Morphological Basis, Method Workflow, and Result Interpretation of Urinary Sediment Microscopy

Urinary sediment microscopy is a core method for analyzing formed elements in urine. It allows direct observation of red blood cells, white blood cells, epithelial cells, casts, crystals, bacteria, fungi, parasites, mucus threads, and other structures. Compared with urine dry chemistry or automated urinary sediment analysis, microscopy places greater emphasis on morphological recognition, background assessment, and confirmation of abnormal structures. It is suitable for comprehensive analysis of renal injury, urinary tract inflammation, crystalluria, infectious factors, and sample contamination.

Keywords: urinary sediment; microscopy; red blood cells; white blood cells; epithelial cells; casts; urinary crystals; bacteria; fungi; parasites; mucus threads; phase-contrast microscopy; formed elements in urine

1 Basic Positioning of Urinary Sediment Microscopy

1.1 Examination Targets

(1) Formed elements

Urinary sediment microscopy mainly examines formed elements concentrated after urine centrifugation, including cellular components, casts, crystals, microorganisms, parasites, mucus threads, lipid droplets, and contaminating particles. Different components differ in origin, morphological stability, and pathological implication, so interpretation should not rely mechanically on quantity alone.

(2) Morphological value

The advantage of microscopy lies in direct observation of morphological features. Whether red blood cells are dysmorphic, whether white blood cells form clusters, the type of epithelial cells, cast matrix and inclusions, crystal morphology, and the background accompanying microorganisms can all provide important information for result interpretation.

(3) Relationship with automated detection

Automated urinary sediment analysis is suitable for high-throughput screening, but it may still be limited in identifying abnormal cells, special casts, rare crystals, fungi, parasites, and contaminants. Microscopy remains irreplaceable for reviewing abnormal results, confirming morphology, and interpreting complex samples.

1.2 Sample Basis

(1) Sample collection

Fresh midstream urine is usually used for urinary sediment examination. The collection container should be clean to avoid contamination from vaginal secretions, semen, feces, disinfectants, paper fibers, or exogenous particles. For female samples, long-term indwelling catheter samples, and pediatric samples, the influence of the sampling process on results should be given particular attention.

(2) Testing time window

Prolonged storage of urine may lead to cell rupture, cast dissolution, bacterial proliferation, pH changes, and crystal precipitation. Ideally, samples should be tested as soon as possible. If immediate testing is not possible, samples should be stored at low temperature and storage conditions should be recorded, although low temperature may also promote formation of certain crystals.

(3) Sample mixing

The original urine sample should be thoroughly mixed before testing to avoid sampling bias caused by sedimentation of formed elements. Insufficient mixing before or after centrifugation directly affects counting results, especially for cells, casts, and crystals.

2 Urinary Sediment Preparation and Microscopic Observation Methods

2.1 Centrifugation and Sediment Resuspension

(1) Centrifugation conditions

Urinary sediment examination usually uses low-speed centrifugation to enrich formed elements. If centrifugal force is too low, recovery of elements may be insufficient; if centrifugal force is too high, cells may rupture or cast structures may be damaged. Laboratories should standardize centrifugation volume, centrifugal force, centrifugation time, and supernatant removal method.

(2) Sediment resuspension

After removing the supernatant, a fixed volume of urine should be retained to resuspend the sediment. Resuspension volume affects microscopic counting results. If different samples are resuspended in inconsistent volumes, results are not comparable.

(3) Slide preparation

The mixed sediment is dropped onto a glass slide and covered with a coverslip for observation. Slide thickness, air bubbles, uneven sediment distribution, and coverslip compression can all affect morphological interpretation. For quantitative observation, multiple fields should be assessed to avoid selecting only abnormal areas or blank areas.

2.2 Microscopic Observation Modes

(1) Low-power observation

Low-power microscopy is mainly used for overall scanning to observe casts, larger epithelial cells, crystals, mucus threads, parasite eggs, or other larger structures. Casts usually need to be screened under low power first and then confirmed under high power.

(2) High-power observation

High-power microscopy is used to identify details of red blood cells, white blood cells, bacteria, fungi, intracellular granules, and small crystals. Red blood cell morphology, leukocyte nuclear structure, budding yeast-like fungi, and bacteria-like motility often require high-power observation.

(3) Phase-contrast microscopy

Phase-contrast microscopy enhances the contrast of transparent structures and is valuable for identifying dysmorphic red blood cells, hyaline casts, cell borders, and low-refractive structures. In the analysis of glomerular hematuria, phase-contrast microscopy is especially useful for observing red blood cell morphological heterogeneity.

(4) Polarized light observation

Polarized light can be used to identify some birefringent crystals and lipid particles. Urates, calcium oxalate, lipid droplets, and some drug crystals may show specific optical features under polarized light, helping distinguish them from amorphous precipitates or contaminants.

Table 1 Common Observation Methods in Urinary Sediment Microscopy

Observation method	Main use	Advantage	Notes
Bright-field microscopy	Routine observation of cells, casts, crystals, and microorganisms	Widely used and suitable for routine examination	Hyaline casts and low-refractive structures are easily missed
Phase-contrast microscopy	Identification of dysmorphic red blood cells, hyaline casts, and cell borders	Higher contrast for transparent structures	Requires proper adjustment of optical path and focal plane
Polarized light microscopy	Observation of birefringent crystals and lipid particles	Helps identify crystals and lipids	Not all crystals show obvious birefringence
Observation after staining	Confirmation of cell nuclei, bacteria, fungi, and abnormal cells	Clearer morphological details	Staining may alter the original morphology of some structures
Automated image review	Confirmation after high-throughput screening	Improves efficiency and enables archiving	Abnormal structures still require manual morphological judgment

3 Morphological Identification of Major Formed Elements

3.1 Red Blood Cells

(1) Normally shaped red blood cells

Red blood cells in urine often appear as round or biconcave disc-like structures with relatively clear edges. In isotonic or mildly hypertonic urine, red blood cell morphology is relatively preserved. In hypotonic urine, red blood cells may swell, rupture, or appear as ghost cells.

