Normally, a little fluid exists as a lubricant between the two layers of the peritoneal lining. Interestingly, men have very little intraperitoneal fluid while women may have up to 20 mL of fluid, depending upon the phase of their menstrual cycle.
Approximately 85 percent of ascites cases are caused by cirrhosis of the liver, and roughly 10 percent of cases are caused by cancer. While the condition is relatively common among peritoneal mesothelioma patients, this cancer is a rare cause of peritoneal effusion overall.
Doctors usually think of other cancers before mesothelioma when peritoneal fluid tests show malignant cancer cells.
People with peritoneal mesothelioma generally go to the doctor with one of three types of symptoms and signs:
- “Dry-Painful” Type
- This type is the most common and is associated with localized abdominal pain because of a significant tumor mass and no ascites.
- “Wet” Type
- Patients with this type present without pain and have many small tumors, abdominal distension (swelling of the abdomen) and ascites.
- “Mixed” type
- This is a combination of the wet and dry types.
Peritoneal effusion can worsen as the cancer spreads. For this reason, the presence of ascites isn’t strongly associated with survival time, but worsening ascites is a sign that the cancer is progressing.
Symptoms and Causes
As fluid builds between the layers of the peritoneal lining, various symptoms may occur, including:
- Abdominal pain
- Abdominal swelling or distention
- Trouble breathing
- Chest pain
- Weight gain
- Loss of appetite
The most common cause of nonmalignant ascites is cirrhosis of the liver.
Malignant ascites is typically associated with cancers of the colon, rectum, lung, pancreas, liver, ovary, uterus, breast or lymphatic system.
About 50 percent of malignant peritoneal effusions are caused by peritoneal carcinomatosis. This is when there are many small deposits of cancer in the peritoneal lining of the abdominal cavity.
Around 13 percent are the result of other cancers spreading to the liver.
Malignant ascites may develop via several mechanisms:
- Cancer cells migrate into lymph nodes and lymphatic channels, blocking the flow of fluid and resulting in fluid accumulation.
- Highly active cancers produce fluid that accumulates in the abdominal cavity.
- Liver metastases that result in functional cirrhosis, which leads to a state called portal hypertension that causes ascites.
Unfortunately, malignant ascites carries a poor prognosis for most people with cancer. The median survival is around five months for most cancers that cause malignant ascites.
However, this is not necessarily the case for peritoneal mesothelioma patients. Half of those who undergo surgery with heated chemotherapy live longer than five years. Approximately 40 percent of peritoneal mesothelioma patients qualify for surgery.
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Various diagnostic tools are used to diagnose peritoneal effusion:
- Physical examination
- CT scan
- Testing fluid obtained via paracentesis (drainage of ascites fluid)
Ascites is among the first diagnoses that will come to a doctor’s mind when a patient goes to the doctor with severe abdominal distension. However, further testing is required to confirm fluid has indeed accumulated in the abdominal cavity.
Imaging tests — such as ultrasonography and CT scans — are the next step in diagnosing peritoneal effusion. These tests can quickly indicate the presence of fluid around the abdomen.
When ascites is new to a patient or the cause is unknown, a paracentesis is ordered to drain the fluid and collect a sample to look for signs of cancer using pathology tests. A paracentesis may be performed for diagnostic and therapeutic purposes.
Treatment of malignant ascites is different from nonmalignant ascites.
- Treatment of nonmalignant ascites involves a low-sodium diet, diuretics, bed rest, antibiotics if there is an infection, therapeutic paracentesis and possibly surgery to reroute blood flow or perform a liver transplant.
- Treatment of malignant peritoneal effusion seeks to manage the buildup of fluid. Therapies include therapeutic paracentesis, placement of a permanent intraperitoneal catheter for ongoing drainage, diuretics and chemotherapy. Some patients qualify for cytoreductive surgery with heated chemotherapy, which extends survival for many patients and resolves ascites in many cases.
The use of diuretics is minimal in malignant ascites because they become less effective as tumors progress. When tumors grow and spread, they create more fluid. Diuretics simply don’t work well enough to manage the fluid buildup.
Chemotherapy can help reduce fluid buildup, and draining the fluid is the most effective way to treat ascites.
A paracentesis is a minor surgical procedure that drains excess fluid from the abdomen using a hollow needle and a drainage tube that collects the fluid into a bag. Some of the fluid is collected for laboratory tests to look for signs of cancer.
This procedure may be performed multiple times to control recurring ascites and associated symptoms such as distention, pain, nausea, vomiting and difficulty breathing.
A paracentesis alone cannot diagnose malignant peritoneal mesothelioma. In many cases, no cancerous cells are found in the ascitic fluid. To get an accurate diagnosis, a tissue biopsy is obtained with either a fine-needle aspiration or a laparoscopic surgical biopsy.
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In cases of severe ascites that recur quickly after repeat paracenteses, placement of a permanent intraperitoneal catheter may be warranted.
Permanent catheters allow constant drainage of ascitic fluid, which relieves distension, pressure, pain, nausea, vomiting and difficulty breathing. Patients no longer have to return to the hospital for repeated paracenteses.
A minor surgical procedure in a hospital setting is required to place the catheter in the peritoneum. Small incisions in the abdomen are made to insert the catheter, which is then connected to a drainage tube. The tube connects to a bag that collects the ascitic fluid. The bag is easily removed from the tube to allow nurses and patients to regularly dispose of accumulated fluid.
Patients and their caregivers are taught how to empty the bag and care for the catheter by a nursing staff before they go home. Some patients may have nurses come to their home to empty the bag and provide ongoing instruction until they are completely comfortable with the process.
Patients who opt to receive chemotherapy may notice a reduction of peritoneal effusion. When chemotherapy effectively kills peritoneal mesothelioma cells the tumors become reduced in size and there are less cancerous cells that produce fluid. Fewer cancer cells means less fluid is produced.
However, ascites can recur when the cancer begins to grow again. A second or third line of chemotherapy can control recurring peritoneal effusions, especially in conjunction with a paracentesis or intraperitoneal catheter.
Cytoreductive Surgery and Heated Chemotherapy
Peritoneal mesothelioma patients who are diagnosed early enough to qualify for surgery also undergo hyperthermic intraperitoneal chemotherapy (HIPEC), also known as heated chemotherapy.
The surgery attempts to remove as much cancerous tissue as possible and is followed by localized chemotherapy that is heated to better penetrate residual cancer cells that surgeons were unable to remove.
This approach is an effective way to control ascites because much of the cancer is removed or killed with chemotherapy, which greatly reduces the production of ascitic fluid.
While peritoneal effusion is a source of discomfort for people with peritoneal mesothelioma, it is treatable and controllable. Proper treatment can control pain and other symptoms in addition to resolving recurring ascites.
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Last Modified May 2, 2019