ORIGINAL ARTICLE

Pre-operative Investigations: Yield and Conformityto National Guidelines

.lliIIIli mlilll77l11l1ililllil Ii Uillillilli

HJuliana, BMedSc*, TA Lim, FRCA*, K Inbasegaran, FANZCA**

'Anaesthesiology Unit, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Hospital Kuala Lumpur,Jalan Masjid, 50586, Kuala Lumpur, "Department of Anaesthesiology and Intensive Care, Hospital Kuala Lumpur,Jalan Pahang, Kuala Lumpur

Introduction

Pre-anaesthetic evaluation is the initial step inpreparing a patient for surgery. At the conclusionof the evaluation, the anaesthetist would havedeveloped a plan for anaesthesia and peri­operative management. Generally, the task is tohave the patient in the best possible conditionprior to surgery, with an ultimate goal of reducingperi-operative morbidity and mortality!.

Laboratory investigations are part of the pre­anaesthetic evaluation. They complement historyand physical examination in detecting andassessing diseases that may be present in a patientprior to surgery. The most common pre-operative

laboratory investigations are the full blood count(FBC), serum electrolytes, blood urea nitrogen(BUN) and serum creatinine, blood glucose,prothrombin time (PT), partial thromboplastintime (aPTT), chest x-ray (CXR), electrocardiograph(ECG) and urinalysis2

•

During the 1970s, the practice of routinelyordering pre-operative laboratory investigationsby doctors world-wide proceeded relativelywithout question. In the 1980s, manyassessments of medical technology concludedthat routine pre-operative investigations withoutsuspected or known patient disease yield anextremely low rate of true positive test results andwere not cost-effective.

This article was accepted: 22 September 2002Corresponding Author: TA Lim, Anaesthesiology Unit, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, HospitalKuala Lumpur, Jalan Masiid, 50586 Kuala Lumpur

Med J Malaysia Vol 58 Nol March 2003 5

ORIGINAL ARTICLE

Studies have shown that the usefulness ofselectively ordered pre-operative tests is highcompared to the practice of routine testing3.4 • Inresponse, several guidelines for ordering pre­operative laboratory investigations have beenproduced. For example, University HospitalConsortium (UHC) of the United States, a non­profit alliance of leading academic medicalcentres, proposed a strategy for pre-operativetesting based on the work by Kaplan and Blery3.5.

In Malaysia, similar guidelines have beenproduced for local use6• These guidelines havebeen available in Hospital Kuala Lumpur (HKL)since 1998. However, no study has been carriedout to see whether the guidelines have beenfollowed, and whether the gUidelines have anyrole in improving cost-effectiveness.

This study was designed to determine the yield ofcommonly ordered pre-operative bloodinvestigations in patients undergoing electivesurgery in Hospital Kuala Lumpur. The study alsolooked at whether the practice of ordering pre­operative investigations followed therecommendations of the national guidelines.

Materials and Methods

A hospital-based, descriptive cross sectional studywas conducted over ten weeks from June 5 toAugust 10, 2001. The study was conducted at theUrology, Mobile and Accident & EmergencyOperation Theatres (OT) in Hospital KualaLumpur (HKL).

Study PopulationPatients above 12 years old, having electivesurgical procedures under general, spinal orepidural anaesthesia, were eligible for inclusioninto the study. Patients were sampled from fivedifferent surgical disciplines: General Surgery,Orthopaedics, Urology, Gynaecology andOphthalmology. Within each surgical discipline,20 morning OT lists were sampled, giving a totalof 100 OT lists sampled during the study period.

6

Data CollectionA standardised pro forma sheet (Appendix 1) wasused to obtain all the reqUired information. Datacollection was carried out in the OT on the day ofsurgery. Relevant information was obtained fromthe admission forms, the patients' medicalrecords, the anaesthetic forms and the laboratoryresult slips. Whenever possible, patients wereinterviewed to confirm the correctness of thedata. The investigations reviewed were:1. Full blood count (FBC)2. Blood urea, serum electrolytes and creatinine

(BUSEC)3. Random Blood Sugar (RBS)4. Prothombin time and activated partial

thromboplastin time (PT/apTT)5. Liver function tests (LFT)6. Electrocardiograph (ECG) and7. Chest x-ray (CXR).

Data AnalysisBlood test results were considered abnormal ifvalues obtained were outside the normal rangeused in HKL. For investigations that consist ofmore than one component (FBC, BUSEC, LFT andPT/aPTT), the investigation was consideredabnormal when at least one abnormal value waspresent in the cluster of results.

