Atypical Appendicitis

Chris White MD, Jason King MD, Brandon Delavar MD
Department of Emergency Medicine, University of Alabama at Birmingham

Appendicitis is a very commonly diagnosed condition in the emergency department that affects up to 1 in 10 individuals over a lifetime (1). The migratory appendiceal base can move into retrocecal, subcecal, and other pelvic positions which is one factor proposed to increase the complexity in diagnosing appendicitis in patients with atypical symptoms. In this report we present an atypical presentation and diagnosis of acute complicated appendicitis.

Case Presentation
A 21-year-old male presented with lower abdominal pain for one day. His pain was constant over the bladder and lower quadrants with associated vomiting, anorexia, constipation, chills, and a sensation of bladder fullness and urinary retention. He denied bloody or dark stools, testicular pain or swelling, dysuria, hematuria, or penile drainage.

Physical exam revealed normal vital signs, a well appearing male with a soft abdomen, normal bowel sounds, and tenderness throughout the lower abdomen most prominent in the suprapubic region. His genitourinary exam was unremarkable and labs were notable for a leukocytosis of 14 with 88% neutrophils and a urinalysis with 1+ blood and 3-10 RBCs. An initial non-contrast computed tomography (CT) scan was negative for any acute abnormality. An enhanced abdominopelvic CT with IV contrast showed no evidence of appendicitis; although, the appendix was not visualized. No secondary signs of inflammation or other findings were detected. Reevaluation was notable for increased tenderness and guarding prompting antibiotic administration and admission to surgery for laparoscopic intervention. Intraoperatively the appendix was identified with associated phlegmon and the appendectomy was complicated by appendiceal rupture with spillage of stool. The pathology report showed acute gangrenous appendicitis with periappendicitis.

We present a case of complicated appendicitis undiagnosed on not one but two separate abdominopelvic CT scans. The optimal protocol for diagnosing appendicitis is unclear, but non-contrast helical CT has a sensitivity of 92.7% and specificity of 96.1% and is considered by many investigators to be an adequate modality for evaluation of appendicitis (3,5,6). Comparing identification of acute appendicitis between enhanced and non-contrast CT imaging the sensitivity of enhanced CT was significantly better than non-contrast imaging (100% vs 90.5%; P=.036) (3). Additional studies have revealed similar sensitivities for enhanced abdominopelvic CT imaging in the diagnosis of acute appendicitis with a performance of 95-100% (2,4). Regarding the visualization of the appendix in patients presenting with RLQ pain, the appendix was unable to be visualized in 13%-14% of cases and only 2% of patients with a non-visualized appendix on enhanced CT were proven to have appendicitis upon surgical exploration (6,8). Interestingly, this case of CT missed appendicitis was noted to have much more complex pathology than simple appendicitis including phlegmon formation and gangrenous changes.

Approximately 2-5% of appendicitis cases can be missed on CT requiring practicing clinicians need to remain vigilant for this diagnosis; obtaining surgical consultations when clinical suspicion remains high despite equivocal or negative diagnostics. Specifically, serial abdominal exams are indicated in such situations and proved to be a paramount factor in our patient’s diagnosis.