Quote from "ESPES Manual of Pediatric Minimally Invasive Surgery" by Ciro Esposito, François Becmeur, Henri Steyaert, Philipp Szavay - "The torsion rate increased with size from 0% in cysts <20 mm to 33% in cysts >50 mm. In between 0 and 40 mm, there is a higher rate of spontaneous resolution, and the median time to postnatal resolution was 10 (5–27) weeks in those treated conservatively [2]. Other publications suggest a similar pattern of spontaneous resolution [3]. So, it is recommended a conservative approach and postnatal ultrasound monitoring. Those cysts which exceed 5 cm and do not shrink postnatally may require surgical treatment [4]." Quote from "ESPES Manual of Pediatric Minimally Invasive Surgery" by Ciro Esposito, François Becmeur, Henri Steyaert, Philipp Szavay - "prenatally simple cysts can be managed expectantly, as complicated cysts have to be operated. In older girls, cyst greater than 50 mm in diameter has a great chance of torsion, and laparoscopy is indicated."