Corpus luteum: Function, formation, and cysts Health ConditionsHealth ConditionsAlzheimer's & DementiaAnxietyArthritisAsthma & AllergiesBreast CancerCancerCardiovascular HealthCOVID-19Dermatology & SkincareDiabetesEnvironment & SustainabilityExercise & FitnessEye HealthHeadache & MigraineHealth EquityHIV & AIDSHuman BiologyInflammatory Bowel DiseaseLeukemiaLGBTQIA+Men's HealthMental HealthMultiple Sclerosis (MS)NutritionParkinson's DiseasePsoriasisSexual HealthWomen's HealthDiscoverNewsLatest NewsOriginal SeriesMedical MythsHonest NutritionThrough My EyesNew Normal HealthPodcastsHow to understand chronic painWhat is behind vaccine hesitancy?The amazing story of hepatitis C, from discovery to cureNew directions in dementia researchCan psychedelics rewire a depressed, anxious brain?Why climate change matters for human healthToolsGeneral HealthDrugs A-ZHealth HubsHealth ToolsBMI Calculators and ChartsBlood Pressure Chart: Ranges and GuideBreast Cancer: Self-Examination GuideSleep CalculatorHealth ProductsAffordable Therapy OptionsBlood Pressure MonitorsDiabetic SuppliesFitness TrackersHome GymsGreen Cleaning ProductsHow to Shop for CBDQuizzesRA Myths vs FactsType 2 Diabetes: Managing Blood SugarAnkylosing Spondylitis Pain: Fact or FictionConnectAbout Medical News TodayWho We AreOur Editorial ProcessContent IntegrityConscious LanguageNewslettersSign UpFollow UsMedical News TodayHealth ConditionsDiscoverToolsConnectSubscribe What is a corpus luteum Medically reviewed by Stacy A. Henigsman, DO — By Lori Smith, MSN, BSN, WHNP-BC — Updated on August 30, 2022A corpus luteum is a mass of cells that forms in an ovary. It is responsible for the production of the hormone progesterone during early pregnancy. The role of the corpus luteum depends on whether or not fertilization occurs. Sometimes, cysts can form in a corpus luteum, leading to painful symptoms. These cysts can go away on their own, but some may require treatment. This article examines the role of the corpus luteum and how it forms. It also takes a look at what happens when corpus luteum cysts form and what how to treat them. A note about sex and gender Sex and gender exist on spectrums. This article will use the terms, “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more. What is the corpus luteum Share on Pinterestsujin jetkasettakorn/Getty ImagesDuring ovulation, an egg is released from a dominant follicle. Following the release of the egg and subsequent fertilization, the follicle seals itself off and forms what is known as a corpus luteum. This mass of cells helps produce the hormone progesterone during early pregnancy. The corpus luteum will continue to produce progesterone until the fetus produces adequate levels to sustain the pregnancy, which usually occurs within weeks 7-9 of pregnancy. Progesterone is essential during early pregnancy because:It allows the uterus to grow without having contractions.It supports the growth of the lining of the uterus.It improves blood flow and oxygen supply. The pregnancy hormone human chorionic gonadotropin (hCG) supports and maintains the corpus luteum. The corpus luteum begins to decrease in size at around 10 weeks of pregnancy. When fertilization or implantation does not occur, the corpus luteum will begin to break down. This causes a decline in estrogen and progesterone levels, leading to the start of another menstrual period. Corpus luteum and the menstrual cycle Hormones play a powerful role in typical menstrual regulation in females. In addition to progesterone and estrogen, essential hormones for ovulation include luteinizing and follicle-stimulating hormone. These hormones are responsible for ovulation and the preparation of the uterus for the implantation of a fertilized egg. A typical menstrual cycle occurs every 25–30 days, at which time the body prepares for ovulation and pregnancy. There are three phases of the menstrual cycle: Follicular phase The follicular phase of the menstrual cycle begins on the first day of a person’s period, at the onset of menstrual bleeding, and lasts until ovulation. This stage typically lasts about 13–14 days. During the follicular phase, the body secretes follicle-stimulating hormones to induce the production of ovarian follicles that contain eggs. One of these follicles will grow into a mature follicle capable of being fertilized, which is known as the dominant follicle. The dominant