The Performance of the APPY1 Test in the Evaluation of Possible Acute Appendicitis

Inclusion Criteria:

- 2 to 20 years old (up until the 21st birthday),

- Right lower quadrant or poorly localized abdominal pain, or tenderness that includes
the right lower quadrant, and/or other features including, but not limited to,
nausea, vomiting, and/or anorexia, requiring acute appendicitis to be added to the
differential,

- Onset of abdominal pain within 72 hours or less,

- Patients of either gender may participate and,

- Patient or accompanying parent or guardian is able to provide informed consent.

Exclusion Criteria:

- History includes prior appendectomy,

- Subjects whose presentation history and physical examination place them at such high
risk of acute appendicitis that it would be clinically reasonable to proceed with
exploratory laparotomy and/or appendectomy without advanced imaging,

- Treatment with any immunosuppressive medication or chemotherapeutic agents within 28
days, or systemic steroids (oral or intravenous) within 14 days,

- History of end-stage, metastatic cancer or an active immune disorder,

- History includes abdominal trauma or invasive abdominal procedures/surgery within the
previous two weeks,

- Patients who have received diagnostic imaging (CT, MRI, or US) for abdominal pain in
the previous two weeks,

- Patients with report of abdominal pain greater than 72 hours,

- History of active bleeding disorder, which may complicate phlebotomy or placement of
peripheral IV catheter,

- Participation in a research study within the previous 30 days,

- Prisoners of an adult or juvenile detention center, and

- Subject, parent or guardian unable to provide informed consent.