What type of urine sediment can indicate urinary obstruction?

The presence of renal tubular cells and casts in urine sediment is indicative of urinary obstruction because it reflects damage or stress to the renal tubules, often due to a blockage in the urinary tract. When there's an obstruction, it can lead to back pressure within the renal system, causing renal tubular cells to slough off and be excreted in the urine. Additionally, casts formed from protein and other cellular debris can also be a sign of injury within the renal tubules, potentially exacerbated by conditions such as hydronephrosis, which results from accumulated urine due to obstruction.

In contrast, other types of urine sediment listed do not specifically suggest urinary obstruction. Crystals and bacteria may indicate infection or metabolic disorders, while red blood cells and white blood cells are typically associated with injury or inflammation but not specifically obstruction. Mucus and epithelial cells are common findings that could relate to several conditions but are not definitive indicators of urinary obstruction.