CHAPTER 8 QUALITY CONTROL PROGRAMS FOR … · This chapter describes the Quality Control programs...

This chapter describes the Quality Control programs which can be used for urinary sediment. The purpose of these programs is to obtain an examination of the urinary sediment of good and reliable quality [1,2]. Internal Quality Control (IQC) and External Quality Assessment (EQA) Programs integrate each other.

Internal Quality Control

An Internal Quality Control (IQC) for urine microscopy should be done each day the test is performed and should adhere to the following recommendations [2]:

- All personnel should follow the same documented procedures using the same equipment, use the same terminology and report results in the same standard format

- Duplicate urine sample examination should be used as a precision check for the identification of the particles. Alternatively, control solutions containing erythrocytes or leukocytes, which are commercially available could be used

- In case of disagreement about the presence or quantity of a microscopic element the examination should be repeated and a shared conclusion should be reached

- Unexpected control results should be identified, and appropriate corrective action should be taken

- Recent reference texts, atlases, papers or online documents should always be available for consultation, and experts’ opinion should be asked for in case of difficult and/or doubtful findings

In order to fulfil these recommendations, in the laboratory of the Renal Unit of Ospedale Maggiore-Policlinico, Milano, where one of the authors of this chapter (F.G.B.) works:

-All the procedures and terminology used are standardized and written in detail in a document which is kept on a shelf over the workbench.

QUALITY CONTROL PROGRAMS FOR URINARY SEDIMENT

S. Secchiero and G.B. Fogazzi

C H A P T E R 8

S. Secchiero and G.B. Fogazzi2

- The microscope is adjusted according to Khöler principle (see Appendix) and phase contrast is centred every time the examination of the urinary samples is started. In addition, a regular servicing of the microscope is done once a year by a specialized technician.

- The exchange of opinions on difficult or doubtful findings is encouraged and regularly done among the four persons who rotate on urine sediment examination.

- Once or twice a week, some samples, chosen among the most pathologic ones, are reviewed for a check by the most expert microscopist of the group.

- All special and interesting findings are documented through a digital camera

permanently mounted on the microscope and filed though a dedicated program. in the computer.

- A specialized library containing several hundreds of scientific papers on various aspects of the urinary sediment examination and 16 atlases in different languages on the same subject is kept in shelves close to the microscope for consultation.

External quality control

Medical laboratories have a long tradition in the organisation of external EQA programs, which started in 1947, when Belk and Sunderman published the results of a clinical chemistry survey in the US [3].

Today, EQA programs are a key instrument for the improvement of laboratory quality, and for some disciplines they are an integral part of laboratories’ overall quality assurance systems [4]. However, in spite of numerous documents and papers which stress the importance of designing appropriate EQA schemes [4-10], several laboratory’s fields still lack EQA programs.

EQA surveys on urinalysis are rare [11-13]. Of the few existing programs, some deal with test strips and quantitative clinical chemistry analytes [12], while others also cover urinary sediment.

The latter topic is included in the program run by Labquality, a Finnish non-profit EQA scheme organisation which provides surveys also for Norway, Baltic states and Poland.

Urinary sediment is also included in the program run in Italy by the Centre of Biomedical Research (CRB), which is an EQA scheme organisation with many programs in different fields of Laboratory medicine (www.centroricercabiomedica.it).

Interestingly, the College of American Pathologists (CAP) has recently introduced an EQA program focused on the new aspects of urinary sediment examination which are associated with the use of automated analyzers (see Chapeter 7).

Features of the Italian EQA Program “Urinalysis Performance”

The Italian EQA program, called “Urinalysis Performance” was set up in 2001 by a promoting Committee which included the representatives of the three Italian societies of

Quality control programs for urinary sediment 3

Laboratory Medicine and of the Italian Society of Nephrology [14].This program is the first, and to date the only, Italian project for the standardisation of

urine analysis. It is addressed to Italian central laboratories, both public and private, and to renal laboratories.

The aims of the program are: the evaluation of the laboratories’ performances; the training support to the participants; the improvement of the efficiency and efficacy of urinary sediment examination.

“Urinalysis Performance” includes two parts: one on test strips (which is not dealt with in this chapter), the other on urinary sediment.

The part on urinary sediment is under the guidance and responsibility of one of us (F.G.B.), who prepares and selects the images and also evaluates the answers of the participants at each survey.

