Basal Body Temperatures |
Cervical Mucus |
LH Surge and Ovulation Prediction |
Vaginal and Salivary Electrolytes |
Ultrasound Based Prediction of Ovulation
31 year old G0 has a history of regular menstrual intervals every 28-31 x 4-5 days, a normal hysterosalpingogram (normal uterine cavity and bilateral tubal patency), a normal postcoital test, and a husband with proven fertility (in a previous relationship) with a normal semen analysis. This woman has been tracking her basal body temperatures using a digital (ear) thermometer for 2-3 months and the pattern is clearly monophasic.
Are the monophasic basal body temperature charts significant in this context?
Basal body temperature charting often provides useful information about ovulation, is (comparatively) inexpensive and does not require much effort or time (on behalf of the patient) in order to collect the data. Therefore, I am generally pleased when a patient is willing to obtain her basal temperatures for a month or two.
In this patient's situation there is relatively strong evidence of ovulation by the history alone. The history of regular menstrual intervals, consistent amount of flow and premenstrual symptoms is highly suggestive of regular ovulation.
Basal body temperatures can frequently identify the time of ovulation (retrospectively) since ovulation usually occurs a day or two prior to the increase in (basal body) temperatures. Pinpointing the exact day of ovulation is often difficult but identification within a day or two is not uncommon. Therefore, a luteal phase defect due to a short luteal phase (time period between ovulation and subsequent menses) can sometimes be picked up with basal body temperatures even when there is a history of regular intermenstrual intervals.
The reason for the monophasic temperature charting is unclear. One would expect a biphasic temperature pattern (a normal ovulatory pattern) given the strong suggestion of regular ovulation by the menstrual history.
I have often seen monophasic temperature patterns when digital thermometers are used. It appears that the subtle changes in temperature are somehow "missed" with most digital thermometers. Therefore, in this situation I would suggest the use of a mercury metabolic thermometer to see whether the monophasic pattern is due to the type of thermometer used. If the pattern becomes biphasic when a mercury thermometer is used then I would not need additional confirmation of ovulation.
In this situation, if the basal temperature charting remained monophasic despite use of a mercury thermometer then I would suggest confirmation of ovulation with a luteal phase progesterone concentration. If the luteal progesterone were clearly ovulatory, then this would represent an example of a woman whose basal body temperatures simply do not accurately reflect ovulation (do not seem to increase with an increase in progesterone concentration). If the "luteal" progesterone concentrations are repeatedly low (multiple progesterone concentrations may be needed prior to expected "menses" due to the inherent pulsatility of luteal progesterone concentrations) then I would generally suggest ultrasound confirmation of ovulation (or identification of anovulation).
It is very uncommon but certainly possible that a woman with a history highly suggestive of regular ovulation is indeed anovulatory. If an anovulatory state is identified, this is very important in terms of both fertility and gynecologic management.
20 year old G0 with a history of irregular menstrual intervals every 25-30 x 2-4 days, a normal hysterosalpingogram (normal uterine cavity and bilateral tubal patency), and a husband with a normal semen analysis yet unproven fertility has been obtaining basal body temperature readings for the past 4 months. The initial month of basal temperatures reflects ovulation around cycle day 15 and the intermenstrual interval for that month was 29 days (consistent with "expected day of menses" given the identified approximate day of ovulation). The following three cycles of basal body temperature charting are monophasic yet the intermenstrual intervals has not changed.
What could account for the initial biphasic pattern followed by monophasic patterns?
The initial biphasic basal body temperatures are consistent with the expected results given this woman's history.
On further questioning, the woman stated that she meticulously checked her temperatures for the initial month prior to rising from her bed each morning. Then when she saw a "good" pattern she began to take her temperatures in the morning at various times, sometimes after brushing her teeth, sometimes after showering, and sometimes after drinking something from the kitchen.
Meticulous attention to the timing of basal body temperatures is important. If a woman gets up and around, drinks something either hot or cold, or has not slept well the night before then the temperatures may be misleading. I also suggest a metabolic mercury thermometer rather than a "regular" mercury thermometer or a digital thermometer since the readings seem to be more consistently informative.
41 year old G1 P1 (when 26 years old) with a history of regular menstrual intervals every 26-27 x 3 days, no prior hysterosalpingogram or postcoital test, and a husband (recently remarried) with a normal semen analysis and proven fertility (in a prior relationship) who now desires to have a baby with her current husband.
Are basal body temperatures suggested in this situation?