(2) Dysmorphic red blood cells

Dysmorphic red blood cells may show variation in size, membrane protrusions, ring shapes, budding forms, echinocyte-like forms, or irregular morphology. If urinary red blood cells are highly heterogeneous in morphology and accompanied by red blood cell casts or proteinuria, a glomerular origin of hematuria is more likely.

(3) Interpretation points

Increased red blood cells should be interpreted together with urinary protein, casts, white blood cells, crystals, and clinical or experimental background. Vigorous exercise, sampling contamination, urinary tract inflammation, stones, glomerular injury, and trauma can all increase urinary red blood cells; counting alone cannot determine the source.

3.2 White Blood Cells

(1) Morphological features

White blood cells in urine are mostly neutrophils. They are larger than red blood cells, and cytoplasmic granules and segmented nuclei can be observed at an appropriate focal plane. In hypotonic urine, white blood cells may swell and cytoplasmic granules may show Brownian-like movement, forming so-called glitter cell-like appearances.

(2) White blood cell clusters

White blood cell clustering often suggests a stronger inflammatory response, but may also be related to sample contamination or admixture of secretions. If bacteria, pus cells, and abundant epithelial cells are also present, infection, contamination, or lower urinary tract inflammation should be assessed comprehensively.

(3) Interpretation points

Increased white blood cells do not necessarily indicate bacterial infection. Sterile inflammation, stone irritation, drug-induced injury, tubulointerstitial lesions, and sample contamination may all increase white blood cells. If infection is the research or diagnostic focus, bacterial observation, urine culture, or molecular testing should be combined.

3.3 Epithelial Cells

(1) Squamous epithelial cells

Squamous epithelial cells are large, flat, and rich in cytoplasm, with small nuclei. A large number of squamous epithelial cells often indicates contamination from the external urethral orifice, vulva, or genital tract, especially in female urine samples.

(2) Transitional epithelial cells

Transitional epithelial cells originate from the renal pelvis, ureter, bladder, and proximal urethra. They may be round, pear-shaped, or tailed, and are medium-sized. A small number can be found in normal urine, whereas a large number should be analyzed together with inflammation, catheterization, stone irritation, or bladder-related lesions.

(3) Renal tubular epithelial cells

Renal tubular epithelial cells are usually smaller, with relatively large nuclei and granular or degenerative cytoplasm. If many renal tubular epithelial cells are found together with granular casts, epithelial cell casts, or changes in kidney injury markers, a renal tubular injury background should be considered.

Table 2 Morphological Interpretation of Cellular Components in Urinary Sediment

Component	Main morphological features	Common source	Interpretation focus
Normally shaped red blood cells	Round, clear edges, relatively uniform size	Urinary tract bleeding, sampling contamination, etc.	Increased count should be interpreted with proteinuria, casts, and crystals
Dysmorphic red blood cells	Variable size, irregular membrane morphology, budding or ring forms	Possible glomerular hematuria	Phase-contrast microscopy is more helpful for identification
White blood cells	Larger than red blood cells, with granules and segmented nuclei	Urinary tract inflammation, contamination, interstitial lesions	Should not be equated with bacterial infection alone
Squamous epithelial cells	Large, flat, small nuclei	External urethral orifice or genital tract contamination	Large numbers suggest sample quality needs evaluation
Transitional epithelial cells	Round, pear-shaped, or tailed, medium-sized	Bladder, ureter, renal pelvis	Large numbers require consideration of irritation, inflammation, or procedural factors
Renal tubular epithelial cells	Smaller, relatively large nuclei, granular cytoplasm	Renal tubules	Increased numbers may suggest renal tubular injury

4 Formation and Classification of Casts

4.1 Basis of Cast Formation

(1) Formation site

Casts mainly form in the distal renal tubules and collecting ducts, and their matrix is mostly related to Tamm-Horsfall protein. Urine concentration, low flow rate, acidic environment, and increased protein facilitate cast formation.

(2) Morphological features

Casts are usually cylindrical, with blunt or broken ends. Their width roughly reflects the lumen size of the site where they formed. Hyaline casts have low refractivity and are easily missed, whereas granular casts, cellular casts, and waxy casts are easier to observe.

(3) Interpretation significance

Casts have strong renal-origin implication because they form in the renal tubular system. When cellular casts, granular casts, or waxy casts are found in urinary sediment, interpretation should prioritize renal parenchymal or tubular injury.

4.2 Common Cast Types

(1) Hyaline casts

Hyaline casts are mainly composed of protein matrix and have weak refractivity. A small number of hyaline casts may be seen in concentrated urine, after exercise, or under mild physiological changes. Increased numbers require interpretation with proteinuria, urine specific gravity, and renal function indicators.

(2) Granular casts

Granular casts contain cell debris, protein granules, or degenerative material, and can be divided into fine granular and coarse granular casts. Increased granular casts often suggest renal tubular epithelial degeneration and shedding or renal parenchymal injury.

(3) Red blood cell casts

Red blood cell casts form when red blood cells are embedded in cast matrix, indicating glomerular or intratubular bleeding. If they occur together with dysmorphic red blood cells and proteinuria, glomerular hematuria is more likely.

(4) White blood cell casts

White blood cell casts indicate that white blood cells entered the renal tubular lumen and became embedded in cast matrix. They are often associated with pyelonephritis, tubulointerstitial inflammation, or other renal parenchymal inflammation. They should be distinguished from white blood cell clusters and white blood cells attached to mucus threads.

(5) Epithelial cell casts

Epithelial cell casts contain renal tubular epithelial cells and are often associated with renal tubular injury, toxic injury, ischemic injury, or acute kidney injury models. Their significance is stronger when free renal tubular epithelial cells are also present.

(6) Waxy casts and fatty casts

Waxy casts have clear edges, strong refractivity, and dense structure, often suggesting slow urine flow and a more severe renal parenchymal disease background. Fatty casts may contain lipid droplets or birefringent lipid structures and are often associated with lipiduria and proteinuria.

