A 19-year-old man presents to the emergency department with symptoms of malaise, nausea, and decreased urine output. He was previously well, and his physical examination is normal except for an elevated jugular venous pressure (JVP) and a pericardial rub. His electrolytes reveal acute kidney injury (AKI). Which of the following findings on the urinalysis is most likely in keeping with acute glomerulonephritis (GN)?