A 41 year old woman interested in fertility would ideally undergo a basic infertility evaluation relatively quickly, including a hormone evaluation and assessment of ovarian reserve, semen analysis, hysterosalpingogram and postcoital test. While these tests are being completed, daily basal body temperature charting can sometimes provide information about the cycle day of ovulation (the follicular phase of the cycle is generally shortened in women with an age related depletion in ovarian reserve), the length of the luteal phase (luteal phase defects may be more common in women with a decreased ovarian reserve), and confirm regular ovulation. Therefore, I generally encourage basal temperature charting while a diagnostic evaluation is taking place.
A 41 year old woman will generally have the best success for fertility if a problem is rapidly identified and treated appropriately. I would not suggest delaying an appropriate treatment plan for such a woman simply in order to obtain several months of basal temperatures.
29 year old G0 with a history of regular menstrual intervals every 26-27 x 2-3 days, a normal hysterosalpingogram (normal uterine cavity and bilateral tubal patency), a normal postcoital test, and a husband with proven fertility and a normal semen analysis has been timing coitus during natural cycles by determining the time of ovulation via the presence of "egg white" cervical mucus.
Is the evaluation of "cervical" mucus characteristics an accurate way to determine the timing of ovulation?
Many women check their "cervical" mucus by obtaining samples of (their) vaginal mucus-like material via digital (finger) vaginal examination. The woman then assesses the appearance and quality of this material.
It is difficult or impossible to reliably obtain mucus from within the cervix on digital vaginal exam. To obtain a sample of cervical mucus in the office, I place a vaginal speculum, center the uterine cervix between the blades of the speculum, and then aspirate mucus from within the (closed) cervix using a syringe.
Digital vaginal exploration and removal of mucus like material may result in a sample that does not accurately represent cervical mucus. Some women are convinced that they are able to obtain cervical mucus reliably and this test may be useful if they are correct.
If mucus from the cervix is obtained, this (cervical) mucus normally displays certain characteristics in the immediate preovulatory phase of the cycle. On gross examination, the elasticity of the mucus increases dramatically, the appearance of the mucus becomes clear (similar to "egg white"), and the amount of mucus present is greatly increased. Microscopic findings of pre-ovulatory cervical mucus also include a characteristic ferning pattern when dried and a reduction in cellularity.
Cervical mucus assumes the characteristics of "pre-ovulatory mucus" due to an increase in estrogen effect. The circulating estrogen concentration is normally greatest in the immediate pre-ovulatory period of a natural cycle. If the woman is taking estrogenic medications or dietary supplements, menotropin medication to increase the number of developing ovarian follicles and eggs (for controlled ovarian hyperstimulation), or has a chronically elevated estrogen concentration (such as with certain estrogen producing tumors) then the appearance of the mucus may be persistently peri-ovulatory ("egg white").
22 year old G0 with a history of regular menstrual intervals every 29 x 4 days has been assessing her cervical mucus each month in order to time intercourse. She has found that her mucus always seems to be thick, nonelastic, cloudy, and scanty in amount.
Do these findings suggest that this woman is not ovulating?
The history of regular menstrual intervals with consistent amount of flow and premenstrual symptoms (strongly) suggests that this woman is ovulating.
It is often difficult to reliably obtain a cervical mucus specimen on self digital vaginal examination. A woman may then become frustrated when she consistently finds scanty thick mucus like material. It is possible that there is good mucus within the cervix and yet the woman is not able to obtain this material for assessment using digital vaginal exams.
In this situation, I would suggest using the history of regular intermenstrual intervals of 29 days to predict ovulation around cycle day 15 (roughly 14 days prior to the onset of the next menstrual flow), and I might suggest confirming this day of ovulation with either basal temperature charting for 1-2 months or an ovulation predictor (LH) kit.
32 year old woman with a history of slightly irregular menstrual intervals every 27-32 x 4-5 days, a normal hormone evaluation (for TSH and prolactin concentration), a normal hysterosalpingogram (normal uterine cavity and bilateral tubal patency), and a husband with unproven fertility (no prior pregnancies) yet a normal semen analysis has been timing intercourse using (self) assessment of her "cervical" mucus without pregnancy.
If the timing of intercourse is accurate, then why is this couple not achieving a pregnancy?
The accuracy of predicting ovulation using self assessment of cervical mucus is controversial. I generally prefer an ovulation predictor (LH) kit for predicting when ovulation is about to occur and basal body temperatures to detect when ovulation has occurred.
