Which condition is characterized by the presence of excess fluid in the abdominal cavity?

The condition characterized by the presence of excess fluid in the abdominal cavity is ascites. This occurs when there is an accumulation of fluid in the peritoneal cavity, which can result from various underlying causes such as liver cirrhosis, heart failure, and certain cancers. Ascites can lead to abdominal swelling and discomfort, and may signify serious health issues related to liver and cardiovascular function.

In contrast, hepatomegaly refers to an enlarged liver, which can be associated with various diseases but does not specifically relate to fluid accumulation in the abdominal cavity. Splenomegaly involves an enlarged spleen, which may occur due to conditions such as infections or liver disease but similarly does not involve excess fluid in the abdominal space. Carcinoma is a type of cancer and, while it can lead to ascites if it spreads to the abdominal lining, it does not directly describe the condition of fluid accumulation itself. This distinction makes ascites the correct answer to the question regarding excess fluid in the abdominal cavity.