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Urine Sediment Examination - A Non-Invasive Diagnostic Intervention.


Urine sediment examination is a useful, non-invasive tool for detection of urinary tract pathology and certain metabolic disorders. Microscopic evaluation of urinary sediment dates back to 19th century, when Sanders and Dickenson described presence of abnormal cellular findings in urinary sediment of men who were subsequently diagnosed with bladder cancer. The modern urine cytology was introduced by Papanicolaou and Marshall in 1947 and it has kept its place to this day in diagnosis of primary and recurrent tumors of urinary tract (Comploj et al., 2015). Apart from diagnosis of bladder cancers, it has various indications that generally fall in to two principal groups: in the evaluation of patients with genitourinary signs and as surveillance tool for patients with history of urinary tract pathology. Inspite of its usefulness, urine sediment examination is perhaps the most under used tool in Veterinary practice. This paper puts on record various conditions that are diagnosed by urine sediment examination.

Materials and Methods

The study was conducted on clinical cases presented for a period of three years. A total of 150 urine samples of different species viz. canine, bovine and ovine suspected for urinary tract pathology were subjected to microscopic examination. All urine samples were collected either by catheterization or cystocentesis. Urine samples were centrifuged and sediment was examined under microscope at low power (100x) and high power (400x) to detect any abnormal constituents. Whenever necessary, sediments were stained with Leishman's stain and examined under microscope.


Out of 150 urine samples subjected to microscopic evaluation, abnormal constituents were found in 120 cases. The results of present study revealed different conditions in different animal species viz. cylindruria, crystalluria, urolithiasis, hematuria, hemoglobinuria, pyuria, bacteriuria and neoplasia (Table 1).

The types of crystals varied in different species which included struvite (Fig. 1), calcium carbonate (Fig. 2), calcium oxalate (Fig. 3), amorphous crystals, ammonium biurate, bilirubin (Fig. 4) and cystine. The pattern and shape of crystals is presented in Table 2. In canines, struvites were the most common crystals observed followed by amorphous crystals, bilirubin, ammonium biurate and cystine crystals. In bovines, calcium carbonate crystals occurred the most, followed by struvites, calcium oxalates, bilirubin and amorphous phosphates. In cattle, a single case of urolith formation characterized by concentric layers around the nidus was recorded (Fig. 5). In sheep and goat, the cases examined were only 4, out of which three cases showed calcium oxalates.

In cylindruria, the types of casts recorded were hyaline casts (Fig. 6), granular casts, epithelial casts (Fig. 7) and leukocyte casts (Fig. 8). Of all the casts, hyaline casts occurred more frequently in bovines and canines. No casts were recorded in sheep and goat.

The different types of cells in urine were leukocytes and few transitional epithelia in cystitis and pyuria, erythrocytes in hematuria and pleiomorphic, multi-nucleated transitional epithelia in transitional cell carcinoma (Fig. 9). Cystitis and pyuria were characterized by presence of more than 5 WBCs per high power field, hematuria with presence of large number of RBCs (usually more than 20 RBCs/high power field).

All conditions were observed either singly or in combination with other conditions. Crystalluria was always associated with either cystitis or hematuria and pyuria was mostly associated with presence of bacteria in urine.


The advantage of urine sediment examination is that it is an easy, non-invasive, atraumatic tool for diagnosis of various metabolic and urinary tract pathology (Comploj et al., 2015). It gives an important data and helps the clinician in prediction of certain conditions such as urolithiasis which are preceded by crystalluria.

The present study revealed that crystalluria is one of the important findings of urine examination. The types of crystals vary in different animal species and crystalluria is an indicator to evaluate the patient for uroliths. Crystals also form as a consequence of disease processes that alter urine composition (Gazi et al., 2016). Crystalluria is also caused by ingestion of certain foods, drugs, change in pH and temperature of urine (Parrah et al., 2013). In present study, struvites were found to be the most common crystals both in canines and bovines. Struvites are crystals of Magnesium ammonium phosphate that form in strongly alkaline urine. Their presence even in small amounts in markedly alkaline urine is indicative of urinary tract infection with urease producing microorganisms usually Proteus mirabilis, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, or less frequently Corynebacterium urealyticum, responsible for encrusted cystitis and/ or pyelitis (Daudon et al., 2016).

In the present study, Calcium carbonate and Calcium oxalate crystals were recorded only in ruminants. Diets high in calcium may result in Calcium carbonate uroliths, while plants such as halogeton or tops from the common sugar beet may be a factor in calcium oxalate formation. Another important type of crystals recorded in the study were amorphous crystals. They can be comprised of urates, phosphates or xanthine. Amorphous urates (Na, K, Mg, or Ca salts) tend to form in acidic urine and may have yellow or yellow-brown color. Amorphous phosphates are similar in general appearance, but tend to form in alkaline urine and lack color. Xanthine crystals are usually in the form of 'amorphous' crystals, however some can resemble ammonium biurate. These crystals occur in Dalmations on allopurinol therapy for urate urolithiasis. Generally, no specific clinical interpretation can be made based on the finding of amorphous crystals. Bilirubin crystals were recorded both in canines and bovines in our study. Bilirubin crystals form from conjugated bilirubin (water soluble) and are needle like to granular crystals that are yellow in color. Bilirubin crystals (or a positive chemical reaction on the urine dipstick) in canine and bovine urine is an abnormal finding and animal should be investigated for an underlying cholestatic process (Parrah et al., 2013). In our study, ammonium biurate and cystine crystals were recorded only in canines. Ammonium biurate crystals are fairly common in dogs and cats with congenital or acquired portal vascular anomalies, with or without concomitant ammonium urate uroliths. They can be seen in urine from normal Dalmatians and Bulldogs, both of which are predisposed to urate urolithiasis. Cystine crystals formation is favored in acidic urine. Cystine crystalluria or urolithiasis is an indication of cystinuria, which is an inborn error of metabolism (Parrah et al., 2013).

