Diagnostic Ultrasound - Abdomen and Pelvis

Ascites
Diagnoses: Abdominal Wall/Peritoneal Cavity
Infected Ascites
• Postoperative, bacterial peritonitis, tuberculosis, acquired
immunodeficiency syndrome, fungal infections
• Fluid with internal echoes, debris, loculations, multiple
septa
• Peritoneal thickening, matted bowel loops, abscess
Malignant Ascites
• Known malignancy, accounts for ~ 10% of refractory ascites
• Lesions in other organs and lymph nodes; primary mass
such as ovary, gut, pancreas
• Loculated collections; fluid in greater & lesser sac
• Bowel loops tethered along abdominal wall
• Thickening of peritoneum; peritoneal seeding or masses
Pseudomyxoma Peritonei
• Gelatinous mucinous accumulation in peritoneal cavity
secondary to benign or malignant mucin-producing
neoplasm
• Echogenic fluid (nonmobile echoes), masses with cystic
spaces or calcification, echogenic septa, liver scalloping, and
bowel displacement
Peritoneal Inclusion Cyst
• Loculated fluid collections in pelvis
PATHOLOGY
General Features
• Etiology
○ Traditionally classified as transudative or exudative
ascites based on protein content
○ Transudate: Clear or straw colored (protein < 25 g/L)
○ Causes: Cirrhosis, heart failure, nephrotic syndrome
– Cirrhosis and portal hypertension is most common
cause (81%)
□ Budd-Chiari syndrome, portal vein thrombosis,
alcoholic hepatitis, fulminant hepatic failure
– Cardiac: Congestive heart failure, constrictive
pericarditis, cardiac tamponade
– Renal: Nephrotic syndrome, chronic renal failure
– Hypoalbuminemia; protein-losing enteropathy
○ Exudate: Yellowish/hemorrhagic (protein > 25 g/L)
○ Causes: Exudate from inflamed or neoplastic peritoneum
– Neoplasm: Colon, gastric, pancreatic, hepatic, ovarian;
metastatic disease (breast/lung, etc.)
– Infections: Bacterial, fungal, parasitic, tuberculosis
– Trauma: Blunt, penetrating, or iatrogenic
□ Diagnostic/therapeutic peritoneal lavage
□ Bile ascites: Trauma, cholecystectomy, biliary or
hepatic surgery, biopsy, percutaneous drainage
□ Urine ascites: Trauma to bladder or collecting
system, instrumentation
□ Cerebrospinal fluid: Ventriculoperitoneal shunts
□ Chylous: Trauma (blunt, penetrating, surgical),
inflammatory, idiopathic
– Bowel pathology: Ischemia, inflammation, obstruction
Gross Pathologic & Surgical Features
• Serum Albumin Ascites Gradient (SAAG) is difference
between serum and ascites albumin; more useful for
diagnosis of portal hypertension
• SAAG < 11g/L = normal portal portal pressure;SAAG >11g/L
= portal hypertension
• Hemorrhagic: Serosanguineous, erythrocytes >
10,000/mm³
• Spontaneous bacterial peritonitis: Cloudy, neutrophils ≥
250 /mm³ (500/mm³ threshold more specific); cultures
negative in 40%
• Chylous: Yellowish white or milky, triglycerides > 2.25
mmol/L
• Pancreatitis: Dark brown-black, amylase > 2000 U/L
• Pseudomyxoma peritonei: Gelatinous, mucinous
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Asymptomatic, abdominal discomfort & distension,
weight gain
• Physical examination: Bulging flanks, flank dullness, fluid
thrill, umbilical hernia, penile or scrotal edema
• Diagnosis: Paracentesis (US guidance or blind tap)
○ All patients with new onset ascites should have a
paracentesis
○ In chronic ascites, fever, abdominal pain, leucocytosis,
renal insufficiency, or encephalopathy are indications for
paracentesis
○ Fluid analysis: Protein, albumin, lactate dehydrogenase,
glucose, amylase, cytology, pH, triglycerides, cell count,
culture
Natural History & Prognosis
• Ascites is associated with increased mortality and morbidity
in chronic liver disease
• Complication: Spontaneous bacterial peritonitis, respiratory
compromise, anorexia, hepatorenal syndrome
Treatment
• Sodium restriction & diuretics
• Refractory cases: Large volume paracentesis
○ Peritoneovenous shunting; LeVeen, Denver
○ Transjugular intrahepatic portosystemic shunting (TIPS)
○ IVC or hepatic vein stenting (Budd-Chiari syndrome)
DIAGNOSTIC CHECKLIST
Consider
• Imaging alone cannot characterize nature or cause of
peritoneal fluid collections; sampling is required
SELECTED REFERENCES
1. Runyon BA et al: Introduction to the revised American Association for the
Study of Liver Diseases Practice Guideline management of adult patients
with ascites due to cirrhosis 2012. Hepatology. 57(4):1651-3, 2013
2. Tirkes T et al: Peritoneal and retroperitoneal anatomy and its relevance for
cross-sectional imaging. Radiographics. 32(2):437-51, 2012
3. Levy AD et al: Secondary tumors and tumorlike lesions of the peritoneal
cavity: imaging features with pathologic correlation. Radiographics.
29(2):347-73, 2009
4. Runyon BA et al: Management of adult patients with ascites due to cirrhosis:
an update. Hepatology. 49(6):2087-107, 2009
5. Hanbidge AE et al: US of the peritoneum. Radiographics. 23(3):663-84;
discussion 684-5, 2003
6. Practice Guidelines from American Association for the Study of Liver
Diseases
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