Timing of oocyte retrieval in cycles with a spontaneous luteinizing hormone surge in a large in vitro fertilization program

FERTILITY AND STERILITY

Vol. 50, No.3, September 1988

Printed in U.S.A.

Copyright c 1988 The American Fertility Society

Timing of oocyte retrieval in cycles with a spontaneous luteinizing hormone surge in a large in vitro fertilization program Kathleen Droesch, M.D.* Suheil J. Muasher, M.D. David Kreiner, M.D.

Georgeanna Seegar Jones, M.D. Anibal A. Acosta, M.D. Zev Rosenwaks, M.D.

Jones Institute for Reproductive Medicine, Eastern Virginia Medical Schoo~ Norfolk, Virginia

Forty-four cycles ~ith a spontaneous luteinizing hormone (LH) surge among 377 in vitro fertilization (IVF) patients were studied for outcome with different timing of oocyte retrieval. Mean number of preovulatory oocytes per retrieval and per transfer was significantly less in these cycles than in controls. Mean number of preovulatory oocytes per retrieval and per transfer was significantly higher when the human chorionic gonadotropin (hCG)-retrieval interval was >35 hours, compared with <24 hours. In cycles with an hCG-retrieval interval of <24 hours, percentage of preovulatory oocytes was higher when serum estradiol (E 2 ) decreased by >15% on the morning after hCG administration compared with a plateau or an increase in serum E 2 • Timing oocyte retrieval after spontaneous LH surge should consider the hCG-retrieval interval and changes in E 2 levels after hCG administration; this may avoid cancellation for many patients. Fertil Steril50:451, 1988

In vitro fertilization and embryo transfer (IVFET) is enabling many infertile couples to conceive. The improvement in the success rate over Steptoe's original method that used the natural cycle is due largely to superovulation. Clomiphene citrate (CC), human menopausal gonadotropin (hMG), and follicle-stimulating hormone (FSH) are presently being used alone or in combination for the recruitment of multiple fertilizable oocytes. Appropriate administration of human chorionic gonadotropin (hCG) to facilitate oocyte maturation is followed by timely retrieval. An endogenous luteinizing hormone (LH) surge before hCG administration has been reported accompanying CC stimulation/ whereas stimulations with hMG and FSH have been associated with a decreased frequency of an LH surge. 2 Messinis et al. 3 found that the endogenous LH surge Received February 19, 1988; revised and accepted May 31, 1988. * Reprint requests: Kathleen Droesch, M.D., Jones Institute for Reproductive Medicine, Hofheimer Hall, 825 Fairfax Avenue, 6th Floor, Norfolk, Virginia 23507. Vol. 50, No.3, September 1988

associated with superovulation was attenuated by factors related to the degree of hyperstimulation. It has been postulated that exogenously stimulated ovaries secrete a substance that may block the estrogen-induced LH surge. 4•5 The occurrence of an endogenous LH surge necessitates prompt retrieval before ovulation. Ideally, timing of retrieval of oocytes should be based on the onset of the surge. Often the exact time of onset is difficult to determine because of infrequent sampling of LH in urine or blood. In addition, the exact time of onset of the surge may be determined, but the approximate time of retrieval may fall during the evening hours (6 P.M. to 6 A.M.). As aresult, many IVF programs face the dilemma of either cancelling the cycle or compromising on the timing of retrieval by scheduling it during daytime hours (6 A.M. to 6 P.M.). The purpose of this paper is to examine cycles associated with spontaneous LH surges in a large IVF program in order to identify those patients at risk of triggering a spontaneous LH surge and to examine the outcome based on varied timing of oocyte retrieval. Droesch et al.