Investigations done were first classified asindicated or not indicated based on the guidelinesfor pre-operative laboratory investigations at HKL(Appendix 2). For blood tests, it was thendetermined whether the result was normal orabnormal. Expected abnormal results wereabnormal results obtained when the test wasindicated, whereas unexpected abnormal resultswere abnormal results obtained from tests whichwere not indicated (Figure 1). The decision toassign a test as indicated or not indicated, and aresult as normal or abnormal was made by one offour specialist anaesthetists. The following ratioswere then calculated:

Med JMalaysia Vol 58 No 1 March 2003

Preoperative Investigations: Yield and Conformity to National Guidelines

Data were analysed using Statistical Packages forSocial Science (SPSS) Version 10.0. Differencesbetween proportions were compared using the X2

test, with Yates' correction where appropriate.Differences between means were compared usingStudent's t-test. A value of p < 0.05 wasconsidered significant. Total deviation rate wascalculated using the ratio:

Conformity to the National Guidelines wasdetermined using the decision algorithm shown inFigure 2. The medical notes of every patient werechecked to see whether any of the above 7 testswere done. The National Guidelines was thenchecked to determine whether any particular testshould have been done. If any test was done andwas indicated, then that test was considered a testdone which -conformed to guidelines. Similarly, ifa test was not done and was not indicated, thattest was considered a test not done whichconformed to guidelines. Tests done which werenot indicated and tests not done which wereindicated were considered tests which did notconform to the guidelines.

Proportion of unexpectedabnormal results

Proportion of expectedabnormal results

Total Deviation rate

No. of expectedabnormal results

Total no. of indicatedblood tests done

No. of expectedabnormal resultsTotal no. of not

indicated blood testsdone

Number of tests thatdid not confirm x 100%Total number of tests

(none & not done)

shows the distribution of respondents by -age andsex. A total of 214 concurrent diseases werereported by 129 respondents. The most commondiseases encountered were cardiovascular disease(29.1% of all patients), renal disease (22.3%) anddiabetes mellitus 07.1%).

Yield ofPre-operative Blood InvestigationsFigure 3 shows the frequencies of the 7 pre­operative investigations ordered among therespondents. Out of 1117 pre-operativeinvestigations, 816 were blood tests, of which 751were available for analysis (Table II). Of 375 teststhat were not indicated, 129 (34.4%) hadabnormal results. The highest percentage ofunexpected abnormal results was seen in FBC,where there were 71 (68.9%) abnormal results outof 103 tests that were not indicated. This wasfollowed by LFT (55.0%), PT/aPTT (28.6%),BUSEC (27.1%) and RBS (0.9%). The proportionsof unexpected abnormal values in the individualcomponents of the blood tests are shown in TableIII.

Out of 230 Hb concentration tests available foranalysis, 94 (40.9%) were outside the normalrange. All abnormal values were lower thannormal, ranging from 5.4 to 11.9 g dL-1

. Expectedabnormal concentrations were detected in 56patients (44.1%) out of 127 in whom the test wasrecommended. The mean (SD) Hb level whenthe abnormal value was expected was 10.1 0.2)g dL-1, while the corresponding value when itwas unexpected was 10.6 (1.4) g dL-1• Thisdifference was not significantly different (t = 1.97,df = 92, P = 0.05). The difference in proportionsof patients with expected and unexpectedabnormal levels was also not statisticallysignificant (X2 = 1.22, df = 1, P = 0.27).

Results

There were 251, patients who fulfilled theinclusion criteria, 140 males and 111 females. Themean (SD) age was 45.5 07.8) years. Table I

Med J Malaysia Vol 58 No 1 March 2003

The mean (SD) Hb level in female patients was11.70.6) g dL-\ while the corresponding value inmales was 12.9 (2.3) g dV. This difference wassignificantly different Ct = 4.219, df = 228, P <0.0l). Furthermore, it was also found that 54.1%

7

ORIGINAL ARTICLE

of female patients presented with abnormal Hblevels compared to more 31.1% of male patients.This difference was also significantly different (X2

= 12.3, df=l, p < 0.01).

The proportion of expected abnormal BUSECresults was significantly higher than theproportion of unexpected abnormal results (TableII). Out of 224 blood urea concentration testsavailable, 17 (7.6%) were abnormal, all of whichwere expected. Thirty-seven patients hadexpected elevated serum creatinineconcentrations while only one patient had anunexpected elevated serum creatinineconcentration. Significantly different proportionsof patients had expected and unexpectedabnormal serum creatinine values (X2 = 15.9, df=l,p < 0.01).

