The authors have declared that no competing interests exist.
Acute appendicitis is one of the most common surgical emergencies globally, with a lifetime incidence of 8.6% in men and 6.7% in women. While acute appendicitis should be managed promptly to reduce the morbidity associated with perforated appendicitis, morbidity from negative appendicectomy is similar to morbidity from uncomplicated appendicitis. Computer tomography is widely used to aid in the diagnosis of acute appendicitis, however, is costly, often has a slow turn around time, and is associated with exposure to ionising radiation. In contrast, ultrasound is cheap, widely available, requires minimal patient preparation, and does not require exposure to ionising radiation. Ultrasonography is becoming increasingly used for adult patients in emergency settings. The literature has estimated the sensitivity of ultrasound for acute appendicitis in adult patients as between 39-96.4%. The sensitivity and specificity of ultrasound for the diagnosis of acute appendicitis is significantly increased when the appendix is visualised. In cases of a non visualised appendix, indirect ultrasound signs can improve the sensitivity to 93.9% and specificity to 85.7%. The variation in sensitivity and specificity for ultrasound in the diagnosis of acute appendicitis in adults may be due to multiple factors. Ultrasonographer experience, a retrocaecal appendix and obesity have all been described. Given the availability, cost and potential to reduce the rate of negative appendicectomy, ultrasound should be considered as the first line imaging modality for adult patients presenting with suspected AA.
Acute appendicitis (AA) is a surgical condition caused by acute inflammation of the vermiform appendix. It is considered to be one of the most common surgical emergencies globally
AA is one of the most common surgical emergencies globally. AA has a lifetime incidence of 8.6% in men and 6.7% in women, with a peak incidence between the second and third decade of life
Diagnostic imaging should be strongly considered in undifferentiated abdominal pain where AA is suspected. Computer tomography (CT) is widely used and is considered by many to be the gold standard in the diagnosis of AA. Sensitivity and specificity for CT in evaluation of AA is between 72-97% and 91-99% respectively
Ultrasonography is becoming an increasingly used modality in emergency settings due to its simplicity and wide availability. Sensitivity for ultrasound in the diagnosis of AA varies widely, quoted between 39-96.4% in the literature
False negative diagnosis of AA is an inherent risk of non-visualisation of the appendix with ultrasonography. Literature evaluating the negative predictive value (NPV) in ultrasound for AA varies widely, with Sezer et al., determining a NPV of 33%
Ultrasonography is a useful imaging modality to aid in the diagnosis of AA, with high sensitivity and specificity if utilised in the correct patient populations by experienced ultrasonographers. While CT has a higher NPV as compared to ultrasound, its cost, lack of availability and required exposure to ionising radiation limit its use as a first line imaging modality. Given the availability, cost, and significant potential to reduce the rate of negative appendicectomy, ultrasonography should be considered as the first line imaging modality for adult patients presenting with suspected AA.