Table 3 Common Casts in Urinary Sediment and Interpretation Points

Cast type	Main morphology	Common associated background	Interpretation focus
Hyaline cast	Transparent, weakly refractive, cylindrical	Concentrated urine, after exercise, mild proteinuria	Small numbers may occur; interpret with quantity and background
Granular cast	Contains coarse or fine granules	Tubular injury, cell degeneration	Increased coarse granules suggest stronger injury background
Red blood cell cast	Contains red blood cells	Glomerular hematuria, renal parenchymal bleeding	Important morphological evidence of renal hematuria
White blood cell cast	Contains white blood cells	Pyelonephritis, interstitial nephritis	Should be distinguished from white blood cell clusters
Epithelial cell cast	Contains renal tubular epithelial cells	Tubular injury, toxic or ischemic injury	Interpret together with free renal tubular epithelial cells
Waxy cast	Broad, clear edges, strong refractivity	Chronic renal parenchymal disease, slow urine flow	Suggests more severe or persistent renal disease background
Fatty cast	Contains lipid droplets and may show birefringence	Lipiduria, severe proteinuria-related states	Polarized light helps confirmation

5 Morphology and Condition Dependence of Urinary Crystals

5.1 Factors Affecting Crystal Formation

(1) Urine pH

Urine pH is an important factor affecting crystal formation. Uric acid, calcium oxalate, and cystine crystals are common in acidic urine, whereas phosphates, carbonates, and magnesium ammonium phosphate crystals are more likely to appear in alkaline urine.

(2) Solute concentration

Concentrated urine, reduced water intake, increased metabolite excretion, or prolonged sample storage can promote crystal precipitation. The presence of crystals does not necessarily mean that stones have formed in vivo; urine freshness, pH, and clinical or experimental background should be considered.

(3) Temperature and storage

Low-temperature storage can promote precipitation of some salt crystals. If sample testing is delayed, crystal number and morphology may differ from those in fresh urine. Therefore, sample storage conditions should be recorded during crystal interpretation.

5.2 Common Crystal Types

(1) Calcium oxalate crystals

Calcium oxalate crystals may appear as envelope-shaped, dumbbell-shaped, or oval structures and are more common in acidic or neutral urine. Large numbers may be related to oxalate metabolism, diet, concentrated urine, or stone risk.

(2) Uric acid crystals

Uric acid crystals often appear as rhomboid, barrel-shaped, rosette-like, or irregular forms and are mostly found in acidic urine. Their color may be yellow-brown, and they should be distinguished from drug crystals or other pigment particles.

(3) Magnesium ammonium phosphate crystals

Magnesium ammonium phosphate crystals often show a coffin-lid shape and are mostly found in alkaline urine. If they are accompanied by increased bacteria, alkaline urine, and elevated white blood cells, a urease-producing bacterial background should be considered.

(4) Cystine crystals

Cystine crystals appear as colorless hexagonal plates and have high identification value. Recurrent appearance should prompt further analysis for cystinuria or related metabolic abnormalities.

(5) Drug crystals

Certain drugs or their metabolites may form crystals in urine, with diverse morphologies. Interpretation of drug crystals requires medication history, urine pH, crystal morphology, and necessary chemical confirmation methods.

Table 4 Common Urinary Crystal Morphologies and Interpretation Points

Crystal type	Common morphology	Common urine condition	Interpretation focus
Calcium oxalate crystals	Envelope-shaped, dumbbell-shaped, oval	Acidic to neutral urine	Large numbers require attention to concentrated urine and stone risk
Uric acid crystals	Rhomboid, barrel-shaped, rosette-like	Acidic urine	Related to uric acid metabolism and sample cooling
Amorphous urates	Fine granular, may aggregate	Acidic urine, low-temperature storage	Easily confused with bacteria or fine particles
Magnesium ammonium phosphate crystals	Coffin-lid shape	Alkaline urine	Associated with urease-producing bacteria and alkaline urine
Amorphous phosphates	Fine granular	Alkaline urine	Can cause urine turbidity
Cystine crystals	Colorless hexagonal plates	Acidic urine	Strongly suggests metabolic abnormality
Bilirubin crystals	Needle-like or granular, yellow-brown	Acidic urine	Interpret with urinary bilirubin and hepatobiliary indicators
Drug crystals	Variable morphology	Related to medication, pH, and concentration	Requires medication history and confirmatory testing

6 Microorganisms, Parasites, and Mucus Threads

6.1 Bacteria

(1) Morphological appearance

Bacteria in urinary sediment are mostly small rods, cocci, or short chains, and individual bacteria are difficult to accurately classify under bright-field microscopy. Large numbers of bacteria may appear as tiny particle-like movement or dense distribution in the field.

(2) Distinguishing contamination from infection

Increased bacteria do not necessarily indicate urinary tract infection. Sampling contamination, prolonged sample storage, and container contamination can all increase bacteria. If increased white blood cells, positive nitrite, positive urine culture, or relevant symptoms are also present, infection becomes more strongly supported.

(3) Influence of sample timing

Prolonged urine storage can cause bacterial proliferation and falsely elevate microscopic results. Bacterial interpretation should pay particular attention to the interval from sampling to testing.

6.2 Fungi

(1) Yeast-like fungi

Fungi in urine often appear as yeast-like structures, round or oval in shape, and budding is common. They are usually larger than bacteria and can be confused with red blood cells, but budding and refractive features help identification.

(2) Hypha-like structures

Some samples may show pseudohyphae or hypha-like structures. If abundant white blood cells, diabetes, immunosuppression, catheterization, or similar background factors are present, fungal urinary tract infection or colonization becomes more likely.

(3) Contamination assessment

Fungi may also be introduced through vulvar, vaginal, or container contamination. Fungal detection should be interpreted with sampling method, repeated samples, and culture results.

6.3 Parasites

(1) Trichomonads

Trichomonas vaginalis-like motile structures may occasionally be seen in urinary sediment, appearing pear-shaped with flagellar movement or undulating membrane-like movement. Motility is more apparent in fresh samples and decreases after prolonged storage, increasing identification difficulty.

(2) Eggs or other parasitic structures

Parasite eggs are rarely found in urinary sediment. If present, they should be distinguished from contaminants, plant cells, starch granules, or crystals. In studies of certain regional parasitic diseases, urine microscopy may serve as an auxiliary observation method.

