To Determine the Diagnostic Accuracy of Total Leukocyte Count in Acute Appendicitis

Objectives: To determine the diagnosis accuracy of total leukocyte count in acute appendicitis keeping histopathology as gold standard.

Material and Methods: The study was performed in Department of General Surgery Lady Reading Hospital , Peshawar from 16th February 2016 to 16th august 2016. In this study a total of 163 patients were observed. Complete history, physical examination, and investigations (KUB), ultrasound abdomen were performed. Decision regarding appendicectomy was made by a single consultant surgeon based on his clinical assessment. All the included patients were prepared for surgery to be operated on the elective list next day same consultant surgeon. Post operatively the appendix specimen was collected, preserved in formalin solution and sent to a single expert histopathologist. The patient’s histopathology reports were followed up for in outpatient department. The exclusions criteria was strictly followed to control confounders and exclude bias in the study results.

Results: Our study shows that mean age was 32 years with SD ± 7.84. 38% patients were male while 62% patients were female. Diagnostic accuracy of AP on total leukocyte count and histopathology as gold standard was analyzed as the sensitivity was 78%, specificity was 27%, Positive predictive value was 94%, Negative predictive value was 8% and the overall diagnostic accuracy was 75%.

Conclusion: Our study concludes that total leukocyte count had sensitivity 78%, specificity 27%, Positive predictive value 94%, Negative predictive value was 8% and the overall diagnostic accuracy was 75% in the diagnosis of acute appendicitis.

Key Words: diagnosis accuracy, total leukocyte count, acute appendicitis, histopathology

Received: June’2019                      Accepted: July’2020

INTRODUCTION

Appendicitis is caused by a blockage of the hollow portion of the appendix,1,2 most commonly by a calcified “stone” made of feces. However, inflamed lymphoid tissue from a viral infection, parasites, gallstone, or tumors may also cause the blockage.3 This blockage leads to increased pressures within the appendix, decreased blood flow to the tissues of the appendix, and bacterial growth inside the appendix causing inflammation.4,5 The combination of inflammation, reduced blood flow to the appendix and distention of the appendix causes tissue injury and tissue death.6 If this process is left untreated, the appendix may burst, releasing bacteria into the abdominal cavity, leading to severe abdominal pain and increased complications.6,7

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Total leukocyte count had sensitivity 78%,
specificity 27%, Positive predictive value 94%.
Negative predictive value was 8% and the overall
diagnostic accuracy was 75% in the diagnosis of
acute appendicitis.

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Acute appendicitis is defined as acute inflammation of the vermiform appendix. It is one of the most common surgical emergencies in both developed and developing countries. Approximately 6% of the population suffers acute appendicitis during their lifetime. It was Reginald Heber Fits who in 1886 described signs and symptoms of acute appendicitis.8,9 Delay in the diagnosis of acute appendicitis can lead to increased mortality and morbidity. The complications of acute appendicitis are perforation and appendicular mass, which are associated with increased mortality of 6% as compared to 1% mortality of uncomplicated appendicitis10. Thus surgeons have a traditional approach of early intervention even in the absence of definitive diagnosis11. Early appendicectomy is the only treatment in majority of cases. Negative appendectomy rate of 15-40% has been reported in the literature and many surgeons would accept this rate as inevitable11. This high negative appendecetomy rate warrants supplementary investigations that can improve the diagnosis accuracy and further reduce the number of negative appendicectomies without thereby increasing the perforation rate.12 In acute appendicitis, total leukocyte count and neutrophil percentage are the most frequency used laboratory tests.13 Most of the studies conclude that 60-90% of all patients with acute appendicitis have total and differential leukocyte counts suggestive of diagnosis. In one study the sensitivity and specificity of total leukocyte count for diagnosing acute appendicitis has been reported as 75.6% and 73.7% with a proportion of 81% acute appendicitis.14 While there is no laboratory test specific for appendicitis, a complete blood count (CBC) is done to check for signs of infection. Although 70- 90 percent of people with appendicitis may have an elevated white blood cell (WBC) count, there are many other abdominal and pelvic conditions that can cause the WBC count to be elevated.15 Appendicitis is most common between the ages of 5 and 40;15 the median age is 28. It tends to affect males, those in lower income groups, and, for unknown reasons, people living in rural areas.16 In 2013 it resulted in 72,000 deaths globally down from 88,000 in 1990.17 In the United States, there were nearly 293,000 hospitalizations involving appendicitis in 2010. Appendicitis is one of the most frequent diagnoses for emergency department visits resulting in hospitalization among children aged 5–17 years in the United States. Appendicectomy is the most common operation performed in general surgery units. A big proportion of patients are operated unnecessary that is not only harmful to the patients but also drains the hospital resources. It also wastes the precious time of medical professionals who perform unnecessary operations. To document the diagnostics accuracy of total leukocyte count, the validation study will be done taking histopathology of remove appendix as gold standard. Based on results of this study we can recommend the use of total leukocyte count in conjunction with history, physical examination and ultrasonography in the diagnostic process of acute appendicitis for improving decision making and reducing the negative appendicectomy rates in this common condition and thus avoiding unwanted operations.

