Final answer:
An abnormal finding in urinary sediment is the presence of 2-5 WBCs per HPF, which could indicate a urinary tract infection.
Step-by-step explanation:
When examining urinary sediment, the presence of 2-5 WBCs per high-power field (HPF) is considered an abnormal finding. This is due to the fact that a typical, healthy urine sample should contain 0-2 RBCs per HPF and may have a few hyaline casts per LPF or no renal cell casts at all. However, an increased number of white blood cells in the urine suggests the possibility of a urinary tract infection (UTI), which requires further investigation and potentially treatment.