Implantation Rate
The percentage of transferred embryos that successfully implant and produce a gestational sac visible on ultrasound.
Full Definition
Implantation rate is calculated as the number of gestational sacs observed on ultrasound divided by the number of embryos transferred, expressed as a percentage. This outcome measure reflects embryo quality, endometrial receptivity, and transfer technique effectiveness. Implantation rates vary significantly based on maternal age, embryo stage and quality, and transfer protocol. In single embryo transfer cycles, implantation rate equals clinical pregnancy rate, but in multiple embryo transfers, implantation rate may exceed pregnancy rate if multiple embryos implant.
Usage
Usage note: Distinguish from clinical pregnancy rate, which measures pregnancies per transfer cycle rather than per embryo.
In Context
- "The clinic reported an implantation rate of 45% for euploid blastocyst transfers." — Outcome statistics
- "Twin pregnancy resulted from a 100% implantation rate with two transferred embryos." — Clinical documentation