Appearance of adnexal masses on US
A functional cyst such as a follicular cyst, corpus luteum cyst, or theca lutein cyst usually has smooth borders and a fluid center. Other cysts may sometimes contain debris, such as clotted blood, that suggests endometriosis or a simple cyst with bleeding into it.
A benign cystic teratoma often has multiple tissue lines, evidence of calcification, and layering of fat and fluid contents.
A benign cystadenoma usually has the appearance of a simple cyst without large septates, whereas a cystadenocarcinoma often contains septates, abnormal blood flow, increased vascularity, or all of these. However, it is impossible to definitively distinguish a cystadenoma from a cystadenocarcinoma using US imaging alone.
Functional cysts usually resolve by the second trimester. A cyst warrants closer scrutiny when it persists, is larger than 5 cm in diameter, or has a complex appearance on US.
CA-125 may be useful after the first trimester
The serum CA-125 level is typically elevated during the first trimester, but may be useful during later assessment or for follow-up of a malignancy.1
A markedly elevated serum level of alpha-fetoprotein (fractionated in some cases) has been reported in some gravidas with an endodermal sinus or mixed germ-cell ovarian tumor.2 Alpha-fetoprotein should be measured when there is suspicion for a germ-cell tumor based on clinical or US findings.
When a mass is discovered during cesarean section
Occasionally, an adnexal mass is detected at the time of cesarean section (FIGURE 1).3 This phenomenon is increasingly common, given the large number of cesarean deliveries in the United States. To eliminate the need for future surgery and avoid a delay in the diagnosis of an ovarian malignancy, inspect the adnexa routinely after closing the uterine incision in all women who deliver by cesarean section.
FIGURE 1 Mass discovered at cesarean section
This cystic tumor was discovered at cesarean section that was undertaken for obstetric indications.
CASE 2 LMP tumor is suspected
A 36-year-old gravida 3 para 1011 makes a prenatal visit during the first trimester. Her previous delivery was a cesarean section through a Pfannenstiel incision for a breech presentation. US imaging reveals a 6-week, 5-day fetus and a complex left adnexal mass, 4.5×3.9×4.1 cm. Imaging is repeated 1 month later at a tertiary-care center and shows an 11-week viable fetus, a right ovary with a corpus luteum cyst, and a left ovary with a 6.6×4 cm cystic mass with extensive vascular surface papillations that is suspicious for a low-malignant-potential (LMP) tumor. In several sonograms prior to the pregnancy, this mass appeared to be solid and was 3 cm in size.
When is surgery warranted?
Surgery is indicated when physical examination or imaging of a pregnant woman reveals an adnexal mass that is suspicious for malignancy, but the physician must weigh the benefit of prompt surgery against the risk to the pregnancy. This equation can be complicated in several ways. For example, surgical staging of clinically early ovarian cancer is more difficult due to the pregnant uterus, which is more extensively manipulated during these procedures. In addition, an optimal operation sometimes necessitates removal of the uterus.
At 13 weeks’ gestation, the patient described in case 2 underwent laparoscopy with peritoneal washings and left salpingo-oophorectomy, but the tumor ruptured during removal. Final pathology showed it to be a serous LMP tumor involving the surface of the left ovary. Washings were in line with this diagnosis.
The pregnancy continued uneventfully, and a repeat cesarean section was performed at 37 weeks through the Pfannenstiel scar, followed by limited surgical staging. Exploration and all biopsies were negative, and the final diagnosis was a stage 1C serous LMP tumor of the ovary.
The patient articulated a desire to preserve her fertility and was monitored with US imaging of the remaining ovary every 6 months.
Does ‘indolent’ behavior of malignancy justify watchful waiting?
LMP tumors comprise a relatively large percentage of ovarian “cancers” encountered during pregnancy. Some authors report the accurate identification of these tumors prospectively, based on ultrasonographic characteristics.4,5 When an LMP tumor is the likely diagnosis, serial observation during pregnancy may be appropriate because of the indolent nature of the tumor. Further studies are needed to refine preoperative diagnosis and determine the overall safety of this approach.
When the problem is acute
In rare cases, a pregnant patient will have (or develop during observation) an acute problem due to torsion or rupture of an adnexal mass. Some ovarian cancers may present acutely, such as a rapidly growing malignant germ-cell tumor or a ruptured and hemorrhaging granulosecell tumor. Emergent surgery is necessary to manage the acute adnexal disease and reduce the likelihood of pregnancy loss. These events are infrequent, occurring in less than 10% of women with a known, persistent adnexal mass during pregnancy.4-14 Furthermore, recent studies have not found a substantial pregnancy complication rate associated with such emergency surgeries.