Hyperbilirubinemia as a predictor of gangrenous/perforated appendicitis: a prospective study
Poras Chaudhary, Ajay Kumar, Neeraj Saxena, Upendra C. Biswal
Postgraduate Institute of Medical Education and Research, Dr Ram Manohar Lohia Hospital (Dr RMLH and PGIMER), New Delhi, India
Abstract
Background The aims of the study were: 1) to establish the role of hyperbilirubinemia as a new diagnostic tool to predict gangrenous/perforated appendicitis; and 2) to compare other variables such as age, duration of symptoms, clinical profile, white blood cell count, C-reactive protein and ultrasound in a similar role.
Methods This is a prospective study conducted on 50 consecutive cases of acute appendicitis admitted to the emergency ward. These were subjected to investigations to support the diagnosis. These cases were also subjected to liver function tests and clinical diagnosis was confirmed perioperatively and post-operatively by histopathological examination. Their clinical and investigative data were compiled and analyzed. Statistical analysis was performed using either chi square test or fisher’s exact test. The level of significance was set at P< 0.05.
Results Total serum bilirubin including both direct and indirect was found to be significantly increased in case of acute suppurative appendicitis. Serum bilirubin was much higher (P <0.000) in cases of gangrenous/perforated appendicitis.
Conclusion Serum bilirubin is an important adjunct in diagnosing the presence of gangrenous/perforated appendicitis.
Keywords Acute suppurative appendicitis, gangrenous/perforated appendicitis, hyperbilirubinemia
Ann Gastroenterol 2013; 26 (4): 325-331
General Surgery, Postgraduate Institute of Medical Education and Research, Dr Ram Manohar Lohia Hospital (Dr RMLH and PGIMER), New Delhi, India
Funding: Financial support was provided by Dr Ram Manohar Lohia Hospital, New Delhi, India
Conflict of Interest: None
Correspondence to: Poras Chaudhary, M.S., General Surgery, Postgraduate Institute of Medical Education and Research, Dr Ram Manohar Lohia Hospital (Dr RMLH and PGIMER), New Delhi, India, Tel.: +98 914 47358, e-mail: drporaschaudhary@yahoo.com
Received 31 March 2013; accepted 13 June 2013
Introduction
Appendicitis is one of the commonest causes of abdominal pain requiring emergency surgery. Often, it is difficult to reach a proper diagnosis. There may not be classical symptoms and signs of appendicitis. Different clinical signs and symptoms always mimic the diagnosis of acute appendicitis, as there are a number of causes leading to pain in right iliac fossa particularly in female patients. Diagnosing acute appendicitis clinically still remains a common surgical problem. Accurate diagnosis can be aided by additional testing or expectant management or both. These might delay laparotomy and lead to appendiceal perforation with increased morbidity and hospital stay [1-3]. A safe alternative seems to be appendectomy as soon as the condition is suspected, a strategy that increases the number of unnecessary appendectomies [4,5]. A timelier and more accurate diagnosis has been attempted by the employment of additional laboratory tests [6-11], scoring systems [12-15], ultrasound imaging [16,17], computed tomography (CT) scan [18,19], scintigraphy [20], MRI [21], and laparoscopy [22-24]. None of these methods stands alone as they all come in support of, and are secondary to a primary clinical assessment.
Hyperbilirubinemia is a new diagnostic tool for perforation of appendix. Hyperbilirubinemia is the result of imbalance between production and excretion of bilirubin by the liver. It may be because of hepatocellular, cholestatic or hemolytic diseases. Liver receives blood mainly through the portal venous system, which receives blood from abdominal organs. Portal blood carries nutrients and other substances absorbed from gut including bacteria and its product (toxins). In a small percentage, even in normal healthy people, bacteria are found in portal blood. It is commonly cleared by detoxification and immunological action of the reticuloendothelial system of the liver that acts as first-line defense in clearing toxic substances, bacteria and its products. But when bacterial load overwhelms the Kupffer cell function, it may cause dysfunction or damage to hepatocytes (liver parenchyma). It reflects a rise in serum bilirubin (SB) alone or in combination with liver enzymes depending upon the type, severity and site of the lesion. Recently, another substance known as cytokines e.g. interleukin (IL)-6, tumor necrosis factor (TNF), has also been considered to be responsible for depressed excretory function of the liver and may lead to increase in SB levels without a rise in liver enzymes.
