One of the most important structures in a woman’s ovary during the early phases of pregnancy is the corpus luteum, a temporary structure. The ruptured follicle becomes the corpus luteum after ovulation, which is responsible for producing progesterone and other vital hormones. These hormones aid in the uterus’s readiness for a potential pregnancy.
The corpus luteum is frequently seen as a small, spherical, or irregularly shaped mass during an ultrasound. Depending on the stage of the menstrual cycle, it can appear differently. Women undergoing early pregnancy monitoring or fertility treatments can feel more at ease knowing what to expect and what is normal.
This article will examine the ultrasound appearance of the corpus luteum and go over common norms as well as possible variations. It can be useful to know what to anticipate from a scan, whether you’re preparing for one or are inquiring about your reproductive health.
| Corpus Luteum Appearance | Norms on Ultrasound |
| Round or oval structure | Size typically 18-30 mm |
| Fluid-filled, may appear slightly uneven | Usually visible from day 14 to 28 of the menstrual cycle |
| Located on the ovary | Present during early pregnancy |
| May have a small amount of internal blood flow | Disappears if pregnancy does not occur |
- What is it?
- Location
- What does ultrasound show?
- About the size
- Pathological conditions
- Insufficiency
- Cystic formation, luteal cyst
- Absence of a corpus luteum and persistence
- Video on the topic
- Ultrasound cyst of the corpus luteum in the ovary
- Corpus luteum with intermittent peripheral blood flow. What does this mean? Dementieva S.N.
- Corpus luteum of the ovary
- Corpus luteum cyst of the ovary on ultrasound, what is it
What is it?
One thing unites all women, regardless of age, race, or height: the laws governing their menstrual cycle are the same, with sequential phases. Follicle maturation follows menstruation; one follicle will eventually become dominant. An egg matures in it, much like in a comfortable bag; the follicle bursts in the middle of the cycle, causing ovulation. After emerging from its "shelter," the egg travels through the pelvic cavity and the fallopian tube, where it can be fertilized in as little as a day or a day and a half.
- Menstruation
- Ovulation
- High probability of conception
In the event of a 28-day cycle, ovulation takes place on the 14th day, 14 days prior to the onset of the menstrual cycle. Since there is often variance from the average value, the computation is imprecise.
In addition to the calendar method, you can check cervical mucus, measure basal temperature, use special tests or mini-microscopes, and test for progesterone, estrogens, LH, and FSH.
With folliculometry (ultrasound), the day of ovulation can be ascertained with absolute certainty.
- Losos, Jonathan B.; Raven, Peter H.; Johnson, George B.; Singer, Susan R. Biology. New York: McGraw-Hill. pp. 1207-1209.
- Campbell N. A., Reece J. B., Urry L. A. e. a. Biology. 9th ed. — Benjamin Cummings, 2011. — p. 1263
- Tkachenko B. I., Brin V. B., Zakharov Yu. M., Nedospasov V. O., Pyatin V. F. Human Physiology. Compendium / Ed. B. I. Tkachenko. — M.: GEOTAR-Media, 2009. — 496 p.
- https://ru.wikipedia.org/wiki/Овуляция
In place of the follicle, a temporary formation is formed from the remains of its membrane — a gland that produces progesterone. Due to the color of the pigment inside it, it was called the corpus luteum. It is difficult to overestimate its importance for a woman, because this formation allows the female body to prepare for a possible pregnancy. Of course, the gland cannot "know" whether the egg is fertilized or not, but progesterone production occurs in any case. This hormone helps prepare the endometrium for possible implantation. While the fertilized egg moves into the uterus during the week after ovulation, the endometrium becomes looser to make it easier for the embryo to implant.
Furthermore, because the baby’s genetic makeup is only half that of the mother, progesterone lowers a woman’s immunity, preventing immune cells from killing the embryo because they believe it to be a foreign body.
Additionally, the mother’s body accumulates fat and nutrients during the early stages of pregnancy due to the influence of progesterone. The hormone helps the uterus bear the fetus by relaxing its muscles and preventing it from straining.
In the absence of conception, the corpus luteum cannot last for an extended period of time. If there is no implantation, the embryo dies and dissolves after 10–12 days, and large-scale progesterone production ceases. Menstruation starts when estrogen takes over all bodily functions. The corpus luteum stops being this before menstruation, changes into a pale body with no functional load, and eventually vanishes completely.
Pregnancy tests become "striped" because the chorionic villi start to produce hCG, a hormone that is easier for most people to understand and recognize after conception and successful implantation. The corpus luteum is prevented from dying by chorionic gonadotropin, which keeps the gland active until the end of the first trimester of pregnancy. The placenta then develops and takes on the roles of the progesterone "factory." Once a pregnancy reaches weeks 11–13, the corpus luteum regresses as unnecessary.
