What are the appropriate diagnostic steps and treatment options for pain in the lower right quadrant?

Right Lower Quadrant Pain: Diagnostic and Treatment Approach

Initial Imaging Strategy

CT abdomen and pelvis with IV contrast is the first-line imaging study for adults presenting with right lower quadrant pain, achieving 95% sensitivity and 94% specificity for appendicitis while identifying alternative diagnoses in 23-45% of cases. 1, 2

Primary Imaging Recommendation for Adults

• Proceed directly to CT abdomen and pelvis with IV contrast as the initial diagnostic study in most adult patients with right lower quadrant pain 1, 2
• This approach provides superior diagnostic accuracy compared to ultrasound-first strategies, with sensitivity of 95% and specificity of 94% for appendicitis 2
• Oral or rectal contrast may be added for better bowel visualization but is not mandatory depending on institutional preference 1
• CT identifies critical alternative diagnoses including right-sided colonic diverticulitis, bowel obstruction, colorectal malignancy, gynecologic pathology, urinary tract conditions, and mesenteric ischemia 2, 3, 4

When to Consider Ultrasound First

• In women of reproductive age with pelvic pain, consider pelvic ultrasound (transabdominal + transvaginal) first to evaluate gynecologic causes while avoiding radiation 2
• Combined ultrasound achieves 97.3% sensitivity and 91% specificity in adult women when performed by experienced operators 2
• Critical limitation: ultrasound fails to visualize the appendix in 20-81% of cases, and equivocal results require CT anyway, resulting in diagnostic delay without avoiding radiation 2
• Ultrasound performance varies dramatically (sensitivity 21-95.7%) depending on operator experience, patient body habitus, and clinical presentation 2

Special Population: Elderly Patients

• CT abdomen and pelvis with IV contrast remains first-line in elderly patients due to atypical presentations, higher perforation rates, and broader differential diagnosis 2
• Consider right-sided colonic diverticulitis (increasingly common with age), bowel obstruction (particularly with prior abdominal surgery), and colorectal malignancy (accounts for 60% of large bowel obstructions in elderly) 2
• Critical pitfall: normal laboratory values do not exclude serious pathology in elderly patients, who frequently have blunted inflammatory responses 2
• Assess for prior abdominal surgery, last bowel movement, rectal bleeding, unexplained weight loss, chronic constipation, and cardiovascular disease 2

Special Population: Pediatric Patients

• Ultrasound is the initial imaging modality of choice in children due to zero radiation exposure and ability to identify appendicitis, intussusception, and other pediatric causes 5
• If ultrasound is equivocal or non-diagnostic, MRI abdomen and pelvis without IV contrast is the preferred next step rather than CT 5
• CT abdomen and pelvis with IV contrast should be reserved for when MRI is unavailable or contraindicated, or when clinical suspicion is very high and ultrasound is non-diagnostic 5
• Children under 5 years present with atypical symptoms more frequently and have higher perforation rates due to delayed diagnosis 5

Differential Diagnosis Beyond Appendicitis

Common Alternative Diagnoses

• Right-sided colonic diverticulitis can precisely mimic appendicitis and is increasingly common with age 2
• Bowel obstruction, particularly adhesive small bowel obstruction in patients with prior abdominal surgery (85% sensitivity, 78% specificity for adhesions) 2
• Gynecologic pathology including ovarian torsion, ovarian cyst rupture, ectopic pregnancy, and pelvic inflammatory disease 2, 3, 4
• Urinary tract pathology including ureteral stones, pyelonephritis, and urinary tract infection 1, 2
• Mesenteric ischemia in elderly patients with cardiovascular disease 2
• Inflammatory bowel disease affecting the ileocecal region 3, 4

Red Flag Presentations

• Right lower quadrant pain with right thigh weakness suggests psoas abscess or retroperitoneal pathology affecting the iliopsoas muscle or lumbar plexus (L2-L4 nerve roots) 6
• This presentation requires urgent contrast-enhanced CT to identify retroperitoneal collections or psoas abscesses (sensitivity 85.7-100%, specificity 94.8-100%) 6
• If psoas or retroperitoneal abscess is identified, initiate broad-spectrum antibiotics immediately and consider percutaneous catheter drainage for collections >3 cm 6

Clinical Assessment Priorities

Key Historical and Physical Examination Findings

• Right lower quadrant pain, abdominal rigidity, and periumbilical pain migrating to the right lower quadrant are the best signs for ruling in acute appendicitis in adults 7
• In children, absent or decreased bowel sounds, positive psoas sign, positive obturator sign, and positive Rovsing sign are most reliable 7
• Clinical scoring systems (Alvarado score, Pediatric Appendicitis Score, Appendicitis Inflammatory Response score) can stratify patients as low, moderate, or high risk 7, 5

Laboratory Studies

• Obtain complete blood count with differential, C-reactive protein, and urinalysis 7, 5
• Critical caveat: clinical determination alone without imaging has an unacceptably high negative appendectomy rate of up to 25% 1
• Clinical decision tools like the Alvarado score have not improved diagnostic accuracy and show mixed results as an adjunct to guide CT use 1

Treatment Approach

Confirmed Appendicitis

• Appendectomy via open laparotomy or laparoscopy is the standard treatment for acute appendicitis 1, 7
• Intravenous antibiotics may be considered first-line therapy in selected patients 7
• For perforated appendicitis with abscess, percutaneous catheter drainage followed by delayed surgery or drainage alone is appropriate 6, 5

Immediate Management While Awaiting Imaging

• Initiate NPO status, IV fluid resuscitation, nasogastric decompression if indicated, broad-spectrum antibiotics if septic, and obtain surgical consultation 2
• Provide adequate pain control with opioids, NSAIDs, and acetaminophen—this does not result in delayed or unnecessary intervention 7

Perforation Risk

• Perforation occurs in 17-32% of patients with acute appendicitis and leads to sepsis 7
• Prolonged duration of symptoms before surgical intervention raises perforation risk 7
• In moderate- to high-risk patients, accomplish surgical consultation quickly to reduce morbidity and mortality 7

Critical Pitfalls to Avoid

• Do not assume appendicitis based solely on right lower quadrant pain—alternative diagnoses are identified in 23-45% of cases 2
• Do not rely on ultrasound alone in obese patients or when clinical suspicion is high—proceed directly to CT to avoid diagnostic delay 2
• Do not assume normal labs exclude serious pathology in elderly patients—they frequently have blunted inflammatory responses 2
• Do not delay imaging when thigh weakness is present—this suggests psoas abscess requiring urgent drainage 6
• In children, do not proceed to CT without attempting ultrasound first unless the clinical situation is immediately life-threatening 5