A Systematic Approach to the Urinary Sediment

 Table 1.

The examination of the urinary sediment has been compared to a liquid biopsy of the kidney and urinary tract. Although it clearly does not reach the anatomical resolution and precision of a tissue biopsy, it oftentimes allows correct identification of the principal site and extent of injury.

Moreover it excels with a couple of distinct advantages: It is fast, cheap and noninvasive. You can repeat it as often as you like. For focal processes it may be more sensitive and less prone to sampling error than a tissue biopsy.

To get the most out of the sediment examination it is important to approach it in a systematic fashion. I recommend the following steps:

  1. Get an idea of the clinical scenario and formulate specific questions.
  2. Be aware of the results of the urine dipstick (pH, density, hemoglobin, albuminuria) and take a look at the macroscopic appearance of the urine and sediment.
  3. Assess the sediment findings within the framework of the three principal pathoanatomical compartments (Table).
  4. Correlate your findings with the clinical information and formulate a conclusion.

In my opinion, best results of urinary sediment examination are obtained with intimate knowledge of the clinical situation. So I strive to look at sediments of patients I treat by myself. Outsourcing of the urinary sediment examination is of course possible, but grasping the “Gestalt” of a sediment from a written report, I find exceedingly difficult.