What is the appropriate workup for a patient presenting with right lower quadrant abdominal pain?

Workup of Right Lower Quadrant Abdominal Pain

CT abdomen and pelvis with IV contrast is the initial imaging study of choice 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

Initial Clinical Assessment

Key History Elements to Obtain

• Prior abdominal surgery (suggests adhesive bowel obstruction with 85% sensitivity) 2
• Last bowel movement and flatus passage (bowel obstruction indicator) 2
• Rectal bleeding or unexplained weight loss (colorectal malignancy accounts for 60% of large bowel obstructions in elderly) 2
• Fever and vomiting (classic for appendicitis but often absent in elderly) 2
• Cardiovascular disease history (mesenteric ischemia risk) 2

Physical Examination Priorities

• Right lower quadrant tenderness and guarding (appendicitis indicators, though 24% of appendicitis cases lack RLQ findings) 3, 4
• Abdominal distension (strongly suggests bowel obstruction) 5
• Peritoneal signs (perforation or advanced disease) 6

Critical pitfall: Pain localization alone is insufficient—24% of appendicitis patients have no RLQ pain or tenderness, and atypical presentations are the norm in elderly patients who frequently lack classic symptoms. 2, 4

Laboratory Testing

• Complete blood count with differential (leukocytosis supports but does not confirm appendicitis) 3
• Urinalysis (exclude urinary tract pathology) 3
• Beta-hCG in all women of reproductive age (mandatory before imaging to exclude ectopic pregnancy) 1

Critical pitfall: Normal laboratory values do not exclude serious pathology—many elderly patients have blunted inflammatory responses and normal labs despite serious infection or perforation. 2

Imaging Algorithm

First-Line Imaging: CT Abdomen and Pelvis with IV Contrast

CT with IV contrast is rated 8/9 (usually appropriate) by the American College of Radiology for suspected appendicitis and achieves superior diagnostic performance across all age groups. 1, 2

Key advantages:

• 95% sensitivity and 94% specificity for appendicitis 1, 2
• Identifies alternative diagnoses including diverticulitis, bowel obstruction, colorectal malignancy, gynecologic pathology, urinary conditions, and mesenteric ischemia 2, 7
• Single comprehensive study that evaluates multiple organ systems simultaneously 2

Technical considerations:

• IV contrast is essential for optimal diagnostic accuracy 1, 2
• Oral or rectal contrast may be added for better bowel luminal visualization but is not mandatory (institutional preference) 1, 2

Alternative: Ultrasound-First Strategy (Limited Scenarios)

Ultrasound may be considered first only in women of reproductive age to evaluate gynecologic causes while avoiding radiation. 2

When ultrasound is appropriate:

• Combined transabdominal and transvaginal approach achieves 97.3% sensitivity and 91% specificity for gynecologic pathology in women 2
• Pelvic ultrasound rated 5/9 (may be appropriate) by ACR for women with pelvic pain 1

Critical limitations of ultrasound:

• Appendix not visualized in 20-81% of cases, creating diagnostic uncertainty 2
• Sensitivity ranges from 21% to 95.7% depending on operator experience, patient body habitus, and clinical presentation 2
• Higher false-positive rates in females 2
• Equivocal results require CT anyway, resulting in diagnostic delay without avoiding radiation 2

Ultrasound is rated only 6/9 (may be appropriate) for suspected appendicitis, significantly lower than CT's 8/9 rating. 1

Differential Diagnosis Beyond Appendicitis

The broad differential in RLQ pain includes: 2, 7

• Right-sided colonic diverticulitis (increasingly common with age, mimics appendicitis) 2
• Bowel obstruction (particularly adhesive small bowel obstruction if prior surgery) 2
• Colorectal malignancy (especially with rectal bleeding or weight loss) 2
• Gynecologic pathology (ovarian torsion, ectopic pregnancy, tubo-ovarian abscess) 2
• Urinary tract conditions (pyelonephritis, nephrolithiasis) 2
• Mesenteric ischemia (especially in elderly with cardiovascular disease) 2
• Inflammatory bowel disease (Crohn's ileitis) 7

Immediate Management While Awaiting Imaging

Initiate the following immediately in patients with suspected surgical pathology: 2

• NPO status 2
• IV fluid resuscitation 2
• Nasogastric decompression (if bowel obstruction suspected) 2
• Broad-spectrum antibiotics (if perforation or sepsis suspected) 2
• Surgical consultation (do not delay for imaging if peritonitis present) 2

Special Considerations for Elderly Patients

Elderly patients require heightened vigilance due to atypical presentations and higher complication rates: 2

• Appendicitis has higher perforation rates due to delayed diagnosis 2
• Atypical presentations are the norm with frequently absent classic symptoms 2
• Present later in disease course with higher complication rates 2
• Consider broader differential including diverticulitis, malignancy, and vascular emergencies 2

When Imaging May Not Be Required

Patients with typical diverticulitis symptoms and no suspected complications may not require imaging if clinical diagnosis is clear. 1 However, this applies primarily to known diverticulitis with recurrent episodes, not initial presentations of RLQ pain where the differential is broad.