ORIGINAL ARTICLE Is Interval Appendectomy Necessary for Appendicular Phlegmon? A Prospective Study Mohammad Reza Motie 1 & Ali Ahmadabadi 1 & Mohammad Vejdani 2 & Alireza Rezapanah 3 & Majid Khadem Rezaiyan 4 & Mohammad Naser Shafiee 5 & Armin Mahdiani 6 Received: 1 November 2016 /Accepted: 24 April 2017 # Association of Surgeons of India 2017 Abstract Appendectomy is accepted as the standard treat- ment of acute appendicitis, but in complicated cases, the treat- ment of choice is not straightforward. In this prospective study, we compared failure rate, complications, and recur- rence rate of three different approaches to complicated appen- dicitis. In a 5-year prospective cohort study, patients with ap- pendicular phlegmon were studied in three groups based on the treatment protocols. Group A included patients who underwent an appendectomy; patients of group B were treated by interval appendectomy; and in group C, conservative man- agement was performed without interval appendectomy. Data analysis was performed using SPSS version 11.5. In total, 3896 patients with acute appendicitis were admitted, and 127 patients with complicated appendicitis were treated. Fifty-four patients were excluded from the study. Differences in age, gender, weight, and duration of symptoms were not statistically significant in the three groups. In group A(N = 23), appendectomy was impossible in 4 patients and 5 patients experienced complications. In group B (N = 24), two patients underwent exploration and appendectomy. In another two patients, a recurrent episode of acute appendicitis with mild signs and symptoms occurred after discharge from the hospital. In group C (N = 25), three patients experienced a recurrent appendicitis. Interval appendectomy is not indicated in all patients and continuous non-operative management may be appropriate in some patients. As the epidemiology of co- lorectal cancer and inflammatory bowel diseases is different in Iran, we recommend other researchers to perform a cost- effectiveness analysis on colon and appendicular neoplasms workup after non-operative management of complicated appendicitis. Keywords Appendicitis . Complications . Phlegmon . Interval appendectomy Abbreviations CT scan Computed tomography SD Standard deviation WBC count White blood cell Introduction Acute appendicitis is one of the most cosmopolitan surgically managed diseases. Annually, it is estimated that 250,000 cases of acute appendicitis occur in the USA which account for about one million days of hospital stay [1]. The incidence rate of positive appendectomy in 10–19-year-old individuals is about 23.3 per 10,000 populations in 1 year, and positive appendectomy has the highest incidence in this period of life. The lifetime risk of acute appendicitis is higher in males than in females (8.6 vs 6.7%) [1]. * Ali Ahmadabadi ahmadabadia@mums.ac.ir 1 Surgical Oncology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran 2 Mashhad University of Medical Sciences, Mashhad, Iran 3 Department of Surgery, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 4 Student Research Committee, Department of Community Medicine and Public Health, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 5 English Department, Faculty of Medicine, Mashhad university of Medical Sciences, Mashhad, Iran 6 Faculty of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Hormozgan, Iran Indian J Surg DOI 10.1007/s12262-017-1644-9