Today, the program consists in 4 surveys/year. - Surveys 1 and 3. Each of these surveys shows two urine sediment particles. Each particle

is shown by both bright field and phase contrast microscopy and, when indicated (e.g., crystals or lipids), also by polarized light (Figure 8.1). The choice of showing the particles by the three types of microscopy has a twofold motivation: (i) bright field microscopy was, and still is, the method most widely used in routine practice and (ii) phase contrast microscopy and polarized light are the method recommended by international guidelines for everyday work (1,2).

For each survey, the participants are asked to identify the particles shown. Moreover, for one of the two particles (selected by the responsible of the program), they are also asked to indicate one clinical association, chosen among 4 or 5 possible options.

Over the years, in order to verify whether the program was able to achieve an improvement in the identification capability of the participants some particles were presented twice by the means of similar but not identical images.

- Surveys 2 and 4. Each of these surveys present a clinical case. These cases were introduced because laboratory medicine is moving towards a clinical support service, and Guidelines and standards emphasise the importance of adding appropriate comments and interpretation of results to medical reports and their assessment (15-21).

Clinical cases consist in a brief clinical history, which also included some key laboratory data and four phase contrast microscopy images of particles found in the urine sediment of the case presented (Figure 8.2). Also for clinical cases the participants are asked to identify the particles shown and to choose one possible clinical diagnosis among 4 to 5 proposed.

For each survey the answers obtained are then evaluated as correct, incorrect, partially correct, and no answer, and scored accordingly (5, 3, 0, and -2 respectively). For clinical association the answer is considered and scored only if the particle (for surveys 1 and 3) or all four particles (for surveys 2 and 4) are correctly identified.

For each survey, the CRB edits a report for each laboratory, containing the judgement and the scores obtained. Moreover, a summary of all participants’ answers is supplied, together with a comment by the responsible of the program on the images shown, their main clinical correlates, and the answers supplied by participants.

At the end of each annual cycle, CRB prepares a report summarising the laboratory’s performances and annual score together with an overview of the results obtained by all laboratories.

Today, the images of each survey are presented in the website of the program (www.urinalysis.net) and the participants give their answers directly through it.


Figure 8.1. Survey 2-2003 for the identification of particles. Top: spindle-like uric acid crystals. Bottom: an oval fat body. For both particles, left, bright field microscopy and, in the inset, polarized light; right, phase contrast microscopy. Note that for each particle the magnification was indicated and, for, crystals also the urinary pH.


Figure 8.2. Survey 2-2007 showing the particles associated with clinical case 1.Top, left: dysmorphic erythrocytes; right: renal tubular epithelial cells. Bottom, left: an erythrocytic cast; right: a waxy cast.The clinical case was presented as follows: a 45-year-old man hospitalised for rapidly progressive renal failure (S-creatinine 1.2 mg/dL three months before hospitalisation) associated with the appearance of high blood pressure (160/95 mm/Hg) and urinary abnormalities. Ultrasounds of the urinary system, normal.

Laboratory findings at hospitalisation:

S-creatinine 2.5 mg/dL (n.v. 0.5-1.0) U-protein/24 hours 1.5 g (n.v. <0.14)

BUN 95 mg/dL (n.v. 15-50) Urinary output/24 hours 1,700 mL

Possible clinical diagnosis (only one is correct)• Acute nephritic syndrome• Nephrotic syndrome• Hypovolemic acute renal failure• Acute pyelonephritis• Unilateral hydronephrosis due to ureteric stone


Results of “Urinalysis Performance”

The identification of particles. From 2001 to 2007, 84 images were sent, which showed 50 elements of urinary sediment (Table 8.1). The correct identification was the highest for bihydrated calcium oxalate crystals (100%) and triple phosphate crystals (99.6%), while it was the lowest for the leukocytic cast (9.2%) and the macrophage (10.9%).

By urinary particle categories, a very high correct identification rate (obtained for each particle from the sum of correct + partially correct answers) was obtained for micro-organisms and crystals, followed in decreasing order by cells, lipids, casts and contaminants (Table 8.2).