(3) Interpretation requirements

Parasite-related interpretation should not rely on a single field. Fresh sample observation, morphological features, motility, epidemiological background, and necessary parasitological confirmation methods should be combined.

6.4 Mucus Threads and Contaminating Structures

(1) Mucus threads

Mucus threads appear as slender, transparent, ribbon-like, or filamentous structures and may increase when urethral or genital secretions are mixed into urine. They have limited pathological specificity, but abundant mucus threads may suggest sample contamination or increased local secretions.

(2) Fibers and starch granules

Paper fibers, clothing fibers, talc, starch granules, and container particles can enter urine samples and create false abnormalities under microscopy. Polarized light and morphological observation help distinguish some contaminants.

(3) Sperm and lipid droplets

Sperm or lipid droplets may be observed in urine. Lipid droplets are strongly refractive round structures and may show characteristic birefringence under polarized light. Sperm are usually related to sample background and collection conditions and should not be misinterpreted as parasites.

Table 5 Interpretation of Microorganisms and Noncellular Structures in Urinary Sediment

Component	Morphological features	Easily confused with	Interpretation focus
Bacteria	Small rod-shaped or spherical particles	Amorphous crystals, debris	Interpret with white blood cells, nitrite, and culture results
Yeast-like fungi	Round or oval, may bud	Red blood cells, lipid droplets	Budding and pseudohyphae help identification
Trichomonads	Pear-shaped, may show motility	White blood cells, epithelial cell fragments	Motility in fresh samples is more valuable
Mucus threads	Transparent filamentous or ribbon-like structures	Hyaline casts, fiber contaminants	Usually have limited pathological specificity
Paper fibers	Long strips with irregular edges	Mucus threads, casts	Often related to sampling or container contamination
Lipid droplets	Round and strongly refractive	Red blood cells, yeast	Polarized light helps confirmation

7 Result Reporting and Standardized Expression

7.1 Quantitative Expression

(1) Count per high-power field

Red blood cells, white blood cells, epithelial cells, bacteria, and fungi are often reported as counts per high-power field. Multiple representative fields should be observed, and counting should not be performed only at the sediment edge or in locally aggregated areas.

(2) Count per low-power field

Casts, larger crystals, and larger structures are often reported as counts per low-power field. Casts may be few in number but have strong significance. When reporting casts, the type should be stated as much as possible, rather than simply reporting “cast positive.”

(3) Semi-quantitative grading

Some laboratories report results as negative, few, moderate, many, or “+, ++, +++.” Semi-quantitative grading is convenient for rapid expression, but standards may differ between laboratories. In research data, unified counting rules should be used whenever possible.

7.2 Morphological Description

(1) Red blood cell morphology

Hematuria analysis should describe whether red blood cells are dysmorphic, whether morphology is heterogeneous, and whether red blood cell casts are present. Simply stating “increased red blood cells” provides limited information about origin.

(2) Cast type

Reports should specify hyaline casts, granular casts, red blood cell casts, white blood cell casts, epithelial cell casts, waxy casts, or fatty casts. Different cast types have markedly different implications.

(3) Crystal type

Crystal reports should specify the type whenever possible and be interpreted with urine pH. If the type cannot be clearly determined, morphology, color, refractivity, and background should be described to avoid overdiagnosis.

7.3 Combined Interpretation with Other Urine Indicators

(1) Combination with urine dry chemistry

Urinary protein, occult blood, leukocyte esterase, nitrite, pH, specific gravity, and glucose provide background for urinary sediment findings. Microscopy can provide morphological interpretation of positive dry chemistry results.

(2) Combination with urine culture

When bacteria and white blood cells are increased, urine culture can further clarify evidence of infection. Microscopy cannot replace culture and antimicrobial susceptibility testing.

(3) Combination with renal function and pathology

When urinary sediment shows dysmorphic red blood cells, red blood cell casts, granular casts, or increased renal tubular epithelial cells, interpretation should be combined with serum creatinine, urinary protein, urinary albumin, kidney injury markers, and histopathological results.

8 Quality Control and Common Misinterpretations

8.1 Preanalytical Errors

(1) Sampling contamination

Large numbers of squamous epithelial cells, mucus threads, bacteria, or fungi may indicate sampling contamination. White blood cell and bacterial results in contaminated samples should be interpreted cautiously, and resampling may be necessary.

(2) Centrifugation differences

Inconsistent centrifugation conditions cause differences in recovery of cells and casts. In research experiments, centrifugal force, time, urine volume, and sediment resuspension volume should be standardized.

(3) Storage influence

Prolonged storage can lead to cell rupture, decreased casts, bacterial proliferation, and increased crystals. Sample timing is a key quality-control variable in urinary sediment examination.

8.2 Microscopic Interpretation Errors

(1) Confusing red blood cells with yeast

Red blood cells and yeast-like fungi can both appear as round structures. Yeast budding, size variation, and refractive features help distinguish them. Staining or culture can be used when necessary.

(2) Confusing mucus threads with hyaline casts

Hyaline casts have relatively regular borders, relatively uniform width, and cylindrical morphology. Mucus threads are more irregular and may be curved, filamentous, or ribbon-like. Phase-contrast microscopy helps distinction.

(3) Confusing crystals with bacteria

Amorphous crystals may appear as fine granules and are easily mistaken for bacteria. Misinterpretation can be reduced by combining urine pH, particle movement, aggregation pattern, and high-power observation.

(4) Misinterpreting contaminants

Fibers, starch granules, oil droplets, and container debris may mimic casts, crystals, or microorganisms. Polarized light, morphological continuity, and repeated sample examination can help confirmation.

