Correspondence:
Majed Ahmad Sarayrah
drmajedsar@hotmail.com

INTRODUCTION

Routine pre-operative investigations are used in most patients admitted for elective minor surgery in order to identify those at high risk of complications. Despite the fact that routine screening tests has no major influence in the management of the elective surgical patients, these tests continue to be performed in some hospitals. It is generally accepted that clinical history and physical examination represent the best method of screening the presence of a disease. Performing routine laboratory tests in patients who appear healthy after such screening is invariably of little use and a waste of resources. Several pre-operative screening investigations in the general surgical population have been evaluated and their benefit questioned. Routine laboratory screening does not remove the possibility of peri-operative complications. In this study, we examined the value of widely accepted pre-operative investigation in otherwise healthy children scheduled for elective minor surgery.

The medical records of the children who underwent routine elective minor surgical procedures in the division of pediatric surgery, King Hussein Medical Center, Amman, Jordan in the period from January 2006 to December 2007 were reviewed with respect to their age, sex, diagnosis, results of pre-operative investigations (complete blood count (CBC), urea and electrolytes), operative and post operative complications. Pre-operative investigations were assumed to be performed one day before surgery. Patients who had active or ongoing disease and those on certain medications such as steroids that reflected active medical illness which could influence the outcome of surgery, were excluded. All abnormal results were identified. The numerical value of each result defined as abnormal when its value fell outside the normal range was determined by the stated reference range on the hospital blood form (mean+_ standard deviations).
Changes in patient management or decision making because of abnormal blood test result were noted. All complications occurring during operative and post-operative periods were noted in detail stating whether the pre-operative blood tests were normal or not. The data were analyzed to determine the frequency of laboratory abnormalities and their effects on cancellations, intra-operative and post-operative complications.

During a one year period, the charts of 430 children scheduled for routine elective minor surgery were reviewed. There were 314 males and 116 females with a mean age of 4 years (range from one month to 13 years). The surgical procedures that had been done were inguinal herniotomy, orchidopexy, hydrocelectomy, repair umbilical hernia, repair epigastric hernia, esophageal dilatation, excision thyroglossal cyst, and excision branchial sinuses and other lumps.

A total of 860 blood tests were done pre-operatively. Eighty-six (10%) results were abnormal. Abnormal hemoglobin levels were obtained in twelve patients (1.3%), the lowest was 8.5 gm/dl in a 3-year old girl with bilateral inguinal hernia. The other eleven had hemoglobin levels between 9-10gm/dl. No operation was canceled due to an abnormal result and no blood transfusions were administered to this group of children. Thirty-one children had abnormal platelet count. Only one, otherwise healthy child had a low platelet count (120*10/L) and the other thirty had a higher platelet count, the highest being 592*10/L. No action was taken and no complications related to abnormal platelet counts were observed. Abnormal white cell counts (WBC) were found in 22 children of whom none were less than 3.0*10/dl and only 4 were more than 14,000. No pre-operative management was altered due to abnormal WBC count and no complication arose. There were 26 abnormal urea and electrolytes results from 430 results. There were 14 abnormal potassium results, but no one was outside the traditionally accepted surgical anesthetic limits of 30.2-5.8 mmol/L. Ten children had abnormal sodium results. The lowest value was 132 mmol/L and the highest was 147 mmol/L. There was no associated anesthetic intervention in any of these patients and there was no operative or post operative complications. Four complications occurred, 2 wound infections, one hematoma at wound site and one hernia recurrence, all of them in patients with normal complete blood count and normal urea and electrolytes.

A policy of routine blood testing before operations has become ingrained in surgical and anesthetic practice. Performing an investigation to detect an abnormality seems a very reasonable action. However, before requesting an investigation, one should answer the following questions:
1. will this investigation yield more information not revealed by history and physical investigation?
2. Will the result alter the management plan?

These questions are of paramount importance if the burden of work on hospital staff is to be reduced, and if patients are not to be subjected to further investigations on the basis of a borderline abnormal result. Delahunt and Turnbul¹⁴ and later Kaplan et al⁵ demonstrated that many pre-operative screening tests in the general surgical population rarely detected abnormalities, and when abnormalities were detected management was not altered significantly. Wilson et a¹⁶ demonstrated that in 96% of cases, the decision regarding fitness for elective surgery can be made on the basis of history and clinical examination alone. In our study, 86 of 860 tests (10%) were abnormal, a figure which is very similar to that found by Johnson7 and Johnson et al⁸. No case was postponed as a result of these investigations. Blery et a¹⁹ believed that the elimination of unnecessary routine test is of great importance, particularly in healthy patients undergoing elective surgery.
Detecting a minor or moderate degree of anemia before a minor surgical procedure may not contribute to the general health of the child. Mild degrees of anemia may not be detected clinically from medical history or physical examination. However, mild anemia should not increase the risk of general anesthesia and the anesthetic techniques need not be modified in any way to accommodate the mildly anemic state. The minimal safe level of hemoglobin required before administration of general anesthesia is unknown. There is no published evidence that operating on children with mild anemia is unsafe.
The prevalence of unanticipated elevations of white blood cell count is very low. Turnbull et al and Rohrer et al assessed management changes related to abnormal white cell counts and found that no patients had a management change. No antibiotic was given pre-operatively or post operatively in the cases of elevated white blood cell count. No management was altered, and no complication arose due to the abnormal results.
The majority of the abnormalities in our series were the high platelet count (30 cases) seemed to be an aberration of the normal range rather than a significant clinical feature. Most of these abnormal results were coincidental findings in tests routinely performed along with the hemoglobin, and there were no indications for them to have been specifically requested. There was no evidence from the clinical records that these results made any difference to the clinical course or outcome. No further tests were deemed necessary in this group. For these reasons, routine platelet counts are not recommended before surgery unless the history and the physical examination suggests a high likelihood of thrombocytopenia or thrombocytosis.
The relationship between electrolyte abnormalities and perioperative morbidity and mortality is poorly defined¹⁸. Pre-operative routine biochemistry testing in routine elective minor surgery has an extremely low yield of abnormal results. The low percentage of patients who had abnormal results regarding potassium and sodium levels was neglected as none were outside the traditionally acceptable surgical and anesthetic limits¹⁹.
We believe that routine pre-operative blood tests are not indicated in all children, and we have recommended the following:
a) A detailed clinical history and physical examination should be performed and findings from these should guide the selection of blood tests;
b) History of pre term birth, a pre-existing medical illness, failure to thrive, recent history of blood loss, and a significant family history of blood diseases such as anemia, are indications for further investigation.

In conclusion, routine pre-operative testing of all patients before minor elective surgery is unjustified. The frequency of unanticipated abnormalities is too low to justify a practice pattern of testing all patients. The practice of selective testing of children, after a careful history and physical examination should decrease the discomfort of the child and the family, as collecting a blood sample from a child can often be an unpleasant experience for all concerned, and reduce laboratory costs without compromising safety and quality of care²⁰.

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