Definition of Splenomegaly
Splenomegaly is defined as a spleen measuring greater than 11-13 cm in length, with mild splenomegaly specifically defined as 11-13 cm and clinically significant splenomegaly as >13 cm. 1
Size-Based Classification
The grading of splenomegaly follows a standardized measurement system:
- Mild splenomegaly: 11-13 cm in length 1
- Significant splenomegaly: >13 cm in length, representing the threshold for clinically significant enlargement 1
- Massive splenomegaly: >10 cm below the left costal margin or spleen weight exceeding 1000 g with largest dimension greater than 20 cm 2, 3
Normal Spleen Parameters
For context, a normal spleen measures approximately 10 cm in length and weighs approximately 150 g 4. Pathological conditions can result in dramatic expansion, with spleens weighing in excess of 2000 g and extending over 30 cm in length 4.
Clinical Detection Methods
- Physical examination: A palpable spleen is detected in 40-50% of cases and represents the most consistent physical sign 2
- Abdominal ultrasound: Recommended for confirmation of splenomegaly and accurate measurement of spleen size 1, 5
- CT imaging: May be needed to evaluate vascular structure and potential complications, particularly in complex cases 2
Important Clinical Context
The definition is primarily anatomical, but clinical significance varies by degree of enlargement. In myeloproliferative disorders, particularly myelofibrosis, massive splenomegaly (>10 cm below costal margin) carries specific prognostic implications 2. For patients being considered for allogeneic hematopoietic cell transplantation, splenomegaly measuring 5 cm or larger below the left costal margin, particularly when exceeding 15 cm, may require pre-transplant intervention 6.