**7. Risk factors**

The most evident risk factor for the scar endometriosis are obstetrical surgical procedures, especially cesarean section (38,41). It is believed that the opening of uterine cavity mainly during cesarean section causes the risk of decidualized endometrium implantation (10,29,53,57). The risk of scar endometriosis is significantly higher, when the cesarean section is performed before the term (44,56,57), though Nominato et al. (41) does not confirm this suggestion. There is no correlation between the parity, number of cesarean sections and the disease prevalence (38) but de Oliveira et al. (44) are of opinion that low parity may increase the risk.

The risk of scar endometrioma is augmented when not proper operative techniques are used (not closing the visceral and parietal peritoneum, using of the same surgical material during opening and closing uterus and abdominal wall, failure to shielding the wound during lack of placenta extraction with subsequent curettage and thorough washing before definitive closure) (38,55).

On the other hand, as it is mentioned by Zhu et al. (59) endometriosis in the postoperative scar may occur not only after operations that need not open the uterus (for example tubal operations).

Pelvic endometriosis seems to be the risk factor of arising scar endometriosis when treated by laparoscopy (10,29). The laparoscopic procedure may cause transportation of endometrial cells in the abdominal wall in women with a predisposition to endometriosis. Agarval and Fong (1) found that spontaneous cutaneous endometriosis was associated with more severe pelvic disease.

Non-surgical risk factors of scar endometrioma are also alcohol consumption and increased menstrual flow (44).

Hyperestrogenismus, even relative, seems to be also a risk factor of endometriosis, though there is a lack of valuable literature data confirming it in relation to scar endometriomas.

The important risk factor is the genetic one. Lattuada et al. (37) reported that the frequency of the PROGINS allele T2 in affected women was 17,2% compared with 11% in controls. They are of opinion that the progesterone receptor mutation increases the risk of endometriosis morbidity two fold. Teng et al. (56) discussing their results mentioned that the antiapoptotic function of the survivin gene may play an important role in endometriotic implant survival and invasion.
