What is the normal spleen span and how is splenomegaly diagnosed?

Normal Spleen Span and Diagnosis of Splenomegaly

Splenomegaly is definitively diagnosed when the spleen measures greater than 13 cm in vertical length on imaging, measured in the coronal plane. 1

Normal Spleen Measurements

Adults

• Normal spleen length: ≤13 cm 1, 2
• Average weight: approximately 150 grams 3
• The 13 cm threshold is established in the Lugano Classification and RECIL 2017 criteria and is widely applied across clinical contexts 1

Pediatric Population

The upper limits of normal splenic length vary by age 4:

• 3 months: ≤6.0 cm 4
• 6 months: ≤6.5 cm 4
• 12 months: ≤7.0 cm 4
• 2 years: ≤8.0 cm 4
• 4 years: ≤9.0 cm 4
• 6 years: ≤9.5 cm 4
• 8 years: ≤10.0 cm 4
• 10 years: ≤11.0 cm 4
• 12 years: ≤11.5 cm 4
• 15+ years (girls): ≤12.0 cm 4
• 15+ years (boys): ≤13.0 cm 4

Grading of Splenomegaly

Imaging-Based Classification

• Mild splenomegaly: 11-13 cm in length 1, 5
• Clinically significant splenomegaly: >13 cm 1, 5

Physical Examination-Based Classification (Myeloproliferative Disorders)

• Severe splenomegaly: ≥5 cm below left costal margin 1, 6
• Massive splenomegaly requiring intervention: >15 cm below left costal margin 1, 6
• Consideration for splenectomy: >20 cm below costal margin 2

Proper Measurement Technique

The correct method for measuring spleen length is in the coronal plane 1, 2:

• Measure vertical length directly on coronal CT images 1
• Alternatively, multiply the number of spleen slices on transverse CT by slice thickness 1
• Can also measure splenic coronal diameter on PET maximum intensity projection images 1

Alternative Measurements

While coronal oblique length >12 cm has 97.8% sensitivity for detecting splenomegaly, it has poor specificity (34.1%) 7. The most reliable measurement is the splenic index (craniocaudal × width × thickness), with splenomegaly defined as index >480 7. If using single measurements, craniocaudal length >9.5 cm or width >10.6 cm are more specific than coronal oblique dimension 7.

Clinical Significance and Pitfalls

Important Caveats

• Spleen size varies considerably in healthy individuals, which is why the spleen is typically not selected as a target lesion in lymphoma trials 1
• Splenomegaly can be present even with normal imaging measurements in infiltrative processes like lymphoma, so clinical context matters 1
• In cirrhosis, 83% of patients have splenomegaly at baseline, and progressive enlargement (≥1 cm increase over 1 year) predicts higher risk of esophageal varices formation (84.6% vs 16.6%) and first clinical decompensation (51.1% vs 19.5%) 8

When Splenomegaly Requires Intervention

In myeloproliferative disorders, patients with splenomegaly ≥5 cm below the left costal margin, particularly when exceeding 15 cm, should be evaluated for treatment before allogeneic hematopoietic cell transplantation 6. Massive splenomegaly is associated with higher risk of delayed engraftment, graft failure, increased non-relapse mortality, and worse overall survival after transplantation 6.