Despite the relative accuracy of these different methods of determining ovulation, this couple has had 1-2 years of "trying" with frequent intercourse in the midcycle without success. In this situation, I would suggest completing the basic assessment including a postcoital test. If the postcoital test is abnormal, then I would suggest several cycles of timed natural cycle intrauterine insemination. If the postcoital test is normal, then the entire basic evaluation is normal and I would consider a pelvic evaluation (laparoscopy and hysteroscopy) to identify and treat pathology in the pelvis.
22 year old with a history of regular menstrual intervals every 28-30 x 4-5 days, premenstrual syndrome (PMS) symptoms, midcycle pelvic discomfort that she believes is caused by ovulation, and biphasic basal body temperature charting.
Would the results of an ovulation predictor kit significantly add information concerning ovulation for this woman?
My belief is that a history of regular menstrual intervals with premenstrual symptoms is a fairly good (reliable) way of detecting that ovulation is occurring. The presence of PMS symptoms (regardless of which symptoms occur) suggests that the hormonal shifts of the menstrual cycle are taking place. Regularity of menstrual flow essentially rules out nonovulatory causes of vaginal bleeding.
I have not found the presence of pelvic discomfort around the time of ovulation to be reliably associated with ovulation. For example, if a woman describes midcycle discomfort (during a particular cycle) on the right side and an ultrasound is performed (at that same time) to identify the location of the ovarian follicle, the ovarian follicle is often found on the contralateral (left) side. It is known that the egg is released from the ovary in a very gentle fashion (not like an explosion) and that the sudden expansion of the ovarian capsule immediately prior to ovulation might actually be the cause of the pelvic discomfort.
Basal body temperature charting can provide (valuable) information concerning the timing of ovulation. The luteal phase of the cycle should be at least 11 days in length (most often 14 days). If the duration of the temperature "elevation" (greater than 98 C) is less than 11 days (in an otherwise unremarkable biphasic BBT chart), I consider an endometrial biopsy to rule out a luteal phase defect (a significant reduction in progesterone effect on the endometrial lining of the uterine cavity).
Of note, the endometrial biopsy reportedly may be normal (in phase with respect to the time of ovulation) despite a short luteal phase duration. Therefore, if the luteal phase duration is consistently shown to be less than 11 days in duration then this is also considered a form of "luteal phase defect" (despite a possible "in phase" endometrial biopsy). Treatment of the variant form of luteal phase defect is generally progesterone supplementation.
The ovulation kits can predict when ovulation will occur (usually within 1-2 days of the color change) whereas the basal temperature charts determine that ovulation has taken place (1-2 days prior to the temperature rise). The ovulation kits are most useful in scheduling procedures that must be timed prior to ovulation (like the postcoital testing or intrauterine inseminations).
28 year old G0 with a history of irregular menstrual intervals, anovulation, excess hair growth (facial, upper abdomen), oily skin occasionally with acne, and excess weight.
Ovulation predictor kit results are always positive. Can ovulation kits be used for this woman to determine when ovulation will occur?
Sometimes (not always).
Ovulation predictor kits detect the presence of increased concentrations of LH. LH is a hormone that begins to dramatically rise (surge) about 36 hours (one and a half days) before ovulation. The kit's "sticks" (test chambers) are typically wetted with a urine sample and the "result region" of the kit's test chamber will change color (to pink or to blue) when the LH concentration is greater than a certain amount (assay sensitivity varies among the available kits).
The "sensitivity" of the test kit is determined by the smallest amount of LH that can be recognized (measured) by a change in color within the kit's result region. The "specificity" of the test kit is determined by the ability of other substances (typically related hormones like FSH, TSH or hCG) to alter the result (change in color) of the test (by cross reacting with the test reagents). The "accuracy" of the test kit is its ability to measure the exact amount of the desired hormone (LH) in the sample (not a variable easily measured in kits that report only positive or negative).
Ovulation predictor kits vary considerably with respect to their sensitivity. However, most ovulation predictor kits are highly specific.
Most women have an increase in (urine) LH concentration (that triggers ovulation) to greater than 35 IU/L during an LH surge. Some ovulation predictor kits are very sensitive and will show a positive result (turn color) at (urine) LH concentrations of about 25 IU/L. This level of sensitivity can be counterproductive since some women have a persistent elevation in circulating (and urine) LH concentration so that their ovulation kit results are "always positive" (reducing their ability to predict ovulation). Finding a kit that will consistently predicts ovulation accurately (ultimately the desired result) but which is not "over sensitive" (always positive regardless of timing of ovulation) is important.
