From the Guidelines

Splenomegaly is associated with a low platelet count, also known as thrombocytopenia, due to the sequestration of platelets in the spleen.

The presence of splenomegaly is a common laboratory sign of portal hypertension (PH), which is often associated with cirrhosis 1.
A low platelet count is the most common laboratory sign of PH, and it correlates slightly with the hepatic venous pressure gradient (HVPG) and the presence of gastroesophageal varices (GEV) 1.
However, a low platelet count alone is not accurate enough to diagnose or exclude clinically significant portal hypertension (CSPH) or GEV 1.
The combination of platelet count with other noninvasive tests, such as liver stiffness and ultrasound, can improve the diagnosis of CSPH 1.
Splenomegaly taken alone is a sensitive but nonspecific sign of PH, and its size should be routinely reported to provide accurate data on the presence of CSPH/varices when combined with platelet count and liver stiffness 1.
The pathophysiological factors responsible for decreased platelet counts in patients with cirrhosis include hypersplenism and decreased hepatic production of thrombopoietin 1.
Thrombocytopenia is a common feature of hypersplenism, which can affect all hematological cell lines 1.
The management of thrombocytopenia in patients with cirrhosis should integrate correction of coagulation factors, and platelet transfusion can work synergistically with local hemostatic means in high-risk procedures or in the presence of bleeding 1.

From the Research

The relationship between splenomegaly and platelet count is complex and can be influenced by various factors, including the underlying cause of splenomegaly and the presence of other medical conditions 2, 3, 4, 5, 6.
Studies have shown that splenomegaly can lead to thrombocytopenia, which is a decrease in the number of platelets in the blood 2, 4, 5, 6.
The severity of thrombocytopenia can vary depending on the size of the spleen and the degree of splenic sequestration, which is the trapping of platelets in the spleen 4.
In some cases, splenomegaly can also lead to an increased risk of thrombosis, which is the formation of blood clots 3.
The treatment of splenomegaly and thrombocytopenia can involve splenectomy, which is the surgical removal of the spleen, and can lead to an improvement in platelet count and a reduction in the risk of thrombosis 5.

The size of the spleen is an important factor in determining the relationship between splenomegaly and platelet count, with larger spleens tend to be associated with more severe thrombocytopenia 2, 4, 6.
The underlying cause of splenomegaly, such as liver cirrhosis or essential thrombocythemia, can also influence the relationship between splenomegaly and platelet count 2, 3.
Other factors, such as the presence of portal hypertension or the use of certain medications, can also impact the relationship between splenomegaly and platelet count 2, 6.

The relationship between splenomegaly and platelet count has important clinical implications, particularly in the management of patients with thrombocytopenia or those at risk of thrombosis 3, 5, 6.
Accurate diagnosis and treatment of the underlying cause of splenomegaly are essential in managing thrombocytopenia and preventing complications such as thrombosis 2, 3, 5, 6.
Splenectomy may be considered in certain cases, such as in patients with severe thrombocytopenia or those who are at high risk of thrombosis 5.