Welcome to chapter 8. The following chapter is called "Monitoring IVF Cycle & Oocyte Retrieval". The author is Professor Jie Qiao.

Transcription

1 Welcome to chapter 8. The following chapter is called "Monitoring IVF Cycle & Oocyte Retrieval". The author is Professor Jie Qiao.

2 The learning objectives of this chapter are 2 fold. The first section deals with monitoring IVF cycles and the second with oocyte retrieval. In the first section, the importance and rationale of monitoring IVF cycle will be discussed. The method of monitoring include serial ultrasound scan of the follicles and hormonal assays or combination of the 2 methods. The second section deals with oocyte retrieval. The timing of retrieval is important so that only mature oocytes are retrieved. The procedure of oocyte retrieval and its associated risk will be covered. 2

3 Many techniques for preparing the ovary for oocyte retrieval have been developed. These techniques include monitoring the natural cycle; clomiphene treatment; administration of clomiphene-hmg; hmg alone; highly purified human FSH (FSH-HP) alone; recombinant human FSH (r-hfsh) alone; combinations of hmg, FSH-HP, and r-fsh-hp; and pulsatile gonadotropinreleasing hormone (GnRH). Most programs currently use a combination of a GnRH agonist plus gonadotropin treatment to stimulate the ovary for in vitro fertilization-embryo transfer (IVF-ET) cycles. 3

4 In vitro fertilization-embryo transfer (IVFET) treatment requires ovarian follicular stimulation to increase the number of oocytes and the chance of a successful treatment outcome. The more mature oocytes can be retrieved in one IVF cycle the better is the chance of having several good embryos, and therefore the chance for a pregnancy. So the purpose of ovarian stimulation is to achieve as many mature oocytes as possible in one cycle. When performing ovarian stimulation in IVF cycles there are obvious reasons why the cycle has to be monitored: to evaluate if the dose of gonadotropins is optimal; to avoid ovarian hyperstimulation syndrome (OHSS) and to find the optimal time for hcg administration. 4

5 The ways of monitoring IVF cycles include hormone assays and ultrasound measurements of follicular diameter and endometrial thickness and morphology. Some investigators have shown that estrogen determinations, whether in urine or serum, provide no additional useful information in the control of ovulation induction. They demonstrated similar efficacy of ultrasound alone compared to more invasive monitoring. So they proposed ultrasound only monitoring of ovulation induction in IVF cycles. However, most literature show the advantage of using both ultrasound and hormone assay. Which method the physicians choose depends on their own experiences and the standard protocols used at the clinic. 5

6 Transvaginal ultrasound scanning of the pelvis to display the ovaries and to directly visualize the presence, size, and number of developing follicles has been used conventionally as a safe and reliable noninvasive method in IVF-ET programs throughout the world. In the long protocol, an ultrasound scan is done on day 21 to exclude any physiological cyst whereas for the short protocol, the ultrasound scan is carried out on day 2 of the cycle before starting gonadotropin stimulation. Further scans on day 8 and beyond will help in deciding if the dosage of gonadotropin need to be increased in patients with poor response. 6

7 Serum hormone assays using estradiol measurement is another important way to monitor IVF cycle. Dose and type of gonadotropin eg. r-fsh can be adjusted according to estradiol levels, follicle stimulating hormone (FSH), luteinizing hormone (LH) and progesterone levels on day 2. An early estradiol measurement can be valuable to choose starting doses of gonadotropin in order to achieve an adequate response. If serum estradiol on cycle day eight is too low the dose of gonadotropin can be increased. This is a simple way to find out if the starting dose has been sufficient. Estradiol levels should be correlated to the number of mature follicles at the time of hcg administration. As a guide, each mature follicle may produce about 1000 pmol/l estradiol. If LH and progesterone levels increase early or estradiol level plateaus hcg can be administrated earlier. 7

8 Combining ultrasound with hormone assay is the most efficient way to monitor IVF cycles. To determine starting dose of gonadotropin, ovarian function is evaluated according to number of antral follicles by ultrasound (antral follicle count, AFC) and serum hormone assay on day two of the cycle. Poor response is predicted if antral follicle count is equal or below five, estradiol level is higher than 100 pmol/l or FSH is equal or higher than 10 miu/l or the ratio of FSH to LH is above 5. In all these situations, starting dose of gonadotropin can be increased. On day eight, follicle diameter and number is scanned by ultrasound to observe rate and synchronism of follicle growth. These values should be matched with the concentrations of estradiol, LH and progesterone. Dose and type of gonadotropin can be adjusted individually. 8

