endometriosis is defined as the existence of endometrial - like tissue outside the uterus which is associated with pelvic pain and infertility and is seen as much as 10% in women in reproductive age and 50% in women with chronic pelvic pain or infertility.[25 ] the most common clinical symptoms of endometriosis include infertility , pelvic mass , dysmenorrhea , pelvic pain , deep dyspareunia , and urinary and cyclic bowel alterations . pathogenesis of this disease is complex and multi factorial ; despite extensive studies its etiology has remained ambiguous . a combination of various published theories , which strived to explain endometriosis impaired immunologic response , genetic predispositions and inflammatory components as possible causes of this disease.[1120 ] ca125 is the cell surface antigen and it is expressed by derivatives of coelomic and mullerianepithelia it is the most common indicator for diagnosis of endometriosis.[132124 ] due to its limitation , it usually increases in advanced stage of endometriosis and yet because of the low sensitivity of this assay its utilization is restricted in detection of minimal or mild endometriosis , therefore it is not suitable for routine screening . showed that the accuracy of ca125 testing is still limited suggesting transvaginal ultrasonography for initial screening of endometriosis . it is broadly accepted that endometriosis is a pelvic inflammatory process that is related to distort functioning of immune cells in the peritoneal area . c - reactive protein ( crp ) level rises radically during inflammation and therefore it is a member of the acute phase reactant . in the clinical practice this protein is supplemented as a marker of on - going inflammation and as for monitoring infectious process . the first of these showed that crp in stage iii and iv in women with endometriosis more likely in those with more advanced disease . more recently did not find significant difference in serum level of crp between patients with endometriosis and healthy controls . diagnosis of endometriosis is a challenging theme ; and despite the broad search for innovative laboratory tests and advances in imaging technologies there are still no easy , non - invasive diagnostic tests available but due to inflammatory process of endometriosis , still crp level may be target of initial screening . therefore , the difference between peritoneal level of crp in women with endometriosis and healthy cases is hypothesized . 392 women who were subject to laparoscopy for the evaluation of infertility or pelvic pain at the isfahan fertility and infertility centre were considered . the patients with hypertension , coronary arterial diseases , diabetes , renal diseases , active pelvic inflammatory disease or polycystic ovarian syndrome were excluded . after laparoscopy the patients were allocated into two groups ; women with ( group i , n = 90 ) and without ( group ii , n = 89 ) endometriosis . this study was approved by ethical committee of isfahan university of medical sciences the venous blood samples were obtained from all patients before laparoscopy . the peritoneal fluid samples were also centrifuged and the supernatant were stored at -20 c until measurement . the serum and peritoneal levels of crp were measured using enzyme immunoassay kit ( monobind inc . , briefly , samples were added to a streptavidin coated wells , and then biotinylated monoclonal and enzyme labelled antibodies were added . reaction between the crp antibodies and native crp formed a complex that bind with streptavidin . after incubation and washing , the enzyme crp antibody bound conjugate is separated from unbound one . 392 women who were subject to laparoscopy for the evaluation of infertility or pelvic pain at the isfahan fertility and infertility centre were considered . the patients with hypertension , coronary arterial diseases , diabetes , renal diseases , active pelvic inflammatory disease or polycystic ovarian syndrome were excluded . after laparoscopy the patients were allocated into two groups ; women with ( group i , n = 90 ) and without ( group ii , n = 89 ) endometriosis . the peritoneal fluid samples were also centrifuged and the supernatant were stored at -20 c until measurement . the serum and peritoneal levels of crp were measured using enzyme immunoassay kit ( monobind inc . , briefly , samples were added to a streptavidin coated wells , and then biotinylated monoclonal and enzyme labelled antibodies were added . reaction between the crp antibodies and native crp formed a complex that bind with streptavidin . after incubation and washing , the enzyme crp antibody bound conjugate is separated from unbound one . there was no statistically significant difference between patients suffering endometriosis and control group in age , respectively : [ 28.9 ( range : 1944 ) versus , 30.2 ( range : 2442 ) ] . the data for crp levels in serum and peritoneal from the patients with endometriosis ( case ) and non - endometriosis ( control ) the results indicated that the serum and peritoneal levels of crp were significantly different between case and control groups ( p < 0.05 ) . no significant difference in serum level of crp between patients with endometriosis and healthy controls was detected ; however there was significant difference in peritoneal level of crp between case and control groups ( p < 0.05 ) . crp levels in serum and peritoneal from the patients with endometriosis ( case ) and nonendometriosis ( control ) the star ( * ) indicates significant difference from control group ( p < 0.05 ) . there was no statistically significant difference between patients suffering endometriosis and control group in age , respectively : [ 28.9 ( range : 1944 ) versus , 30.2 ( range : 2442 ) ] . the data for crp levels in serum and peritoneal from the patients with endometriosis ( case ) and non - endometriosis ( control ) is demonstrated in figure 1 . the results indicated that the serum and peritoneal levels of crp were significantly different between case