US Grading:
1 = Normal completely visualized appendix
2 = Partially visualized appendix - no findings to suggest appendicitis
3 = Non-visualized appendix - no findings to suggest appendicitis
4 = Equivocal study - e.g. peri-appendiceal inflammation or borderline appendiceal enlargement but otherwise normal appendix
5 = Appendicitis
-5a = Not perforated
-5b = Perforated