Changes in size of the functional cyst on ultrasonography during early pregnancy

To clearly define the clinical behaviors of the functional cyst by ultrasonography and distinguish this cyst from other sonolucent ovarian cysts in pregnancy, changes in functional cyst size during early pregnancy were retrospectively evaluated with the cyst diameters derived from ultrasonic records of 58 pregnant patients with functional cysts. Of the 58 cases, 7 cases of functional cysts over 6 cm in diameter and 5 cases after 15 weeks were observed. Percent changes in cyst size per weeks of gestation were calculated from diameters of all cases. These percent changes were averaged respectively in four chronologic groups (5-7, 7-9, 9-12, and 12-15 weeks of gestation). As a result, although the mean percent change in cyst size showed a tendency to increase from 5 to 7 weeks (+0.9% per week), it turned negative after 7 weeks, and the decreasing tendency grew as gestation advanced (7-9 weeks: -8.3% per weeks; 9-12 weeks: -11.7% per weeks; 12-15 weeks: -15.2% per week). Therefore, the result showed that the maximum cyst size is reached at about 7 weeks with gradual diminution thereafter and the sonolucent ovarian cyst may be followed as a functional cyst, even if it is large or persists after 14 weeks.