Objective: to determine :

The different types of gynecologic pelvic or pelvic abdominal masses necessitating surgical intervention associated with increased CA125 levels.
The relation between initial level of CA125 and histopathological nature of the mass.
In malignant cases: relation between preoperative CA125 level and stage of the tumor.
After surgery: whether decline in increased CA125 level occurs 6 months after surgery or not.

Methods: The study was conducted during a period from April 2017 to April 2018.
. IBM-SPSS ( version 24) was used for statistical data analysis.
Results: The mean age of the study group was 44±11 years, with a range of 17-67 years.The most common surgical problem of our study group was myoma, present in 22 cases (37.3%). This was followed by simple serous cyst and endometrial carcinoma (8 cases each, 13.6%), then endometriotic cyst and mature cystic teratoma (6 cases each, 10.2%), then ovarian fibroma, ovarian cancer and endometrial hyperplasia (5 cases each, 8.5%), adenomyosis (3 cases, 5.1%) and lastly mucinous cystadenoma (one case, 1.7%).The mean CA125 of our study group had a mean of 38.6 U/ml, with a very high standard deviation of over 59 U/ml; reflected in the very wide range from 4.5 up to 446 U/ml.The highest mean level of CA125 was seen among patients with ovarian cancer (160.6 U/ml). This was followed by ovarian fibroma (57.5 U/ml), then adenomyosis (42.7 U/ml), endometriotic cyst (42.6 U/ml), simple serous cyst (22.2 U/ml), mucinous cystadenoma (22 U/ml), myoma (21.9 U/ml), endometrial carcinoma (20.2 U/ml) and lastly endometrial hyperplasia (17.6 U/ml).CA 125 level was normal in all cases of myoma, dermoid cyst, simple serous cyst, mucinous cystadenoma, endometrial hyperplasia, and endometrial carcinoma.CA125 elevated in all cases of ovarian cancer, endometriotic cyst, adenomyosis and elevated in 60% in cases of ovarian fibroma. Most cases of ovarian cancer (80%) had marked elevation in CA125 level (level >100 U/ml ) and the increase in CA125 level was more marked with increase staging of the cancer , all cases of endometriotic cyst had mild to moderate elevation in CA125 level which were > 100 U/ml , all cases of adenomyosis had mild elevation in CA125level which not more than     50 U/ ml, in cases of ovarian fibroma CA125 level were normal in about 40% of the cases and elevated in about 60% of the cases (40% had moderate elevation in CA125 level which was> 100 U/ml and 20% had marked elevation with CA125 level < 100 U/ml .).There was proportional relationship between CA125 level and ovarian cancer stage, mean CA125 level in stage I was 85.8 U/ml versus 372.3 U/ml in stage II ( P < 0.001).All cases of endometrial cancer early diagnosed in stage I had normal CA125 level (10.6 – 28.3 U/ml).All cases with preoperative elevated CA125 level, the level returned to the normal when repeated 6 months postoperatively, cases of ovarian cancer, CA125 level returned to the normal after receiving six cycles of chemotherapy postoperatively.
Conclusion: CA125 is a simple and good screening test and should be routinely recommended for all cases of pelvic or pelvic abdominal masses before operative intervention, It helps to guess the diagnosis of ovarian cancer cases (it's level mostly >100 U/ml). It helps in the differential diagnosis between endometriotic cysts (elevated CA125 level ) and hemorrhagic ovarian and dermoid cysts (normal CA125 level ).It also helps in the differential diagnosis between uterine fibroids and adenomyosis being elevated in the latter.CA125 serum level can suggest the stage of ovarian cancer. In cases with elevated preoperative CA125 levels, it is expected that this level will normalize within 6 months postoperatively.