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Revista Brasileira de Anestesiologia

Print version ISSN 0034-7094

Rev. Bras. Anestesiol. vol.64 no.1 Campinas Jan./Feb. 2014 

Scientific Article

Indication of preoperative tests according to clinical criteria: need for supervision

Aline Pallaoro Garciaa 

Karen Adriana Pastorioa 

Rodrigo Lopes Nunesa 

Giovani Figueiredo Locksb 

Maria Cristina Simões de Almeidac 

aUniversidade Federal de Santa Catarina, Florianópolis, SC, Brazil

bHospital Universitário da Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil

cDepartment of Surgery, Hospital Universitário da Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil


Background and objectives:

The indiscriminate order for additional tests on pre-anesthetic evaluation is common in clinical practice, which entails additional costs and the possibility of false-positive results. The aim of this study was to analyze whether preoperative tests in elective surgeries are ordered according to clinical criteria and assess the unnecessary costs for the institution.


Evaluation of preoperative investigations in adult patients undergoing elective non-cardiac surgery. Tests were ordered by surgeons according to the Anesthesia Service protocol. Demographic data, physical status, comorbidities, and type of ordered supplementary examination were evaluated. The tests performed were compared with the indicated tests. The cost of screening was based on Datasus' table.


1063 patients were evaluated. It was found that 41.9% of the tests performed on patients classified as ASA-I were not indicated. In ASA II group, 442 tests (17.72%) were made unnecessarily. The ordered percentages of blood count, creatinine, coagulation profile, chest X-ray, and ECG were high in groups ASA I-II. Only 40 (5.25%) of the examinations made in ASA III group were not indicated. In ASA IV group, 22.5% of the required tests were not performed. We highlight an annual saving of 13% (R$ 1923.13) if tests were done according to the protocol.


Preoperative tests are not always ordered according to clinical criteria, which results in higher costs for the institution.

Key words: Medicalexaminations; Assessment in healthcare; Hospital costs


Justificativa e objetivos:

a solicitação indiscriminada de exames complementares na avaliação pré-anestésica é comum na prática clínica e implica custos adicionais e a possibilidade de resultados falso-positivos. Os objetivos desta pesquisa foram analisar se os exames pré-operatórios em cirurgias eletivas são solicitados segundo critério clínico e avaliar os custos desnecessários para a instituição.


foram avaliadas as solicitações de exames pré-operatórios em pacientes adultos submetidos a cirurgias eletivas não cardíacas. Os exames foram solicitados pelos cirurgiões, conforme protocolo do Serviço de Anestesia. Foram avaliados dados demográficos, estado físico, comorbidades e tipo de exame complementar solicitado. Os exames feitos foram comparados com os exames indicados. O custo dos exames foi baseado na tabela Datasus.


foram avaliados 1.063 pacientes. Verificou-se que 41,9% dos exames feitos nos pacientes classificados como ASA I não estavam indicados. No grupo de risco ASA II foram feitos 442 exames (17,72%) sem necessidade. Perceberam-se elevadas porcentagens na solicitação de hemograma, creatinina, coagulograma, raios X de tórax e ECG nos grupos ASA I-II. Apenas 40 (5,25%) dos exames feitos no grupo ASA III não estavam indicados. Nos pacientes do grupo ASA IV, 22,5% dos exames necessários não foram feitos. Ressalta-se uma economia anual de 13% (R$1.923,13) caso os exames fossem feitos conforme o protocolo.


os exames pré-operatórios nem sempre são solicitados de acordo com critérios clínicos, o que resulta em maiores custos para a instituição.

Palavras-Chave: Exames médicos; Avaliação em saúde; Custos hospitalares


Justificativa y objetivos:

la solicitud indiscriminada de exámenes complementarios en la evaluación preanestésica es común en la práctica clínica e implica costes adicionales y la posibilidad de resultados falso-positivos. Los objetivos de esta investigación fueron analizarsi los exámenes preoperatorios en las cirugías electivas son solicitados secundando el criterio clínico, y evaluar los costes innecesarios para la institución.