This part of the program also showed that quite often participants used an inappropriate terminology to define some particles. This happened especially with renal tubular epithelial cells, transitional epithelial cells, and squamous epithelial cells which were often defined as “cells from the high, intermediate, or low urinary tract” respectively. For other particles such as erythrocytes and calcium oxalate crystals, the terminology used was often incomplete, without specification whether the erythrocytes were isomorphic or dysmorphic and calcium oxalate was mono- or bihydrated.

The particles presented twice. Twenty-four particles were presented twice. For 6 particles (25.0%) there was a 4.6% to 27.7% (14.6 ± 8.5) decrease in the correct identification rate when the particle was presented for the second time; for 4 other particles (16.6%) there were non substantial differences between the first and the second survey (0 to + 0.2%); for the majority of particles (14 out of 24, 58.3%), the identification rate increased by 2.6% to 77.2% (24.7 ± 19.7). For 11 out of 14 such particles (78.5%), the improvement between the first and second survey was statistically significant (Table 8.3).

The clinical association. In the cycles from 2001 to 2003, when participants were free to indicate one association of their choice, a very wide spectrum of answers was supplied, and the answers were often of difficult interpretation mostly because of the arbitrary and vague terminology used. Moreover, there was a high rate of “no answer” (11.8 ± 5.5%, 5-28% per survey).

Subsequently, with the introduction of multiple-choice answers, the correct clinical association was indicated by more than 80% of participants for all but one particle (i.e., cholesterol crystals). Moreover, there was a substantial decrease of the rate of “no answer” (2.5 ± 1.6%, 0.0 to 5.6% per survey) (Table 8.4).

The clinical cases. For the first case presented (Figure 8.2), among 168 laboratories out of 325 which correctly identified all four elements presented (51.7%), the correct diagnosis (acute nephritic syndrome) was given by 86.9% of participants. For the second clinical case, among 125 laboratories out of 310 which correctly identified all the four elements shown (40.3%), the correct diagnosis (ureteric stone) was given by 95.2% of participants (Table 8.4).


Table 8.1. The particles sent to participants for identification in the period 2001-2007 and the answers received.

urinary sediment particleanswers (%)

Number of participantsCorrect Partially

correct incorrect Noanswer

CellS (N = 9)

Isomorphic erythrocytes 89.3 2.4 7.9 0.4 291

Dysmorphic erythrocytes 45.2 41.6 13.2 0.0 250

Acanthocytes 52.0 20.8 25.6 1.6 250

Leukocytes 96.9 1.4 1.4 0.3 291

Macrophage 10.6 0.3 83.4 5.7 309

Renal tubular epithelial cells 51.9 1.0 44.0 3.1 291

Deep transitional epithelial cells 45.2 41.6 12.4 0.8 250

Superficial transitional epithelial cells 41.9 14.8 42.3 1.0 291

Squamous epithelial cells 88.1 0.0 11.9 0.0 361

liPiDS (N = 4)

Aggregates of lipid droplets 61.2 29.8 6.1 2.9 245

Oval fat body 55.9 2.4 39.6 2.1 245

Fatty cast 74.7 0.9 24.0 0.4 229

Cholesterol crystals 53.9 1.6 42.9 1.6 245

CaSTS (N = 15)

Hyaline 78.6 0.4 19.7 1.3 234

Hyaline-granular 74.3 0.0 24.8 0.9 234

Finely granular 64.1 1.7 33.8 0.4 234

Coarsely granular 59.9 0.6 38.9 0.6 321

Waxy 88.5 1.3 9.8 0.4 234

Granular-waxy 45.8 22.0 31.4 0.8 361

Erythrocytic 61.1 5.7 33.2 0.0 229

Leukocytic 5.5 3.7 90.8 0.0 327

Containing renal tubular epithelial cells (RTECs) 38.9 12.7 48.4 0.0 229

Erythrocytic + RTECs 66.4 16.6 16.6 0.4 263

Leukocytic + RTECs 83.2 10.1 6.7 0.0 356

Haemoglobinic 91.0 2.5 6.5 0.0 355


urinary sediment particleanswers (%)

Number of participantsCorrect Partially

correct incorrect Noanswer

Hyaline-granular cylindroid 68.0 15.8 16.2 0.0 291

Cylindroid containing erythrocytes 48.5 4.1 47.4 0.0 365

CrYSTalS (N = 13)

