Which characteristic indicates the presence of calcium oxalate dihydrate crystals?

The presence of calcium oxalate dihydrate crystals is primarily indicated by their distinct octahedral structure. These crystals typically exhibit a characteristic form that resembles two pyramids base to base, which aligns with the octahedral shape. When observed under a polarized light microscope, these crystals can be identified easily due to their unique geometric arrangement, making them an important finding in urine sediment analysis.

Other crystal forms like flat plates or cylindrical shapes do not correlate with the calcium oxalate dihydrate specifically. Flat plate crystals can sometimes relate to different types of crystals such as uric acid or phosphates, while cylindrical shapes are usually indicative of other entities, such as casts. Irregular forms do not provide a definitive identification for calcium oxalate dihydrates. Hence, the identification of the octahedral structure is key in confirming the presence of calcium oxalate dihydrate crystals in a urine sample.