One of the most common clinical syndromes associated with chronic anovulation is polycystic ovarian syndrome (PCOS), which is an endocrinology (hormonal) disorder that is classically characterized by an elevated ratio of circulating LH to circulating FSH. These hormones (LH and FSH) are secreted by the (brain's) pituitary gland and regulate ovarian egg maturation and the menstrual cycle. If there is an abnormality in the relative amounts of these secreted hormones, then egg maturation can be arrested. PCOS is also commonly associated with obesity, excess hair growth, oily skin and acne, and insulin resistance.
Women with PCOS often have a persistent elevation in LH secretion, which may result in ovulation kits (especially those with a high sensitivity for LH) always appearing "positive." In these cases, trying a few of the different commercially available kits may allow a woman to find a kit that will become positive only in the presence of an LH surge (ovulation).
34 year old woman with an abnormal postcoital test result and subtle male factor (abnormal semen analysis) is scheduled for (natural cycle) intrauterine inseminations (IUIs) timed with ovulation predictor kits.
When is the best time to perform the IUI with respect to the positive ovulation predictor kit result?
The egg is generally thought to be fertilizable for about 24 hours after ovulation. The sperm undergoes a series of changes after ejaculation referred to as "capacitation" (which allows the sperm to then fertilize an egg). Capacitation usually occurs within a few hours of ejaculation. The time that the sperm survives in the uterine cavity or fallopian tubes is unknown but generally is thought to be about 1-2 days.
Given these time parameters, it would (theoretically) be ideal to perform the IUI as close to ovulation as possible. The time of ovulation following a positive (urine) LH ovulation predictor kit has been studied and reportedly occurs 1-2 days later (with the kits calibrated to test positive at an LH sensitivity of about 40 IU/L).
There is an ongoing controversy as to whether 1 or 2 IUIs per cycle is ideal. I generally suggest that 1 IUI per cycle for 2 separate cycles is more effective than 2 IUIs in one cycle. If the cost is a very important factor for the couple, I think that it is more cost effective to perform 1 IUI per cycle for twice as many cycles. If cost is not so important, or optimizing success with every cycle is critical (such as with a decreased ovarian reserve), then reconsideration of 2 IUIs (on the day of or day after a positive ovulation kit result and again on the next day) is reasonable.
Urinary LH concentrations have a diurnal rhythm (regular daily pattern of increases and decreases) such that the first morning urine generally has a low level of LH (and is not used for testing with the ovulation predictor kit). The best urine samples (for detecting ovulation by LH concentration) are generally collected between 10 A.M. and 8 P.M..
29 year old G0 with a history of anovulation, ovulation induction with clomiphene citrate (with biphasic basal body temperatures and menses at 100 mg a day on cycle days 5-9) and an abnormal postcoital test during clomiphene citrate induced cycles. Intrauterine inseminations (IUIs) are planned to coincide with ovulation.
Are ovulation predictor kits accurate during clomiphene citrate cycles?
Yes, but only starting several days after the last clomiphene citrate tablet.
Clomiphene citrate acts to "trick" your body into believing that there is a lack of circulating estrogen, which results in the pituitary gland releasing greater amounts of FSH and LH. The elevated LH concentration within 3 days of the last clomiphene tablet (clomiphene is classically given on cycle days 5-9) may cause a false positive (ovulation predictor kit) result, so I ask my patients to begin (ovulation predictor kit) testing on cycle day 13 of a clomiphene citrate cycle (in which the medication is taken cycle days 5-9). If the ovulation kit is performed within 3 days of the final clomiphene citrate pill there is a significant chance that the result will be a "false positive."
A 24 year old woman has a history of irregular menstrual intervals every 25-38 x 2-5 days. Ovulation predictor (LH) kits do not appear to turn positive when they have been used. The basal body temperature charting is monophasic rather than biphasic (ovulatory).
What testing may be useful in documenting whether the menstrual intervals are "ovulatory" or just break through bleeding?
In a situation like this, where "menstrual intervals" are irregular and ovulation cannot be documented with either basal body temperatures or ovulation predictor (LH) kits, the least expensive method of confirming ovulation is usually serial (weekly) serum progesterone concentrations during a cycle. That is, the woman may have progesterone concentrations performed every week for 3-6 weeks (from the onset of one cycle to the onset of a subsequent cycle), with the initial progesterone concentrations normally being "follicular" (preovulatory) and the following concentrations often being "luteal" (postovulatory). The progesterone concentrations during the luteal phase are pulsatile but generally have a concentration greater than 3-4 mcg/L (ng/mL).
