CBC
Normal WBC does not rule-out<unk> 
Only 80% of patients will have leukocytosis with left shift
Urine pregnancy
Urinalysis
Leukocytes will be present in 40% of patients
Serum Lactate
Does not necessarily define level of severity (if<unk>  is present.)
Can aid in trending effective resuscitation once the diagnosis is made.
CRP
Normal CRP AND WBC makes<unk>  unlikely
Normal WBC does not rule-out<unk> 
Only 80% of patients will have leukocytosis with left shift
Leukocytes will be present in 40% of patients
Does not necessarily define level of severity (if<unk>  is present.)
Can aid in trending effective resuscitation once the diagnosis is made.
Normal CRP AND WBC makes<unk>  unlikely
Early surgical consultation should be obtained before imaging in straightforward cases
Not universally necessary; consider in:
Women of reproductive age
Men with equivocal presentation
Perforation may result in false negative study
Imaging modalities
Ultrasound
First choice for pregnant women and children
Limitations: operator-dependent, difficult to visualize with obesity, gravid uterus, bowel gas, guarding, lack of patient cooperation
Findings: noncompressible appendix >6mm in diameter, wall thickness greater or equal to 3 mm
Other supportive findings: aperistalsis, distinct wall layers, target appearance in axial view, appendicolith, periappendiceal fluid, prominent echogenic periappendiceal fat
CT
First choice for adult males and nonpregnant women with equivocal cases
Women derive the greatest benefit from preoperative imaging (lower neg appy rate)
Contrast (both PO and IV) is unnecessary but typically ordered
MRI
When unable to identify appendix in children or pregnant women
Women of reproductive age
Men with equivocal presentation
Ultrasound
First choice for pregnant women and children
Limitations: operator-dependent, difficult to visualize with obesity, gravid uterus, bowel gas, guarding, lack of patient cooperation
Findings: noncompressible appendix >6mm in diameter, wall thickness greater or equal to 3 mm
Other supportive findings: aperistalsis, distinct wall layers, target appearance in axial view, appendicolith, periappendiceal fluid, prominent echogenic periappendiceal fat
CT
First choice for adult males and nonpregnant women with equivocal cases
Women derive the greatest benefit from preoperative imaging (lower neg appy rate)
Contrast (both PO and IV) is unnecessary but typically ordered
MRI
When unable to identify appendix in children or pregnant women
First choice for pregnant women and children
Limitations: operator-dependent, difficult to visualize with obesity, gravid uterus, bowel gas, guarding, lack of patient cooperation
Findings: noncompressible appendix >6mm in diameter, wall thickness greater or equal to 3 mm
Other supportive findings: aperistalsis, distinct wall layers, target appearance in axial view, appendicolith, periappendiceal fluid, prominent echogenic periappendiceal fat
First choice for adult males and nonpregnant women with equivocal cases
Women derive the greatest benefit from preoperative imaging (lower neg appy rate)
Contrast (both PO and IV) is unnecessary but typically ordered
When unable to identify appendix in children or pregnant women
Clinical scoring system, where a score (Total=10) is composed on presence/absence of 3 signs, 3 symptoms and 2 lab values to help guide in case management.
≤3 =<unk>  unlikely
≥7 = Surgical consultation
4-6 = Consider CT
MANTRELS Mnemonic: Migration to the right iliac fossa, Anorexia, Nausea/Vomiting, Tenderness in the right iliac fossa, Rebound pain, Elevated temperature (fever), Leukocytosis, and Shift of leukocytes to the left (factors listed in the same order as presented above).
Appendicitis
Cervicitis
Perforated appendicitis
Uvulitis
Peritonitis
Orchitis
Abdominal aortic aneurysm
Diverticulitis