Oocyte retrieval with an LH surge

451

MATERIALS AND METHODS

From January 1984 to September 1986, 756 patients underwent 1455 attempts at IVF-ET, resulting in 1210 retrieval cycles. Only cycles eventuating in oocyte retrieval were included in the study. Of these, 377 were stimulated with FSH, 117 with hMG, and 716 with a combination ofFSH/hMG. Monitoring of patients was performed according to previously published protocols. 2 In brief, serum estradiol (E 2 ) was measured by radioimmunoassay (RIA) daily beginning on day 3 of the cycle. Daily pelvic and ultrasound examinations were performed beginning on day 6. HCG (10,000 IU) was administered according to previously published criteria. 2 Oocyte retrieval was performed 35 to 36 hours later. In patients at high risk for a spontaneous LH surge, serum LH measurements were taken by RIA at 8 A.M., 12 noon, and 4 P.M. daily, beginning on day 7 of the cycle. Results of the 8 A.M. measurements were available at 3 P.M. the same day, while measurements taken at noon or 4 P.M. were not available until3 P.M. on the following day. Highrisk factors for a spontaneous LH surge included a history of spontaneous LH surge in a previous IVF cycle, failure of recruitment of multiple follicles as indicated by ultrasound examination and serum E 2 , rapidly rising E 2 , or the presence on ultrasound of a disproportionately large follicle in comparison to other recruited follicles. The occurrence of a spontaneous LH surge was defined by serum LH that increased by more than twice the mean of the two previous samples. 6 If a spontaneous LH surge was detected from an 8 A.M. sample, hCG was administered that afternoon, and oocyte retrieval was performed the following day. When a spontaneous LH surge was detected from a noon or 4 P.M. blood sample from the previous day, hCG was given immediately, and retrieval was performed the following afternoon. If hCG had already been administered on the previous day, as was often the case, oocyte retrieval was performed promptly that afternoon. On occasion,. oocyte retrieval was performed 34 to 36 hours after hCG administration, despite detection of a spontaneous LH surge several hours before hCG administration. This occurred primarily in patients whose serum E 2 plateaued or increased over the previous day's value. The retrieved oocytes were classified into four categories: preovulatory, immature, atretic, and fractured zona, as reported by Veeck et al. 7 All pre452

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Oocyte retrieval with an LH surge

ovulatory oocytes were incubated in Ham's F-10 medium (Gibco, Grand Island, NY), supplemented with 7.5% human fetal cord serum, for 18 to 35 hours, depending on germinal vesicle breakdown and extrusion of the first polar body. Sperm concentrations of 5 X 104 ml were used for insemination. High sperm concentrations (2 to 5 X 105 ml) were used in oligospermic patients. The concepti were transferred on the second day after laparoscopy. All patients who underwent ET received supplemental progesterone (P) (25 mg in oil intramuscularly [IM]) daily, starting on the day of transfer and continuing until a negative ,8-hCG test result was obtained on luteal day 11 to 13. If the ,8-hCG result was positive, the patient was given Delalutin (250 mg IM; Squibb, Inc., Princeton, NJ) weekly until the 18th week of pregnancy. Patients who had an endogenous LH surge were divided into two groups based on the hCG aspiration interval (hCG-ASP). Group 1 consisted of those patients with an hCG-ASP ~ 35 hours. Group 2 consisted of those patients with an hCGASP < 24 hours. E 2 levels were measured in most patients on the day after hCG administration. Patients in group 2 were further divided, based on the change in serum E 2 from the day of hCG administration compared to the following morning: Group 2A had a plateau (decrease of <15%) or an increase in serum E 2 • Group 2B had a decrease in serum E 2 of ~15%. Statistical analysis was performed using the Student's t-test. RESULTS

Of the 1210 retrieval cycles performed, an endogenous LH surge was detected in 44 cycles. As a control population, 1160 cycles during the same time period not experiencing an LH surge were used. Stimulation protocols consisted of hMG, FSH, or a combination ofFSH/hMG. The mean age of patients exhibiting an LH surge was significantly higher (36.6 ± 3.64) compared to the control population (34.1 ± 3.78) (P < 0.05). There was no significant difference in the type of stimulation used between the two groups. Mean baseline E 2 , mean E 2 on the day of LH surge or hCG administration, and mean day of LH surge or hCG administration did not differ significantly between the two groups (Table 1). The classification of oocytes obtained during retrieval revealed significantly fewer preovulatory oocytes (PO) (34.9%) and more immature oocytes Fertility and Sterility

Table 1 Characteristics of Cycles with a Spontaneous LH Surge Compared to Control Cycles Cycles with LHsurge Number of cycles Stimulation % HMG FSH Combination ofFSH/hMG Mean age ± SD" Mean baseline estradiol (E 2 ) ±SD Mean E 2 ± SD on day of LH surge (study) or hCG administration (control) Mean day± SD of LH surge (study) or hCG administration (control)

Control cycles

44

1160

3 (6.80) 15 (34.1) 26 (59.1) 36.6 ± 3.64b

113 (9.7) 363 (31.2) 684 (58.9) 34.1 ± 3.78

28.0 ± 16.0

33.0 ± 27.0

725.1 ± 354.7

699.2 ± 361.6

8.95 ± 1.18

9.17 ± 1.02

• SD, standard deviation. b P<0.05.