se evaluaron las solicitaciones de exámenes preoperatorios en pacientes adultos sometidos a cirugías electivas no cardíacas. Los exámenes fueron solicitados por los cirujanos, conforme al protocolo del servicio de anestesia. Se evaluaron los datos demográficos, el estado físico, las comorbilidades y el tipo de examen complementario solicitado. Los exámenes que se hicieron se compararon con los exámenes indicados. El coste de los exámenes se basó en la tabla Datasus.


se evaluaron 1.063 pacientes. Se verificó que un 41,9% de los exámenes realizados en los pacientes clasificados como ASA I no estaban indicados. En el grupo de riesgo ASA II se hicieron 442 exámenes (17,72%) sin necesidad. Notamos altos porcentajes en la solicitud del hemograma, creatinina, coagulograma, rayos X de tórax y ECG en los grupos ASA I-II. Cuarenta (40) (5,25%) de los exámenes hechos en el grupo ASA III no estaban indicados. En los pacientes del grupo ASA IV, un 22,5% de los exámenes necesarios no se hicieron. Destacamos aquí una economía anual de un 13% (R$ 1.923,13) si los exámenes se hiciesen de acuerdocon el protocolo.


los exámenes preoperatorios no siempre se solicitan de acuerdo con los criterios clínicos, lo que trae como resultado, más costes para la institución.

Palabras-clave: Exámenes médicos; Evaluación en sanidad; Costes hospitalarios


Preoperative evaluation is the fundamental basis for managing surgical patient and it may reduce risks and contribute to a better surgical outcome.1 In this context, we highlight the clinical history and physical examination, which in most cases are responsible for disease diagnosis.2

The selection of preoperative laboratory tests (specific or imaging tests) should be performed as a complementary measure to the clinical suspicion. The indiscriminate and routine testing is unnecessary and involves, besides the additional cost for the institution,3 the possibility of false-positive results,4 with more or less serious consequences for patients.

This research was conducted with the aim of analyzing whether preoperative tests in elective surgeries are ordered according to clinical criteria and evaluate the costs of these so-called "routine" tests for the institution.


After approval by the Human Research Ethics Committee, under the number 1059/2009/SC, and obtaining the written informed consent, the preoperative tests ordered for adult patients undergoing non-cardiac elective surgery were prospectively evaluated over a period of one year. The institution routine prescribes the preoperative examinations ordered by surgeons, according to the protocol given by the Anesthesiology Service. In the pre-anesthetic evaluation (PAE), anesthesiologists completed for this research a specific form that included patient demographics, physical status, existing comorbidity, and type of supplementary examination ordered by the surgeon. The tests (ordered by the surgeon) were compared with tests indicated according to the institution protocol.

The costs for each exam were based on the unified table of Datasus. Results are expressed as absolute frequency (relative frequency or percentage).


A total of 1063 patients were evaluated, whose demographics and physical condition according to the American Society of Anesthesiologists (ASA) are shown in Table 1. Among patients, there was a higher prevalence of females, aged between 41 and 65 years, Caucasian, and ASA I-II.

Table 1 Demographics and ASA physical status. 

    n (%)
  Male 387 (36.4)
  Female 647 (60.9)
  Not registered 29 (2.7)
Age (years)  
  18-40 355 (33.4)
  41-65 429 (40.3)
  Over 65 117 (11.0)
  Not registered 162 (15.3)
  White 916 (86.2)
  Black 37 (3.5)
  Yellow 16 (1.5)
  Mixed 25 (2.4)
  Not registered 69 (6.4)
  I-II 842 (79.2)
  III 152 (14.3)
  IV 13 (1.2)
  Not registered 56 (5.3)

Table 2 shows the protocol for ordering preoperative tests established by the anesthesiology team of the institution, according to the ASA physical status, comorbidities and type of surgery to be performed.

Table 2 Protocol of the institution for ordering preoperative tests. 

  Hematocrit Platelets/TAP/APTT Glucose Creatinine Electrolytes Chest X-rays ECG
[1] X            
[2] X X          
[3] X           X
[4] X X         X
[5] X   X X X X X
[6] X         X X
[7] X X   X      
[8] X   X X   X X

[1], Patient ASA I, < 40 years, surgery without loss.[2], Patient ASA I, < 40 years, surgery with loss and/or bleeding disorder.[3], Patient ASA I or II, >40 years, surgery without loss.[4], Patient ASA I or II, >40 years, surgery with loss and/or bleeding disorder.[5], Heart disease and/or diabetes and/or nephropathy.[6], Pulmonary disorder.[7], Liver disorder.[8], Age >60 years.

