Diagnostic Approach to Acute Appendicitis

Clinical Presentation and Diagnosis

The combination of nausea, vomiting, and right lower quadrant (RLQ) pain is the classic presentation of acute appendicitis, which typically begins with periumbilical or epigastric pain that migrates to the RLQ, accompanied by anorexia, nausea, and vomiting, according to the American College of Surgeons 3
Back pain in this context may represent retroperitoneal irritation from an inflamed or retrocecal appendix, which can produce a positive psoas sign, as noted by the American College of Emergency Physicians 2

Obtain contrast-enhanced CT abdomen and pelvis immediately as the primary diagnostic imaging modality, which achieves sensitivities of 85.7-100% and specificities of 94.8-100% for identifying appendicitis, recommended by the American College of Radiology 1, 2
CT with IV contrast (without enteral contrast) provides diagnostic accuracy of 90-100% sensitivity and 94.8-100% specificity while avoiding delays associated with oral contrast administration, as suggested by the Society of Abdominal Radiology 2

Order C-reactive protein and complete blood count, as CRP levels are significantly higher in appendicitis versus other etiologies, and normal inflammatory markers have 100% negative predictive value for excluding appendicitis, according to the Infectious Diseases Society of America 2
Test for psoas sign (pain with hip extension or flexion), which suggests appendicitis or retroperitoneal pathology and explains the back pain component, as recommended by the American Academy of Orthopaedic Surgeons 2

If appendicitis is confirmed, proceed directly to appendectomy as standard treatment, recommended by the American College of Surgeons 2
If perforated appendicitis with abscess, consider percutaneous drainage followed by delayed surgery, as suggested by the Society of Surgical Oncology 2
If CT is negative but clinical suspicion remains high, diagnostic laparoscopy is recommended, which has both diagnostic and therapeutic value, according to the American College of Surgeons 1

Provide IV fluid resuscitation for dehydration from vomiting,ｰrecommended by the American Society of Anesthesiologists 2
Administer antiemetics (dopamine antagonists like metoclopramide or prochlorperazine, or serotonin antagonists) for nausea and vomiting control, as suggested by the National Comprehensive Cancer Network 4