Platyhelminthes are also known as flatworms because they are worms with a flat body. This is the main external morphological feature that differentiates them from nematodes (roundworms).
Even though 85 percent of kidney stones are small enough to pass during urination, fewer than 50 percent of patients chose this option. A person with a normal-size ureter can usually pass a kidney stone with a diameter less than 5 mm (about 3/16 of an inch) without significant pain or risk of kidney damage.
As mentioned, a kidney stone does not normally cause symptoms simply by sitting in the kidneys . However, stones can sometimes move through the ureter towards the bladder and begin causing issues, depending on certain factors. The symptoms of passing a kidney stone in men, for instance, can sometimes be affected by prostate size. Other factors include the actual size of the person, whether they have been able to pass kidney stones in the past, and the size of the stone itself.