How to manage abdominal pain and ascites in a patient with peritoneal carcinomatosis?

Management of Abdominal Pain in Peritoneal Carcinomatosis with Ascites

Opioids are the drugs of choice for managing abdominal pain in patients with peritoneal carcinomatosis and should be administered with appropriate anti-constipation measures to prevent complications. 1

Pain Management Strategy

First-line Approach

• For mild pain: Acetaminophen (paracetamol) up to 3g/day oral or IV 1
  • Avoid NSAIDs due to increased risk of GI bleeding, ascites decompensation, and nephrotoxicity, especially with portal hypertension 1

For Moderate to Severe Pain

• Morphine is the preferred opioid 1
  • Start with oral route if patient can tolerate
  • Switch to parenteral (IV) or transdermal routes if:
    • Patient has impaired swallowing
    • Gastrointestinal obstruction is present
    • Poor PO intake (as in this case) 1

Critical Considerations with Opioids

• Always implement a purging program when starting opioids to prevent constipation and hepatic encephalopathy 1
  • Use osmotic laxatives preemptively
  • Consider naltrexone to limit opioid-induced constipation in the GI tract 1

Adjunctive Pain Management Options

• Hypofractionated radiotherapy may be considered for localized pain if identifiable focal lesions are present 1
• Percutaneous or EUS-guided celiac plexus blockade for patients with poor tolerance to opiates 1

Management of Ascites

Diagnostic Paracentesis

• Perform diagnostic paracentesis to:
  • Confirm peritoneal carcinomatosis (cytology has 96.7% sensitivity with three samples) 1
  • Rule out spontaneous bacterial peritonitis (SBP) or secondary peritonitis 1
  • Tests should include cell count with differential, total protein, albumin, and cytology 1

Therapeutic Paracentesis

• Consider therapeutic large-volume paracentesis for symptomatic relief of abdominal distension and pain 1
• Drainage of ascites should be considered especially if associated with intra-abdominal hypertension 1

Chemotherapy Considerations

• For patients with peritoneal carcinomatosis with bowel obstruction, continuous infusion 5-FU may enable oral food intake in up to 41% of patients 1
• Weekly paclitaxel has shown improvement in ascites volume in 39% of gastric cancer patients with peritoneal carcinomatosis 1

Nutritional Support

• Assess nutritional status as it impacts survival in advanced cancer 1
• Consider additional parenteral nutrition for patients with poor oral intake and progressive cachexia 1
• Evaluate for early palliative care involvement, especially if the "surprise question" (would you be surprised if the patient died within 30 days?) is answered "no" 1

Monitoring and Follow-up

• Monitor response to treatment at regular intervals
• Follow ascites with ultrasound or CT as needed 1
• Repeat paracentesis if symptoms worsen or new signs of infection develop (fever, increasing pain, encephalopathy) 1

Common Pitfalls to Avoid

1. Failing to provide adequate pain control - undertreatment of pain is common in peritoneal carcinomatosis
2. Not addressing constipation prophylactically when starting opioids
3. Using NSAIDs which can worsen ascites and cause bleeding
4. Ordering unnecessary CA125 testing - this marker is elevated in all patients with ascites regardless of cause and may lead to confusion 1
5. Delaying palliative care involvement - early integration improves quality of life and symptom management

This patient with peritoneal carcinomatosis, significant ascites, and poor oral intake requires aggressive symptom management focusing on pain control with opioids and therapeutic paracentesis, with careful attention to preventing opioid-induced complications.