In present study, cylindruria revealed different types of casts such as hyaline, granular, leukocyte and epithelial. Cylindruria can be found in low numbers in healthy animals but pathologically associated with glomerular proteinuria, renal tubular cell degeneration, inflammation or hemorrhage. Leukocyte casts and epithelial casts occur in all types of nephritis and their presence indicate greater degree of kidney disease (Parrah et al., 2013).

A certain number of transitional and epithelial cells are normal in urine. Their presence in high numbers are indicative of cystitis, pyelonephritis or urinary tract infection. In present study, in two cases, transitional cell carcinomas were diagnosed by urine cytology which were further confirmed by histopathology. In our study, other conditions diagnosed were hematuria and hemoglobinuria. Centrifugation of urine itself helps us in differentiating the two conditions where in there is a clear supernatant in hematuria and no clear supernatant in hemoglobinuria (Stockham and Scott, 2008).

Hence, we conclude that urine sediment examination profile helps the clinician in diagnosis and to choose treatment modalities of certain metabolic and urinary tract disorders.


Comploj, E., Trenti, E., Palermo, S., Pycha, A. and Mian, C. (2015). Urinary cytology in bladder cancer: Why is it still relevant. Urologia. 82: 203-05.

Daudon, M., Frochot, V., Bazin, D. and Jungers, P. (2016). Crystalluria analysis improves significantly etiologic diagnosis and therapeutic monitoring of nephrolithiasis. Comptes Rendus Chimie. 19: 1514-26.

Gazi, M.A., Makhdoomi, D.M., Mir, S.A. and Sheikh, G.N. (2016). Urinalysis - A diagnostic factor for urolithiasis and prognostic factor for its recurrence in young ruminants. J. Vet. Sci. Technol. 7: 336.

Parrah, J.D., Moulvi B.A., Gazi, M.A., Makhdoomi, D.M., Athar, H., Din, M.U, Dar, S. and Mir, A.Q. (2013). Importance of Urinalysis in Veterinary practice - A Review. Vet. World. 6: 640-46.

Stockham, S.L. and Scott, M.A. (2008). Urinary system. In: Fundamentals of Veterinary Clinical Pathology. 2nd Edn., Blackwell Publishing, Iowa. p. 415-87.

Ch. Sudha Rani Chowdary (1), P.V. Sagar (2), M. Raghunath (3) and J. Chintaiah (4)

Department of Veterinary Clinical Complex NTR College of Veterinary Science Sri Venkateswara Veterinary University (SVVU) Gannavaram - 521102 (Andhra Pradesh)
Table 1: Conditions diagnosed with urine microscopic examination

       Condition (*)           Canine   Cattle and   Sheep and
                               (n=64)     Buffalo       Goat
                                          (n=52)       (n=4)

A.     Crystalluria
  i.   Struvite                   12         11          -
 ii.   Calcium oxalate             -          6          2
iii.   Calcium carbonate           -         21          1
 iv.   Amorphous                   9          2          -
  v.   Bilurubin                   4          5          -
 vi.   Ammonium biurate            2          -          -
vii.   Cystine                     1          -          -
B.     Cylindruria
  i.   Hyaline casts              10         18          -
 ii.   Granular casts              5          6
iii.   Leukocyte casts             4          5
 iv.   Epithelial casts            4          2
C.     Neoplasia                   2          -          -
       (transitional cell
D.     Others (urolithiasis,      42         49          2
       pyuria, bacteruria,
       hematuria and

(*) All conditions occurred either singly or in association with other

Table 2: Patterns and shapes of urinary crystals

Type of crystals                  Shape and pattern

Struvite            Colorless three dimensional prism like ('coffin
Calcium carbonate   Colorless to yellow brown spheroids with radial
Calcium oxalate     Dihydrate crystals, colorless squares with corners
                    connected by intersecting lines (resembling an
                    envelope), monohydrate crystals: spindle, oval and
                    dumbell shaped
Amorphous           aggregates of finely granular material
Bilirubin           Yellow needle like to granular
Ammonium biurate    brown or yellow-brown spherical bodies with
                    irregular protrusions ('thorn-apples')
Cystine             Flat colorless plates with hexagonal shape
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Title Annotation:Clinical Article
Author:Chowdary, Ch. Sudha Rani; Sagar, P.V.; Raghunath, M.; Chintaiah, J.
Publication:Intas Polivet
Date:Jul 1, 2018
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