MO110: Ultrasound Evaluation of Post-COVID Kidney Disease
Authors: Rostyslav Bubnov 
Published: May 2022

Abstract

BACKGROUND AND AIMS
COVID can affect many organs including kidneys involving various possible pathophysiological mechanisms [1]. Post-COVID conditions require focused approach for diagnosis, personalized treatments and rehabilitation. Ultrasonography (US) can provide accurate information for detecting kidney disease [2]. Shear wave elastography (SWE) is a recognized ultrasound method, still having a limited use in nephrology, yet can be used for early detections of kidney abnormalities.
The aim of this study was to evaluate semiotics and the added diagnostic value of US for post-COVID kidney disease.

METHOD
We included 20 cases to the study (23–68 years; 8 women) who underwent COVID-19 during last 3 months with signs of kidney disease (proteinuria, increased levels of creatinine, uric acid in blood, hypertension) and other clinical, laboratory symptoms of nephropathy after COVID-19 without specific data of previous history of kidney disease. The control group included 20 healthy individuals (9 women), with mean age 37 ± 7 years without clinical, laboratory signs of nephropathy according to disease history. All patients underwent general clinical, lab tests; abdominal US including precise multiparameter US of kidneys as in [2] measuring renal resistive index (RI), did SWE, and sensitive Doppler (B-flow and similar) in parenchyma and vessels using curved abdominal transducer of US systems: LOGIQ 9 (GE Healthcare), Toshiba Aplio and Hitachi Arietta.

RESULTS
We detected US changes in all age groups, both in females and males. Severe kidney disease signs included thinning, increasing echogenicity of kidney parenchyma (P &lt; .05), detection of fibrotic changes and small hyperechoic inclusions, hilly margins, anaechoic strips under the capsule, RI increasing in segmental arteries over 0.75, and decreasing velocities under 25 cm/s. SWE showed increased parenchyma stiffness to 10 ± 1.7 kPa (6–13 kPa) versus 4.2 ± 1.2 kPa (P &lt; .05).
Moderate changes included mild decrease of kidney medullary differentiation, RI increasing in segmental arteries over 0.7; parenchyma stiffness increased to 7.2 ± 1.5 kPa (5–10 kPa), P &lt; .05.
In 16 patients we diagnosed hypertension; all patients had increased RI over 0.75; pyelonephritis was in 2 patients.
Three patients had the following abnormalities: amyloid kidney after COVID-19 was in two patients (male 62 years and female 58 years) manifesting on US with increased echogenicity small kidney, decreased blood flow and increasing RI (Figure 1).
One patient had collapsing glomerulopathy [3] manifesting with proteinuria; kidney biopsy with immunohistochemistry performed 1 month after beginning of COVID-19 showed collapsing focal segmental glomerulosclerosis; US symptoms were unspecific (Figure 2).

CONCLUSION
Multiparameter ultrasound is an effective method for early detection of various types of kidney disease in patients after coronavirus disease, potentially effective to distinguish signs of nephropathy associated to COVID-19. Evaluation of renal RI and increased stiffness of kidney parenchyma are reliable markers.