The correlation of ASA physical status classification with the exams is shown in Fig. 1. The high percentages of complete blood count, creatinine, coagulation profile, chest X-rays, and ECG ordered in patients ASA I-II draw attention.

Figure 1 Preoperative tests ordered according to the ASA physical status classification. 

Fig. 2 shows the type of preoperative examination ordered according to age. The emphasis is on the high percentage of exams ordered in patients up to 40 years.

Figure 2 Preoperative tests ordered according to age. 

The type of preoperative examination ordered according to the number of comorbid conditions is shown in Fig. 3. Even in patients without comorbidity, additional tests were widely ordered.

Figure 3 Preoperative tests ordered according to the number of comorbidities. 

Fig. 4 shows the ordering of preoperative tests according to age and comorbidities. In general, it can be seen that the ordering pattern is repeated, even when young and healthy patients are compared to patients over 40 years of age with or without comorbid conditions.

Figure 4 Preoperative tests ordered according to age and number of comorbidities. 

Realization and indication of complementary tests were compared according to the institution protocol. Costs and number of tests performed and indicated in the PAE were compared (Tables 3-6). It was found that 41.9% of tests performed in patients classified as ASA I were not indicated (Table 3). In patients classified as ASA II, 442 tests (17.72%) were made without necessity (Table 4). Regarding patients classified as ASA III, only 40 (5.25%) of the performed tests were not indicated by the protocol. However, in patients classified as ASA IV, there were fewer ordered tests than recommended and 16 (22.5%) required tests were not made (Table 4).

Table 3 Comparison between quantity and cost of tests ordered recommended by the institution's protocol for patients classified as ASA I. 

ASA I = 249 Unit cost   Performed test   Indicated test   Total saved
      n Total cost   n Total cost   n Total cost
Hematocrit R$ 4,11   186 R$ 764,46   249 R$ 1.023,39   -63 -R$ 258,93
Urea R$ 1,85   104 R$ 192,40   43 R$ 79,55   61 R$ 112,85
Creatinine R$ 1,85   99 R$ 183,15   43 R$ 79,55   56 R$ 103,60
Glucose R$ 1,85   54 R$ 99,90   14 R$ 25,90   40 R$ 74,00
Sodium R$ 1,85   14 R$ 25,90   40 R$ 74,00   -26 -R$ 48,10
Potassium R$ 1,85   116 R$ 214,60   40 R$ 74,00   76 R$ 140,60
TAP R$ 2,73   126 R$ 343,98   1 R$ 2,73   125 R$ 341,25
TTPA R$ 5,77   91 R$ 525,07   1 R$ 5,77   90 R$ 519,30
ECG R$ 5,15   68 R$ 350,20   71 R$ 365,65   -3 -R$ 15,45
Chest X-rays R$ 9,50   25 R$ 237,50   11 R$ 104,50   14 R$ 133,00
Total     883 R$ 2.937,16   513 R$ 1.835,04   370 R$ 1.102,12

Table 4 Comparison between quantity and cost of tests ordered and recommended by the institution's protocol for patients classified as ASA II. 

ASA II = 591 Unit cost   Performed test   Indicated test   Total saved
      n Total cost   n Total cost   n Total cost
Hematocrit R$ 4,11   481 R$ 1.976,91   591 R$ 2.429,01   -110 -R$ 452,10
Urea R$ 1,85   308 R$ 569,80   238 R$ 440,30   70 R$ 129,50
Creatinine R$ 1,85   307 R$ 567,95   238 R$ 440,30   69 R$ 127,65
Glucose R$ 1,85   218 R$ 403,30   145 R$ 268,25   73 R$ 135,05
Sodium R$ 1,85   145 R$ 268,25   205 R$ 379,25   -60 -R$ 111,00
Potassium R$ 1,85   272 R$ 503,20   205 R$ 379,25   67 R$ 123,95
TAP R$ 2,73   307 R$ 838,11   3 R$ 8,19   304 R$ 829,92
TTPA R$ 5,77   229 R$ 1.321,33   3 R$ 17,31   226 R$ 1.304,02
ECG R$ 5,15   159 R$ 818,85   305 R$ 1.570,75   -146 -R$ 751,90
Chest X-rays R$ 9,50   68 R$ 646,00   119 R$ 1.130,50   -51 -R$ 484,50
Total     2494 R$ 7.913,70   2052 R$ 7.063,11   442 R$ 850,59