The proportion of abnormal RBS values was20.3% when the test was indicated. However,only 0.9% of unexpected abnormal RBS resultswere found out of 106 tests that were notindicated. This difference in proportions wasstatistically significant (X2 = 18.0, df=l, P < 0.01).

Conformity to National GuidelinesOf the 1117 pre-operative investigations done,625 (56.0%) conformed to the guidelines (TableIV). The highest conformity was the ECG, where80% of 148 ECGs done followed the guidelines.On the other hand, the most overused test wasthe PT/aPTT, where only about 9.4% of 64 testsdone followed the guidelines (Figure 4a).

.Conformity to the guidelines, however, includesnot only tests done following the guidelines, butalso tests not done because no indications forordering the tests was present in the guidelines.With regards to the latter, 575 (90%) of 640 pre­operative tests not done conformed to theguidelines (Table IV). Indications were actuallypresent in 65 (10%) instances where the testswere not done. Among tests not done, the

. highest conformity occurred in PT/aPTT (99%),followed by LFT (92%), and the lowest occurredin ECG (75%) (Figure 4b).

The proportion of tests done which conformed tothe guidelines (56.0%) was significantly lowerthan the proportion· of test not done whichconformed (89.8%; x2 = 215.8, df = 1, P < 0.01).Total deviation rate was 31.7%.

Table I: Distribution of Respondents by Age and Sex

Age (years) Male Female Total

< 20 14 5 19

20 - 29 26 13 39

30 - 39 18 23 41

40 - 49 23 30 53

50 - 59 16 18 34

60 - 69 22 15 37

70 - 79 18 6 24

> 79 3 1 4

Total 140 (56%) 111 (44%) 251 (100%)

8 Med J Malaysia Vol 58 No 1 March 2003

Pre-operative Investigations: Yield and Conformity to National Guidelines

Table II: The Yield of Pre-operative Blood InvestigationsBlood Done Results

Investigation Indicated Not TOTAL Normal Abnormal Comparing proportions of expected

indicated Expected Unexpected and unexpected abnormal results

FBC 127 103 230 64 95 71 X2 = 0.98, df= 1, p = 0.32

BUSEC 154 70 224 131 74 19 X2 = 8.67, df= 1, p < 0.01

LFT 10 40 50 24 4 22 X2 = 0.25, df = 1, P = 0.62

PT/aPTT 6 56 62 43 3 16 X2 = 0.38, df = 1, p = 0.54

RBS 79 106 185 168 16 1 X2 = 18.0, df = 1, p < 0.01

TOTAL 376 375 751 430 192 29

.Table III: Proportion of unexpected abnormal values seen in this and previous studies

Blood Investigation Proportion of unexpected Proportion of unexpected abnormalabnormal values seen in this study values seen in previous studies 8,9,10,12

FBC:Hb 36.9% 0- 10%TWBC 19.4% 0.1 - 9.5%Platelet count 9.7% 0-11.8%RBC count 55.3%

BUSEC:Blood Urea 0% 1.0%

Serum Sodium 17.1% n 10Serum Potassium 10.0% n 10Serum Creatinine 1.4% 0.2% - 2.4%

LFTTotal Protein 15.0% nlaSerum Albumin 47.5% n/a

Total Bilirubin 15.0% nlaCoagulation Studies

PT 19.6% 0% - 2.9%

APTT 5.4% 1.4%

RBS 0.9% 1.8% - 5.5%

n 10 = not available

Table IV: Number of pre-operative investigations done according to guidelines recommendations

Conform to guidelines Did not conform to guidelines TOTAL

Tests done 625 492 1117

Tests not done 575 65 640

TOTAL 1200 557 1757

Mad J Malaysia Vol 58 No 1 March 2003 9

ORIGINAL ARTiClE

9.4% .

,---1I- I-10. I-..J 0.

~Q.

(.)III10.

a::><(.)

(.)W

~III

Percentage of laboratory blood testswhich were done that conformed tothe National Pre-anaestheticInvestigations Guidelines

100 ~

180.4%

:: j140

20

o

Fig. 4a:

No

~L;;J

No

YesNo

~L;;J

Yes

Yes

Laboratory Blood Test Result

Fig. 1: Algorithm for classifying a bloodinvestigation result

Pre-operative investigation

Percentage of laboratory blood testswhich were not done that conformedto the National Pre-anaestheticInvestigations Guidelines.*All patients had a pre-operative FBC.

