renal tubular epithelial cell casts (RTECC), red blood cell casts (RBCC), acanthocytes, and lipids. Abundance of casts was assessed by an adaptation of the Perazella score (cast number/low power field).

Results

A total of 16 urine specimens were collected and divided into RT (n=16) and 4^oC (n=14). Overall, only 4.6% (3/65 data points) revealed a change in density of findings. By 48 hours, GC, WxC, RTECC and RBCC did not change in presence or abundance at either RT or 4^oC. By 1 week, 90% (9/10) did not change GC score for both RT and 4^oC, 75% (3/4) and 80% (4/5) did not change WxC score at RT and 4^oC, respectively, and 83.33% (5/6) and 100% (7/7) did not change RTECC score at RT and 4^oC, respectively. For samples with acanthocytes, at RT, 2 did not change in abundance for up to 1 week, whereas 1 changed from 40% to 25% at 48 hours. At 4^oC, 1 case did not change in acanthocyte abundance for up to 1 week, whereas 1 changed from 40% to 25% at 48 hours. For samples with lipids, 100% (5/5 at RT, 3/3 at 4^oC) maintained lipid presence for up to 1 week.

Conclusion

Our findings challenge the traditional knowledge and demonstrate that immediate inspection of the urinary sediment, although recommended, is not essential in clinical practice. Collected specimens can be kept for later examination in the event that an expert observer is required for corroboration of findings. Further research is necessary to precisely determine at which point urinary sediment quality begins to decay.