Uric acid 99.2 0.0 0.4 0.4 243

Calcium oxalate monohydrated 66.3 26.7 6.2 0.8 243

Calcium oxalate bihydrated 58.4 41.6 0.0 0.0 243

Triple-phosphate 99.6 0.0 0.4 0.0 243

Calcium phosphate 91.7 0.0 8.3 0.0 265

Calcium phosphate plate 71.0 0.0 27.4 1.6 263

Amorphous urates 86.4 1.1 12.5 0.0 265

Amorphous phosphates 80.4 3.4 16.2 0.0 291

Ammonium biurate 90.1 8.2 0.0 1.7 365

Cystine 94.7 0.0 5.3 0.0 265

Amoxycillin 12.1 50.4 36.0 1.5 355

Indinavir 63.4 0.6 26.1 1.5 344

Ciprofloxacin 25.4 42.8 31.5 0.3 327

MICRO-ORGANISMS (N = 4)

Bacteria 97.3 0.9 1.8 0.0 223

Candida 99.1 0.0 0.9 0.0 223

Trichomonas vaginalis 93.3 1.4 5.3 0.0 223

Eggs of Schistosoma haematobium 87.0 3.2 9.4 0.4 223

CONTAMINANTS (N = 5)

Starch 50.6 0.4 47.8 1.2 245

Glass fragment 79.5 0.0 17.8 2.7 263

Fibre 91.1 0.7 8.2 0.0 291

Fungal spore (Alternaria) 61.1 29.3 8.3 1.3 324

Pseudocast 22.3 0.4 73.8 3.5 229

Table 8.1. Continued


Table 8.2. Correct identification rates observed for each of the 6 categories of urinary parti-cles presented during the period 2001-2007.

Particle Number presented Mean ± sd Median range

Micro-organisms 4 95.5 ± 4.0 96.4 90.2-99.1

Crystals 13 85.6 ± 14.3 91.7 62.5-100

Cells 9 71.6 ± 27.6 86.8 10.9-98.3

Lipids 4 70.1 ± 16.5 66.9 55.5-91.0

Casts 15 69.7 ± 21.4 74.3 9.2-93.5

Contaminants 5 67.0 ± 29.7 79.5 22.7-91.8


Table 8.3. First and second answers concerning the identification of the particles which were presented twice.

urinary sediment particle Correct + partially correct identifications (%)

I II Change (%) p-value

CORRECT IDENTIFICATION: DECREASE

Waxy cast 89.8 85.2 -4.6 0.123

Deep transitional cells 86.8 80.9 -5.9 0.054

Bilirubinic cast 74.7 60.1 -14.6 <0.001

Uric acid crystals 99.2 82.3 -16.9 <0.001

Hyaline cast 79.0 61.0 -18.0 <0.001

Isomorphic erythrocytes 91.7 64.5 -27.7 <0.001

CORRECT IDENTIFICATION: UNCHANGED

Calcium oxalate bihydrated crystals 100 100 0 -

Leukocytes 98.3 98.4 +0.1 0.924

Candida 99.1 99.3 +0.2 0.762

Triple-phosphate crystals 99.6 99.4 +0.2 0.807

CORRECT IDENTIFICATIONS: INCREASE

Dysmorphic erythrocytes 86.8 89.4 +2.6 0.359

Egg of Schistosoma haematobium 90.2 93.6 +3.4 0.129

Calcium oxalate monohydrated crystals 93.0 96.6 +3.6 0.066

Fatty cast 75.6 86.4 +10.8 0.001

Finely granular cast 65.8 82.4 +16.6 <0.001

RTECs 52.9 69.6 +16.7 <0.001

Starch 51.0 70.2 +19.2 <0.001

Oval fat body 58.3 83.2 +24.9 <0.001

Erythrocytic cast 66.8 96.3 +29.5 <0.001

RTECs cast 51.6 83.5 +31.9 <0.001

Superficial transitional cells 56.7 89.1 +32.4 <0.001

Macrophage 10.9 44.4 +33.5 <0.001

Cholesterol crystals 55.5 99.7 +44.2 <0.001

Leukocytic cast 9.2 86.4 +77.2 <0.001


Table 8.4. Answers concerning the clinical association in the period 2004-2007.

urinary sediment particle

N with access to

clinical association

Correct clinical association

(Chosen among 4 to 5 options)

answers (%)