Table 6 Common Misinterpretations in Urinary Sediment Microscopy and Corrective Directions

Easily misinterpreted situation	Possible confusing object	Correction method
Yeast mistaken for red blood cells	Red blood cells, lipid droplets	Observe budding and size differences; stain or culture if necessary
Mucus threads mistaken for hyaline casts	Hyaline casts	Observe edge regularity, width consistency, and cylindrical structure
Amorphous crystals mistaken for bacteria	Bacteria	Interpret with urine pH, high-power morphology, and sample freshness
White blood cell clusters mistaken for white blood cell casts	White blood cell casts	Determine whether cast matrix and cylindrical borders are present
Fibers mistaken for casts	Mucus threads, hyaline casts	Observe refractivity, edges, and contamination background
Lipid droplets mistaken for red blood cells or yeast	Red blood cells, yeast	Use polarized light or observe refractive features
Epithelial cell fragments mistaken for abnormal cells	Atypical cells	Combine nuclear morphology, repeated samples, and cytology if necessary

9 Selection of Staining Solutions for Urinary Sediment Microscopy

Table 7 Staining Solutions and Auxiliary Staining Reagents Related to Urinary Sediment Microscopy

Cat. No.	Product Name	Grade/Specification	Corresponding observation target	Application positioning
U1511467	Urine Sediment Stain (Sternheimer Method)	BioReagent,Biological Stain,for microscopy	Urinary sediment cells, casts, low-refractive structures	Core staining solution for urinary sediment microscopy; enhances contrast of red blood cells, white blood cells, epithelial cells, casts, mucus threads, and related structures
N1511064	Neutral Red-Methyl Blue Stain Solution	BioReagent,Biological Stain,for microscopy	Cell nuclei, cytoplasm, urinary sediment cell structures	Used for auxiliary observation of urinary sediment cell morphology, helping distinguish white blood cells, epithelial cells, and cell fragments
N1511106	New Methylene Blue Stain Solution	BioReagent,for microscopy,Biological Stain	Cell nuclei, cytoplasm, live cell structures	Used for auxiliary staining of urinary sediment cellular components; suitable for enhancing identification of white blood cells, epithelial cells, and some degenerative structures
L774207	Loeffler's Methylene Blue Staining Solution	BioReagent, Biological Stain, for microscopy, 0.6%	Bacteria, cell nuclei, cell fragments	Used for auxiliary observation of bacteria and cellular structures in urinary sediment
L1509206	Löffler's Methylene Blue Staining Solution (0.1%)	BioReagent,for microscopy,Biological Stain	Bacteria, cellular structures	Suitable for auxiliary staining of bacteria or cell nuclei under low-concentration background
L1509207	Lv's alkaline methylene blue staining solution (0.23%)	BioReagent,for microscopy,Biological Stain,0.23%	Bacteria, cellular structures	Used for review of microorganisms and cellular structures in urinary sediment
L1509208	Löffler's Methylene Blue Staining Solution (0.4%)	BioReagent,Biological Stain,for microscopy,0.4%	Bacteria, cellular structures	Used to enhance contrast of bacteria and cellular morphology
U1511114	Unna Alkaline Methylene Blue Staining Solution	BioReagent,Biological Stain,for microscopy	Cell nuclei, bacteria, mucus-related structures	Used for auxiliary observation of urinary sediment cells and microbial structures
M774783	Methylene Blue-Acid Fuchsin Staining Solution	BioReagent, Biological Stain, for microscopy	Cells, bacteria, sediment background structures	Used for composite staining of urinary sediment smears to improve contrast between cells and background
T1511054	Toluidine Blue O Stain Solution (0.5%, Borate Method)	BioReagent,Biological Stain,for microscopy,0.5% in deionized water	Cell nuclei, mucus-like components, cell fragments	Used for auxiliary identification of urinary sediment cell nuclei and mucus thread-related structures
M1511200	Toluidine Blue O Stain Solution (0.5%, Phosphate Method)	BioReagent,Biological Stain,for microscopy,0.5% in deionized water	Cell nuclei, mucus-like components	Used to enhance background observation of cellular and mucus components
T1511053	Toluidine blue staining solution (1%, borate method)	BioReagent,Bioactive,for microscopy	Cell nuclei, epithelial cells, mucus threads	Suitable for auxiliary staining of urinary sediment cellular components and mucus-like structures
T1511052	Toluidine Blue O Stain Solution (1%, Phosphate Method)	BioReagent,for microscopy,Biological Stain	Cell nuclei, cytoplasm, mucus-like structures	Used to enhance urinary sediment cell borders and nuclear structures
T1511051	Toluidine Blue O Stain Solution (For Cells)	BioReagent,Biological Stain,for microscopy	Urinary sediment cells, epithelial cells, white blood cells	Suitable for urinary sediment cell morphology review and auxiliary observation of abnormal cells
S774843	Standard Gram Staining Kit	BioReagent, Biological Stain, for microscopy	Bacteria	Used for Gram staining review of bacteria-positive urinary sediment samples, helping distinguish Gram-positive and Gram-negative bacteria
E774844	Enhanced Gram Staining Kit	BioReagent, Biological Stain, for microscopy	Bacteria	Used for morphological confirmation of urinary bacteria; suitable for samples with weak bacterial background or requiring improved staining contrast
A1506559	Crystal Violet Ammonium Oxalate Solution (0.1%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,0.1%	Bacterial primary stain	Can serve as a primary staining component in Gram staining for urinary sediment bacteria
A1506560	Crystal Violet Ammonium Oxalate Solution (0.4%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,0.4%	Bacterial primary stain	Used for auxiliary identification of bacterial morphology and Gram staining-related workflows
A1506561	Crystal Violet Ammonium Oxalate Solution (1%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,1%	Bacterial primary stain	Used for urinary sediment bacterial staining review
C774835	Crystal Violet and Citric Acid Staining Solution	BioReagent, Biological Stain, for microscopy, 0.1%	Bacteria, cellular structures	Used for auxiliary staining of bacteria or cellular sediment
C1506003	Crystal Violet Staining Solution Kit	BioReagent,for cell culture,for microscopy	Bacteria, cellular sediment	Used for auxiliary staining of cell or microbial adherent structures
