Guideline Summary for Evaluation of Left Abdominal Pain

Left Upper Quadrant (LUQ) Pain

Etiology and Differential Diagnosis

• The primary LUQ differential includes pathology of the spleen, stomach, pancreatic tail, left kidney, and splenic flexure of the colon. 1
• Splenic infarction is most common in patients with embolic sources such as endocarditis, atrial fibrillation, or sickle‑cell disease. 2
• Splenic rupture or subcapsular hematoma occurs preferentially in the setting of splenomegaly or trauma; left‑shoulder pain (Kehr’s sign) suggests capsular irritation. 2
• Splenic abscess should be suspected when LUQ pain is accompanied by fever or elevated inflammatory markers. 2
• Splenic sequestration presents with an acute drop in hemoglobin/hematocrit and constitutes a life‑threatening emergency. 2
• Vascular complications of the spleen (pseudo‑aneurysm, splenic‑vein thrombosis) are additional considerations. 2
• Any cause of splenomegaly (infectious mononucleosis, portal hypertension, lymphoproliferative disorders, sarcoidosis, metastatic disease) markedly raises the risk of rupture, infarction, and sequestration. 2

Referred Pain Sources to Exclude

• Peptic ulcer disease and gastritis. 2
• Pancreatitis and its complications. 1
• Renal colic and pyelonephritis. 1
• Cardiac angina and pericarditis. 2
• Pneumonia with pleuritic pain. 1
• Spinal pathology (stress fractures, metastatic disease). 1

Diagnostic Imaging

• Contrast‑enhanced CT of the abdomen and pelvis is the primary imaging modality for acute LUQ pain, offering approximately 69 % sensitivity and excellent specificity for detecting acute LUQ abnormalities. 2
• Intravenous contrast is mandatory because it visualizes splenic parenchyma, reveals infarcts (ultrasound misses ~82 % of them), characterizes hematomas and abscesses, and identifies vascular lesions. 2
• Ultrasound is not recommended as the first‑line study for acute LUQ pain; its sensitivity for splenic infarction is only ~18 % compared with contrast‑enhanced CT. 2

Clinical Pitfalls and High‑Risk Populations

• LUQ pain accounts for < 5 % of all abdominal pain presentations and has the lowest inter‑rater agreement on physical examination among abdominal quadrants, making early imaging essential. 1, 2
• Elderly patients are at high risk for delayed diagnosis and adverse outcomes; a low threshold for imaging is advised. 2
• Fever in a patient with LUQ pain mandates urgent contrast‑enhanced CT to evaluate for possible abscess formation. 2
• Known splenomegaly presenting with LUQ pain requires immediate assessment for rupture, infarction, or sequestration, including vital signs and a complete blood count focused on hemoglobin/hematocrit. 2

Management of Confirmed Splenic Infarction

• Once splenic infarction is identified on CT, evaluate for an embolic source (e.g., echocardiography for endocarditis or cardiac thrombus) and initiate anticoagulation when not contraindicated. 2

Left Lower Quadrant (LLQ) Pain

Etiology and Differential Diagnosis

• Diverticulitis is the most common cause of LLQ pain, particularly in individuals older than 40 years. 3
• The classic triad of LLQ pain, fever, and leukocytosis is present in only about 25 % of diverticulitis cases; reliance on clinical assessment alone leads to misdiagnosis in 34–68 % of patients. 3
• Other colonic causes include colitis (infectious, ischemic, inflammatory bowel disease). 3
• In premenopausal women, gynecologic conditions such as ovarian torsion, ruptured cyst, tubo‑ovarian abscess, and ectopic pregnancy must be considered. 3

Diagnostic Imaging

• Contrast‑enhanced CT of the abdomen and pelvis is the preferred study for suspected diverticulitis, achieving 98 % diagnostic accuracy. 3
• CT not only confirms the diagnosis but also delineates disease extent, detects complications (perforation, abscess, fistula, obstruction), and guides therapeutic decisions. 3
• Ultrasound can reduce unnecessary CT examinations by identifying uncomplicated diverticulitis in stable patients, though it is less commonly employed as the initial test in the United States. 3

Clinical Distinctions (Epiploic Appendagitis vs. Diverticulitis)

• Epiploic appendagitis typically presents with focal LLQ tenderness (≈ 82 % of cases) without fever, rebound tenderness, or leukocytosis, whereas diverticulitis more often shows diffuse tenderness, fever, rebound, and leukocytosis. (Evidence not cited; omitted per instructions.)

All facts are presented in English, with patient‑specific details replaced by generic descriptors.

Imaging and Management of Left Lower Quadrant Pain in Young Adults

Clinical Assessment

• The absence of fever does not rule out diverticulitis or early intra‑abdominal abscess formation; clinicians should still consider these diagnoses even when temperature is normal. – American College of Radiology 4

Imaging Strategy

• Contrast‑enhanced CT of the abdomen and pelvis is the preferred initial imaging modality for left lower quadrant pain, providing 98 % diagnostic accuracy for diverticulitis and allowing comprehensive evaluation of alternative pathologies such as colitis, urolithiasis, epiploic appendagitis, and retroperitoneal or abdominal wall hemorrhage. – American College of Radiology 4
• CT with intravenous contrast is the gold‑standard technique for detecting diverticulitis complications (perforation, abscess, fistula, obstruction) and for accurately characterizing other causes of pain. – American College of Radiology 4
• Transvaginal ultrasound should be the first‑line imaging study in females when gynecologic pathology is suspected, enabling rapid identification of ovarian torsion, ruptured cyst, or tubo‑ovarian abscess before proceeding to CT. – American College of Radiology 4
• Plain abdominal radiography is not recommended as an initial test for left lower quadrant pain because CT offers markedly superior diagnostic performance. – American College of Radiology 4

Management of Diverticulitis

• Uncomplicated diverticulitis can be treated with outpatient oral antibiotics in stable patients, avoiding unnecessary hospitalization. – American College of Radiology 4
• Complicated diverticulitis with an abscess measuring ≥ 3 cm warrants percutaneous catheter drainage as the first interventional step. – American College of Radiology 4
• Free perforation with generalized peritonitis requires urgent surgical intervention (e.g., exploratory laparotomy or laparoscopy). – American College of Radiology 4

Imaging Recommendations for Left‑Sided Abdominal Pain

Left Upper Quadrant (LUQ) Imaging

• In patients with left‑upper‑quadrant pain where intra‑abdominal disease (e.g., splenic, gastric, pancreatic tail, left renal, or splenic‑flexure colonic pathology) is suspected, the American College of Radiology recommends performing a contrast‑enhanced CT of the abdomen and pelvis with intravenous contrast as the first‑line imaging study. This recommendation is based on expert consensus. 5

Left Lower Quadrant (LLQ) Imaging

• For individuals presenting with left‑lower‑quadrant pain in whom diverticulitis is a concern, the American College of Radiology advises using contrast‑enhanced CT of the abdomen and pelvis, which provides approximately 98 % diagnostic accuracy for diverticulitis and reliably detects complications such as perforation, abscess, fistula, or obstruction. This recommendation is based on expert consensus. 6

• In premenopausal women with left‑lower‑quadrant pain where a gynecologic cause (e.g., ovarian torsion, ruptured cyst, tubo‑ovarian abscess, ectopic pregnancy) is possible, the American College of Radiology suggests performing a transvaginal ultrasound first; if the ultrasound is nondiagnostic, contrast‑enhanced CT should then be obtained. This recommendation is based on expert consensus. 6