European Journal of Cardiovascular Medicine

The most frequent reason for emergency surgery is appendicitis [1,2].  Although the appendix is one of the surgically most researched organs, we are still a long way from creating a single test (either radiological or laboratory) that can definitively identify acute appendicitis.  Acute appendicitis has been diagnosed using standard blood tests like white blood cell (WBC) count, neutrophil count, C-reactive protein (CRP), bilirubin, alanine transaminase (ALT), and albumin. More recently, new blood markers for acute appendicitis have been proposed, including procalcitonin, interleukin-6 (IL-6), serum amyloid-A (SAA), granulocyte colony-stimulating factor (G-CSF), and calprotectin [3–10].

In order to distinguish between simple and complex appendicitis, blood results ratios such as the white cell lymphocyte ratio, white cell neutrophil ratio, and neutrophil ratio have also been investigated [11].  All of these individual tests have serious problems with sensitivity and specificity.  In an attempt to improve the sensitivity and specificity of these widely used blood tests, some studies have integrated different blood indicators (such as WBC count, neutrophil count, and CRP), according to a systematic review by Kabir et al.  Despite the positive outcomes of these combined blood panels, Kabir acknowledges that further study is required in this field [10].

Acute appendicitis is therefore still primarily a clinical diagnosis.  This may have a lot of repercussions.  Complications from a delayed or missed diagnosis may include perforation, the development of an abscess, or in the worst situations, death [1].  Additionally, it may be overdiagnosed; according to hospital reports, the negative appendectomy rate ranges from 3.3% to 26.7% [12–18].  Every negative appendectomy results in a patient undergoing a needless surgical operation.  In addition to the risks of hospitalization, such as deep vein thrombosis, pulmonary embolism, and hospital-acquired infection, it exposes the patient to risks of surgery, including anesthesia, bleeding, peri-operative infection, abdominal viscera perforation, pain, scarring, and the formation of adhesions and a collection after surgery.  Utilizing hospital resources, including inpatient beds, which are already scarce, is another unintended consequence.

Therefore, the purpose of this study was to evaluate the diagnostic utility of commonly accessible inflammatory biomarkers for acute appendicitis. To determine whether this might improve the sensitivity and specificity of diagnosing histologically inflamed acute appendicitis, inflammatory biomarkers were also examined in various combinations.

This study was a retrospective and descriptive observational study done in a tertiary medical college in central India from 1st October 2023 to September 2024 on a total of 241 patients of acute appendicitis undergoing appendectomies in the dept. of General surgery. We reviewed all of the admission bloods for the patients - including their white blood cell (WBC) count, their neutrophil count, and their C-Reactive protein (CRP) value. We also reviewed all of the histology to identify the inflamed appendices, and analyzed all of this information together.

The blood results (WBC, neutrophils, and CRP) and histology for all of these patients were reviewed and analysed using an Excel spreadsheet. A review of the ultrasound (US) imaging done on each of these patients was also carried out. Normal CRP levels are considered as <=5 mg/L - regardless of age of patient. CRP levels of >5 mg/L are considered high. Reference ranges for normal WBC serum levels are 4 - 11 (x109/L) in the adult population. Reference ranges for normal WBC serum levels are 4 - 14.5 (x109/L) in the paediatric population (age <=12 years old). WBC <4 (x109/L) is considered low for the adult and paediatric population. WBC >11 (x109/L) is considered high for the adult population. WBC >14.5 (x109/L) is considered high for the paediatric population (age >12 years old). The normal reference range for the absolute neutrophil count (ANC) is 1.5 - 8 (x103/mL) for the adult and paediatric population. ANC is considered low if it is <1.5 (x103/mL). ANC is considered high if it is >8 (x103/mL).

Descriptive statistics were used to assess patient demographics and blood results against the histological findings. The Pearson Chi2 test was used to analyse the variables. A p-value of less than 0.05 was taken to be statistically significant. All statistical analyses were performed using the software Stata/IC 13.1 (StataCorp., College Station, TX, USA) for Mac (64-bit Intel).

In our study, a total of Two hundred forty-one appendectomies were performed between 1st October, 2023 and 30th September, 2024. One hundred seventy-five (73%) appendixes had histopathological findings of inflammation, 173 of these (98.8%) were reported as inflamed. One appendix was found to have a mucinous neoplasm, and one appendix contained a neuroendocrine carcinoid tumour. Sixty-six appendixes had normal histopathological findings - this includes one appendix that had a faecolith noted on analysis. The negative appendectomy rate was 27.4%.

A breakdown of the demographics and operative method can be found in Table 1. One hundred thirty-one (54%) of the patients were male and 110 (46%) were female. In total, 54 (22%) patients who underwent an appendectomy were aged 12 or under, 62 (26%) patients were aged between 13 and 18, and 125 (52%) patients were over 18 years old. The mean age of all 241 patients was 25.4 years.

