Should sexual intercourse be avoided during the embryo transfer cycle? Life-threatening ruptured heterotopic pregnancy after single thawed embryo transfer: case report and review of the literature.

BACKGROUND: To report the life-threatening complication of a raptured heterotopic pregnancy occurring from thawed single embryo transfer. CASE REPORT: A 33-year-old woman underwent in vitro fertilization (IVF) under a step-up regimen. After oocyte collection, blastocysts were frozen, and a single frozen-thawed blastocyst was then transferred according to the natural cycle. On day 17 after embryo transfer, an intrauterine pregnancy was confirmed. On day 28, she complained of sudden abdominal pain and ultrasonography revealed marked fluid retention in the peritoneal cavity. Emergency laparoscopy was performed, revealing hemoperitoneum and a ruptured interstitial heterotopic pregnancy (HP), which was then resected laparoscopically. Because sexual intercourse had occurred shortly before the transfer, a HP comprising a spontaneous pregnancy and a pregnancy achieved by assisted reproductive technology was assumed. The fetus in the uterus survived and was delivered. CONCLUSION: In this case, however, despite the single embryo transfer during the natural-cycle frozen-thawed embryo transfer process, the risk of life-threatening complication as a HP as a consequence of spontaneous pregnancy after sexual intercourse remained.

Scaled tests and modeling of effluent stack sampling location mixing.

A three-dimensional computational fluid dynamics computer model was used to evaluate the mixing at a sampling system for radioactive air emissions. Researchers sought to determine whether the location would meet the criteria for uniform air velocity and contaminant concentration as prescribed in the American National Standards Institute standard, Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities. This standard requires that the sampling location be well-mixed and stipulates specific tests to verify the extent of mixing. The exhaust system for the Radiochemical Processing Laboratory was modeled with a computational fluid dynamics code to better understand the flow and contaminant mixing and to predict mixing test results. The modeled results were compared to actual measurements made at a scale-model stack and to the limited data set for the full-scale facility stack. Results indicated that the computational fluid dynamics code provides reasonable predictions for velocity, cyclonic flow, gas, and aerosol uniformity, although the code predicts greater improvement in mixing as the injection point is moved farther away from the sampling location than is actually observed by measurements. In expanding from small to full scale, the modeled predictions for full-scale measurements show similar uniformity values as in the scale model. This work indicated that a computational fluid dynamics code can be a cost-effective aid in designing or retrofitting a facility's stack sampling location that will be required to meet standard ANSI/HPS N13.1-1999.