What labs and diagnostic imaging are recommended for a 21-year-old female patient presenting with right middle abdominal pain, nausea, and decreased appetite without fever?

Diagnostic Approach for Right Middle Abdominal Pain in a 21-Year-Old Female

For a 21-year-old female presenting with right middle abdominal pain, nausea, and decreased appetite without fever, the initial diagnostic workup should include complete blood count, liver function tests, and abdominal ultrasonography as first-line imaging. 1, 2

Initial Laboratory Evaluation

The following laboratory tests should be ordered:

• Complete blood count (CBC) to assess for leukocytosis
• Liver function tests (AST, ALT, bilirubin, alkaline phosphatase)
• Basic metabolic panel (electrolytes, creatinine, BUN)
• C-reactive protein (CRP) and/or ESR as inflammatory markers
• Urinalysis
• Pregnancy test (essential in women of reproductive age)
• Lipase (to rule out pancreatic pathology)

While some studies suggest CBC results rarely affect clinical decision-making in young women with abdominal pain 3, a systematic approach is still warranted given the broad differential diagnosis.

First-Line Imaging

Ultrasonography

• Ultrasonography of the abdomen is the first-line imaging modality for right middle abdominal pain, with an ACR appropriateness rating of 9 (highest) 1
• Ultrasound is particularly valuable because:
  • It has no radiation exposure
  • Provides excellent visualization of the gallbladder and biliary system
  • Can identify gynecological pathology in young women
  • Helps identify appendicitis if the pain is more toward the right lower quadrant
  • Can be performed quickly and is readily available

Right middle abdominal pain in a young female could represent several conditions including:

• Biliary pathology (cholecystitis, cholelithiasis)
• Appendicitis (if pain migrates from periumbilical to right lower quadrant)
• Gynecological conditions (ovarian cysts, torsion, PID)
• Hepatic pathology

Second-Line Imaging (if ultrasound is inconclusive)

If ultrasonography results are inconclusive:

1. CT of abdomen with contrast media (ACR appropriateness rating of 6) 1

   • Provides excellent visualization of appendix, bowel, and other abdominal structures
   • Should be performed with IV contrast to increase diagnostic yield 1
   • Oral contrast is optional and may delay diagnosis without significantly improving diagnostic accuracy 1

2. MRI of abdomen without and with contrast media (ACR appropriateness rating of 6) 1

   • Particularly useful if biliary pathology is suspected but ultrasound is inconclusive
   • Preferred in pregnant patients when ultrasound is inconclusive 2
   • Excellent for visualization of both normal caliber and dilated bile ducts 1

Step-Up Diagnostic Approach

Following a step-up approach as recommended by the World Society of Emergency Surgery 1:

1. Begin with clinical assessment and basic laboratory tests
2. Proceed to ultrasonography as first-line imaging
3. If diagnosis remains unclear, proceed to CT with IV contrast or MRI depending on suspected pathology

Special Considerations

• In this age group and with these symptoms, gynecological causes must be considered, including ovarian torsion, which requires prompt surgical intervention 4
• The absence of fever does not rule out infectious causes; appendicitis can present without fever in up to 50% of cases 1
• Consider rare diagnoses such as appendagitis epiploica, which has been reported in young women with similar presentations 5

Common Pitfalls to Avoid

• Failing to obtain a pregnancy test in women of reproductive age
• Relying solely on laboratory findings without imaging, as many serious conditions can present with normal lab values
• Overlooking gynecological causes in young women with abdominal pain
• Delaying imaging in patients with persistent symptoms despite normal laboratory findings

By following this diagnostic algorithm with appropriate laboratory testing and ultrasonography as first-line imaging, followed by CT or MRI if needed, the correct diagnosis can be established efficiently while minimizing radiation exposure in this young female patient.