Ascites is defined by the abnormal accumulation of fluid within the peritoneal cavity, the space inside the abdomen that houses the digestive organs. This fluid buildup, which can range from minor amounts to several liters, is often a sign of a significant underlying health issue. Ascites frequently indicates advanced disease, most commonly affecting the liver, and requires prompt diagnosis and management.
The Physical Nature of Ascites
The fluid that makes up ascites is not located in the superficial layers of the abdominal wall, meaning it cannot be gathered or “pinched” like subcutaneous fat. Ascites is an accumulation within the peritoneal space, which is deep inside the body, surrounding the internal organs. Because the fluid is free-floating within this large internal cavity, the swelling it causes is typically smooth, symmetrical, and tense.
During a physical examination, this deep fluid collection reacts differently than surface fat or localized edema. Unlike soft, pliable subcutaneous fat, ascites often results in an abdomen that feels hard and distended. Doctors may use the “fluid wave test” to detect the ripple of fluid transmitted across the abdomen, a physical sign absent in cases of simple weight gain.
Primary Causes and Risk Factors
Ascites is most commonly a complication of severe liver disease, with cirrhosis responsible for approximately 80% of cases. Cirrhosis causes scarring that impedes blood flow, leading to portal hypertension (high blood pressure in the vein leading to the liver). This increased pressure forces fluid to leak into the peritoneal cavity.
Another element is the liver’s decreased ability to produce proteins, particularly albumin. Low albumin levels reduce the osmotic pressure in the blood, allowing fluid to escape the bloodstream and accumulate. Other significant causes include congestive heart failure, which causes back-pressure in the venous system, and kidney failure, which impairs the body’s ability to excrete salt and water. Advanced cancers can also lead to ascites by irritating the abdominal lining or blocking lymphatic drainage.
Recognizing the Signs of Fluid Buildup
The presence of ascites often manifests through several noticeable symptoms that develop progressively. The first is a rapid increase in body weight, accompanied by a noticeable and uncomfortable increase in abdominal girth, often described as bloating or fullness.
As the condition advances, the volume of fluid creates intense pressure within the abdomen, leading to persistent discomfort and a feeling of heaviness. A large fluid buildup can push upward on the diaphragm, which may cause shortness of breath, especially when lying down. Swelling in the ankles and lower legs, known as peripheral edema, also frequently accompanies ascites.
Medical Diagnosis and Management
Confirming the presence of ascites typically begins with a physical examination, where a doctor may test for a fluid wave or shifting dullness. Imaging techniques, particularly an abdominal ultrasound, are then used to confirm the diagnosis. A medical professional may also perform a diagnostic paracentesis, which involves using a fine needle to withdraw a fluid sample for laboratory analysis.
This fluid analysis determines the cause of the accumulation and checks for infection, such as spontaneous bacterial peritonitis. Management focuses on addressing the underlying condition and controlling fluid buildup. Dietary changes, specifically restricting sodium intake to less than 2,000 milligrams per day, are a foundational part of treatment.
Medications known as diuretics are often prescribed to increase the body’s excretion of salt and water. This commonly involves a combination of spironolactone and a loop diuretic, such as furosemide. For severe cases or those that do not respond to medication, a therapeutic paracentesis may be performed to drain large volumes of fluid, providing immediate relief.