(10) (44.5%) in cycles with an endogenous LH surge compared with control cycles (49.7% and 32.6%, respectively) (P < 0.05). This resulted in fewer PO per cycle (1.73 ± 1.70), fewer PO transferred per cycle (1.47 ± 1.13), and fewer pre-embryos (PE) per transfer (2.61 ± 1.46), compared with control cycles (3.13 ± 2.14, 2.54 ± 1.53, and 3.35 ± 1.75, respectively) (P < 0.05) (Table 2). Of the 44 cycles, 36 went to transfer, resulting

in 8 pregnancies (18.2%). Within the 1160 control cycles, 1041 went to transfer and 267 pregnancies resulted (23.0%). Cycles in group 1 (hCG-ASP >35 hours) tended to produce more PO (44.7%) and fewer 10 (31.9%) compared to group 2 (hCG-ASP <24 hours) (32.2% and 48.0%, respectively). The mean PO per cycle, mean PO per transfer, and mean PEper transfer were significantly greater in group 1 than in group 2 (3.5 ± 3.2, 2. 75 ± 1.5, and 4.50 ± 2.08 compared with 1.45 ± 1.18, 1.31 ± .99, and 2.38 ± 1.21, respectively) (P < 0.05) (Table 3). When the outcome of each group was compared with the control population, the classification of oocytes in group 1 was found to be comparable to control cycles. Cycles in group 1 had a proportion of PO and 10 (44.7% and 31.9%, respectively) similar to control cycles (49.7% and 32.6%, respectively). Cycles in group 2 had significantly fewer PO (32.3%; P < 0.05) and more 10 (48.0%; P < 0.05) than the control cycles. This resulted in significantly fewer PO and PE transferred/transfer in group 2 (1.31 ± 0.99 and 2.38 ± 1.21, respectively) than in control cycles (2.54 ± 1.53 and 3.35 ± 1.75, respectively; P < 0.05). Embryo transfers in group 1 resulted in one pregTable 3 Classification and Outcome of Oocytes Retrieved and Transferred in Cycles with a Spontaneous LH Surge Based on the Time of Oocyte Retrieval after hCG Administration

Table 2 Classification and Outcome of Oocytes Retrieved and Transferred in Cycles of Patients with an LH Surge Compared to Control Cycles Cycles with LHSurge Preovulatory oocytes (%) Immature oocytes (%) Fractured zona(%) Atretic oocytes (%) Fertilization rate of preovulatory oocytes % Polyspermia rate of preovulatory oocytes % Mean preovulatory oocytes per cycle ± SDb Mean preovulatory oocytes transferred per cycle with transfer ±SD Mean number ofpreembryos(preovulatory and immature) transferred per transfer ± SD • P<0.05. b SD, standard deviation.

Vol. 50, No.3, September 1988

76 (34.9)" 97 (44.5)" 15 (6.9) 30 (13.8)

Control Cycles 3628 (49.7) 2382 (32.6) 456 (6.2) 831 (11.4)

78.4

85.3

8.6

8.2

1.73 ± 1.70"

3.13 ± 2.14

1.47 ± 1.13"

2.54 ± 1.53

2.61 ± 1.46"

3.35 ± 1.75

Number of cycles Preovulatory oocytes (%) Immature oocytes (%) Fractured Zona (%) Atretic oocytes (%) Fertilization rate of preovulatory oocytes % Polyspermia rate of preovulatory oocytes % Mean preovulatory oocytes per cycle ±SD" . Mean preovulatory oocytes transferred per cycle with transfer ±SD Mean number of preembryos (preovulatory and immature) transferred per transfer ± SD Pregnancy(%)

HCG-retrieval >35 hours

HCG-retrieval <24 hours

6 21 (44.7) 15 (31.9) 5 (10.6) 6 (12.8)

38 55 (32.2) 82 (48.0) 10 (5.8) 24 (14.0)

63.2

83.6

8.3

8.7

3.5 ± 3.2b

1.45 ± 1.18

2.75 ± 1.5b

1.31 ± .99

4.50 ± 2.08b 1 (16.6)

2.38 ± 1.21 7 (18.4)

• SD, standard deviation. b P<0.05.