MATERIAL AND METHODS

This cross sectional validation study was conducted at surgical department of Lady Reading Hospital, Peshawar from 16/02/2016 to 16/8/2016. A total of 163 patients were observed. Inclusion criteria were Males and females above 12 - 65 years of age with clinically diagnosed cases of acute appendicitis with any total leukocyte count. Patients with ovarian cyst (US /CT detected), Patients with right sided ureteric colic (KUB and US detected).Diagnosed cases of appendicular mass and abscess (US / CT detected) were excluded. They had act as confounders and if included these conditions may introduce a bias in the study results. After taking permission from the hospital ethical committee all the patients presenting with symptoms of abdominal pain that migrate to right iliac fossa, anorexia, nausea, vomiting, fever, tenderness in the right iliac fossa, rebound tenderness in the right iliac fossa and fulfilling the inclusion criteria were admitted in surgical D unit through OPD and Emergency Department. All the included patients were explained the purpose and procedure of the study and an informed written consent was obtained. Complete history, physical examination, investigations and ultrasound abdomen was performed Decision regarding appendicectomy was made by a single consultant surgeon based on his clinical assessment. All the included patients were prepared for surgery to be operated on the elective list next day same consultant surgeon. Post operatively the appendix specimen was collected, preserved in formalin solution and sent to a single expert histopathologist. The patient’s histopathology reports were followed up for in outpatient department. The exclusions criteria was strictly followed to control confounders and exclude bias in the study results. Patient’s characteristics i.e., name age, gender, clinical findings, investigations and biopsy report were recorded into a proforma. All the data was analyzed be SPSS version 10.0, Frequency and percentages were calculated for categorical variables like gender, leukocytosis while numerical variables like age were presented with Mean + SD. The sensitivity, specificity, positive predictive value and negative predictive value and accuracy of leukocytosis was then be determined by taking histopathology as gold standard from table below.

Sensitivity = (a/a+c) x 100
Specificity = (d/ d+b) x 100
Positive predictive value = (a/ a+b) x 100
Negative predictive value = (d/ d+ c) x 100.
Accuracy = a +d/a +b+c x 100

RESULTS

In this study the age distribution among 163 patients was analyzed as 30(18%) patients were in age range 18-25 years, 54(33%) patients were in age range 26-35 years. 47(29%) patients were in age range 36-45 years, 24(15%) patients were in age range 46-55 years. 8(5%) patients were in age range 56-65 years. Mean age was 32 years with SD ± 7.84.
Gender distribution among 163 patients was analyzed as 62(38%) patients were male while 101(62%) patients were female. Acute appendicitis on total leukocyte count was among 163 patients was analyzed as AP on total leukocyte count was positive in 127(78%) patients and was negative in 36(22%) patients. While AP on histopathology was positive in 152(93%) patients and was negative in 11(7%) patients. (table No 3,4). Diagnostic accuracy of AP on total leukocyte count and histopathology as gold standard was analyzed as the sensitivity was 78%, specificity was 27%, Positive predictive value was 94%, Negative predictive value was 8% and the overall diagnostic accuracy was 75%. Diagnostic accuracy of total leukocyte count with respect to age and gender is given in tables.

