What is the role of ultrasound in diagnosing typhoid fever?

Role of Ultrasound in Diagnosing Typhoid Fever

Ultrasound is a valuable diagnostic tool for typhoid fever, especially in endemic areas, as it can detect characteristic findings such as splenomegaly, mesenteric lymphadenopathy, and hepatobiliary changes before serological tests become positive.

Key Ultrasound Findings in Typhoid Fever

• Splenomegaly is the most consistent finding, present in up to 100% of confirmed typhoid cases 1, 2
• Mesenteric lymphadenopathy is a significant finding that helps differentiate typhoid from other bacterial enterocolitis, with more pronounced enlargement in typhoid patients 3
• Hepatomegaly with normal parenchymal echotexture occurs in approximately 31% of cases 1, 2
• Prominent intrahepatic bile ducts are seen in about 65% of typhoid patients 2
• Bowel wall thickening, particularly in the terminal ileum and cecum, is observed in 35-85% of cases 1, 2
• Gallbladder abnormalities including thickened walls (16-62%), biliary sludge (23%), and acalculous cholecystitis 1, 2

Clinical Utility of Ultrasound in Typhoid Diagnosis

• Ultrasound can provide early diagnostic information within the first week of symptoms, before serological tests like Widal become positive 1, 2
• It serves as a non-invasive, economical, and reasonably sensitive diagnostic tool when serology is equivocal and cultures are negative 1
• A normal ultrasound examination early in the course of febrile illness may help rule out typhoid fever 2
• Ultrasound can help differentiate typhoid from other bacterial enterocolitis like non-typhoidal Salmonella and Campylobacter jejuni infections 3

Diagnostic Algorithm for Suspected Typhoid

1. For patients with fever and suspected typhoid, especially in endemic areas or with relevant travel history, consider abdominal ultrasound within the first week of symptoms 1, 2
2. Look specifically for the constellation of splenomegaly, mesenteric lymphadenopathy, and hepatobiliary changes 1, 2, 3
3. If ultrasound findings are consistent with typhoid and clinical suspicion is high, empiric treatment may be justified while awaiting culture results 2
4. In patients with fever and abnormal liver function tests, ultrasound can help identify typhoid as a potential cause 4

Ultrasound in Detecting Complications

• Ultrasound can detect serious complications of typhoid fever including:
  • Intestinal perforations (seen in approximately 1% of cases) 2, 5
  • Ascites (observed in about 3% of cases) 2
  • Acalculous cholecystitis (found in 16% of cases) 2

Limitations and Considerations

• Ultrasound findings must be interpreted in the clinical context, as individual findings are not pathognomonic for typhoid 1, 2
• The sensitivity of ultrasound depends on the expertise of the sonographer and quality of equipment 6
• Ultrasound cannot replace blood cultures as the gold standard for diagnosis but serves as a complementary tool 1, 2
• Follow-up ultrasound examinations may be useful to monitor disease progression and response to treatment 2

Special Considerations in Critical Care Settings

• In critically ill patients with fever, abdominal ultrasound is recommended when there are abdominal symptoms, abnormal physical examination findings, or liver function abnormalities 6
• Ultrasound has advantages over other imaging modalities including lack of radiation exposure, general availability, and safety 6