|Year : 2016 | Volume
| Issue : 2 | Page : 52-57
Empty follicle syndrome: Case series and review of literature
Ritu Punhani, Kundavi Shankar, Thankam Rama Varma
Department of Reproductive Medicine and Women's Health, Madras Medical Mission Hospital, Chennai, Tamil Nadu, India
|Date of Web Publication||14-Oct-2016|
Flat No. 289, Aravali Apartments, Alaknanda, Kalkaji, New Delhi
Source of Support: None, Conflict of Interest: None
Background: Failure to aspirate oocytes from apparently normally growing ovarian follicles with normal steroidogenesis after ovarian stimulation and meticulous follicular aspiration is referred to as empty follicle syndrome (EFS).There are two types of EFS, namely genuine (GEFS) and false (FEFS). It is a rare condition of obscure etiology. EFS does not predict reduced fertility potential in future cycles although it can recur due to a biological abnormality in the availability of mature oocytes that are retrievable. A case series of 12 patients of EFS is described here. The literature has been reviewed and definition, prevalence, risk factors, etiopathogenesis, and therapeutic approaches are discussed here. Objective: To assess the prevalence, identify the risk factors, and management options for GEFS. Design and Setting: This retrospective, observational study was conducted at the Institute of Reproductive Medicine, Madras Medical Mission Hospital, Chennai, India. All patients who had no oocytes retrieved in in vitro fertilization (IVF) treatment cycles from January 2014 to December 2015 were included and oocyte donation cycles were excluded from the study. All patients were stimulated by antagonist protocol, EFS cycles were identified, and then demographic variables and ovarian hyperstimulation strategies were evaluated. Methods: A literature search was undertaken using the phrase "empty follicle syndrome" in PubMed and several studies and case reports were identified. Results: Among 860 IVF cycles, 18 were identified as EFS cycles. Of the identified EFS cycles, 14 had genuine and 4 had FEFS. The reason for the occurrence of FEFS in this study was premature ovulation. The prevalence of GEFS at our center during the study period was 2.09% (18 Χ 100/860) and the rate of recurrence of GEFS was 100%. Conclusion: Accurate timing of final oocyte maturation, properly scheduled ovarian hyperstimulation, instructions to the patients, and full workup for IVF are essential for the successful recovery of oocytes. We assert that GEFS as an entity exists and confirm that patients with EFS present a real challenge to manage. No factors have been identified in this study which can predict EFS, unlike in literature. Furthermore, it was also found that no single treatment strategy is universally effective.
Keywords: Beta human chorionic gonadotropin, empty follicle syndrome, false, genuine, oocyte retrieval, trigger
|How to cite this article:|
Punhani R, Shankar K, Varma TR. Empty follicle syndrome: Case series and review of literature. IVF Lite 2016;3:52-7
| Introduction|| |
Coulam et al.  was the first to describe empty follicle syndrome (EFS). It is a condition in which after apparently successful ovarian stimulation no oocytes are retrieved. The etiology remains enigmatic and some even doubt its existence. ,,, EFS is an uncommon frustrating event, with a reported incidence of 0.04-7%  in patients undergoing ovum pickup.
Two types of EFS are reported in literature genuine (GEFS) and false (FEFS). In a systematic review of EFS by Stevenson and Lashen in 2008, 33% of EFS cases were identified as genuine and 67% as false.  In this case series, we have included 12 patients and 18 in vitro fertilization (IVF) cycles of EFS, out of which eight patients had GEFS and four had FEFS. We have also done the literature review of this debated syndrome.
