Recurrent implantation success in consecutive embryo transfer cycles: a unique case report

Abstract

We describe here a unique case of a woman with an azoospermic male partner conceiving each time during ten consecutive in-vitro fertilization embryo transfer (IVF-ET) cycles. A 27 year old woman reported with primary infertility to our out-patient department at the Institute of Reproductive Medicine, Salt Lake, India in November 2001. Ten consecutive IVF-ET cycles including both, fresh and frozen embryos were performed over a span of ten years. Following each ET, the woman became pregnant; however, viable babies were not achieved. Finally, after the tenth consecutive IVF-ET cycle, a caesarean section (CS) was performed at 30 weeks and twin babies weighing 1.3 kg and 1.25 kg, respectively, were delivered and both the babies survived. It seems unlikely that the woman's conception with each embryo transfer was merely coincidental; a persistently receptive window of implantation with a high embryo implantation rate is evident. This case motivated us to introduce the term, repeated implantation success (RIS). We hypothesize that for successful implantation, expression of various factors during each cycle may be possible only in genetically pre-determined women. Identification of these genetically pre-determined set of marker(s) could help in predicting the chances of a successful pregnancy in women undergoing IVF.

Keywords:

• endometrial receptivity
• IVF, successful implantation

Case Report

Implantation is the rate-limiting event in assisted reproductive technique (ART) and is perhaps the most important reason as to why progress in ART has plateaued, despite the tremendous advances in the fertilization rates [D'hauterive et al. 2002]. It is generally agreed that in addition to obtaining good quality embryos from patients undergoing ART, a receptive endometrium is crucial for successful implantation and clinical pregnancy. Although extensive research into the molecular events has led to an advanced understanding of the endometrial physiology, uterine receptivity still remains a biological mystery [Giudice 1999; Makker and Singh 2006].

We present here an interesting case report where a 27 year old woman reported with primary infertility to our out-patient department at the Institute of Reproductive Medicine, Salt Lake, India in November 2001. The Institutional Review Board agreed to the presentation of the case. The woman had been married for seven years, with a 19.16 body mass index (BMI), and was on levothyroxine tablets (Eltroxin, GlaxoSmithKline Pharmaceuticals Ltd., Nasik, Maharashtra, India) 50 µg daily, as she was hypothyroid. She had a regular menstrual cycle with uterus size normal and both tubes patent, as evidenced by laparoscopy. Evaluation of the infertile couple revealed the cause of infertility to be azoospermia of the male partner with karyotype 46 XY. The right testis, with a volume of 3 cc, was located in the superficial inguinal region and the left testis had a volume of about 15 cc. The first percutaneous epididymal sperm aspiration/intra-cytoplasmic sperm injection-embryo transfer (PESA/ICSI-ET) resulted in a spontaneous miscarriage at 8 weeks in December 2001. Next, following endometrial preparation, frozen embryo transfer (FET) was attempted. Pregnancy resulted and continued up to 12 weeks, but ended in spontaneous miscarriage.

A PESA/ICSI-ET was performed for the second time where three embryos were transferred and two cryopreserved. At 28 weeks the woman delivered twin babies, weighing 800 g and 700 g, respectively. Both the babies, however, died after 7 days. A FET was attempted with the two remaining frozen embryos, but spontaneous miscarriage occurred at 14 weeks of gestation. Subsequently, all possible causes of recurrent miscarriage were ruled out. The following tests were carried out to confirm that there was no apparent cause of recurrent pregnancy loss: thyroid-stimulating hormone (TSH) and antithyroid antibody tests, antiphospholipid antibodies test (anticardiolipin antibodies and lupus anticoagulants IgG and IgM), congenital thrombophilias, TORCH (toxoplasmosis, rubella, cytomegalovirus, and herpes) tests, paternal and maternal chromosomal analysis, hysterosalpingography, and hysteroscopy to rule out uterine defects. Abnormal fasting level of homocysteine and diabetes mellitus were also excluded. Further, mid-luteal serum progesterone was assessed to exclude luteal phase defect.

