What condition is defined by the formation of thick sheets of connective tissue extending from the perirenal space to the dome of the bladder?

The formation of thick sheets of connective tissue extending from the perirenal space to the dome of the bladder is characteristic of retroperitoneal fibrosis. This condition involves an abnormal growth of fibrous tissue in the retroperitoneal space, which can encase and compress structures such as the ureters, kidneys, and blood vessels. The exact cause is often idiopathic, but it may be associated with medications, infections, or malignancies.

In contrast, nephrolithiasis refers to the presence of kidney stones, which can cause obstruction but do not involve the formation of fibrous tissue. Ureteral obstruction, while it can result from external compression, does not specifically describe the condition involving the thick fibrotic sheets. Hydronephrosis is the dilation of the renal pelvis and calyces due to obstruction, which can be a result of conditions like nephrolithiasis or ureteral obstruction but again does not describe the fibrous tissue itself.

Thus, retroperitoneal fibrosis is the most accurate term for the condition being described, as it specifically refers to that thickening of connective tissue in the retroperitoneal space.