The freeze-all strategy has emerged as an alternative to fresh embryo transfer
(ET) during in vitro fertilization (IVF) cycles. Although fresh
ET is the norm during assisted reproductive therapies (ART), there are many
concerns about the possible adverse effects of controlled ovarian stimulation
(COS) over the endometrium. The supra-physiologic hormonal levels that occur
during a conventional COS are associated with modifications in the
peri-implantation endometrium, which may be related to a decrease in pregnancy
rates and poorer obstetric and perinatal outcomes when comparing fresh to
frozen-thawed embryo transfers. The main objective of this study was to assess
the available literature regarding the freeze-all strategy in IVF cycles, in
regards to effectiveness and safety. Although there are many potential
advantages in performing a freeze-all cycle over a fresh ET, it seems that the
freeze-all strategy is not designed for all IVF patients. There is a need to
develop a non-invasive clinical tool to evaluate the endometrial receptivity
during a fresh cycle, which enables the selection of patients that would benefit
from this strategy. Today, it is reasonable to perform elective cryopreservation
of all oocytes/embryos in cases with a risk of OHSS development, and in patients
with supra-physiologic hormonal levels during the follicular phase of COS. It is
not clear if all normal responders and poor responders may benefit from this
strategy.
The objective of the present systematic review and meta-analysis was to examine the literature and to identify the results of randomized controlled trials (RCTs) comparing the use of letrozole to clomiphene citrate (CC) for ovulation induction in patients with polycystic ovary syndrome (PCOS). An exhaustive electronic literature search was performed using the MEDLINE and EMBASE databases until October 2014. Seven prospective RCTs comparing the use of letrozole to CC in PCOS patients met the inclusion criteria. Overall, the seven included studies accounted for 1833 patients (906 in the letrozole group and 927 in the CC group) and for 4999 ovulation induction cycles (2455 in the letrozole group and 2544 in the CC group). Five of the included studies reported data on live birth rates. There was a statistically significant increase in the live birth and pregnancy rates in the letrozole group when compared to the CC group, with a relative risk (RR) = 1.55 (95% confidence interval (CI): 1.26-1.90; I(2) = 0%) and RR = 1.38 (95% CI: 1.05-1.83; I(2) = 61%), respectively. There were no differences in the multiple pregnancy, miscarriage and ovulation rates between the two groups. Our study found that letrozole is superior to CC when considering the live birth and pregnancy rates in patients with PCOS.
The value of hysterosalpingosonography (HSSG) as a diagnostic tool was evaluated in 76 patients and compared to hysteroscopic, laparoscopic, and/or hysterosalpingographic (HSG) findings. Saline solution and Dextran 60 were used as distension media. Patients were divided in three groups: group A (n = 22), patients submitted for control post-tubal electrocoagulation. Group B (n = 38), patients with a history of pathological metrorrhagias, and group C (n = 16) infertile women with possible tubal pathology. Comparison between the different diagnostic techniques for the evaluation of the uterine cavity and tubes was carried out. Our results indicated that HSSG had more sensitivity but less specificity than hysteroscopy or HSG in the diagnosis of uterine cavity pathology. Hysteroscopy seems to be the best technique for the diagnosis of endometrial pathology, and HSSG seems to be the most effective in the study of the myometrium. HSSG cannot be considered a reliable and accurate method for the diagnosis of tubal patency.
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