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Table 4 Classification and Outcome of Oocytes Retrieved and Transferred in Cycles with a Spontaneous LH Surge and Retrieval Less than 24 Hours After hCG Administration Based on the Change in E 2 levels on the Day After hCG Administration

Number of cycles0 Preovulatory oocytes (%) Immature oocytes (%) Fractured zona (%) Atretic oocytes (%) Fertilization rate of preovulatory oocytes % Polyspermia rate of preovulatory oocytes % Mean preovulatory oocytes per cycle ± SD Mean preovulatory oocytes transferred per cycle with transfer ±SD Mean number of pre embryos (preovulatory and immature) transferred per transfer ± SD Pregnancy (%)

·~;;.15%

E2< 15% ortE2

20 34 (40.0) 38 (44.7) 3 (3.5) 10 (11.8)

13 16 (25.0) 34 (53.1) 7 (10.9) 7 (10.9)

73.5 16.0

100 0.0

1.70 ± 1.17

1.61 ± 2.46

1.40 ± .82

1.33 ± 1.30

2.13 ± 1.24 4 (20.0)

2.83 ± 1.19 2 (15.3)

a Five patients were excluded because of no E 2 measurement taken on the day after hCG administration.

nancy (16.6%) compared with seven pregnancies (18.4%) in group 2. The pregnancy rates for both groups were lower than the 23.0% pregnancy rate for the control population. Group 2 was further subdivided based on the E 2 level on the day after hCG administration. Cycles with E 2 levels decreasing by ~15% (group 2B) were noted to have more PO (40.0%) and fewer 10 (44.7%) compared with cycles in which E 2 decreased by <15% or increased (Group 2A) (25.0% and 53.1 %, respectively). In group 2A, two pregnancies (15.3%) occurred, while four pregnancies (20%) occurred in group 2B (Table 4). DISCUSSION

The aim of gonadotropin stimulation and patient monitoring is to obtain the greatest possible number of mature oocytes. Pregnancy rates have been shown to rise along with increased numbers of fertilizable oocytes.8 At the Norfolk clinic, transfer of only one PE was found to result in a pregnancy rate of 20%, while a constant improvement in pregnancy rates was seen with the transfer of increasing numbers of PE. 8 An endogenous LH surge occurs in a significant 454

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percentage of IVF patients.9- 11 Lejeune et al. 12 found a 21.5% incidence rate in their study population, while Eibschitz et al. 13 reported an incidence of 11.6%. Particular patients tend to be at higher risk for an LH surge. Development of a disproportionately large follicle or failure to recruit multiple mature follicles has been associated with an endogenous LH surge. 14 In the present study, the patients experiencing an LH surge tended to be older than the control population (P < 0.05). These patients may have had a smaller cohort of follicles from which to recruit, leading to fewer follicles developing. This may have resulted in less production by the available follicles of substances inhibitory to the positive feedback effect of E 2 on LH secretion.4·5 Baseline and peak E 2 levels were not different in the two groups, suggesting factors other than E 2 contributing to an endogenous LH surge. Appropriate timing of oocyte retrieval is essential to obtain mature oocytes. Oocyte retrieval performed prematurely may result in increased immaturity of the oocytes obtained, while delayed retrieval may result in postmaturity or spontaneous ovulation before retrieval. In the natural cycle, the onset of an LH surge is followed 35 to 36 hours later by ovulation. 15 In addition, the LH surge signals resumption of meiosis16 and luteinization of the follicleP In IVF cycles, an endogenous LH surge may require rescheduling for earlier oocyte retrievals in order to avoid postmaturity or spontaneous ovulation. Unfortunately, only continuous serum LH monitoring can detect the exact onset and peak of the LH surge and allow accurate timing of oocyte retrieval. Intermittent serum monitoring will allow only an estimate of the onset of the surge. Consideration must be given not only to the onset of the LH surge but also to the availability of the operating room and embryology laboratory. Not all IVF centers have the luxury of an operating room and embryology laboratory available 24 hours a day. Compromises may be needed concerning when to schedule cases, based on the additional factors. In patients with an endogenous LH surge, the quality of oocytes obtained is directly related to the accurate timing of the retrieval. A smaller percentage of PO and a greater percentage of 10 were obtained in patients experiencing a surge, suggesting that optimal timing of the retrieval may not have been attained because of an inability to pinpoint the exact onset of the surge. This resulted in fewer PO and PE transferred and lower pregnancy rates, although the small number of patients did notallow the difference to be statistically significant. If Fertility and Sterility