If the woman's serial progesterone concentrations are persistently low (less than 1 ng/mL) this strongly suggests anovulation (and treatment should be initiated accordingly). If the progesterone concentrations suggest that ovulation is taking place, then further investigation is often able to pinpoint the time of ovulation
33 year old G0 with a history of regular menstrual intervals every 30-32 x 4 days and a serum progesterone concentration from cycle day 26 of 8.5 ng/mL.
Can the day of ovulation or quality of the egg be determined by the progesterone concentration in the blood?
The progesterone concentration increases at ovulation due to an elevation in circulating LH concentration. The progesterone concentration is normally pulsatile and elevated during the luteal phase of the menstrual cycle (usually is greater than 3-4 ng/mL). The exact circulating concentration of progesterone does not reflect (cannot be used to determine) the time (cycle day) of ovulation.
Some gynecologists seemingly use the value of the circulating progesterone concentration during the luteal phase of the cycle to identify "good eggs" from less than ideal eggs. To my knowledge, research on this issue is very scanty and does not support such conclusions. I simply use circulating progesterone concentration values to confirm (or rule out) ovulation. If a luteal phase defect (due to progesterone insufficiency) is suspected, I generally use the endometrial biopsy for diagnosis.
35 year old G0 with a history of regular menstrual intervals every 27 x 3 days, "unexplained infertility" after a thorough evaluation (including a hormone evaluation, semen analysis, hysterosalpingogram, postcoital test, and pelvic evaluation), with luteal phase progesterone concentrations on 3 independent cycles that were greater than 7 ng/mL. Serial ultrasounds have not been able to identify the time of ovulation via a collapse in the dominant ovarian follicle.
Could the basis of this couple's infertility be due to a failure to release the egg at the time of ovulation?
I generally do not obtain luteal phase progesterone concentrations during an infertility evaluation unless documentation of ovulation is very difficult. In this situation, the couple had progesterone concentrations already obtained at another office that further confirm that ovulation appears to be occurring.
I generally do not obtain serial ultrasound exams to determine the day of ovulation since they can be expensive, time consuming (for patients), and unreliable (the collapse of the dominant ovarian follicle is often missed with even daily ultrasound exams). I do sometimes suggest serial ultrasound examinations during the follicular phase of the cycle to determine the presence of a dominant mature follicle (generally one that is greater than 18 mm diameter) in order to time the administration of hCG (to trigger ovulation).
A syndrome called "luteinized unruptured follicle syndrome" (LUFS) has been proposed in the past but LUFS has never really been proven to exist. Human eggs are microscopic in size (require a microscope to see since they cannot be seen with the naked eye) and therefore cannot be identified with ultrasonography. Ultrasound exams are able to identify and follow the growth of ovarian follicles, which are cysts within the ovary that contain eggs. In a natural (spontaneous) cycle, the dominant ovarian follicle grows to a certain diameter (often 18-30 mm) and then the LH surge occurs to (normally) trigger ovulation (the release of the mature egg into the pelvis). If the dominant ovarian follicle does not release its follicular fluid and the egg following an LH surge, then this would be LUFS syndrome. In this situation, the follicle does not rupture, the egg is "trapped" in the ovarian cyst so that it cannot be fertilized, and the elevated circulating LH concentration can luteinize the ovarian follicular cyst so that it produces abundant progesterone. If this occurs, the circulating progesterone concentration might (would be expected to) increase normally.
The use of frequent serial ultrasounds to document ovulation (the release of follicular fluid with the egg from the ovarian dominant follicle) is unreliable. The dominant ovarian cyst may in fact release the fluid (collapse) and then reaccumulate with fluid between the scheduled ultrasound exams. In this situation, ovulation would be missed.
LUFS syndrome is difficult to confirm (rule in) or refute (rule out), due to the inherent variability in the time required for the ovarian follicle to collapse and reaccumulate and the microscopic size of a human egg. I have not been convinced by the available literature that this syndrome actually exists and I generally do not recommend testing of this sort to identify potential LUFS patients. I generally focus on clinically proven causes of subfertility and then treat "unexplained infertility" (if found) with treatments that have been shown to be effective (rather than look for possible causes with unproven clinical merit).
26 year old G0 with a history of irregular menstrual intervals every 27-33 x 3-5 days has been using a variety of "home products" to detect ovulation.
Which of the commercially available home health products may be useful for this woman?
