Tubal ring sign is one of the ultrasound signs of a tubal ectopic. It comprises of an echogenic ring which surrounds an unruptured ectopic pregnancy. It is said to have a 95% positive predictive value (PPV) for ectopic pregnancy.
It can be mimicked by a normal corpus luteum. To differentiate the two, bimanual exam can be useful to differentiate an ovarian corpus luteum (moves with ovary) or a tubal ectopic (moves separately from the ovary). Normal ovarian tissue may also be noticeable around a corpus luteum.
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