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Reproduction in domestic animals = Zuchthygiene2026; 61(2); e70183; doi: 10.1111/rda.70183

Comparative Evaluation of Follicular Flushing Frequency and Scraping Time During Ovum Pick-Up in Mares: Effects on Oocyte Recovery Rate and Technical Considerations.

Abstract: Transvaginal ultrasound-guided follicular aspiration or ovum pick-up (OPU) has become the standard technique for oocyte collection in mares for intracytoplasmic sperm injection (ICSI). Although repeated follicular flushes and wall scraping are commonly used to improve oocyte recovery rate (ORR), the relative contribution of each remains unclear. This study aimed to compare the effects of multiple flushes versus controlled scraping time on ORR in mares. A controlled trial was conducted in two phases: (1) an ex vivo phase using slaughterhouse ovaries (n = 32), and (2) an in vivo phase in clinically healthy mares (n = 9). Follicles were assigned to two groups: multiple flushes (MF, 10 flushes with intermittent scraping, lasting 18 s in total) or single flush (SF, 18 s of continuous scraping followed by 1 flush). A total of 489 follicles were aspirated ex vivo and 143 in vivo. Results showed no significant difference in ORR between MF and SF groups in either phase (ex vivo: 63.8% vs. 59.5%; in vivo: 48.3% vs. 44.3%; p > 0.05). However, MF used significantly more flushing medium per follicle in the ex vivo model (p < 0.05). No significant differences were found in aspiration time or incidence of clots and blockages in the aspiration lines. A significant correlation was observed between clot number and aspiration system blockage (r = 0.497, p = 0.036). Continuous scraping without repeated flushing reduces medium usage but may increase operator fatigue and the risk of clot formation and system obstructions. Therefore, optimising scraping duration could improve the efficiency of oocyte recovery procedures while simplifying the technique and reducing costs. Further research is required to refine scraping protocols, reduce operator fatigue, and prevent complications related to clot formation.
© 2026 The Author(s). Reproduction in Domestic Animals published by Wiley‐VCH GmbH.
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Publication Date: 2026-02-12 PubMed ID: 41674388PubMed Central: PMC12895297DOI: 10.1111/rda.70183Google Scholar: Lookup
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  • Journal Article
  • Comparative Study

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study evaluated two common techniques used during ovum pick-up (OPU) in mares—multiple follicular flushes with intermittent scraping versus continuous scraping followed by a single flush—to determine their effects on the oocyte recovery rate (ORR) and potential technical challenges.

Background

  • Ovum pick-up (OPU) via transvaginal ultrasound-guided follicular aspiration is used to collect oocytes from mares for intracytoplasmic sperm injection (ICSI), a reproductive technology.
  • Enhancing the oocyte recovery rate is critical for the success of ICSI procedures.
  • Two methods are commonly used to improve ORR during OPU:
    • Repeated follicular flushing combined with intermittent scraping of the follicle wall.
    • Continuous scraping with a single flush afterward.
  • The specific contribution of flushing frequency versus scraping duration in ORR had not been clearly established prior to this study.

Study Design

  • The research was conducted in two phases:
    • Ex vivo phase: Using ovaries collected from 32 slaughtered mares to simulate controlled follicular aspiration (total 489 follicles).
    • In vivo phase: Using 9 clinically healthy live mares (total 143 follicles aspirated).
  • Follicles were randomly assigned to one of two treatment groups for aspiration:
    • Multiple Flushes (MF): 10 follicular flushes with intermittent scraping lasting a total of 18 seconds.
    • Single Flush (SF): Continuous scraping for 18 seconds, followed by a single flush.

Key Findings

  • Oocyte Recovery Rate (ORR):
    • No statistically significant difference between MF and SF groups in either ex vivo or in vivo phases:
      • Ex vivo: 63.8% (MF) vs. 59.5% (SF)
      • In vivo: 48.3% (MF) vs. 44.3% (SF)
  • Flushing Medium Use:
    • MF technique used significantly more flushing medium per follicle in the ex vivo phase compared to SF (which has cost and resource implications).
  • Aspiration Time and Technical Issues:
    • No significant differences were found in the overall aspiration time or the incidence of clots and blockages within the aspiration lines between the two methods.
    • However, there was a significant positive correlation between the number of clots formed and blockages in the aspiration system (r = 0.497, p = 0.036), indicating clot formation can negatively impact the procedure.
  • Operator Considerations:
    • Continuous scraping (SF method) may increase operator fatigue because of longer, uninterrupted scraping action.
    • MF may mitigate operator fatigue but increases medium usage.

Conclusions and Implications

  • Since ORR was similar between MF and SF, the choice of technique may hinge on balancing medium consumption, operator fatigue, and technical ease.
  • Continuous scraping with fewer flushes reduces medium used but might increase fatigue and clot-related complications.
  • Multiple flushing reduces clotting risk at the expense of using more medium.
  • Optimizing scraping duration and technique could enhance procedural efficiency, reduce costs, and improve operator comfort.
  • Further research is needed to refine scraping protocols, mitigate operator fatigue, and minimize clot formation to prevent aspiration blockages.

Cite This Article

APA
Márquez-Moya A, Carreras-Vico N, Sala-Ayala L, Martínez-Boví R, Cuervo-Arango J. (2026). Comparative Evaluation of Follicular Flushing Frequency and Scraping Time During Ovum Pick-Up in Mares: Effects on Oocyte Recovery Rate and Technical Considerations. Reprod Domest Anim, 61(2), e70183. https://doi.org/10.1111/rda.70183

Publication

Reproduction in domestic animals = Zuchthygiene
ISSN: 1439-0531
NlmUniqueID: 9015668
Country: Germany
Language: English
Volume: 61
Issue: 2
Pages: e70183
PII: e70183

Researcher Affiliations

Márquez-Moya, Adrián
  • Equine Fertility Group, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, Alfara del Patriarca, Spain.
Carreras-Vico, Nerea
  • Equine Fertility Group, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, Alfara del Patriarca, Spain.
Sala-Ayala, Laura
  • Equine Fertility Group, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, Alfara del Patriarca, Spain.
Martínez-Boví, Rebeca
  • Equine Fertility Group, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, Alfara del Patriarca, Spain.
Cuervo-Arango, Juan
  • Equine Fertility Group, Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, Alfara del Patriarca, Spain.

MeSH Terms

  • Animals
  • Female
  • Horses
  • Oocyte Retrieval / veterinary
  • Oocyte Retrieval / methods
  • Ovarian Follicle
  • Oocytes

Grant Funding

  • GIR24-12 / Universidad San Pablo - CEU

Conflict of Interest Statement

: While preparing this work, ChatGPT was used as an AI‐assisted tool to refine the language and clarity of our written text. Following its use, we thoroughly reviewed and edited the content to ensure accuracy and appropriateness, taking full responsibility for the final published version of the article. The authors declare no conflicts of interest.

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