Ultrasound Workup for Liver Schistosomiasis
Abdominal ultrasound is the gold standard imaging modality for evaluating hepatosplenic schistosomiasis, with systematic assessment of periportal fibrosis, liver morphology, portal vein diameter, splenomegaly, and collateral vessels being the essential components of the workup. 1, 2
Primary Ultrasound Assessment
Essential Ultrasound Findings to Document
Periportal Fibrosis (Symmers' Fibrosis)
- This is the pathognomonic finding in hepatosplenic schistosomiasis, detected in approximately 85-86% of cases 3, 2
- Grade periportal fibrosis according to WHO standardized methodology to ensure reproducibility across examinations 1, 4
- Periportal thickening appears as echogenic bands extending from the porta hepatis along portal vein branches 2
Liver Morphology Changes
- Assess for characteristic atrophy of the right hepatic lobe with compensatory hypertrophy of the left lobe, present in approximately 89% of patients 3
- Document rounded inferior marginal edge of the liver 3
- Evaluate for hepatic granulomas 2
Gallbladder Wall Thickening
- Examine for thickening of the gallbladder wall associated with periportal fibrosis extending from porta hepatis branches, observed in approximately 68% of cases 3
- This finding is distinct from biliary disease and typically occurs without gallstones 3
Portal Hypertension Assessment
Portal Venous System Evaluation
- Measure portal vein diameter—widening indicates portal hypertension 2, 5
- Measure splenic vein diameter 5
- Measure superior mesenteric vein diameter 5
- These measurements demonstrate excellent interobserver agreement (intraclass correlation coefficient 0.525-0.913) 5
Portal Vein Complications
- Assess for portal vein thrombosis (substantial interobserver agreement, kappa = 0.714-0.795) 5
- Evaluate for cavernous transformation of the portal vein (perfect interobserver agreement, kappa = 1.0) 5
Collateral Circulation
- Document presence of collateral vessels, a frequent but nonspecific finding 2
Splenic Assessment
- Measure longitudinal diameter of the spleen (excellent interobserver agreement, r = 0.828-0.869) 5
- Calculate splenic index (excellent interobserver agreement, r = 0.816-0.905) 5
- Evaluate for splenic nodules 2
Technical Considerations and Pitfalls
Critical Limitation in Mixed Liver Disease
- Ultrasound is not reliable for assessing periportal fibrosis in patients with concomitant cirrhosis from other causes (hepatitis B, C, or alcohol) 3
- In decompensated hepatosplenic schistosomiasis with cirrhosis, approximately 44% of patients cannot be classified for grade of fibrosis due to advanced cirrhosis 3
- When cirrhosis coexists, consider alternative imaging such as MRI for more precise evaluation of periportal thickening and vascular anatomy 6
Standardization Requirements
- Use standardized WHO methodology for grading periportal fibrosis to ensure valid comparisons over time and between different examiners 1, 4
- Methodology has varied considerably in epidemiological studies, making unstandardized assessments difficult to interpret 4
Operator Dependence
- Ultrasound is highly operator-dependent; examiners should receive specialized training in schistosomiasis-specific findings 4
- Despite operator dependence, ultrasound demonstrates high reproducibility for main morphological parameters of portal hypertension in schistosomiasis when performed systematically 5
Complementary Investigations
Laboratory Assessment
- Obtain serology for schistosomiasis (positive at 4-8 weeks post-infection) 1
- Perform concentrated stool microscopy, though sensitivity is low 1
- Consider stool PCR if available for higher sensitivity 1
Additional Imaging When Indicated
- MRI provides more precise information about gallbladder, periportal thickening, and abdominal venous system compared to ultrasound, particularly in complex cases 6
- Upper gastrointestinal endoscopy is indicated when portal hypertension is suspected to evaluate for esophageal varices 1, 3
Clinical Context
When to Suspect Hepatosplenic Schistosomiasis