What is the primary care approach for a patient with abdominal pain below the umbilicus that changes from right to left?

Primary Care Approach to Migratory Lower Abdominal Pain

For a patient with abdominal pain below the umbilicus that migrates from right to left, obtain CT abdomen and pelvis with IV contrast as the definitive diagnostic study after initial laboratory evaluation, as this presentation suggests multiple possible pathologies requiring comprehensive imaging assessment. 1

Initial Clinical Assessment

The migratory nature of lower abdominal pain below the umbilicus is atypical and warrants systematic evaluation to differentiate between:

• Right-sided pathology including appendicitis, right colonic diverticulitis, inflammatory bowel disease, or gynecologic conditions 1
• Left-sided pathology including sigmoid diverticulitis, colonic disorders, or genitourinary disease 1, 2
• Bilateral or diffuse processes such as infectious enterocolitis, inflammatory bowel disease, or functional disorders 1, 3

Mandatory First-Line Laboratory Testing

Before any imaging, obtain:

• Complete blood count (CBC) to assess for leukocytosis indicating infection or inflammation 4, 5
• Comprehensive metabolic panel to evaluate electrolyte imbalances and organ function 4
• Urinalysis to rule out urinary tract infection or nephrolithiasis 5, 2
• Pregnancy test for all females of reproductive age - this is non-negotiable before any imaging to prevent unnecessary radiation exposure and identify ectopic pregnancy 4, 5
• Pancreatic enzymes (lipase/amylase) if upper abdominal involvement is suspected 4

Imaging Strategy

CT abdomen and pelvis with IV contrast is the imaging modality of choice for this presentation because:

• It achieves 95% sensitivity and 94% specificity for appendicitis while simultaneously evaluating alternative diagnoses 1
• CT changes the leading diagnosis in 51% of patients and alters management decisions in 25% of cases with nonspecific abdominal pain 1
• For right lower quadrant pathology, CT identifies non-appendiceal causes in 94.3% of cases, including colonic diverticulitis (8%), bowel obstruction (3%), inflammatory bowel disease, and gynecologic conditions 1
• For left lower quadrant pain, CT is the most widely used examination for diagnosing diverticulitis and detecting complications 1

Why Not Plain Radiography?

• Plain X-rays have limited diagnostic value with low sensitivity (49%) for bowel obstruction and minimal utility for identifying specific causes of lower abdominal pain 1, 5
• Radiography should be reserved only if free perforation (pneumoperitoneum) or complete obstruction is strongly suspected 1

Why Not Ultrasound First?

• While ultrasound is excellent for right upper quadrant pathology, it has limited utility for lower abdominal pain evaluation compared to CT's comprehensive assessment 5, 2
• Ultrasound may be considered for gynecologic evaluation in women of reproductive age if pelvic pathology is the primary concern 1

Management Algorithm

1. Obtain detailed history focusing on:

   • Pain onset, duration, and migration pattern
   • Associated symptoms (fever, nausea, vomiting, changes in bowel habits, urinary symptoms)
   • Gynecologic history in women (last menstrual period, sexual activity)
   • Previous abdominal surgeries or similar episodes 3, 6

2. Perform targeted physical examination assessing:

   • Vital signs for fever, tachycardia, or hypotension suggesting sepsis or perforation 1
   • Abdominal tenderness location, guarding, rebound, or peritoneal signs
   • Bowel sounds (hyperactive suggests obstruction; absent suggests peritonitis) 1
   • Digital rectal examination if lower rectal pathology suspected 1

3. Order first-line laboratory tests as outlined above 4, 5

4. Obtain CT abdomen/pelvis with IV contrast if:

   • Diagnosis remains unclear after initial evaluation 1, 4
   • Any alarm features present (fever, severe pain, peritoneal signs, hemodynamic instability) 1
   • Laboratory abnormalities suggest serious pathology 1

5. Treat identified pathology according to specific diagnosis:

   • Appendicitis: surgical consultation 1
   • Diverticulitis: antibiotics ± interventional drainage for abscess 1
   • Bowel obstruction: surgical evaluation 1
   • Gynecologic pathology: appropriate specialist referral 1

Critical Pitfalls to Avoid

• Never skip pregnancy testing in women of reproductive age before ordering CT - this prevents unnecessary radiation exposure and identifies life-threatening ectopic pregnancy 4, 5

• Do not rely solely on laboratory tests without appropriate imaging when clinical suspicion warrants further investigation - normal laboratory values do not exclude serious pathology 4, 3

• Avoid repetitive testing once a functional pain diagnosis is confidently established after organic pathology is excluded 3, 6

• Do not delay imaging in patients with alarm features (fever, peritoneal signs, hemodynamic instability) as these suggest complications requiring urgent intervention 1

• Consider colon cancer in the differential, particularly if CT shows pericolonic lymphadenopathy >1 cm or if the patient is over 50 without age-appropriate screening 1

Special Considerations

For patients where CT demonstrates diverticulitis with abscess, local perforation, or fistula, colonoscopy should be performed after acute inflammation resolves due to higher likelihood of underlying colon cancer 1

In elderly patients, maintain high suspicion for serious pathology as typical signs may be absent and laboratory tests may be normal despite serious infection 1