One hundred seventy-seven (73%) appendixes were removed laparoscopically, and 64 (27%) were removed as an open procedure. Of the 64 open appendectomies performed, 42 (66%) were performed on the paediatric population (<=18 years old) even though they represented 48% of the total number of appendectomies.

CRP analysis

A CRP was done on 173 of the 175 patients who had a histologically inflamed appendix, and 61 of the 66 normal appendixes. The CRP was normal in 41 (24%) inflamed appendixes, and elevated in 132 (76%) inflamed appendixes. Out of the 66 non-inflamed appendixes, CRP was normal in 41 (67%) patients, and was elevated in 20 (33%) patients. The mean CRP values for the inflamed appendixes was 59.2, and it was 22.5 in the normal appendixes. The results are summarised in Table 2 below.

The sensitivity of using an elevated CRP to diagnose a histologically inflamed appendix was 76%. The specificity was 67%. The positive predictive value (PPV) of an elevated CRP was 87%. The negative predictive value (NPV) was 50%.

WBC analysis

A full blood count (FBC) was done on 174 of the 175 patients who had a histologically inflamed appendix, and 64 of the 66 normal appendixes. The WBC was normal for 43 (25%) inflamed appendixes, low for two (1%) of them and elevated in 129 (74%) inflamed appendixes. Out of the 64 non-inflamed appendixes, WBC was normal in 40 (63%) patients and elevated in 24 (37%) patients. The mean WBC count for the inflamed appendixes was 15.1 and 10.2 for the normal appendixes. The results are summarised in Table 3 below.

The sensitivity of using a high or low WBC to diagnose a histologically inflamed appendix was 75%. The specificity was 63%. The positive predictive value of a high or low WBC was 85%. The negative predictive value was 48%.

Neutrophil analysis

The neutrophil count was normal for 31 (18%) inflamed appendixes, and elevated in 143 (82%) inflamed appendixes. Out of the 64 non-inflamed appendixes where an FBC was done, neutrophil count was normal in 40 (63%) patients and elevated in 24 (37%) patients. The mean neutrophil count for the inflamed appendixes was 12.4 and 7.1 for the normal appendixes. The results are summarised in Table 4 below.

The sensitivity of using a high neutrophil count to diagnose a histologically inflamed appendix was 82%. The specificity was 63%. The positive predictive value of a high neutrophil count was 86%. The negative predictive value was 56%.

Histology and combined blood panel results

Out of the 175 histologically inflamed appendixes, 174 had either an FBC or CRP taken. Ninety-nine (57%) patients had a combination of elevated CRP, leukocytosis (or leukopenia), and neutrophilia. Seven patients with histologically confirmed appendicitis had a normal CRP, WBC count and neutrophil count. Five of these seven patients were under the age of 18. The sensitivity of either a high CRP, leukocytosis or neutrophilia was 96%. The specificity was 45%. The positive predictive value of abnormal blood results was 83%. The negative predictive value was 81%. These results are summarised in Table 5.

TABLE 1 showing breakdown of inflamed versus non-inflamed appendixes.

Table 2 showing Correlation of histology and C-Reactive protein (CRP) results.

                          * 2 patients did not have a CRP taken

                          ^ 5 patients did not have a CRP taken

Table 3 showing Correlation of histology and white blood cell (WBC) results.

                           * 1 patient did not have a WBC taken

                           ^ 2 patients did not have a WBC taken

Table 4 showing Correlation of histology and neutrophil count.

                          * 1 patient did not have a neutrophil count taken

                          ^ 2 patients did not have a neutrophil count taken

Table 5 showing Correlation of histology and any raised blood marker.

Table 6 showing Summary of findings for each blood results.

All patients who visit the emergency department with symptoms of infection or inflammation undergo a routine blood panel. This includes an FBC, CRP and a metabolic/renal profile. Currently, there is no single blood or urine marker that can accurately diagnose acute appendicitis. The blood markers currently used are not sensitive or specific enough for this purpose. Our study has shown that by combining commonly used blood markers, their sensitivity to detect acute appendicitis can be increased to 96%.

A comprehensive study conducted by Kabir et al. has shown that relying solely on a white blood cell count to diagnose appendicitis is not reliable, as it can be elevated in response to various inflammatory conditions [10]. Shogilev et al. Describe multiple different cut-off values ranging from 9.4 to 14.6 (x109/l) with no clear recommendation on which one is best in the context of identifying acute appendicitis [3]. It is important to note that the commonly accepted range for a normal white blood cell count is between 4 and 11 (x109 /l), so some of the studies included in Shogilev's analysis were using counts that would be considered normal. By accepting low threshold wbc counts, we would anticipate an increase in sensitivity but a decrease in specificity - rendering the test less valuable. Our study revealed that the white blood cell count had the lowest sensitivity (75%) and specificity (63%) among the three blood results we analyzed. The sensitivity and specificity of the systematic review conducted by Shogilev et al. (65-85% and 32-82%, respectively) were within the given range.

