What could be causing nausea, vomiting, back pain, and right lower quadrant pain, and how should it be managed?

Diagnostic Approach to Nausea, Vomiting, Back Pain, and Right Lower Quadrant Pain

This symptom constellation most likely represents acute appendicitis, and you should immediately obtain a contrast-enhanced CT scan of the abdomen and pelvis to confirm the diagnosis and guide surgical management. 1, 2

Clinical Reasoning

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 3. Back pain in this context may represent retroperitoneal irritation from an inflamed or retrocecal appendix, which can produce a positive psoas sign 2.

Immediate Diagnostic Workup

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 1, 2. Specifically, 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 2.

Laboratory Testing

• 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 2
• Obtain a basic metabolic panel to assess for dehydration and electrolyte abnormalities from vomiting 2

Physical Examination Priorities

• Test for psoas sign (pain with hip extension or flexion), which suggests appendicitis or retroperitoneal pathology and explains the back pain component 2
• Assess for migratory pain pattern from periumbilical region to RLQ, which increases the likelihood of appendicitis 2
• Evaluate for rebound tenderness and guarding in the RLQ, which are part of the classic appendicitis presentation 3

Alternative Diagnostic Pathway (If CT Unavailable)

If CT is not immediately available, start with point-of-care ultrasound (POCUS) as the most appropriate first-line diagnostic tool when imaging is indicated 1. However, ultrasound has variable sensitivity (51.8-81.7%) and specificity (53.9-81.4%) 3, and if inconclusive, you must proceed to CT 1.

Critical Differential Diagnoses to Consider

While appendicitis is most likely, the CT will also evaluate for:

• Psoas abscess or muscle strain (explains back pain, especially if there's history of heavy lifting) 2
• Infectious enterocolitis or typhlitis (particularly if immunocompromised, presenting with RLQ pain, fever, and diarrhea) 2, 4
• Perforated appendicitis with abscess formation (if symptoms have been present for several days) 2
• Mesenteric adenitis or diverticulitis (less common but identifiable on CT) 2

Management Based on CT Findings

If appendicitis is confirmed: Proceed directly to appendectomy as standard treatment 2.

If perforated appendicitis with abscess: Consider percutaneous drainage followed by delayed surgery 2.

If CT is negative but clinical suspicion remains high: Diagnostic laparoscopy is recommended, which has both diagnostic and therapeutic value 1.

Critical Pitfalls to Avoid

• Do not delay imaging for oral contrast administration, as this increases time to diagnosis and potentially increases perforation risk without improving diagnostic accuracy 2
• Do not rely on clinical scoring systems alone (such as Alvarado score) for diagnosis, as they may not accurately exclude appendicitis, particularly with atypical presentations 2
• Do not dismiss the diagnosis based on atypical symptom sequence, as the classic presentation occurs in only approximately 50% of cases 3

Symptomatic Management While Awaiting Imaging

• Provide IV fluid resuscitation for dehydration from vomiting 2
• Administer antiemetics (dopamine antagonists like metoclopramide or prochlorperazine, or serotonin antagonists) for nausea and vomiting control 5, 6
• Consider analgesics cautiously, noting that pain medication may reduce the reliability of physical examination findings like the sonographic Murphy sign 5