| Patients and methods|| |
Between January 2014 and December 2015, 860 IVF treatment cycles were performed at Madras Medical Mission Hospital using antagonist protocol. In all patients, the gonadotropin used was recombinant follicle stimulating hormone (r-FSH) and the antagonist used was cetrorelix acetate. Monitoring was by transvaginal scan and serum estradiol estimation, which started from day 6 of stimulation. Trigger injection was given when three or more follicles of 18 mm diameter were visualized on the scan. Triggering agent used were either highly purified urinary human chorionic gonadotropin (hCG) and recombinant hCG (r-hCG) or dual trigger with GnRH agonist (GnRHa) and low dose of hCG. Transvaginal ultrasound directed follicle aspiration was performed 35-36 h after trigger injection. All oocyte collections in the unit were performed by experienced operators. All patients except one (of advanced maternal age) were offered a second cycle of IVF, but only four patients of GEFS and two of FEFS group decided to go for the second cycle. Three flushes were given in all patients who had the second cycle of IVF. The stimulation protocol for second IVF cycles was also an antagonist, but the triggering agent was changed as shown in [Table 1].
In all these cases, enquiries confirmed that there was no human or pharmaceutical error. The drugs used for trigger had not expired were properly stored and were administered at the right time, and this was done to differentiate GEFS from FEFS.
Results of case series
The demographic variables and baseline investigations are summarized in [Table 2]. All the patients in this study had primary subfertility. The common indications for IVF among these patients were unexplained infertility (33.3%), male factor (33.3%), tubal factor (16.2%), resistant PCOS (8.4%), and poor ovarian reserve (8.4%). The baseline investigations mentioned here serve as measures of ovarian reserve and help mainly to predict response to ovarian stimulation, and to lesser extent, the likelihood for achieving a successful pregnancy with assisted reproductive technology (ART). Antral follicle count (AFC) is the sum of antral follicles in both the ovaries as observed with transvaginal ultrasound during the early follicular phase. Antral follicles have been defined as measuring 2-10 mm in mean diameter in the greatest two-dimensional plane. A low AFC is considered to be 3-6 total antral follicles and is associated with poor response to ovarian stimulation. A serum FSH level obtained on cycle day 2-4 is commonly used as a measure of ovarian reserve. When serum FSH values are normal, but serum estradiol level is elevated (60-80 pg/ml) in the early follicular phase, there is limited evidence for association with poor response to gonadotropins stimulation. Serum antimüllerian hormone is a gonadotropin-independent marker of ovarian reserve, and low serum values (<1 ng/ml) have been associated with poor responses to ovarian stimulation and poor pregnancy outcomes in IVF. Only three patients of GEFS had decreased ovarian reserve.
The cycle characteristics of the first IVF are shown in [Table 3]. All the patients were stimulated by antagonist protocol using r-FSH. The β-hCG of the follicular fluid on the day of oocyte retrieval (OR) was positive in six patients of GEFS, and their serum β-hCG values were between 76.2 and 121.32 mIU/ml. In spite of detectable hCG in both blood and follicular fluid, no oocytes were collected, and all the follicular aspirates were clear without any cells. Among the eight patients of GEFS, two patients did not have follicular fluid β-hCG and serum β-hCG estimation as they had got a dual trigger. All the patients with FEFS had premature ovulation diagnosed by an ultrasound done on the day of OR, just before starting the procedure of retrieval and thus latter was cancelled. β-hCG estimation was not done for FEFS patients.
Among the 12 patients of EFS, 6 (4 GEFS + 2 FEFS) opted for the second cycle of IVF. One patient of the GEFS group with advanced maternal age was advised for oocyte donation. The characteristics of second IVF cycle are shown in [Table 1]. The antagonist protocol was used again for stimulation, but the trigger was changed. During second cycle, oocytes were collected from the FEFS patients, but no oocytes were retrieved from the GEFS patients, in spite of repeated flushing during OR. Thus, all of them had recurrent EFS, which is even rarer.
Review of literature
A literature search was undertaken using the phrase "empty follicle syndrome" with no restrictions (of language or others) since the condition was first reported in 1986 by Coulam et al. In this review, we thoroughly searched the literature to identify several studies and case reports regarding EFS published to date in PubMed. The references of the articles found in the search were also explored. The papers included were observational studies, scientific reviews, case reports or case series, and letters or comments. Only the studies that have been published in English were included in the study.
| Discussion|| |
EFS was first reported by Coulam et al. in 1986.  It is not strictly a syndrome, but a sporadic, unpredictable event. The diagnosis of EFS cannot be predicted by the pattern of ovarian response to stimulation, either sonographically or hormonally. EFS has been classified into "genuine" (GEFS) and "false" (FEFS) types. GEFS is defined as a failure to retrieve oocytes from mature follicles after apparently normal folliculogenesis and steroidogenesis with optimal β-hCG levels on the day of OR. Such patients usually do not respond to a rescue protocol.