S774779	Safranin O Solution	BioReagent, Biological Stain, for microscopy	Bacterial counterstain	Used as a Gram stain counterstaining component for urinary bacterial review
F1508179	Red dyeing solution	BioReagent,Biological Stain,Suitable for microbiology,for microscopy	Bacterial counterstain	Used for counterstaining in Gram staining, acid-fast staining, or microbial staining
S1508170	Safranin O Staining Solution (0.1%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,0.1%	Bacterial counterstain, cellular background	Used for urinary sediment bacterial counterstaining or background contrast enhancement
S1508173	Safranin O Staining Solution (0.5%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,0.5%	Bacterial counterstain, cellular background	Used for counterstaining bacteria and cellular sediment
S1508175	Safranin O Staining Solution (1%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,1%	Bacterial counterstain, cellular background	Used for urinary sediment bacterial review and cellular background staining
S1520401	Safranin O Staining Solution (5%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,5%	Bacterial counterstain, contrast staining	Suitable for microbial staining workflows requiring stronger counterstaining background
A1510404	Antacid Stain Solution (Kinyoun Cold Staining Method)	BioReagent,Biological Stain,for microscopy,Suitable for microbiology	Acid-fast bacilli	Used for auxiliary staining confirmation when acid-fast bacilli are suspected in urine samples
A774580	Acid-Fast Staining Solution (Ziehl-Neelsen Method)	BioReagent, Biological Stain, for microscopy	Acid-fast bacilli	Used for microscopic review of urinary acid-fast bacilli
A1510398	Antacid Stain Solution (Modified Kinyoun Cold Staining Method)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy	Acid-fast bacilli, some oocyst-like structures	Used for auxiliary identification of acid-fast positive structures
A1510396	Antacid Stain Solution (Auramine O-Rhodamine Fluorescence Method)	BioReagent,Biological Stain,Suitable for microbiology,for microscopy	Acid-fast bacilli	Used for fluorescence microscopic screening of urinary acid-fast bacilli
A1510389	Antacid Staining Solution (Auramine O Fluorescence Method)	BioReagent,Biological Stain,for microscopy,Suitable for microbiology	Acid-fast bacilli	Used for acid-fast bacilli fluorescence screening and review
A1456454	Acid-Fast Fluorescent Staining Solution‌ (Aggregation-induced emission, AIE)	BioReagent, for microscopy, Biological Stain	Acid-fast bacilli	Used for rapid fluorescent identification of acid-fast structures
F1508791	Fungal Fluorescence Staining Solution (One Step)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy	Fungi, yeast-like structures, pseudohyphae	Used for fluorescent auxiliary identification of fungi or yeast-like structures in urinary sediment
A1456457	Fungal Fluorescent Staining Solution (AIE)	BioReagent	Fungi, yeast-like structures	Used for rapid fungal fluorescence identification, suitable for review of suspected fungal-positive urinary sediment samples
L774540	Lactophenol Cotton Blue Staining Solution	BioReagent, Biological Stain, for microscopy	Fungal hyphae and spores	Used for fungal morphology observation; can assist identification of fungal contamination or infection-related structures in urinary sediment
L1508768	Lactic Acid Taipan Blue Staining Solution (0.05%)	Bioactive,BioReagent,Suitable for microbiology,for microscopy,0.05%	Fungi, microbial structures	Used for auxiliary observation of fungal morphology
L1508766	Lactic Acid Magenta Staining Solution (0.01%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,0.01%	Fungi, microbial structures	Used for staining fungi and some microbial structures
C1508784	Cryptococcus Neoformans Staining Solution	BioReagent,Suitable for microbiology,Biological Stain,for microscopy	Encapsulated fungi, Cryptococcus-like structures	Used for auxiliary identification of encapsulated yeast-like structures in urine or related samples
C1508185	Capsule Staining Solution (India Ink Method)	BioReagent,Biological Stain,Suitable for microbiology,for microscopy	Encapsulated fungi, encapsulated bacteria	Used for negative staining of capsule structures; can help distinguish yeast-like fungi from cell fragments
G774822	Glycogen PAS Staining Kit (Special For Fungi)	BioReagent, Biological Stain, for microscopy	Fungal cell wall, polysaccharide structures	Used for fungal structure confirmation, suitable for further review of fungal-positive urinary sediment samples
P1508789	Protozoa Encystment Staining Solution (2% Iodine Solution)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,2% iodine solution	Protozoan cysts, parasite-like structures	Used for auxiliary identification of suspected parasitic or contaminating protozoan structures in urinary sediment
P1508790	Protozoa Encystment Staining Solution (4% Iodine Solution)	4% iodine solution	Protozoan cysts, parasite-like structures	Used to improve morphological contrast of protozoan cyst-like structures
S1506558	Standard Lugol's iodine solution (1%)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,1%	Protozoa, starch-like contaminants, some parasite structures	Used for auxiliary differentiation of parasite-like structures and starch granule contaminants in urinary sediment
L1508168	Lugol's Staining Solution (5%, Sterile)	BioReagent,Suitable for microbiology,Biological Stain,for microscopy,sterile,5%	Protozoa, parasite-like structures	Suitable for wet-mount auxiliary staining requiring sterile background
L1508783	Nematode Staining Solution (Iodine Method)	BioReagent,Biological Stain,Suitable for microbiology,for microscopy	Nematode-like structures, parasite-like structures	Used for auxiliary observation of suspected nematode or parasite contaminating structures in urinary sediment
N1510447	Nematode Staining Solution (Polychrome Blue Method)	BioReagent,Biological Stain,Suitable for microbiology,for microscopy	Nematode-like structures	Used for confirmation of nematode-related morphology; usually only supplementary in routine urinary sediment
M1508780	Microfilariae Staining Solution (Hematoxylin Stain)	BioReagent,Biological Stain,Suitable for microbiology,for microscopy	Microfilaria-like structures	Used for morphological review of suspected parasitic structures
M1508781	Microfilariae Staining Solution (Borax Blue)	BioReagent,Biological Stain,Suitable for microbiology,for microscopy	Microfilaria-like structures	Used for staining confirmation of parasite-related structures
