What are the potential causes and treatments for left upper quadrant rebound pain and abdominal distension?

Left Upper Quadrant Rebound Pain and Abdominal Distension: Diagnostic and Management Approach

Immediate Diagnostic Priority

CT abdomen and pelvis with IV contrast is the preferred initial imaging modality for evaluating left upper quadrant pain with rebound tenderness and abdominal distension, as it provides comprehensive assessment of all potential life-threatening causes with excellent diagnostic accuracy. 1

Critical Clinical Context

The combination of rebound pain and abdominal distension represents peritoneal irritation with potential for serious pathology requiring urgent evaluation. Rebound tenderness with abdominal distension occurs in 82.5% of patients with peritonitis and increases the probability of abdominal compartment syndrome. 2

Differential Diagnosis by Likelihood

High-Priority Life-Threatening Causes

• Splenic pathology (rupture, infarction, abscess) - requires immediate CT evaluation as it can present with isolated left upper quadrant tenderness and distension 1
• Perforated viscus (gastric perforation, colonic perforation) - rebound tenderness with distension suggests diffuse peritonitis requiring emergency surgical evaluation 2
• Acute pancreatitis - commonly presents with left upper quadrant pain and abdominal distension, requires pancreatic enzyme measurement 3, 1
• Intestinal obstruction - absence of flatus (90%) and abdominal distension (65.3%) are cardinal features requiring urgent imaging 2
• Mesenteric ischemia - consider if patient has atherosclerotic risk factors; requires lactate level and CT angiography 3, 1

Atypical Presentations Requiring High Index of Suspicion

• Malrotation with left-sided appendicitis - acute appendicitis can present as left upper quadrant pain in patients with undiagnosed intestinal malrotation; CT will reveal both the malrotation and inflamed appendix 4
• Internal hernia with incarcerated contents - can present with acute left upper quadrant pain and distension; requires CT for diagnosis 5
• Intra-abdominal abscess - fever with rebound tenderness and distension suggests abscess formation requiring CT identification and drainage 1

Post-Procedural Considerations

• Iatrogenic colonoscopy perforation - if symptoms develop within 48 hours of colonoscopy (91-92% of cases), abdominal pain with distension and rebound tenderness (82.5%) strongly suggests perforation requiring immediate CT 2

Mandatory Initial Laboratory Workup

Order the following tests immediately for all patients: 3

• Complete blood count - leukocytosis with left shift indicates infection or inflammation (present in 40% of perforations) 2, 3
• Comprehensive metabolic panel including liver enzymes - elevated alkaline phosphatase suggests biliary pathology 3
• Amylase and lipase - elevation strongly suggests pancreatitis as cause of left upper quadrant pain 3
• Lactate level - if mesenteric ischemia suspected based on clinical presentation 3
• Pregnancy test for all women of reproductive age - mandatory to exclude ectopic pregnancy 3

Additional tests based on clinical suspicion: 3

• Coagulation studies (PT/INR, PTT) if splenic rupture or hematoma suspected 3
• Procalcitonin if presentation delayed >12 hours and infection suspected 2

Imaging Strategy

First-Line Imaging

CT abdomen and pelvis with IV contrast (rated 8/9 "usually appropriate" by American College of Radiology) 1

• Provides comprehensive evaluation of splenic, pancreatic, gastric, colonic, and vascular pathology 1
• Detects free intraperitoneal air with 92% positive predictive value for perforation 2
• Alters diagnosis in nearly 50% of cases with nonlocalized abdominal pain 1
• Identifies unexpected findings including malrotation and atypical appendicitis 1, 4

Imaging Findings Indicating Surgical Emergency

• Free intraperitoneal air - indicates perforation requiring surgical consultation 2
• Free intraperitoneal fluid with peritoneal enhancement - suggests peritonitis 2
• Splenic laceration or hematoma - may require emergent splenectomy 1
• Bowel obstruction with closed loop - requires urgent surgical decompression 2

Alternative Imaging (Only if CT Unavailable)

• Plain abdominal radiographs have limited diagnostic value (PPV 92% for perforation but insensitive for other pathology) 2
• Ultrasound has limited utility due to overlying bowel gas and rib shadowing 1

Management Algorithm Based on Clinical Presentation

If Peritonitis Present (Rebound + Distension + Fever/Leukocytosis)

1. Immediate surgical consultation - do not delay for imaging if patient unstable 2
2. Obtain CT with IV contrast if patient hemodynamically stable 1
3. Start broad-spectrum antibiotics immediately after blood cultures if sepsis suspected 2
4. NPO status, IV fluid resuscitation, nasogastric decompression if obstruction or perforation suspected 2

If Stable Without Peritonitis

1. Obtain CT abdomen/pelvis with IV contrast as first-line diagnostic test 1
2. Complete laboratory workup as outlined above 3
3. Reassess after imaging - CT will guide definitive management in >90% of cases 1

Red Flags Requiring Emergency Evaluation

The following findings mandate immediate emergency surgical evaluation: 6, 1

• Fever with rebound tenderness and distension (suggests perforation or abscess) 2
• Inability to pass gas or stool with progressive distension (suggests complete obstruction) 2, 6
• Signs of shock (tachycardia, hypotension, altered mental status) 2
• Bloody stools with peritoneal signs (suggests ischemic bowel or perforation) 6
• Recent colonoscopy within 48 hours (high suspicion for iatrogenic perforation) 2

Common Diagnostic Pitfalls

• Assuming benign etiology without imaging - CT alters diagnosis in 49% of cases; clinical examination alone is insufficient 1
• Failing to consider atypical appendicitis - malrotation can cause left upper quadrant appendicitis requiring high index of suspicion 4
• Relying on absence of classic peritoneal signs - in spinal cord injury patients or immunocompromised patients, rebound and guarding may be absent despite serious pathology 7
• Delaying imaging in post-colonoscopy patients - 91-92% of perforations present within 48 hours; early CT is critical as delayed diagnosis >24 hours significantly increases need for surgery 2
• Missing pregnancy test in reproductive-age women - ectopic pregnancy can present with left upper quadrant pain and peritoneal signs 3
• Normal laboratory values excluding serious pathology - imaging remains necessary based on clinical presentation even with normal labs 3

Specific Etiologies and Their Management

Splenic Pathology

• CT with IV contrast identifies splenic rupture, infarction, or abscess 1
• Surgical consultation required for rupture or large hematoma 1

Pancreatitis

• Elevated lipase >3 times upper limit of normal confirms diagnosis 3
• CT identifies complications (necrosis, pseudocyst, abscess) 1

Perforated Viscus

• Free air on CT mandates surgical exploration 2
• Broad-spectrum antibiotics and surgical consultation immediately 2

Intestinal Obstruction

• CT identifies level and cause of obstruction 2
• Nasogastric decompression and surgical evaluation required 2