The association between the elevated SB levels and the variety of infectious diseases has been noted in few studies [25-27]. This finding most commonly occurs in neonates with gram negative bacterial infection. It has also been described in patients with severe intra-abdominal infection. The pathogenesis is thought to be because of bacteremia or endotoxinemia causing impaired excretion of bilirubin from the bile canaliculi. There are only a few reports in the literature that describe the finding of hyperbilirubinemia in patients with either severe post-operative infection after appendectomy or with complicated appendicitis.
The present study has been designed to evaluate the association between hyperbilirubinemia in cases of acute appendicitis and its complications. The significance of other parameters such as age, duration of symptoms, total leucocyte count (TLC), ultrasonography, Alvarado score and C-reactive protein (CRP) has also been evaluated in these cases.
The establishment of a possible role of hyperbilirubinemia as a predictor of gangrenous/perforated appendicitis has been stressed so that SB levels upon admission can be used in conjunction with other diagnostic tests such as ultrasonography and CT to help determine the presence of perforation and aid in proper clinical management.
Materials and methods
Study design
This was a single-center cohort, prospective study conducted by the department of Surgery from October 2008 to April 2010. 50 consecutive cases of acute appendicitis admitted in surgical unit 1 were recruited in the study. These were subjected to investigation to support the diagnosis. Investigation included total leukocytes count, differential leukocytes count, ultrasound, liver function tests (LFT) and CRP. The protocol was approved by the ethical review board of the Institute. According to the principles of the declaration of Helsinki 1975, written, informed consent was obtained from all participants.
Participants
The patients were selected from those attending the emergency department at the hospital. The age of patients varied from 15 to 64 years with most of the patients falling within the age range from 15-24 years. Inclusion criteria were: patients of 15 years of age and above scheduled for appendectomy for acute appendicitis at the emergency unit of our hospital. Exclusion criteria were: appendectomy performed incidentally or for other indications; age below 15 years; patients with appendicular lump; history of alcoholic liver disease; hemolytic or liver diseases associated with hyperbilirubinemia; history of gastrointestinal or hepatopancreatobiliary malignancy in the past. 64 patients were enrolled, 14 excluded. Out of these 14 patients, 3 had presence of liver abscesses, 4 had multiple large mesenteric lymph nodes, 2 had the presence of peritoneal tubercles suggestive of tuberculosis and 5 patients had multiple liver nodules suggestive of cirrhosis. Patients were clinically evaluated by detailed history, routine examination on initial contact with patients and the following investigations were done; complete hemogram, liver function test (LFT) (Table 1), kidney function test (KFT), blood sugar, CRP, serum proteins, X-ray chest posteroanterior (PA) view these investigations blood samples were drawn within half an hour of presentation in the emergency department and radiological investigations were done within 2 h of admission. Determination of SB was done with photometric testing using 2,4-dicholoroaniline. This method is based on the principle that in acidic solution, direct bilirubin forms a red colored azocompound with diazotized 2,4-dicholoroaniline. A specific mixture of detergents enables a safe determination of the total bilirubin.
Routine LFT results were compared with laboratory reference values given in Table 1. Alvarado scoring criteria is given in Table 2. These cases were operated and clinical diagnosis was confirmed per-operatively and post-operatively by histopathological examination. Final histopathological examination was considered as a gold standard for diagnosing and categorizing patients as having normal appendix, acute appendicitis and acute appendicitis with perforation and/or gangrene. Their clinical and investigative data were compiled and analyzed. Based on histopathological examination patients were categorized as negative (acute appendicitis without perforation or gangrene) and positive (acute appendicitis with perforation and/or gangrene).