FEFS is defined as a failure to retrieve oocytes in the presence of low β-hCG, which could be either due to an error in the administration or bioavailability of hCG, and these patients are likely to respond to a rescue protocol. FEFS is unlikely to recur if all precautionary measures are taken in the subsequent cycles. Two classes of EFS can be differentiated by hormone levels on the day of OR. A literature search has shown that when hCG is used for a trigger, the minimum serum β-hCG concentrations consistent with adequate trigger ranges from 5 to 161 mIU/mL. ,,, However, in the case of GnRHa trigger, no cutoff levels of luteinizing hormone (LH) or progesterone on the day of the OR have been proposed so far. In all our patients of GEFS, the β-hCG concentration was consistent with adequate trigger range as reported in the literature.
Driscoll et al.  reported a different median serum hCG concentration after r-hCG 250 μg and 5000 IU urinary hCG due to the immunoassays used to measure serum hCG. Urinary hCG may contain dissociated and oxidized subunits that may have no biological activity but would be detected by immunoassay. r-hCG due to the absence of contaminant urinary proteins and the exact standards applied during the production process may make it possible to predict the risk of unsuccessful OR more accurately.
Prevalence and risk factors
EFS is an uncommon event, estimated to occur in 0.045-7% of patients undergoing IVF. ,,, These differences may result from different exclusion criteria. In some studies, patients with poor response to ovulation induction or premature ovulation were included while in others not. GEFS prevalence is 0-1.1%. The prevalence of EFS in our study was 2.1%, and among the 12 patients of EFS, 8 (66.6%) had GEFS and 4 (33.3%) had FEFS.
Some investigators showed that GEFS could be a manifestation of low ovarian reserve.  Risk factors suggested for EFS and its recurrence are advanced age, longer duration of infertility, higher baseline FSH levels, and lower E 2 levels before the hCG injection.  These risk factors are similar to those of low ovarian reserve, and this suggests that ovarian aging may be involved in the etiology of EFS. EFS may be a gradual biological occurrence related to ovarian aging. In the present study, none of the above-mentioned risk factors had any significant association in either prediction of GEFS or its recurrence.
Recurrent GEFS cases are scarce although some investigators have estimated the risk of recurrence. Zreik et al.  estimated that women with one EFS cycles had a 20% risk of recurrence in subsequent IVF cycles and these women had a poor success rate. The chances of recurrence of EFS increase with the age of women (24% recurrence rate for women aged 35-39, and 57% for those aged >40). Recently, Baum et al.  have reported that recurrent EFS occurred in 15.8% of subsequent cycles which is consisted with previous studies.  Recurrent EFS may be a variant phenotype of poor response. 
The etiology of GEFS is obscure. Since it was first described, various authors have been skeptical about its existence. GEFS is presumably related to intrinsic ovarian dysfunction  and various hypothesis which have been suggested include dysfunctional folliculogenesis or premature apoptosis of the growing oocytes, , defective function of granulosa cells,  faulty oocyte development and maturation,  immature oocytes that were zona-free,  strong attachment of cumulus cell complexes to the follicular wall, and dysfunctional ovulation induction. In rare cases, follicles may need longer exposure to hCG to undergo cumulus expansion and separate from the follicular wall. , Genetic causes of EFS have also been suggested such as LH/hCG receptor mutations,  altered expression of genes regulating cumulus expansion, and those involved in cellular processes and apoptosis, which results in increased loss of oocytes during late folliculogenesis due to apoptosis. Pericentric inversion of chromosome 2 has been reported by Vujisic et al.  in a patient who had multiple failed OR.
