What could be causing pain on the left side of my upper stomach that worsens when I bend at a 90° angle?

Left Upper Quadrant Pain Worsening with Forward Bending

CT abdomen and pelvis with IV contrast is the most appropriate initial imaging study for evaluating left upper quadrant pain in adults, as it provides comprehensive assessment of potential causes including splenic pathology, gastric issues, pancreatic disease, and colonic disorders. 1

Most Likely Diagnostic Considerations

Splenic Pathology

• Splenic flexure syndrome (trapped gas in the colon's splenic flexure) commonly causes left upper quadrant pain that worsens with bending, as forward flexion increases intra-abdominal pressure and compresses the distended bowel segment 1
• Splenic infarction, subcapsular hematoma, or splenomegaly can cause positional pain aggravated by movement or pressure 1

Gastric and Pancreatic Causes

• Gastritis or gastric ulcer may cause left upper quadrant pain worsening with bending, as this position increases gastric pressure and acid reflux 2
• Pancreatic tail pathology (pancreatitis, mass) presents with left-sided pain that can worsen with certain positions 2
• The British Society of Gastroenterology recommends urgent CT imaging in patients ≥60 years with abdominal pain to exclude pancreatic cancer, particularly with persistent symptoms 2

Musculoskeletal Considerations

• Costochondritis or intercostal muscle strain causes reproducible pain with specific movements including forward bending, though this is typically chest wall rather than intra-abdominal 1
• Abdominal wall hernias may become symptomatic with increased intra-abdominal pressure from bending 1

Colonic Pathology

• Diverticulitis of the descending or sigmoid colon can present with left-sided pain, though typically lower quadrant 1
• Colonic obstruction or distension causes pain that worsens with positional changes 1

Immediate Assessment Required

Red Flag Symptoms Requiring Urgent Evaluation

• Fever, tachycardia, or hypotension suggest infection, perforation, or ischemia requiring emergency evaluation 2
• Peritoneal signs (guarding, rebound tenderness, rigidity) indicate potential perforation or acute abdomen necessitating immediate surgical consultation 2, 3
• Inability to pass gas or stool with vomiting suggests obstruction 4

Essential Laboratory Testing

• Complete blood count to assess for leukocytosis (>14,000 suggests infection or ischemia), anemia, or thrombocytosis 2
• Metabolic panel, C-reactive protein, and lipase to evaluate for pancreatitis, electrolyte abnormalities, and inflammatory markers 2
• Elevated lactate with low bicarbonate indicates potential intestinal ischemia requiring urgent intervention 2

Imaging Strategy

First-Line Imaging

• CT abdomen and pelvis with IV contrast is the preferred initial study, changing diagnosis in 49% of cases and management in 42% of patients with nonlocalized abdominal pain 2
• CT provides rapid, comprehensive evaluation of solid organs, bowel, and vascular structures with sensitivity >95% for most acute pathology 1, 3

Alternative Imaging Considerations

• Abdominal ultrasound may be appropriate if gallbladder or hepatobiliary pathology is suspected, though less comprehensive than CT 1
• Plain radiography has limited utility (sensitivity <50% for most causes) and should not delay definitive imaging 1

Critical Pitfalls to Avoid

• Do not dismiss positional pain as purely musculoskeletal without excluding intra-abdominal pathology, as serious conditions like splenic infarction or pancreatic disease can present with positional symptoms 1, 2
• Do not delay imaging based on benign physical examination in patients ≥60 years, as CT changes diagnosis in approximately 50% of cases with nonspecific pain 2
• Do not overlook malignancy in older patients with new-onset symptoms, as colorectal and pancreatic cancers can present with vague positional abdominal pain 2

When to Seek Immediate Care

• Severe pain with fever, vomiting, or inability to tolerate oral intake requires emergency evaluation 3
• Development of peritoneal signs, hemodynamic instability, or bloody stools mandates immediate surgical consultation 2, 4
• Progressive symptoms despite conservative management warrant urgent imaging and specialist evaluation 1