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.
Surgery is often not necessary because most kidney stones can pass through the urinary tract with plenty of water, usually 2 to 3 quarts per day. A person susceptible to stone formation should try to drink enough fluids throughout the day to produce at least 2 quarts of urine in every 24-hour period.