Neutrophil count can also be used to help identify an inflamed appendix, although it is not given as much importance in the literature compared to white blood cell count. It can also be raised in any infectious condition and typically suggests a bacterial cause. Kabir and colleagues reviewed ten studies that investigated the involvement of polymorphonuclear (PMN) cells and discovered a range of sensitivity and specificity values, ranging from 71-89% and 48-80%, in diagnosing acute appendicitis. The variation in these values is due to the fact that different papers employed different thresholds for determining sensitivity and specificity. The data points ranged in value from 7 to 13. In our study, we set a threshold of more than 8 to identify cases with a high neutrophil count. By analyzing the data, we discovered that the neutrophil count exhibited the highest sensitivity (82%) among all the blood results we examined, and it also had the joint highest specificity (64%) - alongside the presence of CRP.

The role of CRP in appendicitis literature is variable. It has been noted in the systematic review by kabir et al. That CRP is better for detecting complicated or late-stage appendicitis as it is a lag indicator and is less useful for early-stage appendicitis [10]. Other studies have shown that it is less helpful for acute appendicitis but a significant increase in temperature is indicative of an abscess or a perforated appendix. Zani et al. discovered that a CRP cut-off value of 40 accurately identified one-third of children with uncomplicated appendicitis, but it correctly identified two-thirds of those with complicated appendicitis. However when they increased their crp cut-off value to 80, they only identified 40% of their perforated paediatric appendixes [7].The authors concluded that the use of a higher cut-off value for the CRP test would have resulted in a higher sensitivity for the diagnosis of appendicitis. These values differ significantly from van den worm et al. Who found that a crp cut-off value of 215 was fair in helping to diagnose complex appendicitis [9] - although it should be noted that the casemix of their study was different to zani. In our study, the mean crp value for appendixes that showed inflammation was 59.7, while those that were normal had a mean CRP value of 23.7. These values were comparable to the mean crp values reported by al-abed et al. for inflamed and normal appendixes, with 73 versus 32 respectively [5]. The sensitivity and specificity values we obtained in our research were 77% and 64%, which were within the range reported by Shogilev et al. (65-85% and 59-73%).

Some studies have been conducted in the field of combining serological markers to enhance the accuracy of diagnosing acute appendicitis. Birchley demonstrates that combining WBC count, neutrophil count, and crp gives an odds ratio of 18 when trying to identify acute appendicitis - although it should be noted that this is only applicable when all of those tests are abnormal [4]. Farooqui et al. Looked at WBC, bilirubin, CRP, and alt and noted that combining these biomarkers increased the predictive value when trying to discriminate between acute appendicitis and non-appendicitis [6].

Our results when we combined the three different blood tests were encouraging. It is worth emphasizing that we combined any abnormal WBC count, neutrophil count, or CRP value - we did not specify that all three results had to be abnormal. They demonstrated a sensitivity for detecting a histologically confirmed appendicitis of 96% - this is encouraging as it demonstrates that if an appendix is histologically inflamed, it is highly likely to be reflected in at least one of the blood results. Therefore if WBC count, neutrophil count, and CRP are all normal, then it is likely that the appendix is normal - if clinical suspicion persists, then either imaging or a diagnostic laparoscopy should be performed. Despite the limited specificity of 44%, it is not surprising as these blood markers could be elevated in response to various inflammatory or infectious conditions. This is similar to findings published by andersson who found that a combination of WBC >10 and a CRP >8 gave an accuracy of 0.96 (area under the curve) for diagnosing appendicitis [19].

The us sensitivity (59%) and specificity (85%) results in our study were not encouraging - but they are similar to a study by yuan et al. Who reported figures of 50% and 98.5% [20] and D’Souza et al. Who reported figures of 51.8% and 81.4% [15] respectively. These figures vary greatly from graceful et al. who reported a sensitivity and specificity of 93.8% and 90.6%, respectively [21]. It is challenging to reconcile the inconsistencies between the various studies, but it could be due to the varying levels of experience among the operators. Our figures imply that us may be a better screening tool, which is then combined with another imaging modality, such as ct, to try and reduce the negative appendectomy rate. At its best, it should be combined with the blood test results, medical history, and physical examination to determine whether or not a patient should undergo surgery.

