Becasue the prediction of ovulation does not always guarantee the occurence of ovulation, various methods have been deviced to accurately detect the presence or occurence of ovulation to a very high degree of accuracy. Below are a list of the various methods of confirming ovulation.
Serum progesterone level; In the luteal phase of the menstrual cycle after ovulation, the corpus luteum in a normal menstrual cycle, begins to produce progesterone in a pulsatile fashion which peaks at exactly the mid luteal period. Measuring this can be used as a means of confirming the occurence of ovulation. To understand the biological process leading unto this, kindly read up the article MENSTRUAL CYCLE, OVULATION AND MENSTRUATION; EXPLANATION OF BASIC PHYSIOLOGY. Because the luteal phase lasts for about 14 days, the serum progesterone level is taken 7 days prior to the next menses. While the cut off for ovulation is a serum progesterone level greater than 30nm/L or 10ng/ml in the UK, various laboratories and countries have different cut off values for ovulation. To add to the confusion, the progesterone level may vary significantly within the same day and may thus be easily assumed to be low if the blood sample were taken at a time when the level of progesterone is low. Finally, progesterone assay must be timed with the menstrual cycle and be done exactly about 7 days prior to the next menses, hence the common day 21 progesterone assay may be errornously low in a woman with a 32 day cycle whose progesterone blood level is expected to peak on day 25 of her cycle. It is therefore not surprising that many gynecologists do not use serum progesterone as a means of confirming ovulation despite its wide spread usage. Finally, in pateints with LUF syndrome, a rarer medical condition, the progesterone blood level may continue to rise despite the absence of ovulation creating what seems like a normal menstrual cycle. This rather uncommon phenomenom is an incresingly common cause of unexplained fertilty and a cause of false positive ovulation signs and symptoms as well as a cause of a false positive normal progesterone assay level in many women with unexplained infertility.
Premenstrual symptoms; Other than the use of the progesterone assay to confirm ovulation, the effects on the body, of the increased progesterone hormone secreted in the luteal phase, may be used to confirm the occurence of ovulation to a high degree of accuracy. The most common symtpom used is the change in the basal body temperature (BBT) seen in the luteal phase of the menstrual cycle a day or two after ovulation. To learn how to use this method, read the article on PRIMARY SIGNS OF OVULATION. Others, such as breast tenderness and increased breast sensitivity, bloating, lower abdominal cramps and emotional changes can also be interpreted as a retrospective confirmation of ovulation. To learn more on this, read the article SECONDARY SIGNS OF OVULATION
Endometrial biopsy; Following ovulation, the progesterone acts on the endometrium converting it from a proliferative endometrium to a secretory endometrium; that is an endometrium rich in glucose and other nutrients meant for the growth and nutrition of an embryo in its earliest stage in case conception occurs. Sampling of the endometrium and visualization under the micoscope may be used as a test therefore to confirm ovulation. This however shares the same shortcoming as above and thus cannot be used to assess for the occurence of ovulation in women with LUF syndrome .
Ultrasonography; transvaginal ultrasonography can clearly define and has been recognized as the standard reference investigation for detecting ovulation. But because it requires experienced technicians, radiologists, or gynecologists to perform it and because it is realtively invasive, expensive, and inconvenient, its use has been mainly limited to clinical settings more specifically in various settings where ART are performed. Using serial ultrasond examinations, the time of ovulation can be determined as the point between the time the dominant ovarian follicule is largest in diameter (usually greater than 20mm) and the point it subsequently collapses or ruptures. Other feautures that suggest ovulation include, increased echogenicity inside the follicle indicating the formation of the corpus luteum, the presence of free fluid in pelvis (or pouch of Douglas) and a thickening of the endometrium seen on the ultrasound as a charecteristic replacement of the “triple-line appearance” of the endometrium by a homogenous, thick, hyperechoic or “luteinized” endometrium. Because of its unique ability to follow up the dominant follicle, it stands a great advantage of being able to diagnose LUF syndrome qwhich on ultrasound will be seen as a failure of the dominant follicle to rupture despite the LH surge prior to ovulation.
Laparoscopy; although more like an incidental finding rather than an indication for laparoscopy, an ovarian stigma may be seen during a laparoscopy done at the luteal phase of the mentrual cycle. Although, the ovarian stigma is a confirmation of ovulation, its absence at laparoscopy doesn’t totally exclude the occurence of ovulation. Due to the highly invasive and expensive nature of laparoscopy, and the accuracy of diagnosis of ovulation via the use of the ultrasound scan, the diagnosis of ovulation via laparoscopy is limited to research or incidental purposes during laparoscopic surgery for other indications and not routinely for the confirmation of ovulation.
Pregnancy; this remains the only certain proof or evidence of ovulation in a natural menstrual cycle. While this can be confirmed by a positive HCG assay result 10 to 14 days after ovulation, only about 25% of all fertilized zygote will undergo implantation at the end of each cycle, suggesting a high wastage of fertilized egg by nature. Therefore, the absence of pregnancy after each cycle despite adequate intercourse doesn’t exclude ovulation. All couples therfore who reside together and desirous of pregnancy are advised to have frequent regular well spaced out sexual intercourse, 3 to 4 times a week rather than burden their mind with unecessary investigations to confirm ovulation which only increase anxiety and emotional distress if at the end of the cycle conception doesn’t occur. If after trying for a year despite observing this, or if there is an obvious cause of infertility identified in the couple or if the woman’s age is greater than 35 years of age, rather than undergoing self treatment, such couples should see a seasoned gynaecologist for consultation. If confirmation of ovulation is necessary, from the above it is obvious that, serial transvaginal ultrasound scan is the most reliable method to to confirm ovuation.
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