How Does Color Doppler Ultrasound Diagnose Corpus Luteum Cysts?

A corpus luteum cyst is a physiological cyst. Color Doppler ultrasound can diagnose corpus luteum cysts by evaluating the size, shape, and echogenicity (i.e., intensity of echo) of the corpus luteum, as detailed below:

1. Size assessment: Under normal circumstances, the corpus luteum measures ≤3 cm in diameter. A cystic cavity exceeding 3 cm in diameter suggests the possible presence of a corpus luteum cyst.

2. Morphological evaluation: Typically, ultrasound gel (acoustic coupling agent) is applied to the abdomen, and a color Doppler ultrasound probe is used for scanning. The resulting image reveals a well-defined, cystic mass located in one ovary.

3. Echogenicity assessment: In the early stage of the cyst, fine internal echoes may be observed; during the intermediate stage, strong echoes appear; and in the late stage, these strong echoes gradually diminish, becoming isoechoic or hypoechoic.

If ultrasound reveals anechoic (fluid-filled) areas in the pelvic cavity, rupture of a corpus luteum cyst cannot be ruled out and requires further evaluation.