Correct incorrect Noanswer

Dysmorphic erythrocytes 248 Glomerular

haematuria 97.6 2.0 0.4

Deep transitional

cells 201

Damage to the deep layers of the

uroepithelium99.5 0.5 0.0

Macrophage 158 Active glomerulonephritis 86.7 12.0 1.3

Granular-waxy cast 165

Renal disease with deterioration of renal

function90.3 7.3 2.4

Cast containing RTECs 269

Acute Renal failure associated with acute

tubular necrosis89.2 10.4 0.4

Leukocytic cast 276 Active proliferative glomerulonephritis 84.0 12.0 4.0

Haemoglobinic cast 323 Haematuria of renal

origin (glomerular) 83.9 10.5 5.6

Bilirubinic cast 140Jaundice associated

with increased conjugated bilirubin

94.3 3.6 2.1

Erythrocytic cylindroid 345 Haematuria of

glomerular origin 89.9 7.5 2.6

Cholesterol crystal 317 Severe proteinuria/

Nephrotic syndrome 74.8 21.4 3.8

Calcium oxalate monohydrated

crystals212

Crystalluria due to drugs (e.g., vitamin C, naftidrofuryl oxalate)

91.9 5.7 2.4

Indinavir crystals 218

Urolithiasis from inhibitors of HIV-1

protease (e.g., indinavir)

95.9 1.8 2.3

Egg of Schistosama haematobium

300Infection of the urinary

system due to a parasite

91.0 5.3 3.7

Starch 225 Urine contamination from environment 92.9 2.7 4.4


Comments to “Urinalysis Performance”

The EQA programs which also include the examination of the urinary sediment are few. However, the results obtained by “Urinalysis Performance” show that there is a great need for such programs.

In fact, our program demonstrates that only some particles such as micro-organisms and the most common types of crystals are known to participants. On the contrary, the knowledge of particles such as renal tubular epithelial cells, and lipids is unsatisfactory, especially if one considers the clinical implications they have.

Our results also show that EQA programs can improve the skills of the participants, as shown by the results obtained for particles which were presented twice. In this respect, it is worth noting that the highest and more significant improvements were obtained for particles of clinical importance such as the erythrocytic and leukocytic casts, which are a marker of active glomerular disease.

EQA programs may be a valuable tool also to expand the knowledge about particles which are known only to specialists. In our program this is clearly demonstrated by the results obtained with the macrophage, which was almost totally misidentified when it was presented for the first time, but whose correct identification increased by 33,5% when it was presented for the second time.

EQA programs may also be used as a tool to improve the knowledge of the clinical implications of the laboratory tests. The results obtained by our program with the first two clinical cases presented confirm the validity of this statement.

For all these reasons more EQA programs on urinary sediment should be set up, and the participation to them should encouraged and sustained, especially bi scientific society of Laboratory medicine.

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[8] ilac. Guidelines for the requirements for the competence of providers of proficiency schemes. ILAC; ILAC-G13; 2000.

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[10] sciacovelli L., zardo L., secchiero S. et al. External quality assessment schemes: need for recognised requirements. Clin Chim Acta 2001; 309:183-99.

[11] taKuBo T., tatsumi N. Quality control in urinalysis. Southeast Asian J Trop Med Public Health 1999; 30 (Suppl 3): 136-48.

[12] Boisson R.C., eynard J.C., crozier M. et al. French experience about quality assessment of quantitative urinary analysis. Chim Clin Acta 2000;297:285-95.

[13] guder W.G., Boisson R.C., Fogazzi G.B. et al. External quality assessment of urine analysis in Europe. Results of a round table discussion during the Symposium ‘From uroscopy to molecular analysis’, Seeon, Germany, September 18-20, 1999. Clin Chim Acta 2000; 297: 275-84.

[14] Fogazzi G.B. “Urinalysis Performance” Programma di Valutazione Esterna di Qualità sul sedimento urinario. Anno 2001-2003. Pisa: Pacini, 2006.

[15] the royal college oF Pathologists. Guidelines for the provision of interpretative comments on biomediacal reports. Bull R Coll Pathol 1998; 104: 25.

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CHAPTER 8 QUALITY CONTROL PROGRAMS FOR … · This chapter describes the Quality Control programs...

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