In FEFS, hCG-related faults are the main mechanism. The improper hCG administration is the most common cause of FEFS,  rapid metabolic clearance, manufacturer defects in hCG production, and low bioavailability of hCG are also proposed causes. ,,, Zegers-Hochschild et al.  showed the reduced in vivo biological activity of some batches of commercially available hCG and described EFS as a pharmaceutical industry syndrome. Hirshfeld-Cytron and Kim  showed that the low bioavailability of hCG after bariatric surgery may induce FEFS as it may alter the absorption of subcutaneously administered hCG; thus intramuscular administration is a safe option for those women. In the present study, enquiries had confirmed that there was no human or pharmaceutical error. The drug used for trigger was not expired, it was properly stored and was administered at the right time. All the patients of FEFS in this case series had premature ovulation diagnosed by ultrasound on the day of OR.
Treatment of EFS is a challenge for the ART specialist as no definitive single treatment is available so far.  Various strategies have been reported in literature to prevent the occurrence of EFS in a subsequent cycle. Some authors recommend repeating the standard ART protocol.  Changing the batch of hCG ,, and using r-hCG to trigger an endogenous LH surge have also been suggested.  r-hCG with its high purity (≥99%) and consistency between batches may be a better choice than urinary hCG.
Since in most of the EFS cases reported in literature, downregulation was achieved by GnRHa (possibly presenting the higher prevalence of agonist over antagonist in ART cycles in the last decade), shifting from an agonist to antagonist protocol has also been suggested.  The first case of EFS with antagonist cycle was reported in 2003, and a successful oocyte recovery cycle was achieved following the triggering of an endogenous LH surge using GnRHa.  Other strategies recommended are the use of r-LH for the trigger and also GnRHa trigger in an antagonist cycle. Prolonging the interval between ovulation trigger and OR is also one of the approaches;  however, like other strategies due to lack of strong evidence, it cannot be universally recommended. Hourvitz et al.  presented two women with EFS who were successfully treated with in vitro maturation. In the present study, half of the GEFS patients had opted for the second cycle of IVF, but none of the management strategies proposed in literature had any benefit, unlike to what is reported in literature.
Readministering hCG and reaspiration of follicles have been suggested as an attempt to rescue the IVF cycle in case of FEFS. ,,,, A second, rescue dose of hCG in case of false EFS has also been proposed,  and successful outcome of IVF cycles has also been reported. , Recently a review of literature had shown that 42.8% of cycles resulted in a healthy live-born fetus when rescue protocol was used,  thus showing it to be a reasonable treatment option for false EFS. In our series, as premature ovulation was the cause of FEFS among all the patients, thus rescue protocol was not attempted. Reichman et al.  have recently proposed a potential preventative strategy for FEFS through assessing the serum hCG the day after the trigger and administering a second bolus of hCG.
| Conclusion|| |
The case series presented here demonstrates the existence of GEFS. All our patients were stimulated with only antagonist protocol because it has been described in the literature that GEFS is more common with agonist protocol. We also tried the various prevention strategies mentioned in literature like changing urinary hCG to recombinant and substituting hCG trigger with GnRHa trigger, but none of them worked for any of our cases. We finally assert that GEFS does exist and also confirm that patients with EFS are a real challenge as no single treatment is universally effective.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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| Authors|| |
I (Dr. Ritu Punhani) have graduated from Kasturba Medical College, Mangalore, with distinctions in seven subjects. I did my postgraduation in obstetrics and gynecology from Sri Ramachandra Medical College, Chennai, in 2004 and was awarded with the "Solvay Pharma India Limited's Gold Medal" in M.S. (OBG). I worked at St. Stephen's Hospital Delhi for 9 years in the Department of Obstetrics and Gynaecology. I am presently doing the National Board Fellowship (FNB) in Reproductive Medicine from the prestigious Institute of Reproductive Medicine, Madras Medical Mission Hospital, Chennai. I got the Dr. Asha Baxi Award for the best poster presentation in ISAR 2016, which was held at Indore this year.
[Table 1], [Table 2], [Table 3]