I generally suggest the ovulation predictor (LH) kits since they are relatively inexpensive, easy to use, and reliable. In some cases, the ovulation predictor kits do not seem to be reliable since they are either always positive or never positive. In these situations, I suggest trying one of the other available brands of the ovulation predictor (LH) kit since different brands may be of increased or reduced sensitivity to LH.
Microscopes (including small hand held versions) allow observation of salivary (saliva = the mouth's fluid) ferning patterns (pattern of arborization that looks like a fern plant leaf) after the saliva dries and crystallization has had a chance to occur. Studies report that the "peak" amount of ferning is highly correlated to the LH surge (the event triggering ovulation), but that assessing the beginning and end of the fertile period using ferning patterns alone is not reliable. If the LH ovulation predictor kits are inaccurate, the utility of the salivary ferning patterns is not clear.
Ovulation prediction using assessment of salivary or vaginal "electrical resistance" with available kits has been proposed but at present these devices are not commonly used (at least in my personal experience). In one good quality study (1989) a statistically significant peak in either the mean salivary or the mean vaginal electrical resistance on a particular day relative to the day of the serum LH peak (surge) could not be demonstrated.
31 year old G1 P1 with a history of regular menstrual intervals every 27-28 x 4-5 days, monophasic basal body temperature charting (rather than an "ovulatory" biphasic pattern), inconsistent results with a variety of ovulation predictor kits and monitors, and evidence of ovulation using luteal phase blood progesterone concentrations (consistently greater than 6 ng/mL within 10-14 days of a subsequent menstrual flow).
Are there additional tests that could detect and/or predict when ovulation is occurring?
Serial ultrasounds are able to follow the development (growth) of an ovarian follicle (ovarian cyst containing an egg) to the point of maturation, at which time ovulation can either be (a) triggered with medication (hCG injection) or (b) confirmed with additional ultrasounds (by the subsequent collapse of the follicle).
Serial ultrasound examinations tend to be expensive and time consuming. If ultrasounds are initiated for these purposes, I generally suggest triggering ovulation with medication (10,000 IU hCG by intramuscular injection is effective) once a mature follicle is identified. I often discourage serial ultrasounds to identify the exact time of spontaneous ovulation since my own clinical experience is that daily ultrasound exams "miss" follicular collapse too often to make this a reliable diagnostic alternative.
31 year old G0 with a history of slightly irregular menstrual intervals every 24-29 x 4-5 days has decided (with her doctor) to initiate serial ultrasound examinations to identify the presence of a mature ovarian follicle (and egg). Administration of hCG medication to trigger ovulation (once the dominant follicle is thought to contain a mature egg) and time intrauterine inseminations is planned.
When should the serial ultrasound exams begin during the cycle for this particular woman?
The intermenstrual intervals vary from every 24 to 29 days, ovulation would be predicted about 14 days prior to onset of the subsequent menstrual flow, and ultrasounds should generally be initiated a few days prior to the earliest expected day of ovulation. Therefore, the day of ovulation may be as early as cycle day 10 in a 24 day cycle so I would generally suggest an ultrasound around cycle day 7-8. Depending on the size of the lead follicle I would then schedule a second ultrasound. When the lead follicle is 18 mm diameter, I usually trigger ovulation with 10,000 IU hCG. Ovulation most often occurs about 36-40 hours after the hCG injection (which allows timing of procedures that depend on ovulation).
28 year old G0 with a history of very irregular menstrual intervals every 1-8 months without medications, appears to ovulate to clomiphene citrate at 100 mg per day (cycle days 5-9) with menstrual intervals every 30-35 x 5-7 days, has difficulty reliably predicting ovulation with commercially available home ovulation predictor (LH) kits, and wants to identify when a mature follicle is present with ultrasound exam so that she can then trigger ovulation with medication (hCG).
When should serial ultrasound exams begin at when should ovulation be triggered for this particular woman?
Ovulation generally occurs about 14 days prior to the subsequent onset of menstrual flow. In this case, ovulation on clomiphene citrate (100 mg a day on cycle days 5-9) may spontaneously occur as early as cycle day 16. In clomiphene citrate cycles, spontaneous ovulation often occurs when the lead follicle is about 25-30 mm diameter.
In order to identify the presence of a mature ovarian follicle, which is generally thought to exist when the lead follicle is 18mm diameter, I would generally suggest ultrasounds starting several days prior to the earliest time of spontaneous ovulation. In this situation, I would most likely start the ultrasounds around cycle day 13-14 and follow up according to the initial findings. I most often trigger ovulation on a clomiphene citrate cycle once the lead follicle is at least 18 mm diameter