Statistical analysis
Statistical analysis was performed by the SPSS program for Windows, version 17.0. Continuous variables are presented as mean ± SD, and categorical variables are presented as absolute numbers and percentage. Data were checked for normality before statistical analysis. Normally distributed continuous variables were compared using the unpaired t test, whereas the Mann-Whitney U test was used for those variables that were not normally distributed. Categorical variables were analyzed using either the chi square test or Fisher’s exact test. A receiver operating characteristics analysis was calculated to determine optimal cut-off values for SB, TLC, CRP, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and Alvardo score. The area under the curve, the sensitivity, and the specificity was calculated to analyze the diagnostic value of all these markers. For all statistical tests, a P value less than 0.05 was considered statistically significant.
Results
General characteristics
Of 50, 40 cases were male and 10 female. Their age ranged from 15-60 years. The average was 27.1 years (Table 3). Duration of symptoms ranged from 1-5 days. Among 50 cases clinically diagnosed as acute appendicitis preoperatively, 42 had acute appendicitis, 3 had gangrenous appendix, 5 cases had perforated appendix and no patient had normal appendix.
Evaluation of LFT (Tables 4,5)
Among 50 cases, total SB (TSB) was raised in 38 (76%) cases whereas 12 (24%) cases had normal TSB level. TSB was more elevated in gangrenous and perforated appendix than those in acute appendicitis (P<0.001). The mean of TSB in acute appendicitis cases without perforation or gangrene was 1.52 mg/dL and the mean of TSB in cases with perforated or gangrenous appendix was 3.62 mg/dL (ranged from 3.0- 5.0 mg/dL).
Liver enzyme ALT was within normal range in 40 (80%) cases, and minimally elevated (<2 times) in 10 (20%) cases. AST was within normal range in 45 (90%) cases, minimally elevated (<2 times) in 4(8%) cases, and moderately elevated (>2 times) in 1 (2%) case. ALP was within normal range in 46 (92%) cases, minimally elevated (<2 times) in 3 (6%) cases, moderately elevated (>2 times) in 1 (2%) case.
Alvarado score (Table 6)
Alvarado score was calculated based on the criteria given in Table 2 and P value for Alvarado score was 0.01.
Comparing different parameters
Comparison of of different parameters- SB, TLC, liver enzymes, Alvarado score, CRP and duration of symptoms and their sensitivity, specificity, positive and negative predictive value with the relevant P values are shown in Tables 7 and 8.
Discussion
In this study of 50 patients, hyperbilirubinemia was found in 30 of 42 patients with acute suppurative appendicitis and in all 8 patients with gangrenous/perforated appendicitis. This hyperbilirubinemia was mixed in type (both conjugated and unconjugated) in most of the patients and at the same time there was no elevation or minimal elevation (<100 U/L) in ALT and AST in most of the cases. Similarly, ALP was either within the normal range or was minimal to moderately elevated.
For gangrenous/perforated appendicitis, the P-value of SB was <0.001, specificity 92.9%, sensitivity 100%, positive predictive value 72.7% and negative predictive value was 100%.
The level of SB was higher than 3 mg/dL in cases of gangrenous/perforated appendicitis while in cases with acute appendicitis it was lower than 3 mg/dL (P<0.05). Broadly, we can say that it was predominantly isolated hyperbilirubinemia in the majority of cases. These findings are almost similar to another reported study [28]. Since these findings were documented at the time of admission, it is unlikely that liver injury because of anesthetic agents, blood transfusion, or medication was the cause of elevated bilirubin levels. Moreover, as per our exclusion criteria patients with alcoholic liver disease, viral hepatitis, hemolytic or congenital liver diseases were excluded from the study.
The most likely explanation of the rise in SB is therefore circulating endotoxinemia as a result of appendiceal infection. Utili et al [29-31] has shown with in vitro infusion of endotoxin into the isolated rat liver that there is a dose-dependent decrease in bile salt excretion from the liver and that it is possible that Escherichia coli endotoxin exerts direct damage at the cholangiolar level.
It was demonstrated by Sisson et al in 1971 [32] that in appendicitis mucosal ulceration occurs early and this facilitates invasion of bacteria into the muscularis propria of the appendix thereby causing classical acute suppurative appendicitis. Subsequent events lead to edema, elevated intraluminal pressure, and ischemic necrosis of mucosa, causing tissue gangrene and perforation [33,34]. This process is associated with progressive bacterial invasion most likely facilitated by bacterial cytotoxins. The number of organisms isolated from patients with gangrenous appendicitis is five times greater than those with acute suppurative appendicitis. Estrada et al [35] also found significantly higher peritoneal culture in patients with gangrenous/perforated appendicitis.