9 Optimal timing of hcg administration is necessary to retrieve high quality oocytes. Too early administration of hcg can result in more immature oocytes. In contrast, if hcg is administered too late it causes high progesterone levels resulting in negative effects on oocytes quality and endometrial receptivity. The ovulation trigger is usually timed according to serum estradiol concentrations and follicle size. In addition, number of follicles, endometrium thickness and morphology, LH and progesterone levels should be considered. When three or more follicles reach a diameter equal or above 17-18mm, endometrium thickness reaches at least 7mm by ultrasound and estrogen levels coinciding with follicle diameter and number (about 1,500-1,800pmol/L per follicle 18mm), hcg should be administered. Oocyte retrieval is scheduled hours after the hcg administration. 9

10 An important part of preventing OHSS is appropriate monitoring of all patients to identify those women with a high risk. Therefore, a combination of ultrasound and estrogen level assays seems to be the most promising method. Via ultrasound scans it is possible to identify patients with a risk of early OHSS when a large number of follicles are present. For these patients serially measurements of serum E2 levels are strongly recommended to estimate their risk levels. Ultrasound alone may not be sufficient to reliably decide whether the stimulation should be stopped or if it is possible to pursue the treatment. Serum E2 measurements have been shown to be closely and positively correlated with OHSS. 10

11 The exact level of serum E2 distinguishing those women who are at risk of OHSS from those who are not, is still debatable. This may be due to the fact that different serum E2 cut-off levels have been used in various reports. In addition to the level of serum E2, the rate of E2 increase in correlation with the number of follicles is an important indicator. A serum E2 level of 13,000 pmol/l is the most commonly used cut-off level. At this level a large number of follicles (> 20) can be displayed by ultrasound scans during controlled ovarian hyperstimulation (COH) (Al-Shawaf and Grudzinskas, 2003). 11

12 It is possible to use ultrasound as the main method and combine this with serum hormone assays when monitoring ovarian stimulation with gonadotropin in IVF cycles. The chosen method should be reliable, convenient, and noninvasive. Whichever method is used to monitor IVF cycle, the stimulating protocol should be adjusted individually. The rationale of monitoring a stimulation cycle is to ensure an optimal number of mature oocytes on the one hand and to prevent OHSS on the other. Serial ultrasound scan and estradiol measurement afford us a reliable and noninvasive method of doing so. We know that in the mid-follicular phase, the follicle will grow at a rate of about 2 mm per day and estradiol production is about 1,000 pmol/l per mature follicle. So with this information, we may monitor the patient at 2 to 3 day intervals. 12

13 hcg (5,000-10,000 IU) is administered when at least two follicles have reached a diameter of 18 mm or more. Some physicians may use a diameter of 17mm, while others wait for three follicles to reach the desired size. The oocyte retrieval is timed 35 to 36 hours after the hcg administration. 13

14 The oocytes are retrieved in one of two ways: through a surgical procedure called laparoscopy or through transvaginal retrieval by ultrasound guidance. Ultrasound-guided retrieval has become the gold standard for almost all procedures. The female patient is placed in a lithotomy position. The procedure is done with a vaginal transducer that carries an aspiration needle. All movements are guided by ultrasound technology. Once the needle is inside the ovary, suction is applied to aspirate the follicular fluid out through a tube and into a collection tube. The aspirated follicular fluid is examined under microscope to identify the oocytes. Once the ovarian follicles have been aspirated on one side, the needle is withdrawn, and the procedure repeated on the contralateral side. After completion, the needle is withdrawn, and hemostasis checked. 14

15 The process takes about 30 minutes and is done under conscious sedation or local, epidural, spinal or general anesthesia. The primary goal is to provide safe and effective analgesia facilitating optimum surgical conditions and a fast post-operative recovery. There is also concern about potential effects of any drugs used on reproductive outcome (Wikland et al., 1990). It has been suggested that the pain associated with oocyte retrieval is intermittent rather than continuous (Zelcer et al., 1992). Conscious sedation is the most popular method of anesthesia used in IVF. Presently, a combination of propofol, fentanyl, and midazolam is most commonly used. It is easy to administer in cooperative and motivated patients and is safe in healthy individuals; it has a relatively low risk for adverse effects on oocyte and embryo quality and pregnancy rates (Kwan et al., 2006). 15

