FOLLICULAR TRACKING IN INFERTILITY INVESTIGATIONS
FOLLICULAR TRACKING IN INFERTILITY INVESTIGATIONS
FEMALE FACTOR INFERTILITYInfertility is the inability of a couple to become pregnant (regardless of cause) after 1 year of unprotected sexual intercourse (using no birth control methods).
Female factor infertility means infertility of a couple because of a problem in the female’s reproductive system. The main causes of female factor infertility are ovulation disorders, tubal disease and endometriosis.
INDICATIONS FOR FOLLICULOMETRY
[1] Monitoring ovulation for infertility checks
[2] To rule out ovarian failure
[3] To rule out anovulatory cycle
[4] To rule out Luteinised follicular syndrome
[5] Gender selection
[6] IUI and IVF [assisted reproduction]
OVARIAN FAILURE FACTORThe diseases of the ovary which most frequently cause infertility are: anovulation from follicular atresia, the empty follicle syndrome, the luteinized unruptured follicle syndrome; chronic anovulation syndromes, within which polycystic ovarian syndrome plays a major role; ovarian endometriosis.
Sonography and Color Doppler US are the first choice procedures in the monitoring of ovarian cycles, which combined with serum hormone values, are able to identify possible changes in the physiologic sequence of the cycle. In follicular atresia, ovaries with minute follicles (3mm or less) and early disappearance of primary follicle are observed on sonography. The empty follicle syndrome characterized by the lack of oocytes within the primary follicle, is of difficult sonographic diagnosis, a possible sign being the missed visualization of cumulus oophorus. The luteinized unruptured follicle syndrome consists in the absence of oocyte expulsion from primary follicle persisting more than 48 hours after LH blood peak.
THE OVARY
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homologous to testes in males, in that they are both gonads and endocrine glands.
Ovaries are oval shaped and, in the human, measure approximately 3 cm x 1.5 cm x 1.5 cm (about the size of a Greek olive). The ovary (for a given side) is located in the lateral wall of the pelvis in a region called the ovarian fossa. The fossa usually lies beneath the external iliac artery and in front of the ureter and the internal iliac artery.
Each ovary is then attached to the fimbria of the fallopian tube. Usually each ovary takes turns releasing eggs every month; however, if there was a case where one ovary was absent or dysfunctional then the other ovary would continue providing eggs to be released.
1. OOGENESISThe female germ cells, called oogonia, lodge in the outer layer, or cortex, of the ovary. They divide rapidly and at the fifth month of a female fetus’s life number up to 6-7 million cells. At that time, they begin maturation and are now called primary oocytes, eventually maturing to become primordial follicles. At birth, a female baby will have 2-4 million primordial follicles. In terms of numbers, birth is the high point, as many of the follicles will degenerate so that, by puberty, a woman will have, on average, about 400,000 of these follicles in her ovaries. It has been generally accepted that these are all the germ cells a woman has for her lifetime because these cells have not been known to multiply during life the way the spermatogonia do. Although there is one recent article that suggests that germ cells in the ovary may be able to regenerate later in life, in humans, for all practical purposes “what you have at birth is what you get for life” is still the case.
2. FOLLICLE DEVELOPMENT
Throughout female life from the onset of menstruation (menarche) to menopause, a small number of these primordial follicles are constantly beginning development. At puberty, hormones from the hypothalamus and pituitary glands in the brain will start to influence ovarian function. Without these hormones, the follices will not survive. The names of the hormones: gonadotropin releasing hormone (GnRH), follicle stimulating hormone (FSH) and luteinizing hormone (LH).
3. OVULATIONWith respect to the ovary, the menstrual cycle is divided into two phases: the follicular phase and the luteal phase. The follicular phase is dominated by the development of the follicle under the influence of FSH, while the luteal phase is dominated by another pituitary hormone, luteinizing hormone (LH). LH and FSH cause the production of prostaglandins and enzymes that disrupt the follicle and release the ovum, or egg, from the ovary. This release into the peritoneal space at the open fringed end of the fallopian duct is called ovulation.
OVARIAN FOLLICLESOvarian follicle is the basic unit of female reproductive biology and is composed of roughly spherical aggregations of cells found in the ovary. They contain a single oocyte (aka ovum or egg). These structures are periodically initiated to grow and develop, culminating in ovulation of usually a single competent oocyte. These eggs/ova are only developed once every menstrual cycle (i.e, once a month).
GRAFFIAN FOLLICLEA mature ovarian follicle in which the oocyte attains its full size and the surrounding follicular cells are permeated by one or more fluid-filled cavities. Also called secondary follicle, vesicular ovarian follicle.The Graafian follicle is characterized by a large, fluid-filled antrum, and an eccentric oocyte. The granulosa cells can be divided into two groups; the zona granulosa is a thin layer along the periphery of the follicle and the corona radiata surrounds the oocyte. The oocyte has undergone the first meiotic division, giving rise to a secondary oocyte and the first polar body. The secondary oocyte is now arrested in metaphase of the second meiotic division and will so remain until fertilization. The first meiotic division appears to be initiated by LH acting on granulosa cells, however the exact mechanism of action is unknown. The Graafian follicle represents the final stage of follicular development before ovulation.
