What is a difficult transfer? Analysis of 7,714 embryo transfers: the impact of maneuvers during embryo transfers on pregnancy rate and a proposal of objective assessment

Clinical pregnancy rate decreases progressively with the use of additional maneuvers during embryo transfer. An objective classification of the instrumentation applied during embryo transfer is proposed.

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Volume 107, Issue 3, Pages 657–663


Alejandro Kava-Braverman, M.D., Francisca Martínez, Ph.D., Ignacio Rodríguez, B.Sc., Manuel Álvarez, M.D., Pedro N. Barri, Ph.D., Buenaventura Coroleu, Ph.D.



To establish the relationship between the degree of difficulty of ET and pregnancy rate (PR), with a view to proposing an algorithm for the objective assessment of ET.


Retrospective, observational study.


In vitro fertilization unit.


Women undergoing assisted reproductive technology (ART) with ET after IVF/intracytoplasmic sperm injection, in whom fresh embryo transfer or frozen–thawed embryo transfer was performed.



Main Outcome Measure(s)

Clinical pregnancy rate (CPR).


A total of 7,714 ETs were analyzed. The CPR was significantly higher in the cases of easy ET compared with difficult ET (38.2% vs. 27.1%). Each instrumentation needed to successfully deposit the embryos in the fundus involves a progressive reduction in the CPR: use of outer catheter sheath (odds ratio [OR] 0.89; 95% confidence interval [CI] 0.79–1.01), use of Wallace stylet (OR 0.71; 95% CI 0.62–0.81), use of tenaculum (OR 0.54; 95% CI 0.36–0.79). Poor ultrasound visualization significantly diminish the CPR.


The CPR decreases progressively with the use of additional maneuvers during ET. An objective classification of the instrumentation applied during ET is proposed.

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Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders. The journal publishes juried original scientific articles in clinical and laboratory research relevant to reproductive endocrinology, urology, andrology, physiology, immunology, genetics, contraception, and menopause. Fertility and Sterility® encourages and supports meaningful basic and clinical research, and facilitates and promotes excellence in professional education, in the field of reproductive medicine.