CAUSES OF PILES. Constipation – this is the most common cause Hard stool/Strain during bowwel movement Faulty toilet habits Obesity Lifting heavy loads Pregnancy and child birth SYMPTOMS OF PILES............. Painless bleeding while passing stools Feeling a lump outside the anus Pruritus ani or itching around the anus Fecal soiling of undergarments If a blood clot forms in the hemorrhoid (Thrombosed hemorrhoid ) it leads to a severely painful swelling which worsens with bowel movement and sitting.