Malignant ascites, a collection of fluid in the peritoneum, is a serious prognostic event in the progression of several tumors. These tumors include breast, colorectal, gastric, pancreatic, hepatocellular and gynecologic cancers. Metastatic disease to the liver, peritoneal lining, or lung; testicular cancer; and, less frequently, melanoma, also lead to malignant ascites.
According to Enck (2002), malignant ascites is classified into four categories. The first is peripheral ascites, the most common type, which accounts for approximately 50% of all cases. This type of ascites is the result of mechanical interference with venous or lymphatic drainage at the level of the peritoneal space.
The second type of malignant ascites is central ascites. In this type of ascites, the tumor invades the liver, causing compression of the portal and lymphatic systems. The decreased oncotic pressure in malignant ascites is caused by limited protein intake and a catabolic state caused by the cancer, not by impaired liver protein synthesis. This type of ascites accounts for approximately 20% of all cases of malignant ascites.
The third type of malignant ascites is mixed ascites, in which the tumor is present both in the liver and on the peritoneal surface. This type, which accounts for approximately 20% of all cases of malignant ascites, is the effect of combined central and peripheral ascites.
The fourth and least common type of malignant ascites is chylous ascites. In chylous ascites the tumor infiltrates the retroperitoneal space and causes obstruction of the lymph flow.
Because most patients with malignant ascites survive only about 2 months, treatment should be conservative. Loop diuretics may be helpful for patients with central ascites, because portal hypertension responds well to these drugs. Repeat paracentesis can be effective in providing relief of the symptoms associated with ascites, although the patient is at risk for infections or damage to the visceral peritoneum.
In addition to the presence of a tumor, factors that contribute to the development of malignant ascites include interleukin-2; tumor necrosis factor; vascular endothelial growth factors; lymphatic obstruction, leading to decreased outflow from the peritoneal cavity; and vascular permeability (Itano & Taoka, 2005).
EPIDEMIOLOGY AND ETIOLOGY
Approximately 10% to 15% of ascites cases are caused by intraabdominal malignancies. Ascites caused by cirrhosis of the liver usually results in excessive fluid formation; however, some tumors, particularly ovarian tumors, alter humoral factors that increase capillary leakage of proteins and fluids into the peritoneum is increased (Groenwald et al., 1993; Garrison et al., 1986). Decreased absorption of ascitic fluid by the diaphragmatic or abdominal lymphatics and increased production of capillary fluid are contributing factors in ascites. Increased net filtration results from increases in the capillary surface, capillary permeability, and the protein concentration, leading to an increase in peritoneal oncotic pressure (Tamsma et al., 2001).
Causes of malignant ascites include liver metastases and hepatocellular carcinomas that occlude hepatocellular flow; peritoneal carcinomatosis; a combination of extensive liver metastasis and peritoneal carcinomatosis; malignant lymph node obstruction, with lymph overflow into the peritoneal cavity; and Budd-Chiari syndrome, which develops when a tumor occludes the hepatic vein (Runyon, 1999).
RISK PROFILE
• Lymphoma; melanoma; breast, ovarian, colorectal, gastric, pancreatic, hepatobiliary, testicular, and uterine cancers.
• Extensive liver involvement from metastatic disease; cirrhosis; congestive heart failure; nephrosis with protein wasting; and, infrequently, complications of radiation.
• Pancreatic disease, hepatic encephalopathy, infectious peritonitis, and gut lymphatic or thoracic duct injury can be etiologies of ascites (BC Cancer Agency, 2007).
• Environment: Exposure to hepatitis has been speculated to be an environmental risk.
• Foods: Nonmalignant causes linked to the formation of ascites include long-term alcohol abuse and a high-sodium diet or increased fluid intake with liver or renal disease.
• Medications: Noncompliance with drug regimens in chronic renal or liver disease and complications of chemotherapy can lead to ascites. Herbal preparations that can affect the liver include alfalfa, echinacea, garlic, goldenseal, licorice, red clover, and St. John’s wort (Wren & Norred, 2003).
PROGNOSIS
Malignant ascites is an indicator of end-stage disease. Treatment focuses on palliation of symptoms, although effective palliation is difficult to achieve. The mean survival time for patients with malignant ascites is less than 4 months, depending on the underlying cancer. However, with the use of peritoneal drains and intraperitoneal chemotherapy, the survival time is increasing.