This elevated load of bacteria in appendicitis causes either direct invasion or translocation into the portal venous system. Direct invasion of bacteria into the hepatic parenchyma interferes with the excretion of bilirubin into the bile canaliculi by a mechanism that is thought to be caused by the bacterial endotoxin and is biochemical in nature rather than obstructive.
Indirect evidence of bacterial translocation from inflamed gastrointestinal tract or peritonitis to the liver via the portal vein and the development of hepatitis and pyogenic liver abscess was observed by Dieulafoy [36]. Two classical findings were described: firstly, simultaneous inflammation of the intestine (e.g. appendix), peritoneum and development of pyogenic liver abscesses, and secondly, bacteriological similarities of the gastrointestinal tract and pyogenic liver abscesses. These bacteria commonly reach liver from intra-abdominal organs, commonly from the appendix.
Direct evidence of bacterial translocation from inflamed organs was observed in clinical and experimental studies. Recently, in one study, blood samples from the superior mesenteric vein in acute appendicitis showed bacteria in 38% of patients. These findings suggest that bacteria may transmigrate and produce portal bacteremia, hepatocellular dysfunction or pyogenic liver abscess. This low percentage of positive blood cultures cannot explain hepatocellular dysfunction in the majority of cases. Thus, there must be other substances involved. It has been shown that liver dysfunction is caused by cytokines released from the gut due to injury/ inflammation. In a study [29,30], rats were subjected to intra-abdominal sepsis from cecal ligation and puncture and the following observations were made: 1) the small intestine is an important source of adrenomedullin release during poly microbial sepsis; 2) norepinephrine induced hepatocellular dysfunction in early sepsis, mediated by activation of α-2 adreno-receptors; and 3) TNF produces hepatocellular dysfunction despite normal cardiac output and hepatic microcirculation [37].
Thus, it is concluded that hepatocellular function is depressed during the early stage of sepsis despite the increased cardiac output and hepatic blood flow and decreased peripheral resistance. The depression of hepatocellular function in the early, hyper-dynamic stage of sepsis does not appear to be due to reduction in hepatic perfusion but is associated with elevated levels of circulating pro-inflammatory cytokines such as TNF and IL-6. Thus up regulation of TNF and/ or IL-6 may be responsible for producing hepatocellular dysfunction during the early hyper-dynamic stage of sepsis.
Our study shows that isolated hyperbilirubinemia without much elevation in the liver enzymes is a significant predictor of appendiceal perforation. This was demonstrated by a study by Estrada et al [35] and other studies [38,39] showing nearly a threefold risk of perforated appendicitis in patients with total bilirubin levels greater than 1 mg/dL. The other factors which we studied in this series were age, duration of symptoms, Alvarado score, total leukocyte count, ultrasonography, and CRP. P value was not significant in any of these criteria except CRP (P<0.001).
The positive predictive value of SB and CRP was 72.7% and 80%, comparable to other published studies [40,41]. The negative predictive value of SB was 100% in our study as compared to 16% in the study by Khan et al. The negative predictive value of CRP was also 100% in our study. Therefore, in suspected cases of appendicitis elevation of SB/CRP can be used as a criterion to diagnose and manage acute appendicitis. Both sensitivity and specificity of elevated total SB level and CRP in acute appendicitis with perforation and/or gangrene is higher as compared to TLC and liver enzyme. This finding is similar to other reported studies [35,42,43].
This study also shows that the Alvarado scoring system is also of great value with a significant P value and comparable sensitivity and specificity.
Therefore, SB estimation, a simple cheap and easily available test in every laboratory, can be added to the routine investigation list of clinically suspected case of acute appendicitis for the confirmation of diagnosis. Since the rise in SB level was significantly higher in patients with appendiceal perforation, it has a definite predictive potential in these cases. Therefore, obtaining SB values upon admission can be used in conjunction with more modern diagnostic tests such as CT scan, ultrasonography to help determine the presence of perforation and thus aid in prompt clinical management.
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