Fig.4b:Test not done

whichconformed to

guideUnes

Test not donewhich did not

conform toguideUnes

100

80

60

No 40

20

0Cl (.) a:: t.l Ul l- I-(.) W >< I:lI III 10. I-

No Yes No w Ul (.) 10. a:: ..J 0.:;:) .!!!III I-

0.

Test donewhich did not

conform toguideUnes

Test donewhich

conformed toguideUnes,

Yes

Yes

Fig. 2: Algorithm for classifying pre-operativeinvestigations

Fec 251

eUSEC 245

Res 200

CXR 153

ECG 148

PT/aPTT 64

LFT 56

0 50 100 150 200 250 300

Fig. 3: Common pre-operative investigationsdone in HKLTotal number of patients = 251Total number of investigations done= 1117

Discussion

This study revealed quite a high percentage ofunexpected abnormal values (34.4%) whencompared to other studies. McKee and Scottreported 16% while Turnbull and Buck reportedonly 4.5%7,8. A comparison between percentagesof unexpected abnormal values in this andprevious studies is shown in Table III. Thepercentages of unexpected abnormal valuesfound in the FBe components were highcompared to other studies8

,9,1O. However, similarto other studies, female patients were more likelyto have abnormal Hb values compared to malepatients. This supports the suggestion that the

10 Mad J Malaysia Vol 58 No 1 March 2003

Pre-operative Investigations: Yield and Conformity to National Guidelines

need for pre-operative Hb measurement in bothsexes may differll .

The percentages of unexpected abnormal bloodurea and serum creatinine values found in thisstudy were within the range previouslyreported8

,9. Similar to previous studies, only asmall percentage of unexpected abnormal valueswas found in RBS8,9,12. However, higherpercentages of unexpected abnormal PT andaPTT values were recorded in this study8,9.

The higher percentages of unexpected abnormalvalues found in the present study may be becauseof how 'indicated' and 'abnormal values' weredefined. While most researchers defined a test asindicated only after the patient has been seen andassessed clinically, laboratory tests done in thepresent study were assigned as indicated whenrecommended by the guidelines. This could havelead to instances where laboratory tests that wererequired clinically being classified 'not indicated'according to the guidelines. This in turn wouldhave lead to a higher percentage of unexpectedabnormalities. However, it is by using this definitionthat an evaluation of the guidelines was possible.

'Normal' values in this study referred to thereference range used in HKL. This may differfrom the wider reference range used in some ofthe other studies. Such a range can be widenedby including not only values found in the normalpopulation, but also all values where notherapeutic intervention was needed. The narrowrange of values used in this study may havecontributed to the high percentage of abnormalvalues. In addition, up to 5% of normalindividuals can have test results that fall outsidethe 'normal' range13 •

The proportion of tests done which conformed tothe guidelines was lower than the proportion oftests not done which conformed. This is becausemany of the tests ordered were not recommendedby the guidelines, and suggests that there is agreater tendency to investigate patients evenwhen it is not recommended. The guidelines

Mad J Malaysia Vol 58 No 1 March 2003

suggest that for healthy patients undergoing short,minimally invasive procedures, investigations maynot be necessary.

Compared to similar studies, the conformity oftests done in the present study was low (56%).BIery et al. found a 70% conformity of tests donewhile Adams et al., found a 96% conformity to theprotocol at County / UH and 88% at the private /Community HospitaI5,14.

Although most recommended tests were actuallydone and most non-recommended tests were notdone, a 32% deviation from the guidelines wasstill seen. This deviation rate is high whencompared to a study done about 15 years agowhere a deviation rate of 18% was reported5•

GUideline~ should only serve ,as a guide andnever as substitute for the doctors' own clinicaljudgement. This could be one of the reasons whydoctors deviate from guidelines. The lowconformity in the present study could also becaused by the doctors not being aware that suchguidelines exist, or because the guidelines werenot adequately circulated. It must be appreciatedthat the guidelines being evaluated are for testsrecommended for administration of anaesthesiaand are not intended for surgical management.As such, certain tests may be deemed necessaryfrom the surgeon's point of view, but may havebeen excluded from the guidelines. Thisemphasises the need for co-operation betweendisciplines when developing Clinical PracticeGuidelines.

