What is a corpus luteum cyst?

Clinically, in women of normal reproductive age, the corpus luteum gradually forms after ovulation. Its primary function is to secrete progesterone and estrogen. If bleeding or other factors cause enlargement of the luteal cavity, a corpus luteum cyst may develop. When patients are affected by abnormalities in coagulation mechanisms, increased intra-abdominal pressure, pelvic inflammatory disease, abdominal trauma, or iatrogenic procedures, such cysts are prone to rupture. So, what exactly is a corpus luteum cyst? The following section addresses this question.  

What Is a Corpus Luteum Cyst?

Generally speaking, the corpus luteum is a transient endocrine structure that forms naturally after ovulation in women of normal reproductive age and typically regresses spontaneously. A mature, normal corpus luteum measures 2–3 cm in diameter and has a cyst-like structure; its wall is rich in blood vessels. When capillary bleeding occurs on the inner wall, blood enters the enclosed cystic cavity, causing the cavity’s diameter to exceed 3 cm—thus forming a corpus luteum cyst. Because corpus luteum cysts lie on the ovarian surface and are under high tension, they are susceptible to rupture. Corpus luteum rupture is a common gynecological emergency; if significant hemorrhage occurs and remains untreated, hypovolemic shock may ensue, threatening life. Therefore, patients are advised to maintain regular lifestyles and attend scheduled follow-up visits.

Knowledge Expansion: Causes of Corpus Luteum Cysts

1. Physiological Factors

In women of normal reproductive age, the corpus luteum gradually forms after ovulation. Its main function is to secrete progesterone and estrogen, which induce morphological and functional changes in the endometrium to prepare for early embryonic development and implantation. If the released oocyte is fertilized, the corpus luteum continues to develop into a pregnancy corpus luteum. This persists until approximately the third month of gestation, when the placenta forms and assumes the endocrine functions previously carried out by the corpus luteum. If fertilization does not occur, the corpus luteum begins to degenerate after about two weeks and ultimately transforms into a fibrous scar tissue.

2. Vascular Bleeding

A mature, normal corpus luteum measures 2–3 cm in diameter and exhibits a cyst-like structure with a highly vascularized wall. Capillary bleeding on the inner wall allows blood to enter the enclosed cystic cavity, resulting in cavity expansion beyond 3 cm—forming a corpus luteum cyst. Due to its location on the ovarian surface and high intracystic tension, such cysts are prone to rupture. Importantly, most corpus luteum cysts require no specific treatment; routine ultrasound monitoring is sufficient, as they typically resolve spontaneously. Intervention is only necessary if complications such as rupture or torsion occur.

The above provides an explanation of what a corpus luteum cyst is. We hope this information is helpful to you.