November 2000
by Gary Frank, RN

Definition: accumulation of excess fluid in the abdominal cavity.

Incidence in cancer patients: 10% of all cases of ascites are caused by cancer. 15% to 50% of all cancer patients will develop ascites. More common with certain tumors, eg. 30% of ovarian cancer patients have ascites on presentation and 60% at death. Endometrial, breast, colon, stomach, and pancreatic cancers also have a high incidence of ascites.

Causes in cancer patients:

1. Most commonly a result of tumor cell deposits in the abdomen (esp. the peritoneum) and decreased protein in the blood. The tumor cell deposits block the reabsorption of fluid by the peritoneum and, since fluid follows protein, the fluid tends to move out of the blood vessels and into the abdomen. Diuretics don’t usually help this type of ascites (because it is not caused by increased venous pressure).
2. Liver disease (including cancers) can obstruct the circulation of blood and the resulting increase in venous pressure can force fluid out of the blood vessels and into the abdominal cavity. Some diuretics (ie. Aldactone) may help this type of ascites by reducing venous pressure in and around the liver.
3. Congestive Heart Failure can also result in increased venous pressure causing fluid to be forced out of the blood vessels into the abdominal cavity. Diuretics may help this type of ascites by reducing venous pressure throughout the body.

Palliative Treatment: Because the most common cause of ascites in advanced cancer patients is that described in #1 above, there is usually no drug therapy that will help reduce ascites in our patients (though clinical trials are ongoing). Furthermore, even in those patients where a trial of diuretics for ascites might be justified in theory, the risk of severe dehydration associated with the use of these drugs in palliative patients is often so high that the use of diuretics may cause more harm than good to the overall well-being of the patient. Therefore, the best approach is often simply good nursing care combined with periodic paracentesis (ie. draining of the ascitic fluid by aseptically puncturing the abdominal wall with a needle attached to a closed collection system).

Potential Complications of Paracentesis: Since paracentesis involves a penetration of the skin and abdominal wall it does present a risk of infection (esp. peritonitis). Therefore, aseptic technique is needed both during the procedure and for dressing care afterwards. Perforation of bowel, other visceral organs, or tumor mass is also a potential complication. Therefore, if there is any doubt as to the location, nature, or approximate size of the fluid deposit, the procedure is best done under ultrasound guidance (esp. if it is the initial paracentesis). Repeated paracenteses may also contribute to fluid volume depletion and protein loss, however, the symptomatic relief gained from this procedure may outweigh the risk of these potential problems.

Nursing Care:

Positioning and Safe Mobilization: Ascitic fluid is often very heavy and causes abdominal distention. Furthermore, because this added weight is composed of fluid held within a relatively malleable space (ie. the abdominal cavity) it tends to shift suddenly with movement. Since these problems often occur in patients who are also already weak and cachetic, there is a very high risk of falls, even moving in bed can be very difficult.

For all these reasons, assistance with positioning and mobilization is often essential for patients with ascites.

Asceptic Technique: See above under "Potential Complications of Paracentesis".

Ascitic Fluid Collection: After paracentesis the puncture site should be dressed with gauze and pressure dressing tape. Sometimes, however, a significant amount of ascitic fluid may continue to ooze or drip from the puncture site. If this is the case an ostomy collection bag may be appropriate for placement around the puncture site. During paracentesis a sterile evacuation bottle is most commonly used.

Bowel care: The weight of the ascitic fluid can impair bowel motility and contribute to constipation. The fluid can also make it quite difficult to assess bowel sounds. For these reasons fairly aggressive bowel care is needed to prevent or manage constipation (especially if the patient is taking opioids or has other risks for constipation).

Risk of Nausea and Vomiting: The weight of ascitic fluid can impair gastric emptying as well as bowel motility and so can contribute to nausea and vomiting. Positioning may help this: the stomach empties towards the right and many patients may be less prone to nausea when lying on their right side with the head of their bed raised. Medications that promote upper gastrointestinal motility (eg, metoclopramide) are also indicated for this problem.

Dyspnea: Adequate ventilation of the lungs requires, among other things, that the diaphragm move freely on inspiration. When the abdominal cavity is distended, as is the case with ascites, this free movement of the diaphragm is impeded. The result can be dyspnea or shortness of breath and even tachypnea, shallow respirations and hypoxemia. When any or all of these problems present, oxygen therapy is usually indicated (along with other medical interventions known to help this type of dyspnea, eg. opioids and paracentesis).

References: Bain, V. Jaundice, Ascites, and Hepatic Encephalopathy. Oxford Textbook

Of Palliative Medicine, 2nd Edition. London: Oxford Press, 1998