<prompt> Which of the following ovarian tumor is most prone to undergo torsion during pregnancy?Serous cystadenomaMucinous cystadenomaDermoid cystTheca lutein cyst  <response>: Ans. is c, i.e. Dermoid cystRef. Novak 14e, p 510; Dutta Obs. 6e, p 310Incidence of dermoid cyst increases two times in pregnancy and it becomes the most commonly diagnosed ovarian tumour during pregnancy. --Dutta Obs. 7e, p 310A benign cystic teratoma is the most common neoplasm to undergo torsion. --Novak 14e, p 510Note: Benign cystic teratoma is another name for dermoid cyst.From the above two lines it is clear that dermoid cyst is the most common ovarian tumour to undergo torsion during pregnancy.For more details on dermoid cyst and other ovarian tumours kindly see Self Assessment and Review Gynaecology by the same author. 