This study aims to investigate the use of preoperative diagnostic imaging before appendectomy in Denmark and whether it has changed over time during the period from 2000-15. Secondly, the study aims to investigate regional, age and gender differences in the same setting.

Acute appendicitis is the most common cause of abdominal pain (1) and appendectomy is the most common emergency surgical procedure performed worldwide (2). During the last decades, there has been a paradigm shift in both diagnosis and treatment of appendicitis - surgical treatment has changed from open to laparoscopic appendectomy (3). Acute appendicitis has traditionally been a clinical diagnosis, but the use of preoperative diagnostic imaging has, in some countries, increased dramatically (4). The use of computed tomography (CT) before appendectomy is in the United States up to 90%, in England 13% and in Holland almost all patients undergo ultrasound and/or CT before appendectomy (1).

The use of antibiotics can be successful in the treatment of uncomplicated appendicitis verified on CT, and the use of CT has significantly lowered the negative appendectomy rate compared to clinical evaluation only (1). But the use of CT is inevitably inducing radiation and increasing lifetime risk of cancer - especially in younger patients who most frequently present with acute appendicitis (1,5). It is estimated that CT of the abdominal region can avoid 12 negative appendectomies but at the cost of one cancer death due to radiation (5). In Denmark surgery is still the only treatment for appendicitis, but how is appendicitis diagnosed? Is acute appendicitis still a clinical diagnosis?

Inclusion Criteria:

• Patients with a diagnosis for appendicitis undergoing appendectomy during the same admission during the period 2000-15

Exclusion Criteria:

• None

All patients in Denmark with a diagnosis for appendicitis undergoing appendectomy during the same admission during the period 2000-15