Simplified vitrification–warming protocol in donor oocytes: artificial intelligence-based oocyte competence and clinical outcomes

Autores de IIS La Fe

• Lucía Murria Aguilar

  Autor

• Laura Conversa Martínez

  Autor

• Julia Gil Gramage

  Autor

• Carla Giménez Rodríguez

  Autor

• 

  Marcos Meseguer Escrivá

  Autor

• Ana Cristina Cobo Cabal

  Autor

Participantes ajenos a IIS La Fe

• Garijo Y.
• Bronet F.

Grupos

• Biomarcadores, Medicina Genómica, Estadística y Análisis masivo de datos en Reproducción humana asistida

Abstract

Research question: Is the simplified procedure for vitrification and warming as efficient as the conventional protocol for human donor oocytes in terms of laboratory and clinical outcomes? Design: This prospective, randomized, proof-of-concept study used sibling donor oocytes. Mature oocytes from 20 donor cycles (n = 245) were randomized at the Cryotop level to a simplified or conventional protocol. In the simplified protocol, oocytes were exposed to equilibration and vitrification solutions for 1 min each before immersion in liquid nitrogen. At warming, cryoprotectant dilution was performed in a single 1 min step using thawing solution at 37°C. The conventional protocol used standard 12–15 min stepwise equilibration, 1 min vitrification, and 10 min multistep warming. Laboratory outcomes, clinical outcomes after single-embryo transfer, and artificial intelligence (AI)-based assessment of oocyte competence before vitrification and after warming were evaluated. Results: Oocyte survival was comparable between the simplified and conventional protocols (97.7% versus 97.4%, respectively). No statistically significant differences were observed in fertilization (83.5% versus 77.7%), usable blastocyst (41.5% versus 47.1%), or good-quality blastocyst (32.1% versus 41.4%) rates. A total of 17 blastocysts were transferred, resulting in comparable implantation (80.0% versus 71.4%) and ongoing pregnancy (60.0% versus 57.1%) rates. AI-based assessment showed comparable estimated oocyte competence before vitrification and after warming, with similar proportions of cohorts classified as having >95% versus =95% probability of obtaining at least one blastocyst. Conclusions: The use of a single-step approach during equilibration and dilution of cryoprotectants – the simplified procedure – yields clinical and laboratory outcomes comparable to conventional vitrification and warming protocols. © 2026 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Keywords

• cryoprotective agent; liquid nitrogen; medroxyprogesterone acetate; triptorelin; Article; artificial intelligence; blastocyst; cell survival; clinical outcome; controlled study; embryo; female; human; human cell; in vitro fertilization; laboratory protocol; nidation; oocyte development; oocyte donor; oocyte maturation; oocyte retrieval; oocyte vitrification; proof of concept; prospective study; randomized controlled trial; sibling donor; single embryo transfer; thawing; warming