The Graafian follicle is identified by the large antrum , and the corona radiata that surrounds the actual oocyte and projects into the antrum
CUMULUS OOPHORUS: a mass of follicular cells surrounding the oocyte in the vesicular ovarian follicle.
FOLLICULAR TRACKING BY ULTRASOUND
Ultrasound Folliculometry is a serial Transvaginal ultrasound scan test carried out to monitor follicular growth . Follicular growth can be best monitored by ultrasound , providing 40–70% effectiveness. Folliculometry is one of the most accurate method for determining ovulation. Ovulation scans allow us to determine accurately when the follicle matures; and when it ruptures. Daily scans are done to visualize the growing follicle, which looks like a black bubble on the screen. Other useful information which can be determined by these scans is the thickness of the uterine lining – the endometrium. The ripening follicle produces increasing quantities of estrogen, which cause the endometrium to thicken. We can get a good idea of how much estrogen the patient is producing (and thus the quality of the egg) based on the thickness and brightness of the endometrium on the ultrasound scan.
In a normal ovarian cycle, a single follicle begin to mature under the influence of the gonadotrophic hormone FSH and LH. The follicle appears sonographically as a vesicular echo free structure on the ovary. While some small follicles from 0.4 to 0.6cm in diameter can usually be seen in both ovaries during the initial days of the cycle, a follicle on one of the ovaries become dorminant starting about day 10, enlarging to a diameter of approximately 1 cm. That follicle grows at an almost linear rate of 2 to 3mm per day over the next 4 to 5 days reaching a size of 18 to 24mm just before ovulation. The follicle may have a somewhat elliptical shape initially , but the preovulatory follicle is generally round.
Research found a good correlation between follicular size by ultrasound and the serum estradiol level .
In folliculometry the follicle diameter is determined by measuring the internal diameter of the follicle in three planes [ long, transverse, anterior-posterior] and taking the average of these diameters.
Sonographic follicular monitoring is started on about 6 to 8 days of the menstrual cycle, on day 10 when the dormant follicle presumably has reached a minimum size of 1cm. The scans are repeated at intervals of 1 to 2 days until ovulation is detected.
Occassionally the Cumulus Oophorus can be identified with a high resolution scanner shortly before ovulation. It appears as a peripheral circular feature within the follicular wall.
During folliculometry [transvaginally] we should make an effort to see the Cumulus mass. When a cumulus mass is seen, it can be taken as evidence of a sign of maturity of that particular follicle and oocyte. Cumulus visualization by ultrasound appears to be an indicator for mature oocytes and successful fertilization. Follicles in which the cumulus cannot be visualized are unlikely to contain mature oocytes or oocytes in which fertilization is achieved.
Normally ovulation is not expected to occur until the follicle has reached a size of 1.7cm.
Once ovulation has occurred , various sonographic changes maybe observed
[1] Complete disappearance of the cystic structure in the ovary.
[2] Collapse of the cystic structure with a decrease in its diameter.
[3] A cystic mass with internal echoes [the corpus hemorrhagicum]
[4] The presence of follicular fluid in the cul de sac.
Serial ultrasound examinations cannot only demonstrate normal follicular development. These include failure of the follicle to mature.
Defficient growth of the follicle and Luteinized unruptured follicle syndrome.
COMPLICATIONS
OVARIAN HYPERSTIMULATION SYNDROME
Ovarian hyperstimulation syndrome (OHSS) is a common
complication in assisted reproductive technologies. It is seen
to occur in ,10% of the treatments, and the severe form is
observed in 0.5–2% of IVF cycles . OHSS
is usually described by enlarged multicystic ovaries, ascites
and haemoconcentration. Acute renal failure due to a hypovolaemic
state following production of protein-rich ascites in
patients with OHSS .
Even though the complication risk related to IVF is low,
one should be aware of a possible compression or damage to the ureters with subsequent development of acute renal failure.
JOAS MEDICAL DIAGNOSTIX, Ikotun Lagos Nigeria, offer comprehensive infertility screening tests for both couples like Transvaginal Scan for uterine and ovarian functions,Ovulation/follicular tracking, HSG to evaluate the fallopian tubes, blood tests for hormone check, semen analysis etc. We also offer a simple assisted reproductive procedure like INTRAUTERINE INSEMINATION [IUI]. For accurate assessment of your fertility situation, contact us at JOAS MEDICAL DIAGNOSTIX, Ikotun Lagos Nigeria.
For FREE Consultation and FREE Counseling. Also for Quality and Accurate Medical Diagnostic Tests Contact JOAS MEDICAL DIAGNOSTIX
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