Ovarian cysts in pregnancy are fairly uncommon; most data on incidence is derived from case reports and case series, and ranges from 0.1 to 2.4% depending on the gestational age. The vast majority are physiological, functional and benign and the risk of malignancy is low (1 to 6 % of all ovarian masses in pregnancy). Incidental diagnosis of simple cysts in asymptomatic women in early pregnancy should be managed expectantly as these usually resolve spontaneously and do not cause any adverse effect on the pregnancy. Ideally all women undergoing first trimester sonography should have their ovaries scanned and in case cysts are found, they should undergo repeat sonography at 6 to 8 weeks, and further follow -up. In case of detection of more complex masses, color Doppler is indicated.
The most common pregnancy-associated ovarian masses are functional cysts (corpus luteum cyst or hematoma), which usually resolve by 16 weeks' pregnancy. Masses which persist beyond this time are usually non- functional; the commonest is the dermoid which accounts for almost half the total cases, followed by endometrioma. They are usually asymptomatic, or patients may present with pain or acute abdomen in the mid or third trimester, mainly due to hemorrhage or torsion. Epithelial ovarian neoplasms in pregnancy are usually benign; cystadenomas account for almost half of these, with serous cystadenoma being the commonest. These cysts are usually thin walled, range from 5 to 20 cm and may be multiloculated, and bilateral in almost 20 % of cases. Non- functional ovarian masses and cystadenomas do not usually resolve, and they need close follow up for size and differentiation from malignant ovarian neoplasms.
The obstetrician should carefully weigh the decision for surgery versus expectant management in pregnancy; retrospective reviews of conservation have shown higher fetal morbidity and mortality, and higher chance of spontaneous rupture of cysts with spillage, and/ or torsion. Hence most authors are in agreement that cyst size in excess of 6 cm after 16 weeks' gestation should be surgically removed in the second trimester, as too early an intervention may carry the risk of miscarriage. In case of laparotomy, a midline incision with minimal uterine handling is the preferred approach. Laparoscopy is feasible and safe during pregnancy and has many advantages over laparotomy. However specific guidelines like avoidance of Veress needle and preference for open laparoscopy method, primary trocar placement (supra umbilical), avoidance of Trendelenberg tilt or lateral tilt, size of the mass relative to the size of the uterus, speed and skill of the surgeon, should be followed. Dermoids should be removed via an endobag during laparoscopic surgery to avoid spillage. In a September 2015 review of more than 500 ovarian masses in pregnancy in the American Journal of Perinatology, Webb et al commented that laparotomy and laparoscopy were both comparable in terms of pregnancy complications like spontaneous abortion, vaginal bleeding and intrauterine fetal death, but incidence of preterm contractions was significantly higher in the laparotomy group and those who were operated in emergency settings. Percutaneous transabdominal aspiration for large simple cysts in second and third trimesters has been used by some authors; this may obviate the need for surgery and also avoid potential issues of preterm labor and fetal problems.