| Purpose:For many years, acute appendicitis remains to be one of the most common causes for emergency surgery in pediatric surgical department, and appendectomy is still the main treatment. Diagnosis of appendicitis is mainly based on the clinical findings from medical history and physical examination, and as technology advances, the diagnosis is more dependent on the laboratory and radiological examinations. However, the diagnosis remains a challenge for pediatricians, since negative appendectomy rates (NAR) has been reported to range from 2-30%, it could even reach up to 57% for children younger than 6-year-old.Negative appendectomy refers to those cases which the patients underwent appendectomy, but the appendix appears to be normal and the pathophysiology had no signs of inflammation. Such high rates of negative appendectomy are no longer acceptable, hence more resources are being put into understanding the cause of negative appendectomy. During this research, we reviewed all cases that underwent negative appendectomy during 1991-2010, attempting to illustrate the change in negative appendectomy rate, its relations with gender and age, and its negative effects on the patients. We also compared all clinical, laboratory and radiological findings of negative appendectomy cases with simple acute appendicitis cases. All in purpose of understand the difference between the two groups preoperatively and lowering the appendectomy rate.Material and Methods:Study population of this research is the cases that underwent negative appendectomy during 1991-2010. All negative appendectomy cases meet the criteria of a normal appendix, which physiopathology was reviewed by the surgical and the pathology department. Negative appendectomy cases can be further divided into two groups:1) misdiagnosed cases:in which based on findings during the operation and physiopathology, an alternate diagnosis was made,2) appendicitis-similar cases: patients presented with similar symptoms as acute appendicitis, but there was with no positive findings during the surgery and the physiopathology show no signs of inflammation.In this study, we analyzed and compared the clinical data for all negative appendectomy and simple acute appendicitis cases, in order to 1) understand the change in negative appendectomy rate and its relation with patients age and gender,2) determine differences in symptoms, laboratory and radiological findings between the two groups,3) illustrate the length of stay, cost and complications of negative appendectomy.Result:1. Change of Negative Rate:(1) During 1991-2010,5469 cases underwent appendectomy after being diagnosed with acute appendicitis,694 of these cases had negative findings, which makes the negative rate 12.7%. Of the 694 cases of negative appendectomy,47 cases (6.77%) were misdiagnosed and 647cases (93.2%) were diagnosed with appendicitis-similar cases.(2) Throughout 20 years, negative appendectomy rate during 1991-1995 period was 14.9%, and it slowly decreased to 7.58% in 2006-2010. This change in negative appendectomy rate was statistically significant (P<0.001).(3) The ratio of male to female for negative appendectomy cases was 1:0.9, and most commonly occurred in children between 8 to 12 years old, and least common in patients younger than 3 years old. Top five most common alternate diagnosis for negative appectomy cases were acute mesenteric lymphadenitis, respiratory tract infections, gastroenteritis, Meckel’s diverticulum and primary peritonitis.2. Analysis of symptoms, signs, laboratory and radiological findings:(1) There was no difference for order of symptoms between negative appendectomy cases and acute appendicitis cases. Abdominal pain appears to be the first symptom, followed with fever and vomit. There was no difference in the occurrence rate of migration pain for both groups, but the difference in occurrence rate of migration pain in 13-16 years old patients were statistically significant.(2) Differences in positive rates for physical examination (guariding, rebound tenderness) and signs (Rovsing’s sign, Psoas sign and Obturator sign) in negative appendectomy cases and simple acute appendicitis were not statistically significant (P> 0.05).(3) Median value of white blood cell count was 11.6*10^9/L for negative appendectomy cases and 11.65*10^9/L for simple acute appendicitis cases, this difference was not statistically significant (P>0.05). Also, the differences in urine WBC, stool RBC and amylase was not statistically significant. However, mean CRP value for negative appendectomy group and simple appendectomy group was 28.07mg/L and 24.36mg/L respectively, this difference was statistically significant (P<0.04). Differences in median values of urine RBC and stool WBC for both groups of patients were also statistically significant (P<0.05).(4) For cases that accepted radiological examination such as X-ray, ultrasound and CT, differences in rates of positive findings were not statistically significant (P<0.05).(5) Positive rate of intra abdominal swab culture for negative appendectomy group was 8.82%, and it was 13.5% for simple acute appendicitis group, this difference is not statistically significant (P<0.050). Most common bacteria in the negative appendectomy group were:staphylococcus, Escherichia coli, p. aeruginosa and Viridans Streptococci. As for the simple acute appendicitis group, the most common bacteria were: Escherichia coli, Sh.boydii, Viridans Streptococci and Pesudomonaspyocyaneum.3. Length of stay, cost and complications of Negative appendectomy(1) During 1991-2010, for negative appendectomy cases, the most common postoperative complications included bowel obstruction, intra-abdominal infection, wound infection and pelvic abscess. The complication rate for negative appendectomy group and simple acute appendicitis group was 2.16% and 1.67% respectively. This difference in complication rates was not statistically significant (P>0.05).(2) During the 20 years, the average length of stay for negative appendectomy group was 6 days, and it decrease from 8 day in 1991-1995 to 5 days in 2006-2010. Also, the average time of antibiotics used after surgery for negative appendectomy group was 3 days,8.25% of patients had to use second line antibiotics and 0.86% needed to use third line antibiotics.(3) Throughout 20 years, the total cost for negative appendectomy group slowly increased, with an average of 2480.9RMB,and its difference with the simple acute appendectomy was not statistically significant(P<0.05).Conclusion:1. Negative appendectomy rate in our hospital during 1991-2010 was 12.7%, and it steadily decreases. The male and female ratio for negative appendectomy group was 1:0.9, and negative appendectomy was most common in older children.2. Symptoms and physical examination findings and radiological examination results has little value in differentiating early stage of appendicitis with other diseases. However, the difference in occurrence rate of migration pain in older children can be helpful in determining whether the patient has simple acute appendicitis. Also, laboratory findings such as CRP value, urine RBC count and stool WBC count appears to be helpful for differentiating simple appendicitis. Negative appendectomy group and simple acute appendicitis group have different intra-abdominal swab culture results, suggesting different pathogens are responsible for the diseases.3. Negative appendectomy group has a complication rate of 2.16%, the most common complications were bowel obstruction, intra abdominal infection, wound infection, and pelvic abscess. The results of analysis on length of stay, cost and the use of antibiotics of the negative appendectomy group proves that negative appendectomy is an unnecessary waste of medical resource. |
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