What is a stagnorn stone?

A stagnorn stone refers to a type of kidney stone that remains lodged in the renal calyx, a part of the kidney's collecting system. These stones are characterized by their propensity to grow larger while being retained in this location, often leading to complications such as obstruction or infection. The environment in the renal calyx may allow these stones to persist and accumulate minerals, leading to their continued growth.

The other choices describe different types of stones or conditions that do not accurately define stagnorn stones. For instance, a stone that dissolves on its own does not fit the definition, as stagnorn stones are typically stable and do not diminish in size. Similarly, while stones located in the bladder or those that cause infection are pertinent topics, they don't encompass the unique attributes of stagnorn stones specifically being retained and enlarging within the renal calyx.