A 19-year-old woman presents to the emergency department with a 16-hour history of abdominal pain, nausea, and low-grade fever. She states the pain began around the umbilicus and later migrated to the lower right side of his abdomen. She has vomited once and reports anorexia. She has no significant medical history and takes no medications. Vital signs show temperature 38.2°C (100.8°F), blood pressure 114/72 mmHg, pulse 100/min, and respirations 18/min. On physical examination, the abdomen is soft but tender in the right lower quadrant with guarding and rebound. Passive extension of the right hip elicits pain. Bowel sounds are present and normal. Laboratory studies reveal a leukocyte count of 13,800/μL with 85% neutrophils. Urinalysis is normal.
A) Acute appendicitis
Acute appendicitis is the most common surgical emergency in young adults presenting with right lower quadrant (RLQ) pain. This patient exhibits the classic progression of symptoms: vague, periumbilical pain (visceral innervation) that migrates to localized RLQ pain (parietal peritoneal irritation), accompanied by anorexia, nausea, low-grade fever, and leukocytosis. The presence of peritoneal signs (rebound, guarding) and a positive psoas sign (pain with hip extension, indicating retrocecal irritation) further supports the diagnosis. Appendicitis is a clinical diagnosis, often confirmed with imaging such as CT in equivocal cases, though treatment should not be delayed in patients with classic findings.
Answer choice B: Crohn disease, is incorrect. Crohn disease can affect any part of the GI tract but commonly involves the terminal ileum, presenting with RLQ pain, diarrhea, weight loss, and often a more indolent course. Acute onset with migratory pain and marked localized tenderness is less typical. Fever and leukocytosis can occur in Crohn flares, but the absence of diarrhea, chronic symptoms, or prior history makes this diagnosis less likely here.
Answer choice C: Ectopic pregnancy, is incorrect. Ectopic pregnancy often presents with lower abdominal pain, possibly localized to one side, and may be associated with vaginal bleeding, hypotension, or signs of rupture. Although it must be ruled out in any woman of reproductive age with abdominal pain, this patient’s presentation is most consistent with appendicitis. A urine β-hCG would be essential to evaluate ectopic pregnancy as a possible etiology.
Answer choice D: Mesenteric adenitis, is incorrect. Mesenteric adenitis can mimic appendicitis, especially in children and adolescents, and typically presents with RLQ pain and sometimes fever. However, the pain is typically less focal and less severe, and systemic symptoms may be milder. A key distinguishing factor is the absence of peritoneal signs with mesenteric adenitis, which are present in this case. Mesenteric adenitis often follows a viral illness.
Answer choice E: Nephrolithiasis, is incorrect. Kidney stones can cause sudden-onset flank pain radiating to the groin, often with hematuria and restlessness due to colicky pain. This patient has localized RLQ tenderness with rebound and a positive psoas sign, indicating peritoneal irritation, and urinalysis is normal. These findings are more consistent with appendicitis than renal colic.
Key Learning Point
Acute appendicitis should be suspected in young patients with periumbilical pain that migrates to the right lower quadrant, especially when accompanied by anorexia, nausea, low-grade fever, and localized tenderness. Early recognition and prompt surgical management are essential to prevent complications such as perforation and abscess formation.
