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History of Tubal Ectopic Pregnancy Enhances Risk of its Future Incidence in IVF-ET Patients
Although embryo transfer (ET), the final step of in vitro fertilization (IVF), is intended to facilitate accurate embryo implantation in the uterine cavity, tubal ectopic pregnancy (TEP) is twice more common following IVF compared to natural conception. Now, a recent study published in the Journal of Assisted Reproduction and Genetics states that a positive history of TEP significantly enhances the incidence of repeated ectopic pregnancies in women undergoing IVF-ET treatment.
Monika Weigert from the Wunschbaby Zentrum, an institute for sterility treatment, Vienna, Austria, and colleagues, conducted a retrospective study on IVF-ET patients, to determine the incidence of TEP with regard to the status of fallopian tubes following previous TEP. The study involved the analysis and comparison of results obtained from 2 groups: 1) patients undergoing 481 cycles of IVF-ET following conservative or surgical treatment of TEP 2) control group, wherein idiopathic or male factor was used for IVF-ET indication. Logistic regression (PROC GENMOD) and a repeated measure model were used for statistical evaluation. The test and control group reported an occurrence of 12 and 1 TEP, respectively. It was also demonstrated that the probability of TEPs (P=0.0028) and pathological pregnancies, such as abortion, biochemical and ectopic pregnancy, (P=0.0411) increased with smoking. The investigators thus concluded that women with previous TEP opting for IVF-ET have a high risk of developing future similar events, with the risk significantly increased in smokers.
Since IVF is associated with increased tubal pregnancy (TP) rates than natural conception, Revel, et al. (Human Reproduction, 2008) speculated that the fallopian tube or embryo could play a key role in the pathological process that leads to ectopic pregnancy. The researchers had previously found that the expression of E-cadherin, a transmembrane protein, may be a useful marker for endometrial receptivity, thereby suggesting its potential role in TP after IVF treatment. In order to determine the role of E-cadherin in TP, the scientists compared the protein expression and localization in tubal implantation sites from spontaneous TP and TP post-IVF. On comparing immunohistochemistry E-cadherin levels in fallopian tube cross-sections between 11 spontaneous (antegrade) and 13 post-IVF (retrograde) TP, researchers found that the semi-quantitative intensity score in IVF tubal samples was more than double to spontaneous TP. Additionally, immunostaining of E-cadherin in cytotrophoblast cells of chorionic villi was more intense in ectopic TP post-IVF. Based on the findings, it was suggested that the adhesion molecule may serve as an indicator of embryo implantation.
Tubal ectopic pregnancy is commonly associated with several risk factors such as smoking, advanced maternal age, pelvic inflammatory disease, and prior tubal damage, although the exact cause is unknown. Therapeutic options to counter TEP include medications like systemic methotrexate, expectant management, and surgeries such as salpingectomy or salpingostomy.
With the current research demonstrating the increased risk of tubal ectopic pregnancy in women undergoing IVF-ET treatment cycles with a previous history of TEP, regular obstetric surveillance is crucial to achieve optimal results during assisted reproduction technologies.
1. Weigert M, Gruber D, Pernicka E, Bauer P, Feichtinger W. Previous tubal ectopic pregnancy raises the incidence of repeated ectopic pregnancies in In Vitro fertilization-embryo transfer patients. J Assist Reprod Genet. 2008 Nov 20. [Epub ahead of print]
2. Revel A, Ophir I, Koler M, Achache H, Prus D. Changing etiology of tubal pregnancy following IVF. Hum Reprod. 2008 Jun;23(6):1372-6. Epub 2008 Apr 1.