Causes of Right Lower Quadrant Pain
Primary Diagnosis to Consider
Appendicitis is the most common surgical pathology responsible for RLQ pain, accounting for nearly 50% of emergency department presentations with abdominal pain, but numerous other conditions can mimic this presentation and must be systematically excluded. 1
Gastrointestinal Causes
Common Bowel Pathology
- Right colonic diverticulitis represents a less frequent but important cause of RLQ pain, particularly in older adults 1
- Colitis (infectious, inflammatory, or ischemic) can present with RLQ tenderness and must be differentiated from appendicitis 1
- Intestinal obstruction (small or large bowel) presents with RLQ pain, often accompanied by hyperactive bowel sounds, distension, and vomiting 2
- Inflammatory bowel disease (Crohn's disease affecting the terminal ileum) commonly causes RLQ pain and can be identified on CT imaging 3, 4
Other Gastrointestinal Conditions
- Constipation/fecal impaction is among the most common CT diagnoses in patients with RLQ pain where no acute surgical pathology exists 3
- Gastroenteritis frequently presents with RLQ pain and represents a common benign diagnosis 3
- Colorectal malignancy accounts for 60% of large bowel obstructions and should be considered, especially with rectal bleeding or unexplained weight loss 2
- Epiploic appendagitis and omental infarction can mimic appendicitis on clinical examination 5
Genitourinary Causes
Urologic Pathology
- Ureteral stone (right-sided) is a common cause of RLQ pain that can be definitively diagnosed with CT imaging 1
- Urinary tract infection or pyelonephritis may present with RLQ pain, particularly when involving the right kidney 4
Gynecologic Pathology (Women of Reproductive Age)
- Benign adnexal masses (ovarian cysts, hemorrhagic cysts) are commonly identified on CT in women with RLQ pain 3
- Ovarian torsion requires urgent surgical intervention and should be considered in women with acute-onset RLQ pain 6
- Ectopic pregnancy is a life-threatening diagnosis that must be excluded in women of reproductive age 4
- Pelvic inflammatory disease can present with RLQ pain and fever 7
- Tubo-ovarian abscess represents a surgical emergency requiring drainage or operative intervention 6
Vascular Causes
- Mesenteric ischemia should be considered in elderly patients with cardiovascular disease presenting with pain out of proportion to physical examination findings 2
- Abdominal aortic aneurysm (particularly right-sided or ruptured) can present with RLQ pain 6
Mesenteric and Peritoneal Causes
- Mesenteric adenitis can mimic appendicitis, particularly in pediatric patients 4
- Peritonitis from perforated viscus (peptic ulcer, diverticulitis) may localize to the RLQ 7
Rare but Important Diagnoses
- Right paraduodenal hernia can present with RLQ pain and intestinal obstruction 7
- Intussusception should be considered in pediatric patients with RLQ pain 8
- Meckel's diverticulitis can mimic appendicitis in younger patients 9
Diagnostic Approach Based on Clinical Presentation
When Rebound Tenderness is Present
CT abdomen and pelvis with IV contrast is mandatory as first-line imaging, achieving 95% sensitivity and 94% specificity for appendicitis while identifying alternative diagnoses in 23-45% of cases. 8 Rebound tenderness has the highest positive predictive value (65%) for complicated appendicitis and indicates peritoneal irritation requiring urgent surgical evaluation 8
When Hyperactive Bowel Sounds are Present
The differential diagnosis shifts toward small bowel obstruction (most likely given hyperactive sounds), early appendicitis, right-sided colonic diverticulitis, colorectal malignancy, or mesenteric ischemia 2. CT with IV contrast remains the mandatory imaging study in this scenario 2
When CT Shows No Acute Pathology
Among patients where CT shows no acute diagnosis, only 14% require hospitalization and 4% need surgical intervention, with the most common findings being constipation, gastroenteritis, colitis, benign adnexal masses, and inflammatory bowel disease 3
Critical Clinical Pitfalls
- Do not rely on "classic" presentations alone, as elderly patients frequently lack typical symptoms, have blunted inflammatory responses, and present later with higher complication rates 2
- Normal laboratory values do not exclude surgical emergencies, particularly in elderly patients where inflammatory markers may be falsely reassuring 2
- In women of reproductive age, always consider gynecologic pathology and pregnancy-related complications before attributing RLQ pain solely to gastrointestinal causes 8, 4