What are the causes of left-sided abdominal pain that is worsened by deep inspiration and palpation?

Left-Sided Abdominal Pain Worse on Inspiration and Palpation

Left-sided abdominal pain that worsens with deep inspiration and palpation most commonly indicates either abdominal wall pathology (particularly anterior cutaneous nerve entrapment syndrome) or pleuritic processes (pneumonia, splenic infarction with capsular irritation), and you must distinguish between these by performing a Carnett test and obtaining appropriate imaging based on the clinical context.

Immediate Diagnostic Approach

Clinical Examination Priorities

• Perform the Carnett test immediately: Have the patient tense their abdominal muscles by raising their head while lying flat; if pain stays the same or worsens during palpation with muscle contraction, this strongly suggests abdominal wall pain rather than intra-abdominal visceral pathology. 1

• Identify a small, circumscribed tender spot: Abdominal wall nerve entrapment typically presents with a localized painful area (often described as a "painful pit") at specific anatomical sites—most commonly the lateral edge of the rectus abdominis or the semilunar line. 2, 1, 3

• Assess for Kehr's sign: If the patient reports referred left shoulder pain accompanying left upper quadrant (LUQ) discomfort, this indicates splenic capsular irritation from infarction, subcapsular hematoma, or impending rupture—a potentially life-threatening condition requiring urgent imaging. 4, 5

• Check vital signs for occult hemorrhage: Tachycardia or hypotension suggests splenic rupture or sequestration and mandates immediate contrast-enhanced CT. 5

Anatomical Localization Determines Next Steps

Left Upper Quadrant (LUQ) Pain

• Order contrast-enhanced CT abdomen/pelvis with IV contrast as the primary imaging study if pain is truly localized to the LUQ and you suspect intra-abdominal pathology (splenic, gastric, pancreatic tail, left kidney, or splenic flexure colon disease). 6, 4, 7

• IV contrast is mandatory because it visualizes splenic parenchyma, detects infarcts (ultrasound misses ~82% of them), characterizes hematomas/abscesses, and identifies vascular lesions such as pseudoaneurysms or splenic vein thrombosis. 4, 5, 7

• Do not use ultrasound as the primary modality for acute LUQ pain; its sensitivity for splenic infarction is only ~18% compared with contrast-enhanced CT. 4, 7

• Exclude referred pain sources first: Obtain ECG and troponin to rule out cardiac angina/pericarditis, and consider chest radiography if respiratory symptoms are present to evaluate for pneumonia with pleuritic pain. 4, 7

Left Lower Quadrant (LLQ) Pain

• Contrast-enhanced CT abdomen/pelvis achieves 98% diagnostic accuracy for diverticulitis and is the preferred initial study for LLQ pain, detecting complications (perforation, abscess, fistula, obstruction) that guide management. 8, 4

• In premenopausal women, perform transvaginal ultrasound first if gynecologic pathology (ovarian torsion, ruptured cyst, tubo-ovarian abscess, ectopic pregnancy) is suspected before proceeding to CT. 8, 4

Abdominal Wall Pain Syndrome

Anterior Cutaneous Nerve Entrapment Syndrome (ACNES)

• This is the most common and frequently missed cause of abdominal wall pain, typically presenting with acute or chronic localized pain at the lateral edge of the rectus abdominis that worsens with position changes or increased abdominal muscle tension. 1

• Common anatomical sites include the semilunar line (most frequent), linea alba between xiphoid and umbilicus, within the rectus muscle itself, or along the costal arch. 3

• Confirm the diagnosis with a diagnostic local anesthetic injection: 50% or greater postprocedural pain improvement confirms nerve entrapment. 1

• Initial treatment is local injection with anesthetic plus corticosteroid, which has a 70-99% overall response rate. 1

• For refractory cases requiring more than two injections, surgical neurectomy generally resolves the pain. 1

Clinical Pitfalls to Avoid

• Failure to recognize abdominal wall pain leads to expensive, unnecessary laboratory tests, imaging studies, consultations, laparoscopies, and exploratory laparotomies—most of which are nondiagnostic and leave patients frustrated. 2, 1

• Repeated forceful contractions during exercise and straining, chronic abdominal wall inflation by obesity, and bloating may cause strain at anatomically predisposed sites. 3

Pleuritic and Splenic Causes

When to Suspect Splenic Pathology

• Fever accompanying LUQ pain mandates urgent contrast-enhanced CT to rule out splenic abscess, which requires early percutaneous drainage to prevent rupture and peritonitis. 4, 5, 7

• Known splenomegaly (from infectious mononucleosis, portal hypertension, sickle cell disease, lymphoproliferative disorders, sarcoidosis, or metastatic disease) markedly increases the risk of rupture, infarction, and sequestration. 4, 5

• Splenic infarction is most common in patients with embolic sources such as endocarditis, atrial fibrillation, or sickle cell disease; once confirmed on CT, obtain echocardiography and initiate anticoagulation when not contraindicated. 4, 5

• Splenic sequestration presents with an acute drop in hemoglobin/hematocrit and constitutes a life-threatening emergency requiring immediate assessment. 4, 5

Pulmonary Causes

• Lower-lobe pneumonia can present as LUQ pain with pleuritic features (worsening on inspiration); obtain chest radiography or chest CT if respiratory symptoms (cough, dyspnea) are present. 7

Algorithmic Decision Framework

1. Perform Carnett test and palpate for a small, circumscribed tender spot

   • Positive Carnett test + localized tenderness → Diagnose abdominal wall pain (likely ACNES); confirm with diagnostic local anesthetic injection 1
   • Negative Carnett test → Proceed to step 2

2. Assess for Kehr's sign, fever, or vital sign instability

   • Present → Order urgent contrast-enhanced CT abdomen/pelvis with IV contrast 4, 5, 7
   • Absent → Proceed to step 3

3. Localize pain to LUQ versus LLQ

   • LUQ → Exclude cardiac/pulmonary causes (ECG, troponin, chest X-ray if indicated), then order contrast-enhanced CT with IV contrast 6, 4, 7
   • LLQ in premenopausal woman → Transvaginal ultrasound first if gynecologic pathology suspected, otherwise contrast-enhanced CT 8, 4
   • LLQ in other patients → Contrast-enhanced CT abdomen/pelvis 8, 4

High-Risk Populations Requiring Lower Threshold for Imaging

• Elderly patients are at especially high risk for delayed diagnosis and adverse outcomes because they often provide unreliable histories and have multiple comorbidities that mask typical findings. 5, 7

• Immunocompromised patients, those with known malignancy, or recent surgery/trauma presenting with fever and LUQ pain have a high likelihood of splenic abscess and require rapid diagnostic workup. 5

• Patients with known splenomegaly presenting with even vague LUQ discomfort should not be dismissed, as capsular expansion heightens the risk of rupture, infarction, and sequestration. 5

Key Diagnostic Pitfalls

• Physical examination of the LUQ has the lowest inter-rater reliability among abdominal quadrants (< 5% of abdominal pain truly localizes there), making early imaging essential rather than optional. 4, 7

• Failure to reproduce pain on palpation does not rule out intra-abdominal pathology; visceral sources such as splenic, gastric, or pancreatic disease often generate non-palpable pain. 7

• Do not rely on the absence of fever to exclude serious splenic pathology; infarction and early abscess formation can be afebrile. 5

• Avoid non-contrast CT for acute LUQ evaluation, as it markedly reduces detection of splenic infarcts, small lesions, vascular abnormalities, and gastrointestinal pathology. 7