How should a teenager presenting with left upper quadrant abdominal pain be evaluated and managed?

Evaluation and Management of Left Upper Quadrant Pain in a Teenager

Initial Imaging Strategy

CT abdomen and pelvis with IV contrast is the preferred initial imaging modality for evaluating left upper quadrant pain in a teenager, providing comprehensive assessment with 98% diagnostic accuracy and the ability to detect unexpected findings including malrotation with atypical appendicitis. 1, 2

• The American College of Radiology rates CT abdomen and pelvis with IV contrast as 8/9 (usually appropriate) for left upper quadrant pain evaluation 1
• CT alters diagnosis in nearly half of cases and identifies alternative diagnoses in 49% of patients with nonlocalized abdominal pain 1
• Plain radiography has very limited diagnostic value and should not be used 1
• 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 1, 3

Critical Differential Diagnoses to Consider

Atypical Appendicitis with Malrotation

• Acute appendicitis should be considered in the differential diagnosis of left upper quadrant pain in adolescents, as intestinal malrotation can result in left-sided appendix location 2
• A 13-year-old female with malrotation presented with left upper quadrant appendicitis, demonstrating that this diagnosis must not be missed 2
• Most malrotation cases are asymptomatic until acute complications develop, requiring imaging for diagnosis 2

Splenic Pathology

• In adolescents, signs of splenic trauma include left upper quadrant pain associated with referred left shoulder pain, hypovolemic shock, or generalized abdominal pain 4
• Contrast-enhanced CT is the gold standard for pediatric splenic trauma 4
• Splenic infarction is the most common diagnosis in patients with left upper quadrant pain and splenic inhomogeneity on imaging 3

Pancreatic Disease

• Acute pancreatitis is confirmed by serum amylase >4× normal or lipase >2× upper limit 1
• CT abdomen and pelvis with IV contrast provides comprehensive evaluation of pancreatic pathology 1

Renal Pathology

• Nephrolithiasis or pyelonephritis should be excluded in cases of nonspecific pain 1
• Urinalysis assists in ruling out urinary tract infection or nephrolithiasis 5

Initial Laboratory Workup

• Obtain complete blood count with differential, C-reactive protein, and urinalysis as the initial laboratory panel 5
• Leukocytosis with left shift (≥75% neutrophils) suggests bacterial infection 5
• Elevated CRP >50 mg/L combined with left upper quadrant tenderness and absence of vomiting provides 97% diagnostic accuracy for inflammatory conditions 5
• β-hCG testing is mandatory in all female adolescents of reproductive age before CT imaging 6, 5
• Serum amylase and lipase should be assessed if pancreatitis is suspected 1

Clinical Assessment Priorities

Red Flag Features Requiring Immediate Imaging

• Fever with leukocytosis indicating inflammatory or infectious processes 1
• Signs of peritonitis (guarding, rebound tenderness, absent bowel sounds) 6
• Inability to tolerate oral intake 6
• Severe or progressively worsening pain 6
• Signs of hypovolemic shock or hemodynamic instability 4

Hemodynamic Assessment in Adolescents

• Normal systolic blood pressure in adolescents is 90 mmHg plus twice the child's age in years 4
• Lower limit is inferior to 70 mmHg plus twice the child's age in years 4
• For fluid resuscitation, three boluses of 20 mL/kg of crystalloid replacement should be administered before blood replacement 4

Special Considerations for Pediatric/Adolescent Population

• The elastic pediatric rib cage may cause transmission of force into the abdominal compartment, making splenic injury more likely even without rib fractures 4
• Adolescents may present with atypical symptoms compared to adults, requiring a high index of suspicion 2
• Ultrasound may be useful as initial imaging in younger patients to reduce radiation exposure, but should be followed by CT if negative or inconclusive 4
• MRI without contrast can provide clinically useful information when available and is preferred in pregnant adolescents 4

Common Pitfalls to Avoid

• Do not dismiss left upper quadrant pain as benign without imaging when clinical suspicion exists 1
• Do not assume typical appendicitis location—malrotation can cause left-sided appendicitis in adolescents 2
• Do not rely on clinical examination alone, as misdiagnosis rates are 34-68% without imaging 6
• Do not order plain radiographs as they provide minimal diagnostic value 1
• Clinical scoring systems perform variably and should not replace imaging in intermediate-risk patients 4

Management Algorithm Based on Imaging Findings

If Splenic Trauma Identified

• Non-operative management is the mainstay in hemodynamically stable children irrespective of injury grade 4
• Likelihood of splenic preservation with non-operative management ranges from 95-100% in pediatric patients 4
• "Less is more" approach with respect to follow-up imaging to reduce radiation exposure 4

If Appendicitis Identified

• Proceed to surgical consultation for appendectomy 4
• Laparoscopic approach with correction of malrotation (Ladd's procedure) if malrotation is present 2

If Pancreatitis Identified

• Supportive care with IV fluids, pain control, and antiemetics 1
• Monitor for complications with serial laboratory studies 1

If Renal Pathology Identified

• Manage according to specific diagnosis (pyelonephritis vs. nephrolithiasis) 1