S1510322	Cryptosporidium Oocyst Staining Solution (Modified Acid-Fast Method)	BioReagent,for microscopy,Biological Stain	Oocyst-like structures	Used for auxiliary identification of suspected acid-fast oocyst-like structures; a special review application
U774811	Monosodium Urate Staining Solution (Gomori Method)	BioReagent, Biological Stain, for microscopy	Urate crystals	Used for auxiliary staining identification of urate-related crystals in urinary sediment
C774862	Calcium salt staining solution (Von, Kossa, silver nitrate)	BioReagent, Biological Stain, for microscopy	Calcium salt deposits, calcium salt crystals	Used for auxiliary identification of calcium salt-related deposits or crystal-like structures
C774863	Calcium Staining Solution (Modified Alizarin Red S Method)	BioReagent,for microscopy,Biological Stain	Calcium salt deposits, calcium salt crystals	Used for auxiliary assessment of calcium salt-related structures such as calcium oxalate and calcium phosphate
P1508560	Calcium Staining Solution (Alizarin Red S Method)	BioReagent,Biological Stain,for microscopy	Calcium salt deposits, calcium salt crystals	Suitable for staining confirmation of calcium salt structures as an auxiliary method for crystal identification
A774867	Alizarin Red S Staining Solution (0.1%, pH4.2)	BioReagent,Biological Stain,for microscopy,0.1%	Calcium salt structures	Used for auxiliary identification of calcium salt-related crystals or deposits
A774528	Alizarin Red S Staining Solution (0.2%, pH4.2)	BioReagent,Biological Stain,for microscopy,0.2%	Calcium salt structures	Used to enhance staining of calcium salt-related structures
A774530	Alizarin Red S Staining Solution (1%, pH4.2)	BioReagent,Biological Stain,for microscopy,1%	Calcium salt structures	Used for auxiliary determination of calcium salt properties in crystals or deposits
B774558	Bile Pigment Staining Solution (Modified Fouchet Method)	BioReagent, Biological Stain, for microscopy	Bile pigments, bilirubin-related crystal-like structures	Used for auxiliary confirmation of yellow-brown bile pigment or bilirubin-like structures in urinary sediment
S774204	Sudan III Staining Solution	BioReagent, Biological Stain, for microscopy, 0.1%	Lipid droplets, fatty casts	Used for auxiliary confirmation of lipid droplets and fatty casts in urinary sediment
S774205	Sudan IV Staining Solution	BioReagent, for microscopy, Biological Stain, 0.1%	Lipid droplets, lipid particles	Used for auxiliary staining of lipiduria-related structures
S774836	Sudan Ⅲ Staining Kit	BioReagent, Biological Stain, for microscopy	Lipid droplets, fatty casts	Suitable for review of lipid components in urinary sediment
S1508362	Sudan Black B Staining Solution	BioReagent,for microscopy,Biological Stain	Lipid particles, fatty components	Used for auxiliary identification of lipid-like sediment structures
S1508441	Sudan Black B Staining Solution	BioReagent,for microscopy,Biological Stain	Lipid particles, fatty components	Used for staining and observing lipid droplets and lipid particles
N774550	Nile Blue Staining Solution (Cain's Method)	BioReagent, Biological Stain, for microscopy	Lipids, lipid droplets	Used for auxiliary identification of lipid-like structures in urinary sediment
A774824	AB-PAS staining kit	BioReagent, for microscopy, Biological Stain	Mucus, polysaccharides, glycoprotein-like structures	Used for auxiliary staining of mucus threads, mucin-like substances, and polysaccharide background
A1507852	Alcian Blue Staining Solution (pH2.5)	BioReagent,for microscopy,Biological Stain	Acidic mucopolysaccharides, mucus-like components	Used for auxiliary observation of mucus threads or acidic mucopolysaccharide-like structures in urinary sediment
A774858	Alcian Blue Staining Solution (pH 2.5)	BioReagent, Biological Stain, for microscopy	Acidic mucopolysaccharides, mucus-like components	Used to enhance mucus thread and mucin-like background
A774857	Alcian Blue Staining Solution (pH 1.0)	BioReagent, Biological Stain, for microscopy	Strongly acidic mucopolysaccharides	Can serve as auxiliary staining for typing mucus-like components
M1508531	Mucicarmine Staining Solution	BioReagent,for microscopy,Biological Stain	Mucus, mucin-like structures	Used for review of mucus threads and mucin-like structures in urinary sediment
M1508677	Mucin HID-AB Staining Solution	BioReagent,for microscopy,Biological Stain	Acidic mucus, sulfated mucopolysaccharides	Used for further differentiation of mucus-like components
M1507827	Mucin Staining Solution (Azure A Metachromatic Method)	BioReagent,Biological Stain,for microscopy,1×	Mucin, mucus-like structures	Used for auxiliary observation of urinary sediment mucus threads and mucin background
G774819	Glycogen PAS rapid staining solution		Polysaccharides, glycoproteins, fungal-related structures	Used for auxiliary confirmation of intracellular polysaccharides, fungal walls, or mucus-like structures
G774820	Glycogen PAS staining kit	BioReagent, Biological Stain, for microscopy	Polysaccharides, glycoproteins, fungal structures	Can serve as an auxiliary staining method for fungi or mucus-like structures in urinary sediment
G774821	Glycogen D-PAS Staining Solution (Amylase Digestion)	BioReagent, for microscopy, Biological Stain	Glycogen, polysaccharide structures	Used for polysaccharide background differentiation, helping distinguish intracellular glycogen from other PAS-positive structures
D774859	Diff-Quik Staining Solution	BioReagent, for microscopy, Biological Stain	White blood cells, epithelial cells, microbial background	Used for rapid staining of urinary sediment smears, assisting observation of cellular morphology and inflammatory background
D1511557	Diff-Quik Stain (Fixative-Free)	BioReagent,Bioactive,for microscopy	White blood cells, epithelial cells, cell fragments	Suitable for rapid review of urinary sediment smears, avoiding the influence of fixative on some structures
W1508772	Wright Stain Solution (ready-to-use)	ready-to-use,Biological Stain,Suitable for microbiology,for microscopy,BioReagent	White blood cells, cellular morphology, microbial background	Used for cellular morphology review of urinary sediment smears
W743386	Wright Staining Kit	BioReagent, Biological Stain, for microscopy	White blood cells, epithelial cells, cell fragments	Used for sediment cell smear staining, helping identify inflammatory cells and abnormal cells