This research has a few constraints. One of the key aspects of this study is that it is a retrospective analysis. No patient-related clinical data was recorded. No complications were observed for any patient. The study did not provide any information regarding the use of ct scans for patients involved in the research. We would suggest conducting a more comprehensive future study that includes detailed clinical information about the patient, which ultimately influenced the decision to bring the patient to the operating room.

Appendicitis is the most frequently encountered surgical emergency globally. No single blood test or radiographic scan has been proven to definitively diagnose appendicitis. Our research builds on that premise and demonstrates that while elevated WBC, neutrophil count, and CRP in isolation can be helpful in aiding the clinical diagnosis of acute appendicitis, they are more useful when combined

1.       The Global disease burden of conditions requiring emergency surgery. Stewart B, Khanduri P, McCord C, Ohene‐Yeboah M, Uranues S, Vega Rivera F, Mock C. https://doi.org/10.1002/bjs.9329. Br J Surg. 2014;101:9–22.

2.       Emergency general surgery and the implications for specialisation. Dawson EJ, Paterson-Brown S. Surgeon. 2004;2:165–170.

3.       Diagnosing appendicitis: evidence-based review of the diagnostic approach in 2014. Shogilev DJ, Duus N, Odom SR, Shapiro NI. West J Emerg Med. 2014;15:859–871.

4.       Patients with clinical acute appendicitis should have pre-operative full blood count and c-reactive protein assays. Birchley D. Ann R Coll Surg Engl. 2006;88:27–32.

5.       Diagnostic markers in acute appendicitis. Al-Abed YA, Alobaid N, Myint F. Am J Surg. 2015;209:1043–1047.

6.       The diagnostic value of a panel of serological markers in acute appendicitis. Farooqui W, Pommergaard HC, Burcharth J, Eriksen JR. Scand J Surg. 2015;104:72–78.

7.       Can common serum biomarkers predict complicated appendicitis in children? Zani A, Teague WJ, Clarke SA, Haddad MJ, Khurana S, Tsang T, Nataraja RM. Pediatr Surg Int. 2017;33:799–805.

8.       Integration of physical examination, old and new biomarkers, and ultrasonography by using neural networks for pediatric appendicitis. Akgül F, Er A, Ulusoy E, et al. Pediatr Emerg Care. 2019

9.       C-reactive protein as a predictor of severity of appendicitis. Van den Worm L, Georgiou E, De Klerk M. https://www.ncbi.nlm.nih.gov/pubmed/28876618. S Afr J Surg. 2017;55:14–17.

10.    How to diagnose an acutely inflamed appendix; a systematic review of the latest evidence. Kabir SA, Kabir SI, Sun R, Jafferbhoy S, Karim A. Int J Surg. 2017;40:155–162.

11.    An appraisal of inflammatory markers in distinguishing acute uncomplicated and complicated appendicitis. Beecher SM, Hogan J, O'Leary DP, McLaughlin R. Dig Surg. 2016;33:177–181.

12.    Histopathological correlations of appendectomies: a clinical audit of a single center. Omiyale AO, Adjepong S. Ann Transl Med. 2015;3:119.

13.    Prospective nationwide outcome audit of surgery for suspected acute appendicitis. van Rossem CC, Bolmers MD, Schreinemacher MH, van Geloven AA, Bemelman WA, Group SACS. Br J Surg. 2016;103:144–151.

14.    Negative appendectomy: an audit of resident-performed surgery. How can its incidence be minimized? Joshi MK, Joshi R, Alam SE, Agarwal S, Kumar S. Indian J Surg. 2015;77:913–917.

15.    The value of ultrasonography in the diagnosis of appendicitis. D'Souza N, D'Souza C, Grant D, Royston E, Farouk M. Int J Surg. 2015;13:165–169.

16.    Emergency appendicectomy in the era of laparoscopy: a one-year audit. Al Hilli Z, Prichard RS, Roche-Nagle G, Leader M, McNamara DA, Deasy J. Ir J Med Sci. 2009;178:473–477.

17.    Emergency appendicectomy: a one year audit. Gibney EJ, Ajayi N, Leader M, Bouchier-Hayes D. Ir J Med Sci. 1992;161:101–104.

18.    Province-wide population survey of acute appendicitis in Canada. New twists to an old disease. Gagné JP, Billard M, Gagnon R, Laurion M, Jacques A. Surg Endosc. 2007;21:1383–1387.

19.    Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Andersson RE. Br J Surg. 2004;91:28–37.

20.    Retrospective audit of patients presenting for ultrasound with suspicion of appendicitis. Yuan F, Necas M. Australas J Ultrasound Med. 2015;18:67–69.

21.    The impact of ultrasound in suspected acute appendicitis. Gracey D, McClure MJ. Clin Radiol. 2007;62:573–578.