Table 5 Comparison between quantity and cost tests ordered and recommended by the institution's protocol for patients 

ASA III = 152 Unit cost   Performed test   Indicated test   Total saved
      n Total cost   n Total cost   n Total cost
Hematocrit R$ 4,11   130 R$ 534,30   152 R$ 624,72   -22 -R$ 90,42
Urea R$ 1,85   96 R$ 177,60   90 R$ 166,50   6 R$ 11,10
Creatinine R$ 1,85   83 R$ 153,55   90 R$ 166,50   -7 -R$ 12,95
Glucose R$ 1,85   69 R$ 127,65   77 R$ 142,45   -8 -R$ 14,80
Sodium R$ 1,85   77 R$ 142,45   71 R$ 131,35   6 R$ 11,10
Potassium R$ 1,85   86 R$ 159,10   71 R$ 131,35   15 R$ 27,75
TAP R$ 2,73   87 R$ 237,51   0 R$ -   87 R$ 237,51
TTPA R$ 5,77   64 R$ 369,28   0 R$ -   64 R$ 369,28
ECG R$ 5,15   48 R$ 247,20   100 R$ 515,00   -52 -R$ 267,80
Chest X-rays R$ 9,50   21 R$ 199,50   70 R$ 665,00   -49 -R$ 465,50
Total     761 R$ 2.348,14   721 R$ 2.542,87   40 -R$ 194,73

Table 6 Comparison between quantity and cost of tests ordered and recommended by the institution’s protocol for patients classified as ASA IV. 

ASA IV = 13 Unit cost   Performed test   Indicated test   Total saved
      n Total cost   n Total cost   n Total cost
Hematocrit R$ 4,11   12 R$ 49,32   13 R$ 53,43   -1 -R$ 4,11
Urea R$ 1,85   8 R$ 14,80   10 R$ 18,50   -2 -R$ 3,70
Creatinine R$ 1,85   9 R$ 16,65   10 R$ 18,50   -1 -R$ 1,85
Glucose R$ 1,85   7 R$ 12,95   10 R$ 18,50   -3 -R$ 5,55
Sodium R$ 1,85   10 R$ 18,50   10 R$ 18,50   0 R$ -
Potassium R$ 1,85   6 R$ 11,10   10 R$ 18,50   -4 -R$ 7,40
TAP R$ 2,73   8 R$ 21,84   1 R$ 2,73   7 R$ 19,11
TTPA R$ 5,77   6 R$ 34,62   1 R$ 5,77   5 R$ 28,85
ECG R$ 5,15   3 R$ 15,45   12 R$ 61,80   -9 -R$ 46,35
Chest X-rays R$ 9,50   2 R$ 19,00   10 R$ 95,00   -8 -R$ 76,00
Total     71 R$ 214,23   87 R$ 311,23   -16 -R$ 97,00

Table 7 shows the total cost of the performed tests compared to the total cost of the indicated tests, regarding patients in general. We emphasize an annual savings of 13% if the tests were done according to the protocol established by the institution.

Table 7 Comparison between quantity and cost of tests ordered and recommended by the institution's protocol. 

