Diagnostic value and effect of bedside ultrasound in acute appendicitis in the emergency department

Noha Eshera, MS4

Article: Gungor F, Kilic T, Akyol KC, et al. Diagnostic value and effect of bedside ultrasound in acute appendicitis in the emergency department. Acad Emerg Med 2017; 24:578–86. 

Background:

Acute appendicitis is a common cause of acute abdominal pain that presents in the ED that requires emergent surgery. The standard of care includes an abdominal CT for diagnosis, which has high sensitivity and specificity. However in cases were the pre-test probability is low, concern for over-exposure to radiation and the necessity of a contrast agent may discourage the use of CT. Ultrasound may be a better alternative for initial evaluation in patients with low probability for acute.

The Study:

-       Type: Prospective observational study

-       Population: convenience sample of ED patients in a tertiary care hospital

-       Exclusion criteria: Pregnancy, unstable vitals

-       Inclusion criteria: >18 years of age, abdominal pain.

-       Objectives:

  1. Evaluate diagnostic accuracy of POCUS in diagnosis of appendicitis in ED.

  2. Compare the accuracy of POCUS performed by ED physicians to radiology-performed US (RADUS).

Methods:

-       POCUS conducted by eight highly experienced US-certified ED physicians, radiology. The US technique for the POCUS was standardized with an imaging protocol. The ED physicians measured their clinical probability on a 100-point scale based on history and physical exam both pre- and post-POCUS. POCUS diagnostic criteria for acute appendicitis included presence of aperistaltic and non-compressible tubular structure with a diameter >6mm located in RLQ.

-       RADUS was performed by blinded radiology residents with at least 1 year of experience. When RADUS was not diagnostic, an abdominal CT was performed.

-       Definitive diagnosis of acute appendicitis was made based on intra-operative findings or pathology results. Definitive diagnosis of no appendicitis was made with negative CT results, intraoperative findings, or relief of the patient’s symptoms during follow-up at 7 and 30 days following discharge from hospital.

Results:

-       264 patients in final analysis, a total of 179 patients underwent operation and appendicitis confirmed in 169 (64%) patients.

-       Appendix was visualized in 83% of patients with POCUS and in 72% of patients with RADUS. There were four false-positives and 13 false-negative results with POCUS.

-       POCUS was found to be 92.3% sensitive and 95.8% specific.

-       RADUS was found to be 76.9% sensitive and 97.8% specific.

Takeaway: The authors showed that POCUS had a higher sensitivity for appendicitis than RADUS which was attributed to the blinding and inexperience of the radiology residents. POCUS allowed ED physicians to move many of their “moderate” probability appendicitis patients into either “low” or “high” probability. The use of an imaging protocol for POCUS assisted with the diagnosis and exclusion of acute appendicitis.