an endogenous LH surge could be anticipated or prevented, hCG administration before the LH surge might permit more accurate timing of the retrieval and more mature oocytes as a result. Use of a gonadotropin-releasing hormone (GnRH) agonist before gonadotropin stimulation in order to prevent the occurrence of an LH surge 18 may prove useful in this group of patients. Once an LH surge has occurred, decisions must be made concerning when to administer hCG and when to perform the retrieval. In the present study, cases performed 35 to 36 hours after hCG administration (group 1) were compared with those performed <24 hours after hCG administration {group 2). A greater percentage of PO and fewer IO were obtained from group 1 than from group 2. Whereas group 1 yielded oocytes comparable to the control cycles, group 2 had significantly.fewer PO and more 10 than the control cycles. This led to a greater number of PO and PE transferred in group 1. An improved rate of transfer of PO and PE should yield improved pregnancy rates. Waiting for nuclear and cytoplasmic maturation to occur before retrieval should ultimately yield higher pregnancy rates. One must question the definition of an endogenous LH surge in instances where, despite the detection of an LH surge several hours before hCG administration and although oocyte retrieval took place 35 to 36 hours after hCG administration, no sign of postmaturity or ovulation was seen. Although all patients met the same diagnostic criteria for an LH surge and there were no differences in LH levels between any of the groups, the definition may not be suitable for all patients. When determining which patients have truly experienced an LH surge and require early retrieval, parameters other than the size of follicles and timing of the LH surge .may need to be considered. Comparing E 2 patterns from the day of the LH surge to the day after the LH surge might assist in predicting oocyte outcome. In cycles performed early (group 2), E 2 patterns were examined and separated into those with decreasing E 2 versus those with increasing or plateauing E 2 (decrease in E 2 <15%). In cycles where E 2 decreased by> 15%, there was a greater percentage of PO and fewer IO as compared to cycles where E 2 plateaued or increased. The decrease in E 2 may indicate a more advanced state of follicular maturation and impending ovulation despite hCG administration <24 hours earlier. This group of patients was more likely to have experienced a true Vol. 50, No.3, September 1988

endogenous LH surge. Cycles with a plateau or an increase in E 2 , having less mature oocytes obtained, may have benefited from waiting to allow further maturation. Within this group may be those cycles with an elevated LH value detected but with no real LH surge. The results indicate that a consideration of the E 2 values, in addition to the LH values, as a parameter may enable more selective adjustment in timing oocyte retrieval. Scheduling retrieval in IVF requires that anumber of parameters be taken into consideration, including the day of stimulation, follicular size, and E 2 values. The occurrence of an endogenous LH surge further complicates the situation, but appropriate timing is possible if all aspects are considered. Each case must be considered individually. When an LH surge occurs, E 2 values may help to determine the most appropriate length of time between hCG administration and oocyte retrieval. Prevention of the endogenous LH surge would be most advantageous in this group of patients, and treatment with a GnRH agonist before gonadotropin stimulation, while increasing the amount of stimulation required, 18 might lead to an improved outcome through more appropriate timing of hCG administration. Acknowledgment. The authors thank Charlotte Schrader, Ph.D., for her editorial assistance. REFERENCES 1. Edwards RG, Fishel SB, Cohen J, Fehilly CB, Purdy JM,

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