The next testicular sperm extraction (TESE)/ICSI-ET cycle resulted in a positive β-hCG test followed by spontaneous miscarriage at 7 weeks. A FET was performed and pregnancy confirmed, which continued up to 22 weeks ending in a preterm delivery. Similarly in the next TESE/ICSI-ET cycle, spontaneous miscarriage occurred at 8 weeks. Subsequent FET resulted in the birth of twin female babies at 29 weeks, weighing 950 g and 830 g, respectively, but the babies did not survive.

After a gap of two years, the fifth cycle was attempted in March 2011. Prior to ICSI, the COMET assay and Polscope were used to evaluate DNA integrity and birefringence of the aspirated spermatozoa, respectively. This time pregnancy continued up to 8 weeks and ended in a spontaneous miscarriage. The subsequent FET led to the birth of twin babies at 30 weeks by lower segment cesarean section (LSCS). Both babies weighed 1.3 kg and 1.25 kg, respectively, and survived.

Discussion

Repeated implantation failure (RIF) is defined as failure of implantation in at least three consecutive IVF attempts, in which one to two embryos of high-grade quality are transferred at each cycle [Simon and Laufer 2012] and is commonly encountered during IVF-ET. Reduced endometrial receptivity, poor embryo quality, and inappropriate transfer techniques are considered to be the major causes of RIF [Margalioth et al. 2006]. In contrast, we describe here a unique case where the woman conceived each time, irrespective of whether average quality, fresh, or frozen embryos were transferred. Out of the total of 25 embryos transferred, 13 embryos implanted resulting in 7 singleton and 3 sets of twin pregnancies with an implantation rate of 52%. Repeated implantation success following ten consecutive ET has not been reported so far. This case tempts us to introduce the concept of repeated implantation success (RIS). It is evident that the window of implantation in this woman was persistently receptive with a high embryo implantation rate.

Various cell adhesion molecules, cytokines, and apical protrusions known as pinopodes expressed during the implantation window have been recognized to be potential biomarkers of endometrial receptivity [Banerjee et al. 2013]. In the present case, the endometrium was found to be receptive in almost every cycle without much inter-cycle variation. It is, therefore, safe to presume that the components responsible for endometrial receptivity were being continuously expressed in each treatment cycle. The high likelihood of implantation and poor obstetric history associated with this case is strongly suggestive of elective single embryo transfer (eSET). However, this option was not considered as the woman had maximum number of miscarriages in her early pregnancies. It is well known that repeated loss of ‘biochemical’ and first trimester clinical pregnancies is more likely due to chromosomal anomaly of the embryo or the fetus. In view of this, each time we presumed that at least one embryo out of the three transferred would have intact chromosomal DNA and result in successful implantation.

It has been reported earlier that there are exceptionally fertile women with unique fertility potential even after the age of 45 years. These women might possess a genetic predisposition towards delaying the normal rate of aging of the ovaries and the oocytes [Laufer et al. 2004; Gielchinsky et al. 2006]. It seems unlikely that the woman's conception with each embryo transfer was merely fortuitous. It is, therefore, reasonable to believe that for successful implantation, expression of various factors during each cycle may be possible only in genetically pre-determined women. Identification of implantation marker(s) in body fluids such as serum and uterine fluid of a cohort of RIS women can be a major breakthrough in predicting the possibility of success in IVF cycles. Women likely to have a successful implantation may be identified by this ‘marker’ during the treatment cycle.

Declaration of interest: The authors report no declarations of interest.

Author contributions: All authors have significantly contributed to the preparation, review of the manuscript, and were involved in the study. Conceived and designed the experiments: BC; Performed the experiments: SG, RC, SG; Analyzed the data: AG, KC, SG; Contributed reagents/materials/analysis tools: AG, KC, BC; Wrote the manuscript: AG, KC, SG.