What is the appropriate evaluation and treatment for a 34-year-old female with no significant past medical history presenting with left upper quadrant pain?

Evaluation and Management of Left Upper Quadrant Pain in a 34-Year-Old Female

CT abdomen and pelvis with IV contrast is the first-line imaging modality for evaluating left upper quadrant pain in this patient, as it provides comprehensive diagnostic accuracy for the wide range of potential pathologies and alters diagnosis in nearly half of cases. 1, 2

Initial Clinical Assessment

The evaluation should focus on identifying specific clinical features that guide urgency and differential diagnosis:

• Assess for peritoneal signs: Rebound tenderness with abdominal distension occurs in 82.5% of patients with peritonitis and mandates immediate surgical evaluation 2
• Check vital signs and fever: Fever with leukocytosis indicates inflammatory or infectious processes requiring urgent imaging 2
• Evaluate for postprandial symptoms: Pain specifically after eating suggests gastric, pancreatic, or mesenteric ischemia 2
• Screen for vomiting: Left upper quadrant pain with vomiting raises concern for pancreatitis or gastric pathology 2

Diagnostic Imaging Strategy

Primary Imaging Recommendation

CT abdomen and pelvis with IV contrast is rated 8/9 (usually appropriate) by the American College of Radiology and should be obtained as the initial imaging study 1, 2:

• Diagnostic accuracy: CT has 69% sensitivity and 100% specificity for acute abdominal abnormalities causing left upper quadrant pain 3
• Clinical impact: CT changes the leading diagnosis in up to 51% of patients and alters management decisions in 25% of cases 1
• Comprehensive evaluation: Assesses splenic pathology, pancreatic disease, gastric abnormalities, vascular conditions, and can detect unexpected findings including malrotation with atypical appendicitis 2, 4
• IV contrast enhancement: Improves detection of bowel wall pathology, pericolic abnormalities, vascular pathology, and intraabdominal fluid collections 1

Alternative Imaging Considerations

Ultrasound has limited utility in the left upper quadrant due to overlying bowel gas and rib shadowing, though it may identify splenic or renal pathology 2:

• Consider ultrasound only if gynecologic pathology is suspected in premenopausal women 1
• Use ultrasound when radiation exposure is a concern, though diagnostic yield is lower 1

Plain radiography is not recommended as it has very limited diagnostic value for left upper quadrant pain 2:

• May detect pneumoperitoneum or bowel obstruction but has poor sensitivity for most causes 1

MRI is not recommended for initial evaluation due to longer acquisition time, less sensitivity for extraluminal air, motion artifacts, and need for contraindication screening 1

Differential Diagnosis and Specific Pathologies

Splenic Pathology

• Splenic torsion: Can present with left upper quadrant pain and may show a "whorled pedicle" or "upside down spleen" sign on CT 5
• CT with IV contrast provides definitive diagnosis 5

Pancreatic Disease

• Acute pancreatitis: Diagnosed by serum lipase >2× upper limit or amylase >4× normal 2
• CT abdomen and pelvis with IV contrast is rated 8/9 for severity assessment and detection of complications 1, 2
• Supportive care includes IV fluids, pain control, and antiemetics 2

Gastric and Intestinal Pathology

• Splenic flexure diverticulitis or colitis: Can extend to the left upper quadrant and is accurately diagnosed by CT 2
• Atypical appendicitis: In rare cases of intestinal malrotation, appendicitis may present as left upper quadrant pain 4
• CT reveals both the malrotation and inflamed appendix 4

Renal Pathology

• Nephrolithiasis or pyelonephritis: Should be excluded in cases of nonspecific pain 2
• Unenhanced CT has sensitivity and specificity near 100% for urolithiasis 1

Vascular Conditions

• Chronic mesenteric ischemia: Consider if postprandial pain with weight loss and atherosclerotic risk factors are present 2
• CT angiography is required to evaluate for mesenteric ischemia 2

Laboratory Evaluation

Obtain the following laboratory tests to guide diagnosis:

• Complete blood count: Elevated white blood cell count suggests infection or inflammation 4, 6
• Serum lipase and amylase: Essential if pancreatitis is suspected 2, 6
• C-reactive protein: Helps assess inflammatory processes 6
• Hepatobiliary markers: Evaluate for hepatic or biliary pathology 6
• Urinalysis: Screen for urinary tract infection or nephrolithiasis 6
• Pregnancy test: Mandatory in reproductive-age women 6

Management Algorithm Based on Clinical Presentation

If Peritoneal Signs Present

• Immediate surgical consultation is required 2
• Obtain CT abdomen and pelvis with IV contrast emergently to detect free intraperitoneal air (92% positive predictive value for perforation) 2
• Start broad-spectrum antibiotics after blood cultures if sepsis is suspected 2
• Initiate NPO status, IV fluid resuscitation, and nasogastric decompression 2

If Fever and Leukocytosis Present

• Consider intra-abdominal abscess from any source 2
• CT abdomen and pelvis with IV contrast is the preferred imaging modality 2
• Free intraperitoneal fluid with peritoneal enhancement suggests peritonitis 2

If Postprandial Pain Without Alarm Features

• Test for H. pylori and treat if positive 2
• Offer acid suppression with PPIs or H2-receptor antagonists if symptoms persist 2
• Consider functional dyspepsia if testing reveals no structural abnormality 2
• Tricyclic antidepressants can be used as second-line options 2

If Alarm Features Present

• Alarm features include: Older age, family history of upper GI malignancy, weight loss, or anemia 2
• These patients require endoscopy to exclude malignancy 2

Common Pitfalls to Avoid

• Do not rely solely on plain radiographs, which have poor sensitivity for most causes of left upper quadrant pain 1
• Do not fail to use contrast enhancement when evaluating for vascular pathologies or abscesses 1
• Do not delay appropriate imaging in patients who may present with atypical symptoms 1
• Do not dismiss pain as benign without imaging when clinical suspicion exists, as CT alters diagnosis in nearly half of cases 2
• Consider atypical presentations such as malrotation with left-sided appendicitis, which requires high index of suspicion 4