Urine sediment test: what the result means

Microscopic examination of urine sediment is done after a general (dipstick) urine test, when a more detailed look is needed at what is floating in the urine. The urine sample is centrifuged, the liquid part is poured off, and the sediment that remains is smeared on a slide and examined under a microscope. The elements are counted per field of view (cells/HPF): erythrocytes (red blood cells), leukocytes (white blood cells), epithelial cells, casts, crystals, bacteria and mucus. Each element can point to a different thing: erythrocytes — bleeding in the urinary tract, leukocytes — inflammation or infection, crystals — a risk of kidney stones, casts — damage to the kidney tubules. The test is usually ordered together with a general urine test, or as a clarification of it, when the dipstick test shows deviations (for example, positive blood, protein or leukocyte esterase). The result is often given as a range (for example, “0–3”, “occasional” or “abundant”) rather than one exact number, because the distribution of cells in the sample is not entirely even.

• When a general (dipstick) urine test finds blood, protein, leukocyte esterase or nitrites
• When a urinary tract infection is suspected — pain or burning when passing urine, frequent urination, discomfort in the lower abdomen
• When kidney stones are suspected — a sudden sharp pain in the back or the flank, blood noticed in the urine
• When monitoring a known kidney disease or its progression
• As part of a routine check-up or before planned surgery
• When changes in the colour, smell or clarity of the urine are noticed

A raised amount of cells or particles in urine sediment depends on what exactly is raised. More erythrocytes than the norm is most often linked to a urinary tract infection, stones, inflammation or trauma; more epithelial cells or mucus — to infection or irritation; abundant crystals — to a risk of stones or to metabolic disorders. It is always worth assessing the result together with a general urine test.

• A urinary tract infection (of the bladder, of the kidneys)
• Kidney stones
• Inflammation, trauma or irritation of the urinary tract
• Kidney disease
• Not enough fluid in the body (which is why crystals build up)
• Some medicines — for example those that reduce acidity, or diuretics — can change how crystals form in the urine
• In rarer cases — a tumour of the bladder or the kidney

Symptoms that may accompany it

• Pain or burning when passing urine
• Frequent urination
• Sharp pain in the lower abdomen, the flank or the back
• Blood in the urine
• Cloudy or unusually coloured urine
• Tiredness

What to discuss with a doctor

• A general urine test and a urine culture — to clarify whether there is an infection and which organism is causing it
• Kidney imaging tests, if stones are suspected
• Creatinine and other kidney function markers
• Fluid intake habits and diet, if crystals were found
• When to repeat the test, so that change over time can be seen