Common things can present uncommonly: An atypical presentation of acute appendicitis
Clinical History
A 35 year old Lithuanian female presented to the Emergency Department with four days of vomiting, diarrhoea and constant, spasmodic suprapubic abdominal pain. She had an accompanying fluctuating fever and complained of increased urinary frequency. On examination she appeared alert and well but was visibly clammy. She was haemodynamically stable and apyrexial. Her abdomen was soft, tender in the left iliac fossa, and bowel sounds were quiet on auscultation.
Misleading elements
Urinalysis showed nitrites (+), leukocytes (2+) and blood (3+) and blood tests revealed a white cell count of 17x109 and a C-reactive protein of 303mg/L. A surgical review was sought owing to the disproportionately high blood inflammatory markers. Due to the suprapubic pain, increased urinary frequency, non-tender right iliac fossa and deranged urinalysis the surgical team advised a diagnosis of a urinary tract infection with possible gastroenteritis.
Helpful details
Despite being apyrexic in the emergency department at 37.1 degrees Celsius the patient reported a fluctuating fever up to 40 degrees Celsius over the two preceding days at home. This seemed out of keeping with a urinary tract infection. Furthermore, although within normal range, her heart rate was 95; higher than would be expected for an otherwise well 35 year old with no significant past medical history. She also reported no gynaecological symptoms or loin pain suggestive of renal involvement.
Differential diagnoses
The general surgeons advised a diagnosis of urinary tract infection with gastroenteritis as a differential diagnosis.
Despite specialist input advising medical management the emergency department team proceeded with a CT abdomen pelvis. This was due to several concerning factors including: clamminess, low grade tachycardia, fluctuating fever, quiet bowel sounds, inflammatory markers that were disproportionately high for a urinary tract infection.
A computerised tomography scan of the abdomen and pelvis with contrast showed a perforated appendix on the left of the abdominal midline. There was local abscess formation surrounding the perforation and prominent dilated small bowel loops consistent with ileus.
Educational relevance
Acute appendicitis is the most common abdominal surgical problem and stereotypically presents with colicky umbilical pain that migrates to the right iliac fossa followed by the onset of vomiting. Diagnosis is typically a clinical decision. However, evidence shows that the classical symptoms may only manifest in half of patients with acute appendicitis and therefore atypical presentations may confuse clinicians. Importantly acute appendicitis has a wider variety of clinical presentations, due to the anatomical variation of the caecal appendix, than may be fully appreciated in clinical practice. For instance, urinary frequency, diarrhoea and uncharacteristic abdominal pain can result from direct irritation of pelvic and subcaecal structures in atypical appendicitis. Microscopic haematuria and leucocytes can be positive on urinalysis further confounding the clinical impression. Clinicians should be alert to the fact that appendicitis can commonly present in an uncommon fashion and should consider the use of imaging to explore the differential diagnoses further.
