I was recently at a dinner party where an elderly woman was complaining that her physicians were unable to determine the reason for her constant abdominal and pelvic pain. She said she was told there was fluid in her abdomen. Despite having multiple blood tests, CT scans, MRI’s and ultrasound scans, they were unable to determine where this fluid was coming from.
Free fluid in the abdomen is referred to as ascites in medical terminology. One of the most common causes of ascites (80 %), is cirrhosis of the liver. This is a result of chronic liver disease and portal hypertension or increased pressure in the liver blood flow. It is the result of an imbalance of pressure between the blood circulation and the abdominal cavity which is a low-pressure space.
Increased portal blood pressure and decreased albumin (a protein in the blood) due to malnutrition or bowel disease are other reasons for a pressure gradient, which results in fluid in the abdomen or ascites.
A less common cause of portal hypertension with no cirrhosis is obstruction of the portal vein by large lymph nodes, a tumor or mass.
Blood clot formation in the hepatic veins (Budd-Chiari syndrome) also creates increased pressure and obstruction of normal blood flow.
Congestive heart failure, hepatitis, pancreatitis, (inflammation of the pacreas which can be due to prolonged alcohol abuse or trauma), constrictive pericarditis and advanced kidney disease can also cause retained fluid in the abdominal and pelvic cavity.
Tumours such as liver and ovarian cancer are also sources of ascites and may not be large enough to detect on imaging studies right away.
There are other less common causes but the main ones are described above.
Many diseases present over a period of time and sometimes it takes longer to determine the cause of abdominal and pelvic fluid. This may be an early sign of a particular disease or disorder which is not advanced enough to be detected by routine tests. Lab tests and imaging studies may need to be repeated until further evidence is revealed.