The pre-operative investigations guidelines aim tomaximise the detection of abnormal values. Alow percentage of unexpected abnormalitiesmean that the guidelines are able to discriminatebetween patients who require certain laboratorytests from those who do not.

In this study, the discriminatory ability of theguidelines was well demonstrated by the BUSECand the RBS. Following the guidelines, almost allpatients who had impairment of renal function

11

ORIGINAL ARTiClE

required a pre-operative BUSEC. Similarly, almostall patients with high blood sugar required aRBS.Unfortunately, the number of patients in thisstudy with LFT and PT/ aPTT results were toosmall to make a useful comparison. Assuming anexpected abnormality rate of 50%, unexpectedabnormality rate of 35% and a power of 80%, thenumber of samples needed for each blood test is167. The results of this study also suggest thatmany patients with anaemia would not have beendetected if the guidelines were rigidly followed.Two reasons could account for this. Clinicalanaemia, which is one of the recommendedcriteria for carrying out a FBC, could have beennoticed but not documented in the patient'snotes. Secondly, there is always an element ofsubjectivity in clinical examination and pallorcould have been missed in a number of patients.This is not surprising as low Hb levels are quitecommon in the population of a developingcountry. For Clinical Practice Guidelines toremain relevant, they need to be reviewedperiodically when new evidence is discovered15

.

The findings of this study suggest that theguidelines available in HKL might not be effectiveenough in detecting abnormal FBC test results,and therefore require review.

Several limitations of this study may havecontributed to the present findings. While otherstudies looked into the percentages of unexpectedabnormalities as well as beneficial changes inpatient management, this study only addressed theunexpected abnormalities encountered. Anyaction taken in response to the abnormal resultswas not documented. This means that abnormalresults encountered in the present study mayormay not be clinically important.

All patients recruited into the study were alreadyseen pre-operatively by the attending anaesthetist

and the decision to proceed with operation wasalready made. Patients who had their operationcancelled by the surgeon or anaesthetist when theblood investigations were grossly abnormal werenot included in this study. While this would havedetermined the yield of clinically significantabnormal pre-operative test results, logisticrequirements for such a study was beyond theresources available. In any case, there wouldhave been little effect on the calculation of theyield and rate of conformity. One of theobjectives of the study was to determine whetherthe yield of expected abnormal results was higherthan the yield of unexpected results. Showingthis to be true in patients who are clinically fit forsurgery supports the need for rational pre­operative laboratory testing.

This study found that the overall rate of expectedand unexpected abnormal values from pre­operative blood investigations to be 51.1% and34.4% respectively. Selective testing based onguidelines is beneficial as shown by the BUSECand RBS. However, the list of indications in thepresent guidelines may need to be modified asmany abnormal values were still left undetected.In addition, low conformity to the guidelinesmight be reflective of disagreement betweendoctors involved in pre-operative care and thepresently available guidelines.

Acknowledgements

The authors would like to thank Dr. NeelimaGhandam and Dr. Khoo Teik Hooi for their helpand advice with the collection of data for thisstudy. The authors would also like to thank theDirector General of Health of Malaysia forpermission to publish this article.

_3mlll••11 iIIllk _113 nF "jill. -12 Med J Malaysia Vol 58 No 1 March 2003

Pre-operative Investigations: Yield and Conformity to National Guidelines

1. Traber KB. Preoperative evaluation. In:Longnecker DE, Murphy FL (eds) Introduction toAnaesthesia. London : WE Saunders Company,1997.

2. Fildes ]], Robin AP. Preoperative andpostoperative care. In: Condon RE, Nyhus LM(eds) Manual of surgical therapeutics. New York:Lippincott Williams & Wilkins, 1996: 212-54.

3. Kaplan EB, Sheiner LB, Boeckmann A], et al. Theusefulness of preoperative screening. ]AMA 1985;253: 3576-81.

4. Charpak Y, BIery C, Chastang C, et al. Usefulnessof selectively ordered preoperative tests. Med Care1988; 26: 95-104.

5. Biery C, Charpak Y, Szatan M, et al. Evaluation ofa protocol for selective ordering of preoperativetests. Lancet 1986; 1: 139-41.

6. Chapter of Anaesthesiologists, Academy ofMedicine of Malaysia. Recommendations on Pre­anaesthetic Assessment. Kuala Lumpur, 1998.