Negative predictive value = 9%,Diagnostic Accuracy = 0=75%

DISCUSSION

Appendicitis is caused by a blockage of the hollow portion of the appendix,1,2 most commonly by a calcified “stone” made of feces. However, inflamed lymphoid tissue from a viral infection, parasites, gallstone, or tumors may also cause the blockage.3 This blockage leads to increased pressures within the appendix, decreased blood flow to the tissues of the appendix, and bacterial growth inside the appendix causing inflammation.4,5 The combination of inflammation, reduced blood flow to the appendix and distention of the appendix causes tissue injury and tissue death.6 If this process is left untreated, the appendix may burst, releasing bacteria into the abdominal cavity, leading to severe abdominal pain and increased complications.6,7 Our study shows that mean age was 32 years with SD ± 7.84. Thirty eight percent patients were male while 62% patients were female. Diagnostic accuracy of AP on total leukocyte count and histopathology as gold standard was analyzed as the sensitivity was 78%, specificity was 27%, Positive predictive value was 94%, Negative predictive value was 8% and the overall diagnostic accuracy was 75%. Similar results were observed in another study conducted by Alam B et al18 in which 147 patients that underwent appendecectomy, including 82 males and 65 females. TLC was raised (above 11000/mm3)in 89 patients while 58 had TLC within normal range (below 11000/ mm3). Depending on operative findings, majority of the patients (68%, n=100) had markedly inflamed appendix while 45 (30.6%) had mildly inflamed and only two (1.4%) had normal looking appendix. On histopathological examination appendix was found to be acutely inflamed in 128 (87%) patients while 19 (13%) patients had negative appendicectomy. The raised TLC had a sensitivity of 64.8%, specificity 89.4%, positive predictive value 97.6%, negative predictive value 27.5%, and accuracy 68%. Similar results were observed in another study conducted by Kamran H et al19 in which TLC is 76.5% sensitive and 73.5% specific, with a positive predictive value of 92.5%. Similar results were observed in another study conducted by Lee WPR et al20 in which TLC was diagnosed in acute appendicitis reported a high sensitivity and moderate specificity of 83% and 62.1% respectively. The positive predictive value and negative predictive value for white cell count were 92% and 96% respectively. Khan MN et al21 had reported the role of raised TLC in the diagnosis of acute appendicitis. The cut off value for positive TLC was 11000/mm3. The results showed that TLC was moderately sensitive (64.8%) and specific (89.4%) for the diagnosis of acute appendicitis; and with high positive predictive value of 97.6% it is a good choice for emergency investigations to cater with suspected cases of appendicitis.

CONCLUSION

Our study concludes that total leukocyte count had sensitivity 78%, specificity 27%, Positive predictive value 94%, Negative predictive value was 8% and the overall diagnostic accuracy was 75% in the diagnosis of acute appendicitis.

4. Persistent Fetal Vasculature with AIDS

A 48-year-old man with AIDS (CD4 lymphocyte count, 27 cells/mm3) presented with headache and fever, with mild blurring of vision in the right eye, 20/40 and 20/20 in the left, with no afferent pupillary defect. The right eye showed marked disc edema, intraretinal hemorrhage, preretinal hemorrhage, vitreous hemorrhage, macular edema, and hard exudates. The left eye had mild sectoral disc edema and a few flame-shaped hemorrhages. There was no evidence of infectious retinitis. Lumbar puncture revealed an open¬ing pressure of 35 cmH2O and positive cryptococcal antigen in the cerebrospinal fluid. The patient was treated with IV amphotericin and fluconazole. On repeat lumbar puncture, the opening pressure was normal (13 cmH2O). The disc edema and hemorrhage resolved, and the patient’s visual acuity returned to 20/20 in both eyes.

Written by Tahira Scholle, MD, Baylor College of Medicine, Houston. Photo by Denise Swartz Thompson, Parkland Hospital, Dallas.

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