M743374	Wright-Giemsa Staining Kit	BioReagent, Biological Stain, for microscopy	White blood cells, cell nuclei, microbial background	Used for urinary sediment smear cytology review and inflammatory cell observation
G743377	Giemsa Staining Solution	BioReagent, Biological Stain, for microscopy, 10X	White blood cells, parasite-like structures, cell nuclei	Used for auxiliary observation of urinary sediment cellular morphology and parasite-like structures
G1508184	Giemsa Staining Solution (Ready-to-use)	BioReagent,ready-to-use,Biological Stain,Suitable for microbiology,for microscopy	White blood cells, parasite-like structures, cell nuclei	Suitable for rapid cytology and microbial background review of sediment smears
M1510448	May-Grunwald Stain Solution	BioReagent,Biological Stain,for microscopy,Suitable for microbiology	White blood cells, cytology smears	Can be combined with Giemsa-type staining for sediment cellular morphology review
P1511562	Papanicolaou Stain Solution (Papanicolaou EA36)	BioReagent,Biological Stain,for microscopy	Urinary exfoliated cells, abnormal epithelial cells	Used for urinary sediment or urine cytology review, suitable for judging epithelial cell morphological abnormalities
P1511529	Papanicolaou Stain Solution (Papanicolaou EA50)	BioReagent,Biological Stain,for microscopy	Urinary exfoliated cells, abnormal epithelial cells	Used for auxiliary staining in urine cytology
P1511527	Papanicolaou staining solution (EA65)	BioReagent,Biological Stain,for microscopy	Urinary exfoliated cells, abnormal epithelial cells	Used for observation of epithelial cell nuclear-cytoplasmic structure and urine cytology review
E1520384	EA36 Staining Solution	BioReagent,Biological Stain,for microscopy	Urinary exfoliated cells, epithelial cells	Can serve as a Papanicolaou staining-related component for morphological observation in urine cytology
O1520397	Orange G6 Staining Solution	BioReagent,Biological Stain,for microscopy	Cytoplasm, keratinized or degenerative cell background	Can serve as a Papanicolaou staining-related component for auxiliary observation of urinary sediment exfoliated cells
H1508526	Hematoxylin-Eosin (HE) High-Definition Consistent Staining Kit (High-Definition Stable Staining)	BioReagent,for microscopy,Biological Stain	Cell nuclei, cytoplasm, exfoliated cells	Can be used for cellular structure review of urinary sediment smears, but is more oriented toward fixed smear observation
H1508460	Hematoxylin-Eosin (HE) Staining Kit (with Differentiating Solution)	BioReagent,for microscopy,Biological Stain	Cell nuclei, cytoplasm, exfoliated cells	Used for observing nuclear-cytoplasmic structures in urinary sediment smears
H1508459	Hematoxylin-Eosin (HE) Staining Kit (with Differentiating Solution and Bluing Solution)	BioReagent,for microscopy,Biological Stain	Cell nuclei, cytoplasm, exfoliated cells	Used for cellular morphology review in fixed sediment smears
E489517	Ematoxylin-Eosin Stain		Cell nuclei, cytoplasm	Used for routine staining of urinary sediment cytology smears
E774785	Eosin Staining Solution ( 1% aqueous solution)	BioReagent, Biological Stain, for microscopy, Water Soluble，1%	Cytoplasm, background counterstain	Used for staining cytoplasm and background structures
E774784	Eosin Staining Solution (0.25% alcoholic solution)	BioReagent, Biological Stain, for microscopy, Alcohol Soluble，0.25%	Cytoplasm, background counterstain	Used for cytoplasmic staining of fixed smears
E1507828	Eosin Staining Solution (Alcohol-Soluble, 0.5%)	BioReagent,Biological Stain,for microscopy,0.5%	Cytoplasm, background counterstain	Used for observing cellular morphology in sediment smears
E774788	Eosin Staining Solution (1% alcoholic solution )	Alcohol Soluble，1%	Cytoplasm, background counterstain	Used for urine cell smears requiring stronger counterstaining
A1456513	Acridine Orange Staining Kit	BioReagent, Biological Stain, for microscopy	Cell nuclei, bacteria, fungi, nucleic acid-positive structures	Used for rapid screening of urinary sediment microorganisms and nuclear structures under fluorescence microscopy
D1372407	DAPI Staining Solution	BioReagent, for microscopy, sterile-filtered, Suitable for Immunofluorescence(IF), 1.0 mg/mL	Cell nuclei, nucleic acid-positive structures	Used for auxiliary observation of cell nuclei and microbial nucleic acid structures under fluorescence conditions
D598342	DAPI staining solution (ready to use)		Cell nuclei, nucleic acid-positive structures	Suitable for nucleic acid staining in fluorescence observation of urinary sediment
P1373641	Propidium iodide (PI) Staining Solution (Ready-to-use)	BioReagent, for microscopy, ready-to-use, sterile-filtered, Suitable for Immunofluorescence(IF)	Dead cells, nucleic acid-positive structures	Used for auxiliary observation related to cellular viability or membrane integrity in urinary sediment
A1456455	‌Double Fluorescent Microbial Staining Solution‌ (Dry-film Method, AIE)	BioReagent	Bacteria, fungi, and other microorganisms	Used for rapid fluorescence screening of urinary sediment microorganisms, suitable for dry slide observation
A1491755	Microbial Dual-Fluorescence Staining Solution (Wet Mount Method, Aggregation-induced emission, AIE)	BioReagent	Bacteria, fungi, and other microorganisms	Used for rapid fluorescence identification of microorganisms in urinary sediment wet mounts
A1456427	Gram Fluorescent Staining Probe‌ (AIE)	BioReagent, 10mM	Bacteria	Used for bacterial fluorescence typing or rapid screening in urine as an auxiliary observation tool

The core value of urinary sediment microscopy lies in morphological identification and contextual interpretation of formed elements in urine. Standardized sample collection, unified centrifugation and resuspension procedures, suitable microscopic observation methods, and stable reporting standards are the basis for improving result reliability. Abnormal findings involving red blood cells, white blood cells, casts, crystals, and microorganisms should be interpreted together with urine dry chemistry, urine culture, renal function indicators, and experimental background, rather than equating a single microscopic finding directly with a specific disease or mechanistic conclusion.

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[1] Urine automatic analyzer operation experiment

[2] Urine Screening Tests