Location
Contrary to what some women believe, the corpus luteum is not found in the fallopian tubes, the uterus, or anyplace else outside the ovaries. It always and only develops on the ovary that was the site of ovulation. A woman’s ovaries are two. At the start of a new cycle, both develop folliculles, but typically one is dominant and the others develop in the opposite direction. Either the left or the right ovary contains the dominant follicle. The location formerly occupied by the vesicle-follicle is now occupied by the corpus luteum.
A woman may occasionally develop two corpora lutea simultaneously. It’s simple to interpret this as meaning that there is a high likelihood of a woman becoming pregnant with twins or even triplets because there was double ovulation, or the simultaneous bursting of two dominant follicles. The natural purpose of double ovulation is for a woman to carry a single fetus; it is not very common to prevent multiple pregnancies through this phenomenon.
Depending on where the ruptured follicles were, temporary glands may form on one ovary or on several after double ovulation.
By secreting hormones like progesterone, the corpus luteum—a tiny, transitory structure that develops in the ovary following ovulation—plays a crucial role in the early stages of pregnancy. It can vary in size and appearance, but in general, it should measure between 2 and 3 centimeters. On an ultrasound, it appears as a solid mass or a sac filled with fluid. Knowing the corpus luteum’s ultrasound appearance aids medical professionals in determining whether it is developing normally and provides a safe environment for a possible pregnancy.
What does ultrasound show?
It is unlikely that an average person with minimal knowledge of the complexities of ultrasound diagnostics will comprehend anything displayed on the scanner screen unless the physician provides a thorough explanation during the examination. When viewed in the ovarian region, the corpus luteum resembles a tiny sac and is anechoic in formation. Since the temporary gland contains a certain amount of liquid medium, there is no echogenicity. Even though the gland forms right after ovulation, an ultrasound scan won’t reveal it for another three to four days because the corpus luteum is so tiny when it first forms.
There are two methods for performing ultrasound: transabdominal and intravaginal, with the latter being thought to be more trustworthy and illuminating.
Once the doctor has established whether the right or left ovary has a temporary gland, he or she measures the gland’s diameter. To determine how well the corpus luteum matches its developmental stage, this indicator is crucial. However, the endometrium’s thickness is measured to evaluate the gland’s performance (recall that progesterone is the primary hormone that affects it).
This gland receives the best blood supply of any gland in the female body, and during the vascularization stage, the blood flow through it is the fastest. Thus, progesterone is flooded into the woman’s bloodstream by the corpus luteum. Furthermore, using Doppler ultrasonography with ultrasound, you can precisely determine the blood flow rate’s characteristics, which also reveal whether the gland is functioning fully or partially.
To put it simply, the ultrasound reveals the following:
- in which ovary the egg matured;
- whether ovulation occurred in this cycle;
- whether the corpus luteum copes well enough with its duties.
If the corpus luteum is not detected or is absent, the doctor states that there was no ovulation in this cycle. There is no need to worry – anovulatory cycles occur in completely healthy women normally up to 2 times a year at the age of 20 to 35 years. But in older women there may be more such cycles – up to 5-6 per year. Therefore, at an older age it is more difficult to conceive a child even with normal health. If the absence of the corpus luteum is detected for several cycles in a row, they talk about anovulation and refer the woman first for examination to a gynecologist-endocrinologist, and then for treatment, since the cause of the absence of ovulation can be a hormonal imbalance, and some ovarian pathologies, and other diseases and conditions.
In these cycles, pregnancy is not possible because the absence of the corpus luteum always signifies the absence of ovulation. However, merely having the gland detected does not indicate that a woman is pregnant; the corpus luteum develops entirely on its own during the second half of the cycle.
Finding the corpus luteum before the anticipated start of the next menstrual cycle has subtleties of its own: if it is regressing, it is likely that the menstrual cycle will start soon; however, if there is no regression, pregnancy is a possibility. However, this is not how a pregnancy is diagnosed; instead, the doctor must ascertain whether a fertilized egg is present in the uterus. Considering the tiny size of the egg, this is nearly impossible to do before the fifth week of pregnancy.
After a pause is something else. In addition to serving as an indirect indicator of pregnancy, a well-visible corpus luteum can also reveal whether or not progesterone production is sufficient to sustain the pregnancy.
About the size
The corpus luteum has a fairly stable size, typically ranging from 10 to 30 mm, in contrast to the follicle, which, when monitored by ultrasound, changes its size every day in the first half of the cycle. Only during the regression stage, when the gland is absorbed, is there a slight decrease in the number of days in the cycle. Consequently, you shouldn’t be concerned if the physician determines that the corpus luteum’s diameter is 11–12 mm, 13–14 mm, 15–16 mm, or 17–18 mm. A normal size is anything that falls between 10 and 30 mm in the value range.
