严重的肾盂积水，仅剩下一层薄薄的肾皮质。这种肾脏是没有功能的，它也是容易发生感染的地方。如果病变是单侧的，原因可能是从肾盂到输尿管口的病变。在本例，一个大的“鹿角”样（因外形象鹿角，故而名之）结石充满了肾盂和肾盏。如果病变是双侧的，原因可能是膀胱三角或尿道前列腺部的病变；或是其它能侵犯两侧输尿管的病变（如大的肿瘤块）。
Here is a kidney with much more advanced hydronephrosis in which there is only a thin rim of remaining renal cortex. Such a kidney is non-functional and a source for ongoing infection. If this process is unilateral, then the problem originates from the ureteral orifice up to the pelvis. In this case, a large "staghorn" calculus (so named because the prominent projections of the stone into the calyces resemble deer antlers) was present that filled up the pelvis and calyceal system. If this process were bilateral, then the problem would originate in the bladder trigone or urethra (or the prostate around the urethra) or some process (such as a large neoplasm) that could impinge on both ureters.