follicle secretes estrogen, which breaks down the non-dominant follicles and stimulates the uterus to begin thickening its lining in preparation for egg implantation. It also causes the luteinizing hormone surge responsible for ovulation. Ovulatory phase The ovulatory phase begins on approximately day 14 of the menstrual cycle. During this time, the luteinizing hormone surges, further stimulating the ovary to release the egg from the dominant follicle. Typically, this phase lasts around 16–32 hours, resulting in ovulation. Luteal phase The body prepares for the implantation of a fertilized egg during the luteal phase of the menstrual cycle. When an ovarian follicle releases an egg during the ovulatory phase, the opened follicle closes off, forming what is called the corpus luteum. The corpus luteum is responsible for producing the hormone progesterone, which stimulates the uterus to thicken even more in preparation for the implantation of a fertilized egg. The hormone estrogen also increases during this time to prepare the uterus for implantation. If there are no fertilized eggs to implant in the thickened uterine lining, the body sheds the lining during menstrual bleeding due to low levels of estrogen and progesterone, and the cycle begins again. What is a corpus luteum defect A corpus luteum defect, also known as a luteal phase defect, occurs when the corpus luteum is unable to produce enough progesterone to prepare the endometrium for implantation and pregnancy. This can cause issues like infertility and miscarriage. According to the American Society for Reproductive Medicine, factors and health conditions that may interfere with the function of the corpus luteum include:polycystic ovary syndrome (PCOS)thyroid dysfunctionendometriosisobesitysignificant weight lossexcessive exercisestresscertain genetic conditions, such as 21-hydroxylase deficiencyhyperprolactinemia Treatment for a corpus luteum defect may vary depending on the cause but often involves progesterone supplementation to support fertility. What is a corpus luteum cyst At times, the corpus luteum can fill with fluid. This buildup causes what is called a corpus luteum cyst, which is a type of functional ovarian cyst. In most cases, corpus luteum cysts will go away on their own without treatment. Corpus luteum cysts may disappear in a few weeks or take up to three menstrual cycles to vanish altogether. Some people who develop these cysts may experience symptoms, such as:pelvic pain, which may present as dull or sharp achingabdominal fullness or heavinessbloatingaching in the lower back and thighspainful intercourseweight gainpainful menstrual bleedingbreast tendernessneed to urinate more frequentlydifficulty emptying the bladderdifficulty emptying bowels completelyabnormal vaginal bleeding Some people may experience a burst cyst, which can cause severe pain and possibly internal bleeding. Larger cysts can cause the ovary to twist on itself (ovarian torsion). This can negatively affect the blood flow to the affected ovary. At times, the corpus luteum cyst may remain past the early stages of pregnancy. If this happens, the cyst has the potential to cause problems. An obstetrician will monitor as appropriate and make referrals to specialists as necessary. Diagnosis of an ovarian cyst A doctor may feel some ovarian cysts during a pelvic exam, but not always. An obstetrician may carry out some diagnostic tests to evaluate and diagnose ovarian cysts, including:a pregnancy test, which may signal the presence of a corpus luteum cysthormone testingpelvic ultrasoundsurgical procedures, such as laparoscopy, where the doctor inserts an instrument into the uterus through a small cut in her abdomen Some doctors may carry out tests to check the levels of certain substances in the blood used to detect ovarian cancer, such as the cancer antigen 125 (CA 125) test. A doctor would most likely request these tests if the cyst is solid and the person is at a higher risk for ovarian cancer. However, CA 125 levels can also rise in noncancerous conditions such as endometriosis. Treatment of cysts Often, corpus luteum cysts resolve without treatment. However, there are times when treatment is necessary. Some treatment options for ovarian cysts include:preventive medications, such as hormonal contraceptivessurgery to remove a large or persistent cyst A doctor will decide whether treatment is