Ultrasound findings in EHEC-associated hemolytic-uremic syndrome and their clinical relevance

Hemolytic-uremic syndrome (HUS) and acute kidney injury (AKI) after infection with Shiga toxin-producing E. coli (EHEC) are clinically important complications. We present a retrospective analysis of abdominal ultrasound findings in patients with HUS caused by EHEC O104:H4 (n = 41).

We assessed intrarenal resistance indices and quantitated kidney parenchymal density by the kidney/liver intensity ratio using computer-based image analysis. Findings in EHEC-HUS were compared to those in AKI due to other reasons (n = 60) and 19 healthy volunteers.

Kidneys in EHEC-HUS patients showed severe morphologic changes with striking parenchymal echogenicity. Renal resistance index was increased in HUS (0.80 ± 0.08) compared to patients with AKI due to glomerulopathy (0.69 ± 0.08, p < 0.001) or patients with other causes of AKI (0.74 ± 0.10, p < 0.01). Parenchymal density was increased in EHEC-HUS (1.39 ± 0.35) compared to AKI due to glomerulopathy (1.18 ± 0.20, p < 0.05), other causes of AKI (1.12 ± 0.21, p < 0.001) and healthy controls (0.86 ± 0.16, p < 0.001). Patients with atypical HUS showed increased parenchymal density (1.43 ± 0.37), similar to those with EHEC-HUS. EHEC-HUS patients who required dialysis treatment had higher parenchymal density (1.58 ± 0.08) compared to those without dialysis (1.14 ± 0.05, p = 0.0004). Extrarenal findings in EHEC-HUS included hepatomegaly (45%), splenomegaly (39%), ascites (84%) and pleural effusions (84%).

Patients with EHEC-HUS had a characteristic constellation of morphologic abnormalities on ultrasound examination, indicating that the effects of HUS are not limited to the kidney but include multiple organs, possibly mediated through systemic capillary leakage. Assessment of parenchymal echogenicity contributes to the differential diagnosis of AKI. Parameters reflecting renal perfusion correlated with severity of disease and thus may have prognostic value in future patient evaluation.