7. McKee RF, Scott EM. The value of routinepreoperative investigations. Ann Roy ColI SurgEng 1987; 69: 160-62.

8. Turnbull ]M, Buck C. The value of preoperativescreening investigations in otherwise healthyindividuals. Arch Intern Med 1987; 147: 1101-05.

Med J Malaysia Vol 58 No 1 March 2003

9. Sanders DP, McKinney FW, Harris WH. Clinicalevaluation and cost effectiveness of preoperativelaboratory assessment on patients undergoing totalhip arthroplasty. Orthopedics 1989; 12: 1449-53.

10. Macpherson DS. Preoperative laboratory testing:Should the test be "routine" before surgery? Medelinof North Am 1993; 77: 289 - 307.

11. Roizen MF, Cohn S. Preoperative evaluation forelective surgery: What laboratory tests sre needed?In: Stoelting RK, Barash PG, Gallagher T] (eds).Advances in Anaesthesia. Chicago: Mosby, 1993.

12. Narr B], Hansen TR, Warner. Preoperativelaboratory screening in healthy Mayo patients:Cost-effective elimination of tests and unchangedoutcomes. Mayo Clinic Proceedings 1991; 66: 155­59.

13. Stoelting RK, Miller RD. Basics of Anaesthesia.London: WE Saunders Company, 2000.

14. Adams ]G, Weigelt ]A, Poulos E. Usefulness ofpreoperative laboratory assessment of patientsundergoing herniorrhaphy. Arch Surg 1992; 127:801-5.

15. Shekella P, Eccles MP, Grimshaw ]M, Woolf SH.When should clinical guidelines be updated? BM]2001; 323: 155-57.

13

Sex:

ORIGINAL ARTICLE

APPENDIX 1PROFORMA SHEET FOR COLLECTION OF DATA

Date:

Reference no:

DEMOGRAPHIC DATA AND SOCIAL HISTORY:

Name:

Registration No:

lIC No:

Address:

Race: Malay / Chinese / Indian/ Others (specify)

Age:

Weight:

Marital Status:

Smoking status: Never / Ex-smoker / Current smoker / Others

Use of Alcohol: Yes / No

SURGICAL INFORMATION:

Type of surgery:

Concomitant Diseases:

Medication: Yes / No

If Yes:

1.

2.

3.

4.

14

Cardiovascular Disease

Renal Disease

Haematological Disease

Liver Disease

Others (specify):

Diabetes Mellitus

Respiratory Disease

Clinical Anemia

Hepatobiliary Disease

Med J Malaysia Vol 58 No 1 March 2003

PRE-OPERATIVE INVESTIGATIONS:

Pre-operative Investigations: Yield and Conformity to National Guidelines

Laboratory Investigation Performed Value

1 ECG N/A

2 FBC:

Hb

TWBC

Platlet count

RBC count

MCH

MCV

3 Coagulation Proitle:

PT

APTT

4 LFTs:

Total Protein

Serum Albumin

Total Bilirubin

Enzymes - AST

ALT

LDH

5 CXR N/A

6 Renal Profile:

Blood Urea

Serum Na+

Serum K+

Serum Creatinine

7 RBS / FBS

Mad J Malaysia Vol 58 No 1 March 2003 15

ORIGINAL ARTICLE

APPENDIX 2GUIDELINES FOR PRE-ANAESmETIC LABORATORY INVESTIGATIONS

Recommended Pre-anaesthetic Investigations

These tests are recommended for administration of anaesthesia and are not intended to limit thoserequired for issues specific to their surgical management.

Full Blood CountAge above 60

Clinical anaemia

Haematological disease

Renal disease

Chemotherapy

Procedures with blood loss >15%

Blood Urea, Serum Electrolytes andCreatinineAge above 60

Renal disease

Liver disease

Diabetes Mellitus

Cardiovascular disease

Procedures with blood loss>15%

Random Blood SugarAge above 60

Diabetes Mellitus

Liver dysfunction

Liver Function TestsHepatobiliary disease

Alcohol abuse

Prothombin Time and activatedPartial Thromboplastin TimeHaematological disease

Liver disease

Anticoagulation

Intrathoracic/ Intra-cranial procedures

ElectrocardiogramAge above 50

Cardiovascular disease

Diabetes Mellitus

Renal disease

Chest X-rayAge above 60

Significant Respiratory disease Cardiovascular

disease

Note: for healthy patients undergoing short, minimally invasive procedures, investigations may not be

necessary.

16 Med J Malaysia Vol 58 No 1 March 2003