A corpus luteum cyst is a type of functional ovarian cyst that arises from the corpus luteum, a temporary endocrine structure formed in the ovary after the release of an ovum (ovulation). When the corpus luteum fails to involute normally, it may become enlarged and fill with serous fluid or blood, resulting in a cystic lesion.
Anatomy and Physiology
- The corpus luteum develops from the remnants of the ovarian follicle after ovulation.
- It secretes progesterone and, to a lesser extent, estrogen, which are essential for maintaining the endometrium in the luteal phase of the menstrual cycle.
- Under normal circumstances, the corpus luteum regresses during the early luteal phase if pregnancy does not occur.
Pathogenesis
- A cyst forms when the luteinized follicle does not undergo the typical involutionary process, leading to fluid accumulation within the luteal cavity (serous cyst) or hemorrhage (hemorrhagic cyst).
- Most corpus luteum cysts are considered physiologic and resolve spontaneously within a few menstrual cycles.
Clinical Presentation
- Many corpus luteum cysts are asymptomatic and detected incidentally during pelvic imaging.
- Symptomatic cases may present with pelvic or lower abdominal pain, a sense of pelvic fullness, or, rarely, acute abdominal pain due to rupture or torsion.
- Menstrual irregularities can occur, particularly if the cyst persists and alters hormone production.
Diagnosis
- Transvaginal ultrasonography is the primary imaging modality, displaying a round or oval anechoic or complex structure within the ovary, often with peripheral blood flow on Doppler studies.
- Characteristics such as size (commonly ≤5 cm), internal echogenicity, and lack of solid components help differentiate corpus luteum cysts from other ovarian masses.
- Serum hormone levels are generally not diagnostic, but β‑hCG testing can be useful to exclude pregnancy‑related ovarian changes.
Management
- Expectant management is the standard approach for uncomplicated corpus luteum cysts because most resolve spontaneously within 2–3 menstrual cycles.
- Follow‑up ultrasonography is recommended to confirm resolution.
- Intervention (e.g., cyst aspiration, laparoscopic cystectomy) is reserved for:
- Persistent cysts larger than ~5–7 cm,
- Cysts causing significant pain,
- Complications such as torsion, rupture with hemoperitoneum, or suspicion of malignancy.
Epidemiology
- Corpus luteum cysts are common, occurring in up to 20 % of women of reproductive age during any given menstrual cycle.
- Their prevalence peaks in the reproductive years and declines after menopause.
Complications
- Rupture: May cause intra‑abdominal bleeding and acute abdomen.
- Ovarian torsion: The weight of the cyst can predispose the ovary to twist on its vascular pedicle, potentially compromising blood flow.
- Hemorrhagic cyst: Intracystic bleeding can enlarge the cyst rapidly and cause pain.
Prognosis
- The prognosis is excellent for uncomplicated cysts, with spontaneous resolution in the majority of cases.
- Timely recognition and management of complications lead to favorable outcomes, preserving ovarian function and fertility.