Tests Unit cost   Performed test   Indicated test   Total saved
      n Total cost   n Total cost   n Total cost
Hematocrit R$ 4,11   856 R$ 3.518,16   1063 R$ 4.368,93   -207 -R$ 850,77
Urea R$ 1,85   523 R$ 967,55   400 R$ 740,00   123 R$ 227,55
Creatinine R$ 1,85   541 R$ 1.000,85   400 R$ 740,00   141 R$ 260,85
Glucose R$ 1,85   361 R$ 667,85   255 R$ 471,75   106 R$ 196,10
Sodium R$ 1,85   505 R$ 934,25   339 R$ 627,15   166 R$ 307,10
Potassium R$ 1,85   345 R$ 638,25   339 R$ 627,15   6 R$ 11,10
TAP R$ 2,73   557 R$ 1.520,61   5 R$ 13,65   552 R$ 1.506,96
TTPA R$ 5,77   407 R$ 2.348,39   5 R$ 28,85   402 R$ 2.319,54
ECG R$ 5,15   290 R$ 1.493,50   512 R$ 2.636,80   -222 -R$ 1.143,30
Chest X-rays R$ 9,50   125 R$ 1.187,50   221 R$ 2.099,50   -96 -R$ 912,00
Total     4510 R$ 14.276,91   3539 R$ 12.353,78   971 R$ 1.923,13


In this study, the outstanding fact is that the preoperative laboratory tests ordered by the surgeon did not follow the protocol recommended by the department of anesthesiology; that is, the ordering does not meet the clinical criteria and, therefore, the cost of these tests is 13% higher for the institution.

Considered as a complementary part of the pre-anesthetic evaluation, preoperative tests confirm and document conditions that may affect the course of anesthesia and postoperative period.4-7 Thus, anesthesiologists seek to increase patient safety regarding adequate perioperative care, better use of available resources, reduced delays and cancelations of surgeries, and positive contribution to greater satisfaction of patients, relatives, and health team.3,6,8,9

Studies show that in the absence of any clinical indication, the likelihood of finding an abnormality in laboratory tests, electrocardiogram, and chest X-ray is significantly small.3,4,7,8,10 When the history and physical examination are considered paramount as prime determinants in the indication of preoperative tests, it is noted that 60-70% of laboratory tests routinely performed are not really necessary.4

In order to rationalize the indication of preoperative tests in elective surgeries, evidence-based guidelines have been published11-13 and, although studies are emphatic about non testing without specific clinical indication,4,6,14-18 the routine of preoperative tests ordering is still common in daily practice.3

Contrary to what the literature recommends, this study showed that the ordering of preoperative tests does not follow strict criteria and is done indiscriminately for young patients without comorbidities.

Although the costs of preoperative tests adopted in this research are not those actually expended by the institution, and therefore it should be carefully analyzed, we cannot fail to note the significant cost of tests ordered indiscriminately. In the current context, this cost is not negligible and becomes an important factor in the increase of annual hospital budgets.3,10,19 From this point of view, an indication of clinical tests is debatable, particularly in healthy patients, as the results may add more risks than benefits. Authors even suggest that in young and healthy patients undergoing minor surgery the preoperative examinations should be abolished.19 Taking this approach into account, by eliminating unnecessary tests in a hospital in England, the annual savings would be £50,000.19 In Brazil, the annual savings in just one medium-sized hospital is estimated at R$157,536.84, according to a previous study.10

Table 7 shows that if the preoperative tests were ordered according to the protocol established by our institution, the annual savings would be 13%. Furthermore, it can be inferred that this economy could be even greater if the basics and more updated principles of evidence-based medicine be applied to update the protocol adopted by the institution. In other words, it is necessary that, in addition to the supervision of existing routines, a constant update of the protocols be performed. It should be noted that although the data are objective about the lack of parameters in the ordering of additional tests, these results should be interpreted with caution, as the size of surgeries was not included as an evaluation criterion in this study.

From this research data, the point to be highlighted is the inadequacy of the institution model, which does not allow the anesthesiologist to order the tests required to plan his anesthesia. Similarly, anesthesiologists must not transfer the responsibility of ordering tests to surgeons. The responsibility of the medical act is not transferable.

Data from this study suggest the need for constant supervision of protocols used in clinical practice, as well as awareness of the importance of preoperative period as a factor of hospital cost reduction and satisfaction of patients and their relatives. The sequence of events, from the preparation of facilities and logistics services, material of preoperative tests ordering, and how the patient can do these tests is an important and necessary step in order to offer a quality medicine for someone who trusts his life to us.

In conclusion, preoperative tests are not always ordered within clinical criteria, resulting in increased cost for the institution.


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Received: July 13, 2012; Accepted: March 20, 2013

Corresponding author. E-mail: (A.P. Garcia).

Conflicts of interest

The authors declare no conflicts of interest.

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