needed based on the size of the cyst, the symptoms that it may be causing, and the person’s age. If a cyst is not causing any symptoms, the doctor will often wait to see how things progress rather than starting any form of treatment. Frequently asked questions Here are a few common questions about the corpus luteum. What does the corpus luteum do if not pregnant If a person does not get pregnant during the menstrual cycle, the body breaks down the corpus luteum. This leads to a decline in hormone levels. What does the presence of corpus luteum mean The corpus luteum is a mass of cells that forms in the ovaries each month during a person’s menstrual cycle. It is responsible for producing key hormones involved in reproductive health and fertility, including progesterone. Do corpus luteum cysts need to be removed A corpus luteum cyst does not usually require treatment and often resolves on its own over time. However, a doctor may recommend treatment in some cases, depending on a person’s symptoms, medical history, age, and the size of the cyst. Summary The corpus luteum helps produce hormones that the body needs during the early stages of pregnancy. It is a vital part of fertility that enables pregnancy to occur. Cysts can sometimes form if the corpus luteum fills up with fluid. If anyone experiences any of the symptoms associated with a corpus luteum cyst, they should speak to a doctor. These cysts can cause painful symptoms, but in most cases, they will go away in time without treatment. Last medically reviewed on August 30, 2022Women's Health / Gynecology 13 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Cable, J. K., et al. (2022). Physiology, progesterone.https://www.ncbi.nlm.nih.gov/books/NBK558960/Diagnosis and treatment of luteal phase deficiency: A committee opinion. (2021).https://www.asrm.org/globalassets/asrm/asrm-content/news-and-publications/practice-guidelines/for-non-members/clinical-relevance-of-luteal-phase-deficiency.pdfDuncan, C. W. (2021). The inadequate corpus luteum.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8812462/Guile, S. L., et al. (2022). Ovarian torsion.https://www.ncbi.nlm.nih.gov/books/NBK560675/Holesh, J. E., et al. (2022). Physiology, ovulation.https://www.ncbi.nlm.nih.gov/books/NBK441996/Ku, C. W., et al. (2021). Gestational age-specific normative values and determinants of serum progesterone through the first trimester of pregnancy.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7893162/Mesen, T. E., et al. (2015). Progesterone and the luteal phase.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4436586/Mobeen, S., et al. (2022). Ovarian cyst.https://www.ncbi.nlm.nih.gov/books/NBK560541/Monis, C. N., et al. (2021). Menstrual cycle proliferative and follicular phase.https://www.ncbi.nlm.nih.gov/books/NBK542229/Oliver, R., et al. (2021). Anatomy, abdomen and pelvis, ovary corpus luteum.https://www.ncbi.nlm.nih.gov/books/NBK539704/Ovarian cysts. (2021).https://www.womenshealth.gov/a-z-topics/ovarian-cystsReed, B. G., et al. (2018). The normal menstrual cycle and the control of ovulation.https://www.ncbi.nlm.nih.gov/books/NBK279054/Thiyagarajan, D. K., et al. (2021). Physiology, menstrual cycle.https://www.ncbi.nlm.nih.gov/books/NBK500020/FEEDBACK:Medically reviewed by Stacy A. Henigsman, DO — By Lori Smith, MSN, BSN, WHNP-BC — Updated on August 30, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageWhat to know about ovarian dermoid cysts Ovarian dermoid cysts are benign and contain materials such as hair and teeth. Learn more here.READ MOREHome remedies for ovarian cyst symptoms In this article, we look at which home remedies can help reduce ovarian cyst symptoms, as well as what to do if a cyst causes severe pain.READ MOREWhat to know about ruptured ovarian cysts Ruptured ovarian cysts are not uncommon and part of the menstrual cycle. It does not often cause symptoms, but a person may experience pain in the…READ MOREOvarian cysts: What you need to know An ovarian cyst forms when fluid collects in a membrane of an ovary. Large cysts can cause symptoms, such as pain. In rare cases, a cyst can become…READ MOREWhat to know about PCOS, acne, and acne treatmentMedically reviewed by Debra Sullivan, Ph.D., MSN, R.N., CNE, COI Acne is common among people with polycystic ovary syndrome, or PCOS. Learn more about the link and the treatments for both conditions here.READ MORE