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.
Anyone who's ever passed a kidney stone before has probably wondered how something so small (usually, anyway!) can cause so much pain. Unfair, we know. About 1 in 11 people will suffer from a kidney stone in their lifetimeâand once you've already had one, you're about 50% more likely to have another.