PROFESSIONAL ASSESSMENT CRITERIA (PAC)
1. Initial history and physical examination: vital signs, weight, abdominal girth, and nutrition. The examiner should record any physical signs and symptoms, such as increased abdominal girth, weight gain, lymphadenopathy, liver enlargement, liver flap, shortness of breath, and edema in the lower extremities. Emotional support plays an important role for those whose prognosis is poor.
2. Assess baseline laboratory panel: include a complete blood count, chemistries, liver function, prothrombin and partial thromboplastin times, urinalysis and blood cultures to aid in an overall metabolic view of the patient.
3. Radiographic studies: chest and abdominal x-ray films to rule out obstruction and computed tomography (CT) scans to detect any tumor growth or obstruction. Magnetic resonance imagining (MRI) can help identify tumor growth, and ultrasound studies can be used to determine the depth of the tumor, search for free fluid in the abdomen, or assist in guided needle biopsies. Positron emission tomography (PET) scans can help locate areas of malignancy that cannot be detected by CT scans.
4. Laboratory values: Paracentesis should be done, and the peritoneal fluid should be sent for cell count, albumin level, culture, total protein, lactate hydrogenase, carcinoembryonic antigen, cytology, a serum ascites albumin gradient (SAAG), and Gram’s staining if infection is suspected.
5. A red blood cell count higher than 20,000/mcL indicates either a traumatic tap or malignancy (Shah, 2006).
6. EGF and sCD44v6 levels are significantly higher in patients with malignant ascites than in those with cirrhotic or tuberculous ascites. VEGF levels are higher in patients with ovarian cancer than in patients with gastric or colon cancer (Dong et al., 2003).
NURSING CARE AND TREATMENT
Elevate head of bed to reduce respiratory compromise and alleviate discomfort
Assess pulse, respiration, blood pressure, and temperature
Monitor for fluid shifts and signs of bacterial peritonitis
Monitor fluid balance through intake and output (I and O) measurements
Assess abdomen and measure girth
Weigh the patient
Assess for lymphadenopathy and lymphedema
Assess for gastroenteral and urologic distress caused by increased abdominal pressure
Monitor function of ascitic drains or shunts if in place
Bed rest
Low-sodium, high-protein, fluid-restricted diet
Diuretic therapy
Serum electrolytes, complete blood count (CBC) daily
Antacids for indigestion as needed
After paracentesis monitor for:
• Hypotension related to hypovolemia or fluid shift
• Infection or peritonitis
After peritoneovenous shunting monitor for:
• Heart failure or pulmonary edema caused by rapid infusion of peritoneal fluid intravascularly
• Shunt malfunction caused by malposition
• Potential fluid volume deficit and potential electrolyte imbalance caused by increased diuresis
• Infection caused by contamination of the intravascular or intraperitoneal system
Assess:
• Pulmonary status (breath sounds, labor of respirations, oxygen saturation) q4h
• Abdomen for rigidity
• For gastrointestinal/genitourinary (GI/GU) compromise
• Paracentesis site or shunt placement incision for signs of infection daily
• Patient comfort q4h
• Weight pattern to evaluate the effectiveness of interventions
• Patient and family coping on a daily basis
Measure:
• Temperature, respirations, pulse, blood pressure q4h
• I and O q8h
• Weight daily
• Abdominal girth daily
• Urine specific gravity daily
Send:
• CBC, serum electrolytes daily
• Drained ascitic fluid for specific gravity, protein count, cell count, bacteriology, amylase, carcinoembryonic antigen (CEA) (Kehoe, 1991)
Implement:
• Activity restriction
• Low-sodium, high-protein, fluid-restricted diet
The cause of the ascites should be determined based on the patient’s history and the physical examination findings. Abdominal paracentesis is performed to determine the etiology of the ascites. Bloody or serosanguineous fluid characterizes malignant ascites. Cirrhotic, nephritic, pancreatic, or cardiac disease results in serous fluid; cloudy fluid is characteristic of infectious peritonitis (Runyon, 1994).
Treatment of malignant ascites is directed toward symptom control. Generally the medical approach is initiated with noninvasive options and proceeds to more invasive treatments as the malignant ascites becomes more refractory.
Management of pain is a priority. Antiemetics and having the patient eat smaller, more frequent meals can relieve abdominal discomfort. Sodium restriction and diuretics can be tried but usually are ineffective.
Peripheral edema and dyspnea are caused by fluid accumulation in the abdomen as a result of poor lymphatic drainage; these symptoms can be managed with paracentesis to drain the fluid.
Initial surgery may be performed to debulk the tumor, but these patients’ poor prognosis does not warrant the risk of surgery.
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