Other conditions that use the dilatation and curettage procedure are Polycystic Ovarian Syndrome wherein the endometrial tissues lining the uterus build-up and become so thick because there is no ovulation hence no normal means to get rid of it. Dilatation and Curettage used to be the most preferred method of abortion, but the World Health Organization warrants its use only when manual vacuum aspiration is unavailable. However, in third world countries, the use of dilatation and curettage as a method of abortion is still employed, but not by doctors. The process involves the measurement of the depth of the intrauterine cavity using a uterine sound, only then is the curetting begun. The curette is inserted into the cervix after its proper dilatation and tissues are scraped out using the sharp edge of the instrument. The Sims curette is a sharp curette used to scrape the endocervical and endometrial linings. It is approximately 11 inches long and its blades range from sizes 1 to 6. The surgeon stops scraping once the uterus has a gritty or sandlike consistency. The procedure is performed slowly and firmly but not to roughly because this may result in perforation and may require an emergency laparotomy or hysterectomy to stop the bleeding. Formation of scar tissue could also result if the curettage is done roughly. This could seal the uterus shut rendering the woman infertile. This condition is called the Asherman syndrome. The blunt blades of Thomas curettes, also sized 1 to 6 are used to finish off the curetting process. For diagnostic processes the Kevorkian curette or the endometrial curette is used to obtain endometrial tissue samples. It is mainly for cutting the peduncle of the growth in contrast to the Sims and Thomas curette that scrape. Its blade is square shaped incontrast with the spoon shaped head of the other two curettes.