16 The increasing popularity of transvaginal ultrasound guided follicular aspiration in patients who are only mildly sedated has prompted us to compare small and large follicular aspiration needles with respect to pain perceived by patients, the oocyte collection rate and the quality of oocytes collected. According to the study of Awonuga et al. in 1996, a greater proportion of patients reported severe to unbearable pain with the 15-gauge compared with the 17-gauge (44% versus 22%) or 18-gauge (44% versus 16%) needles. There was no significant difference between the needles regarding the oocyte collection rate, fertilization rate, proportion of oocytes with fractured zonae, cleavage rate, implantation rate, and pregnancy rate per cycle. 16

17 Opinion varies on the benefit of follicular flushing during ovum pickup to retrieve oocytes which would otherwise be missed in a single aspiration attempt. A double-lumen needle allows simultaneous flushing and aspiration of follicles, the theoretical advantage of double-lumen needle is that a potentially greater number of oocytes may be retrieved. However, in 1989, Scott and colleagues compared single- and double-lumen needles for transvaginal follicular aspiration in a prospective randomized study and found no differences between the two needles in the number of oocytes obtained for IVF. The double-lumen needle was more flexible and frequently deviated from the projected path as observed by ultrasound. The single-lumen needle may be preferable because it is technically easier to use. 17

18 No data exist comparing follicular flushing to direct aspiration during oocyte retrieval. The theoretical rationale is that flushing offers an advantage to the patient, with a larger number of oocytes being collected and thus a higher potential for achieving a pregnancy. However, a study (Knight et al., 2001) of a large patient group (n = 2378), suggest that there is no difference in the outcome of ART (from oocyte collection through to pregnancy rate) whether or not aspiration of follicles is accompanied by flushing. First principles of surgery advocate the shortest possible operating time, the simplest procedure and minimum amount of tissue handling as maxims for reducing complication. Therefore, as a routine, flushing would seem superfluous in ART. 18

19 Postoperative pelvic infections may result from direct inoculation of vaginal micro-organisms into the peritoneal cavity by the collecting needle. Disinfection of the vagina is not advisable as shown by comparative vaginal disinfection with povidone-iodine and normal saline. Disinfection of the vagina with povidone-iodine was related to a lower pregnancy rate (van Os et al., 1992). Rinsing with saline did not increase the risk of infection and pregnancy rate was significantly higher in the normal saline group. Intravaginal administration of probiotics immediately after oocyte retrieval did not affect the number of oocytes retrieved, fertilization rate, number of embryos transferred, or pregnancy rate (Gilboa et al., 2005). Furthermore, intravaginal administration of lactobacilli following oocyte retrieval did not affect the prevalence of lactobacilli during embryo transfer, or the pregnancy rate. Intravaginal probiotic supplementation immediately after oocyte retrieval has no effect on vaginal colonization or pregnancy rate in IVF cycles. 19

20 The oocyte retrieval procedure requires some form of anesthesia, and both the surgery and the anesthesia carry potential risks. Most of the surgical complications surrounding oocyte retrieval stem from two basic components of the surgery: a needle must be passed through the vagina and into the ovary, and a number of other organs and sensitive tissues lie nearby. There are also studies concerning the complications caused by infections, such as peritonitis. Besides the risks associated with the surgical retrieval, women undergoing oocyte retrieval also face certain potential risks from the anesthesia used to minimize their pain during the surgery. Nevertheless, the overall potential risks of oocyte retrieval are generally very small. 20

21 There are two important principles relating to oocyte collection. Firstly, maintenance of suction: follicular fluid may be lost if entry into and exit from the follicle are made in the absence of suction. Secondly, movement of the needle tip within the follicle may damage the oocyte. It is a common practice during oocyte collection to rotate the needle within the follicle. It is possible that damage may occur as the oocyte is scraped from the follicular wall by the edge of the needle, particularly in small follicles or in the collapsed follicle. 21

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