With the increasing use of ultrasound in the first trimester, asymptomatic adnexal masses are being diagnosed earlier in pregnancy, leaving providers with an often difficult clinical scenario. The reported incidence of adnexal masses ranges from 1 in 81 to 1 in 8,000 pregnancies, and 0.93%-6% of these are malignant (Gynecol. Oncol. 2006;101:315-21; Am. J. Obstet. Gynecol. 1999;181:19-24). In light of this, the importance of recognizing adnexal masses and knowledge of their management are crucial for any practicing obstetrician gynecologist.
Differential diagnosis
Dr. Paola A. Gehrig
In pregnancy, the majority of adnexal masses are benign simple cysts less than 5 cm (BJOG 2003;110:578-83). As such, the majority of masses (probable corpus luteum cysts) detected in the first trimester (70% in one study) will resolve by the early part of the second trimester (Clin. Obstet. Gynecol. 2006;49:492-505). Adnexal masses are commonly physiologic or functional cysts. Benign masses with complex features can include corpus luteum, mature teratomas, hydrosalpinx, theca lutein cysts, or endometriomas. Complex adnexal masses greater than 5 cm are most likely mature teratomas (Am. J. Obstet. Gynecol. 2001;184:1504-12). Degenerating or pedunculated fibroids can mimic an adnexal mass and may cause pain, clouding the diagnosis.
Of the rare malignant lesions that occur in pregnancy, approximately half are epithelial tumors and one-third are germ cell tumors. Of the epithelial neoplasms, up to 50% may be low-malignant-potential tumors.
Diagnostic evaluation
Imaging: Transvaginal ultrasound is regarded as the modality of choice when evaluating adnexal pathology. Abdominal ultrasound may be especially helpful when the ovaries are outside of the pelvis, especially later in gestation. MRI without contrast may aid in distinguishing leiomyoma and ovarian pathology, which is vital when planning surgery. However, MRI with gadolinium is not recommended as its safety in pregnancy has not been established.
Tumor markers: None of the available tumor markers may be reliably used to diagnose ovarian cancer in pregnancy. CA-125 is elevated in epithelial ovarian cancer, but it is also elevated in pregnancy. However, significant elevations (greater than 1,000 U/mL) are more likely to be associated with cancer.
Dr. Daniel L. Clarke-Pearson
Markers for germ cell tumors include alpha-fetoprotein (AFP), lactate dehydrogenase (LDH), and human chorionic gonadotropin (hCG). Maternal serum levels of AFP (MSAFP) normally rise in pregnancy, although extreme values (less than 500 ng/mL) are associated with neural tube defects while levels greater than 1,000 ng/mL may be associated with an ovarian germ cell tumor (especially when greater than 10,000 ng/mL). LDH is elevated in women with ovarian dysgerminomas and is reliable in pregnancy outside of HELLP syndrome (hemolysis, elevated liver enzymes, low platelets). Of course, hCG is elevated in pregnancy, negating its value as a germ cell tumor marker. Inhibin B may be elevated in association with granulosa cell tumors; however, it is also elevated in early gestation.
Management
Because most corpus luteum will resolve, it is recommended to electively resect adnexal masses in the second trimester when they meet the following criteria: lesions are greater than 10 cm in diameter; they are complex lesions (Fertil. Steril. 2009;91:1895-902; Obstet. Gynecol. 1999;93:585-9).
Benign-appearing but persistent simple cysts in the second trimester may be managed conservatively, as approximately 70% will resolve. Thus, routine removal of persistent cysts is not recommended (BJOG 2003;110:578-83). Risk factors for persistent lesions include size greater than 5 cm and complex morphology (Obstet. Gynecol. 1999;93:585-9).Providers may consider serial ultrasounds of ovarian cysts to detect an increase in size or change in character that may warrant further investigation.
Surgery is considered in asymptomatic women meeting the above criteria, to diagnose malignancy or reduce the risk of torsion or rupture. Torsion has been found to be more likely in the late first and early second trimester, with only 6% occurring after 20 weeks. Corpus luteum cysts may on occasion persist into the second trimester and can account for up to 17% of all cystic adnexal masses (Am. J. Obstet. Gynecol. 1999;181:19-24). It is important to remember that if a corpus luteum is surgically resected in the first trimester, progesterone needs to be replaced to avoid pregnancy loss. Of those complex lesions diagnosed in the first trimester that persist into the second trimester, up to 10% may be malignant.
Dr. Stephanie A. Sullivan
Providers who feel comfortable with laparoscopic techniques can proceed with minimally invasive surgery, with optimal timing in the early second trimester (J. Minim. Invasive Gynecol. 2011;18:720-5). Care should be taken to consider fundal height when choosing trocar placement. If there is a high suspicion for malignancy, providers may want to proceed via laparotomy, which should be via a vertical midline incision. Tocolytic therapy given prophylactically at the time of surgery has no proven benefit and should not be routinely administered.