and control groups ( p < 0.05 ) . no significant difference in serum level of crp between patients with endometriosis and healthy controls was detected ; however there was significant difference in peritoneal level of crp between case and control groups ( p < 0.05 ) . crp levels in serum and peritoneal from the patients with endometriosis ( case ) and nonendometriosis ( control ) the star ( * ) indicates significant difference from control group ( p < 0.05 ) . the serum and peritoneal levels of crp between women with endometriosis and infertile women without endometriosis was compared in the present study . no significant difference between the serum level of crp between the two groups was found , which also complies with the findings of matarese et al . and xavier et al . according to the findings compared to the control group , the crp level of the peritoneal fluid were higher in patients with endometriosis ( p<0.05 ) . pelvic endometriosis is a chronic inflammatory disease that is in association with a general inflammatory response in the peritoneal cavity . macrophage constitutes 82- 99% of the all the cell population of peritoneal fluid.[3739 ] literature has repeatedly reported an increase of total peritoneal fluid cell numbers , cell concentration and macrophages in endometriosis patients in compare to the control.[4043 ] the study of dunselman et al . also confirmed that there is an increase in the number and concentration of peritoneal cells in patients with endometriosis as compared to the control group . the rise in the number of peritoneal macrophages in women with endometriosis may signify that the endometrial tissue in the peritoneal cavity is recognized as a foreign entity that should be eliminated , thus cells such as retrograde endometrial tissues are killed by peritoneal macrophages and their presence concludes into inflammatory process . previous studies also reported that the peritoneal fluid mononuclear cells in women with endometriosis are more than in controls and that most of these cells have a more differentiated phenotype . . a severe inflammatory process will conclude into considerable change of the number of peritoneal cells . in vitro studies indicated that crp can be produced by vascular and organ - specific cells in response to inflammatory stimulus.[4650 ] furthermore , the study of haider et al . demonstrated that the peripheral blood mononuclear cells ( pbmc ) also contribute to the crp production . the concentration of complement factors , acute - phase proteins and immunoglobulins in the abdominal cavity may be increased after vascular permeability has changed in patients with endometriosis . moreover , in an advanced stage of differentiation , macrophages secret some of the acute phase proteins and complement factors . it is likely that the increase of crp in peritoneal fluid of endometriosis patients is resulted from peritoneal macrophages producing them in response to the local inflammation in peritoneal cavity . many studies maintain this notion , proposing that various local products such as cytokines are secreted by the activated macrophages in the peritoneal fluid of women with endometriosis.[375356 ] the peritoneal macrophages are strong producers of inflammatory cytokine.[5760 ] in the peritoneal fluid of women with endometriosis there is an increased number of cytokines and pro inflammatory cells . assumes that cytokines can be produced by immune competent cells as well as by endometrial implant . moreover , they can also be produced by ectopic endometrial tissue.[6264 ] macrophages are the major source of cytokines . cytokines that are originated in bone marrow circulate as monocytes and move to different body cavities , and cytokines that are released abundantly during inflammatory process can also stimulate crp activation in peripheral blood mononuclear cells . crp is a member of the class if acute phase reactants and it rise dramatically during inflammatory processes occurring in the body . it seems that the other cause of this increment in crp level is due to a rise in the peritoneal concentration of some cytokines , which is produced by macrophages that induced crp production . our findings suggested higher peritoneal fluid crp level in endometriosis patients in comparison to non - endometriosis patients , but no differences in serum level . however , it is further recommended that a combination of different markers might be helpful in this regard and other studies can investigate to find such useful markers .
background : endometriosis is defined as the existence of endometrial - like tissue outside the uterus . diagnosis of endometriosis is a challenging theme . despite the broad search for innovative laboratory tests and advances in imaging technologies , there are still no easy , non - invasive diagnostic tests available . due to inflammatory process of endometriosis , still c - reactive protein 
 ( crp ) level may be the target of initial screening . 
 the aim of this study was to investigate crp levels as a marker of inflammatory process in serum and peritoneal fluid of patients with endometriosis.materials and methods : in a case control study , 179 patients with endometriosis ( n = 90 ) and without endometriosis ( n = 89 ) were evaluated . 
 the venous blood samples were obtained from all patients before laparoscopy and the peritoneal fluid samples were collected from pelvis before any manipulation . 
 student s t - test was applied to compare the parameters between two groups.findings:there was no significant difference between the crp serum level in patients with endometriosis and infertile women without endometriosis . 
 there was a significant difference in peritoneal level of crp between case and control groups ( p < 0.05).conclusions : the findings suggested that measurement of this marker in patients serum or plasma can not be used to diagnose endometriosis . it is further recommended that a combination of different markers might be helpful in this regard that could be studied in future .