A doctor will not be able to determine when ovulation occurred by the size of the corpus luteum to the day, given that the range of normal sizes is still quite large. It is believed that during the first week after ovulation, on average, the corpus luteum reaches a size of up to 17-19 mm, 10 days after ovulation – 20-27 mm, and in the last five days of the cycle (if there is no pregnancy) it begins to decrease to 15 mm. Therefore, with a big stretch, we can say that a diameter of 21-22 mm corresponds to an ovulation period of 7-9 days, and a diameter of 23-24 mm indirectly indicates ovulation about 10-11 days ago. In the heyday of the gland, when its size is maximum, there can be values of 25, 26-27 and 28-29 mm, but in this case it will be difficult to calculate when ovulation actually occurred.
Given that the corpus luteum’s initial size in women can range from small to large, it is only possible to determine the ovulation period if the doctor measures the corpus luteum’s size at least every other day. Such an examination is not necessary in real life.
Insufficient corpus luteum may be inferred indirectly if the gland measures only 8–9 mm or less. Because of this, having a child is seriously threatened due to the small gland’s low progesterone production. The so-called luteal cyst, also known as the corpus luteum cyst, is discussed as a potential cystic formation if the upper limit of the norm is exceeded (31, 32, 40 mm or more). It has an 80 mm diameter.
Pathological conditions
It is not possible to find specific normative tables for corpus luteum size in medicine, as the characteristics of this transient gland are thought to be highly individualized. This implies that the ultrasound protocol should only be understood by a physician. Let us examine the pathological conditions that can be found on an ultrasound of the corpus luteum and ovaries.
Insufficiency
A rather typical issue, typically linked to low progesterone production. Even in cases where fertilization is successful, insufficient corpus luteum phase can result in unsuccessful implantation, which prevents pregnancy. This is rife with miscarriage and frozen pregnancy in the early stages. Endocrine infertility is the result of a woman’s prolonged lack of luteal phase.
A tiny, transient formation on the ovary (less than 10 mm) and a thin endometrium may be signs of this pathology. However, the diagnosis won’t be made until the results of a blood test confirm progesterone insufficiency. If there is a suspicion of corpus luteum insufficiency, it is advised to perform it for the first time on the 16–19th day of the cycle and to repeat it after two days.
Deficiency does not mean death. And it’s successfully treated today. The doctor advises the woman to take progesterone preparations, such as "Utrozhestan" or "Duphaston," which come in cream and gel forms. An intramuscular progesterone oil solution is used during hospital treatment.
When a woman becomes pregnant, she is immediately placed under closer medical observation, and progesterone preparations should be continued until the placenta develops during the first trimester.
Cystic formation, luteal cyst
Doctors are not always able to determine why a corpus luteum cyst forms. This is thought to be impacted by a woman’s level of physical activity as well as physiological issues, such as the failure of the previous corpus luteum to recede, which leaves a cavity full of fluid—a cyst—forming.
Large, clearly visible cystic formations can be seen on ultrasonography; however, this is not a cause for alarm as most cysts resolve on their own in two to three cycles without the need for surgery.
Even during pregnancy, a cyst can disappear without affecting the fetus’s development in the mother’s womb or the conception process.
Absence of a corpus luteum and persistence
It is possible to detect no corpus luteum at all when a follicle is present. This essentially indicates that there was no ovulation, no follicular membrane rupture, and no egg release. Since the follicle’s size remains constant and it can be seen for up to ten days straight following the anticipated day of ovulation in this instance, persistence can be easily assessed using ultrasound in dynamics. The ultrasonographer observes an increase in follicle size when one of these follicles develops into a follicular cyst.
Pregnancy won’t happen in such a cycle, but protracted menstrual delays are possible. A doctor prescribes treatment; the most common type of therapy is the use of hormonal agents.
Generally, a woman’s ability to become pregnant and carry on the family line is fully restored after the persistent follicle is removed.
Early pregnancy is crucial for the corpus luteum, which produces the hormones needed to keep the process going. It shows up as a tiny, spherical structure inside the ovary on an ultrasound, frequently with a fluid-filled core.
Depending on the stage of the menstrual cycle or pregnancy, its appearance and size can change, but its diameter usually ranges from 2 to 3 centimeters. During certain stages of the cycle or in the first trimester of pregnancy, it is normal to see the corpus luteum on an ultrasound.
The corpus luteum may have an impact on fertility or the course of a pregnancy if it looks abnormal or does not function normally. But for the most part, it does its job and goes away on its own when it’s finished.
