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.
Stones between 2 to 4 mm take 12 days while 4-6 mm stones take about 22 days to pass out of the body. Kidney stones take about 40 days to pass out on its own without any medication of other intervention. Antispasmodics are usually prescribed to relax the ureter and ease the passage of kidney stones. When on antispasmodic, it may take about 5 to 7 days to pass out the kidney stone. If the kidney stone does not pass out on its own within 2 months, other medical intervention are considered.