ASCITES

Ascites means free fluid in the peritoneal cavity. It causes abdominal distention. It is detected clinically by the sign of “shifting dullness” (the line of dullness to percussion shifts laterally as the patient turns on his side), but there must be at least 500cc of free fluid. Ultrasound scans will detect as little as 100cc.

Pathophysiology – The subphrenic lymphatic plexuses become blocked with tumor. Fluid is exuded by both tumor-involved and normal peritoneum, mediated locally by vasoactive products. Sodium retention also occurs in malignant ascites which explains why diuretics can be effective. Ascites due to peritoneal deposits can occur with almost any carcinoma, but is seen most often in carcinomas of breast, ovary, colon, stomach, pancreas and bronchus.

Symptoms are due to pressure:

•  Abdominal discomfort

•  Inability to bend or sit upright

•  Leg edema

•  Dyspnea

•  Heartburn

Summary of management options:

1. Analgesia for discomfort or dyspnea

2. High dose diuretics

3. Paracentesis

4. Peritoneovenous shunt

There is no place for intra-peritoneal instillations of cytotoxics, which are usually ineffective. A wide variety of agents have been used (including bleomycin, fluorouracil, thiotepa and quinacrine). Several studies have shown a partial response in about 30% of patients, but in practice the results are usually disappointing. Ascites can sometimes resolve in response to systemic chemotherapy (for example, fluorouracil for gastrointestinal malignancies).

1. Analgesics – Ascites can sometimes cause a feeling of tightness and discomfort which responds well to low doses of opioid analgesics. (see Analgesics, Dyspnea)

2. Diuretics – The recommended starting dose is spironolactone 200mg per day with furosemide 40mg per day. It usually begins to work within 5 days, and the ascites resolves over 2 to 4 weeks in about 70% of patients. Girth measurements are taken twice weekly and should decrease. If there is no decrease after one week, increase the doses to spironolactone 200mg 2 times a day with furosemide 120mg per day. Follow-up is needed with these high doses to avoid dehydration. Spironolactone may cause nausea.

High dose diuretics can effectively reduce malignant ascites. In one study 13 of 15 patients with malignant ascites had an excellent response to spironolactone started at 150mg per day, and increased by 50mg per day if average daily weight loss was less than 0.5kg. All patients showed increased sodium excretion.

There is a case report of intravenous infusions of furosemide (100mg in 100ml saline at 5ml per hour) effectively reducing ascites when oral diuretics had failed.

If the patient has a short prognosis (gross hepatomegaly and jaundice, for example) then paracentesis to relieve symptoms quickly is indicated, rather than starting diuretics.

«  Do not give potassium supplements with spironolactone (which is potassium-sparing) because hyperkalemia can occur.

3. Paracentesis is a useful emergency measure when a patient has a tense ascites causing severe discomfort, dyspnea or inability to sit up. It occasionally needs to be repeated. It is safe to drain off the first 4 liters quickly, and then a further 6 liters more slowly at 2 liters per hour.

Procedure:

• Use 0.5% bupivacaine as a local anesthetic, which prevents pain at the drainage site from 6 to 8 hours.

• The bladder should be empty. Marked bowel distention is a contraindication to paracentesis.

• The ideal site is the left ileac fossa (10cm from the mid-line to avoid the inferior epigastric artery). Puncture sites should be away from scars.

• A good method is to use a pediatric trocar and cannula which connects straight into a urinary drainage bag.

• Ascitic fluid occasionally continues to dribble from the paracentesis site. Explain to the patient that this may occur, and apply a colostomy bag to collect the leaking fluid. If leakage has not stopped within 48 hours, consider suturing.

• Paracentesis can easily be performed in the home.

4. Peritoneovenous shunts – A shunt can effectively control malignant ascites. The use of a shunt for ascites due to cirrhosis was first introduced in 1962. In 1974 Leveen developed a shunt with a one way pressure-sensitive valve, and in 1979 Denver developed a shunt which has the advantage of a pumping chamber to reduce the incidence of occlusion (which occurs eventually in about 30% of patients).

The shunt can be inserted under local or general anesthesia. The fenestrated peritoneal tube is inserted in the right or left hypochondrium, the valve chamber is placed over a lower rib, and the venous end of the shunt is led subcutaneously to a neck incision above the clavicle and introduced through the internal jugular vein into the superior vena cava. The operation is covered by antibiotics for three days.

The insertion of a shunt is contraindicated if the ascitic fluid is particularly viscous due to infection or blood, or if it is loculated.

There is no evidence that the shunt increases distant  metastases.

Occlusion due to fibrin deposition or omental plugging can usually be detected by ultrasound. If it does not respond to pumping, the shunt has to be replaced. Rarely occlusion may be due to thrombosis around the venous end of the shunt, which may respond to anti-coagulation.

Insertion of a shunt does not affect prognosis. It can produce excellent palliation of symptoms even though the abdomen is not totally emptied of fluid. The shunt can remain patent and effective for months and years.

Mrs. R. T., age 27, was diagnosed as suffering from carcinoma of the ovary in November, 1982 and treated with chemotherapy. She developed ascites, and a peritoneovenous shunt was inserted in July, 1985. She was referred for hospice care in November, 1986. She developed rigors and the shunt was removed in March, 1987 (after being in place for 1 year and 10 months). The rigors settled and the abdominal distention did not recur, possibly because the skin of the abdominal wall had become indurated and less able to distend. She continued her part-time job until the week she died, two months later.

The author and publisher have taken precautions to ensure that the information in this book is error-free. However, readers must be guided by their own personal and professional standards of good practice in evaluating and applying recommendations made herein. The contents of this book represent the views and experience of the author, and not necessarily those of the publisher.