Section: Hepatobiliary Sub-section: Liver Curriculum: Curriculum, page 87
Definition
Accumulation of fluid within the peritoneal cavity
Aetiology
- Transudate
- Cirrhosis
- Portal hypertension
- Hepatic
- Cardiac
- Budd-Chiari syndrome
- Hypoalbuminemia
- Exudate
- Peritoneal disease
- Malignant ascites
- Infectious peritonitis
- Other etiologies
- Chylous ascites
- Pancreatic ascites
- Myxedema
- Peritoneal disease
Pathophysiology
Malignancy-related ascites
- Peritoneal carcinomatosis
- Causes blockage of the draining lymphatic channels
- Or tumor cells producing fluid into the peritoneal cavity
- Cancer can cause portal hypertension due to obstruction of the portal vein or liver failure
- Lymphomas may cause lymph node obstruction with the accumulation of chylous ascites
Portal hypertension related ascites
- Increase portal pressure (typically HVPG >12mmhg)
- PTH causes release of vasodilator substance (NO)
- Vasodilation of the splanchnic circulation
- This leads to capillary permeability, enhancing fluid leakage into the peritoneum
- This also leads to decreased renal blood flow due to relative hypovolemia
- Activation of the RAAS
- Leads to sodium and water retention as the driving cause
- Low albumin leads to decrease oncotic pressure worsening ascites
Clinical
- Patients with ascites typically report progressive abdominal distension that may be painless or associated with abdominal discomfort
- Weight gain, shortness of breath, early satiety, and dyspnea resulting from fluid accumulation and increased abdominal pressure
- Examination - dullness, shifting dullness
Investigations
- USS - fluid
- CT/MRI - may also show evidence of cirrhosis
Abdominal paracentesis
Two questions:
- Is the fluid infected?
- Is portal hypertension present?
Tests:
- Appearance assessment
- Clear - Uncomplicated ascites in the setting of cirrhosis is usually translucent yellow
- Bloody - traumatic tap, malignancy
- Cloudy - Infected fluid, spontaneous bacterial peritonitis
- Milky - Chylous ascites, Malignancy, cirrhosis, and lymphatic disruption after abdominal surgery
- Serum-to-ascites albumin gradient (SAAG)
- Subtracting the ascitic fluid albumin value from the serum albumin value
- Gradient <11 g/L indicates that the patient does not have portal hypertension
- Gradient ≥11 g/L predicts that the patient has portal hypertension
- Cell count and differential
- Identifies infected ascitic fluid
- Total protein concentration
- Ascitic fluid can be classified as an exudate if the total protein concentration is ≥2.5 or 3 g/dL and a transudate if it is below this cutoff.
- Exudate/transudate system of ascitic fluid classification has been replaced by the SAAG, which is a more useful measure for determining whether portal hypertension is present
- Gram stain
- Cytology
- Amylase - raised in pancreatic ascites
Procedure:
- Left lower quadrant - 2 finger breaths in and up from ASIS
- Mark the site
- Prep and drape
- Local anaesthetic
- Needle is placed
- Aspirate
Complications
- Ascitic fluid leak
- Bleeding
- Bowel perforation
- Infection
- Death
Management
Peritoneal carcinomatosis
- Abdominal paracentesis is the primary treatment
- Often needs repeating every one to two weeks
- Peritoneal ports or indwelling tunneled catheter drainage systems are an option
- Risk of infection
- Can have large volumes of fluid removed without fear of hemodynamic sequelae (unlike portal hypertesion)
- Diuretics may be helpful in patients with portal hypertension
- eg, patients with massive liver metastases, cirrhosis with hepatocellular carcinoma, or malignant Budd-Chiari syndrome
- No dietary sodium restriction so as not to impair their quality of life.
- Denver shunt - peritoneovenous shunt (PVS)
- Negative pressure in the chest allows fluid to move from the high‐pressure intraperitonium to the chest through the one‐way valve tube through subcutaneous tissue of the chest wall to the internal jugular vein to the superior vena cava
- Surgical debulking and chemotherapy
Portal hypertension