Percutaneous catheter drainage of uncomplicated amoebic liver abscess: prospective evaluation of a clinical protocol for catheter removal and the significance of residual collections

Utility of Contrast-Enhanced Ultrasound in Optimizing Hepatic Abscess Treatment and Monitoring

Background/Objectives: Untreated hepatic abscesses (HAs) have an 80% mortality rate and can be caused by bacteria and fungi. Previously managed with surgery, current treatments now utilize interventional radiology and antibiotics, reducing complications to 2.5%. This study evaluates contrast-enhanced ultrasound (CEUS) for better drainage placement and monitoring, overcoming conventional ultrasound's limitations in detecting the HA liquefied portion. Methods: We conducted a retrospective study of 50 patients with HAs confirmed via computed tomography (CT) scans. Inclusion criteria comprised specific clinical symptoms and laboratory parameters. Both B-mode and CEUS were utilized for initial and follow-up imaging. Results: In the CEUS studies, the mean size of HAs was 6.26 cm, with pus displaying significantly lower echogenicity compared to the HA pouch and liver parenchyma in all phases. Classification by size (>6 cm, <6 cm) and volume (>113 mL, <113 mL) revealed differences in the assessment of fluid volume between CEUS and B-mode. Conclusions: CEUS is valuable for diagnosing, performing therapeutic procedures, and monitoring HA. It provides precise real-time assessment of HA morphology, including dimensions and volume. If the liquefied volume of an HA exceeds 113 mL, it may qualify for drainage placement. CEUS can replace CT as an effective, less harmful, and cheaper method, eliminating the need for multiple radiological departments. While CEUS is a safer, cost-effective alternative to CT for HA evaluation and monitoring, comprehensive clinical evaluation remains essential. Therefore, CEUS should be part of a broader diagnostic and monitoring strategy, not a stand-alone solution.

Amebic liver abscess by Entamoeba histolytica

Amebic liver abscesses (ALAs) are the most commonly encountered extraintestinal manifestation of human invasive amebiasis, which results from Entamoeba histolytica (E. histolytica) spreading extraintestinally. Amebiasis can be complicated by liver abscess in 9% of cases, and ALAs led to almost 50000 fatalities worldwide in 2010. Although there have been fewer and fewer cases in the past several years, ALAs remain an important public health problem in endemic areas. E. histolytica causes both amebic colitis and liver abscess by breaching the host’s innate defenses and invading the intestinal mucosa. Trophozoites often enter the circulatory system, where they are filtered in the liver and produce abscesses, and develop into severe invasive diseases such as ALAs. The clinical presentation can appear to be colitis, including upper-right abdominal pain accompanied by a fever in ALA cases. Proper diagnosis requires nonspecific liver imaging as well as detecting anti-E. histolytica antibodies; however, these antibodies cannot be used to distinguish between a previous infection and an acute infection. Therefore, diagnostics primarily aim to use PCR or enzyme-linked immunosorbent assay to detect E. histolytica. ALAs can be treated medically, and percutaneous catheter drainage is only necessary in approximately 15% of cases. The indicated treatment is to administer an amebicidal drug (such as tinidazole or metronidazole) and paromomycin or other luminal cysticidal agent for clinical disease. Prognosis is good with almost universal recovery. Establishing which diagnostic methods are most efficacious will necessitate further analysis of similar clinical cases.

CT of amebic liver abscess: different morphological types with different clinical features

Purpose

To identify different morphological types of amebic liver abscess (ALA) based on CT findings and to assess whether they have different clinical features.

Method

CT images of 112 symptomatic patients with ALA were analyzed to identify the imaging features distinctive of each morphological type. The following CT findings were investigated: the presence of abscess wall, rim enhancement, edge characteristic, septa, intermediate density zone, and peripheral hypodensity. Abscesses from each type were further evaluated for their clinical presentations, laboratory findings and outcomes.

Results

We identified three types of ALAs: type I, II and III. Type I abscesses (66%) were characterized by absent or incomplete walls, ragged edges and peripheral septa; their edges exhibited irregular and interrupted enhancement. Type II (28%) had a complete wall characterized by rim enhancement and peripheral hypodense halo. Type III (6%) demonstrated a wall but without enhancement. Clinically, type I abscesses presented acutely with severe disease. They had significantly deranged laboratory parameters, higher incidence of rupture and higher rate of inpatient or intensive care unit admission. The severity of the disease prompted immediate percutaneous drainage in most type I abscesses (81%). Two of them died from multiple organ failure. The type II or III abscesses, on the other hand, had delayed presentations with mild to moderate disease, with near normal laboratory findings.

Conclusion

ALAs have three different CT morphological types, with different clinical and laboratory features. Percutaneous drainage is indicated in most of type I abscesses.