Follicular Flushing Using Double Lumen Needle Versus Direct Aspiration in Low Prognosis Patients According to the POSEIDON Criteria (FLUSHING)

This is a prospective, randomized, controlled clinical trial designed to evaluate whether follicular flushing increases the number of cumulus-oocyte complexes (COCs) retrieved compared to single aspiration in patients with poor ovarian response belonging to Poseidon groups 3 and 4.

A total of 40 patients with poor ovarian response belonging to Poseidon groups 3 and 4 will be included. In each patient, one ovary will be randomized to the study technique (follicular flushing), and the other ovary will be randomized to the control technique (single aspiration).

Study Overview

• Status: Completed
• Conditions: Low Ovarian Reserve; Poor Response to Ovulation Induction; Poor Response to Ovulation Induction Poseidon Type IV
• Intervention / Treatment: Procedure: follicular aspiration; Procedure: follicular flushing

Detailed Description

This is a prospective, randomized, controlled clinical study designed to evaluate the effect of follicular flushing on the number of cumulus-oocyte complexes (COCs) retrieved, compared to single aspiration, in patients with poor ovarian response classified as Poseidon groups 3 and 4.

A total of 40 patients will be included. All participants will receive a standardized stimulation protocol consistent with current practice for patients diagnosed with low ovarian reserve. After meeting all inclusion criteria, controlled ovarian stimulation will begin within the first four days of the menstrual cycle, using an antagonist protocol in all cases.

Starting on the 6th day of ovarian stimulation, daily administration of a GnRH antagonist at a dose of 0.25 mg (Ganirelix® or Cetrorelix®) will be initiated. Final oocyte maturation will be triggered once at least one follicle reaches a diameter of ≥17 mm, using either 250 μg of recombinant hCG (Ovitrelle®; Merck Serono) or 0.2 mg of triptorelin acetate (Decapeptyl®), or a double trigger. Oocyte retrieval will be performed 36 hours after triggering final oocyte maturation.

On the day of oocyte retrieval, randomization will be performed using a computer-generated randomization list. In each patient, one ovary will be randomly assigned to the control group (single aspiration), and the contralateral ovary will be assigned to the study group (follicular flushing). Simple random allocation will be used. Each patient will be allowed to participate in the study only once.

Oocyte retrieval procedures will be performed by four trained physicians to evaluate the reproducibility and generalizability of the technique. Follicles will be aspirated using 17G needles in both groups. For follicular flushing, the same needle model used for single aspiration (Cook) will be employed. To eliminate dead space, the needle will be prefilled with flushing medium before beginning the procedure. Aspiration pressure will be maintained at 190 mmHg during oocyte retrieval.

In the single aspiration group, after aspirating all follicles, the needle will be rinsed with flushing medium to minimize the risk of oocyte retention inside the needle.

In the follicular flushing group, if no cumulus-oocyte complex (COC) is recovered during the initial aspiration, follicular flushing will be repeated until a COC is obtained, up to a maximum of three flushes. After three flushes, if no COC is retrieved, the procedure will be completed by rinsing with flushing medium to prevent possible oocyte retention within the needle.

The embryologist will immediately inform the physician performing the oocyte retrieval whether a COC has been recovered, in order to determine whether to continue flushing or proceed to the next follicle (open flushing technique).

The duration of the procedure will be recorded from needle insertion to its withdrawal for each ovary in both groups.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Spain
  • Alicante
    • Alicante, Alicante, Spain, 03016
      • Instituto Bernabeu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Pacientes con baja respuesta ovárica grupos POSEIDON 3 y 4 (< 35 años y RFA <5 y/o AMH < 1.2 ng/ml o > 35 años≥ 35 años y RFA <5 o AMH <1.2 ng/mL respectivamente)

  1. Pacientes menores o igual a 43 años.
  2. Índice de Masa Corporal (IMC) de 18-35 kg/m2
  3. Estimulación ovárica para ICSI
  4. Presencia y accesibilidad de ambos ovarios.
  5. Ausencia de patología ovárica
  6. Cuando se cumplan los criterios de desencadenamiento para la maduración final del ovocito, cada ovario debe contener al menos un folículo mayor o igual a 14 mm.
  7. Haber dado su consentimiento por escrito.

Exclusion Criteria:

• Presence of a single ovary.

Presence of ovarian pathology.

Use of conventional IVF as the fertilization method.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Single Aspiration Arm; Oocytes will be retrieved from one ovary using single follicular aspiration	Procedure: follicular aspiration; In the single aspiration group, after aspirating all follicles, the needle will be rinsed with flushing medium to prevent the possibility of oocyte retention within the needle.
Experimental: Follicular Flushing Arm; Oocytes will be retrieved from the contralateral ovary using follicular flushing, with up to three flushes per follicle if no cumulus-oocyte complex is obtained initially	Procedure: follicular flushing; Follicles will be aspirated using 17G needles of the same gauge in both groups. For follicular flushing, the same type of needle used for single aspiration (Cook) will be employed. To eliminate dead space, the needle will be prefilled with flushing medium before starting the procedure. Aspiration pressure will be maintained at 190 mmHg during oocyte retrieval. In the follicular flushing group, if no cumulus-oocyte complex (COC) is recovered during the initial aspiration, follicular flushing will be performed until a COC is obtained, up to a maximum of three times. After three flushes, if no COC is retrieved, the procedure will be completed by rinsing with flushing medium to minimize the possibility of oocyte retention within the needle.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
number of cumulus-oocyte complexes	number of cumulus-oocyte complexes (COCs) retrieved after each aspiration	During the egg retrieval

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Oocyte recovery rate	number of oocytes retrieved / number of follicles ≥11 mm on the day of final oocyte maturation trigger	day of the egg retrieval
Fertilization rate	number of 2PNs / number of MII oocytes	1 day after the egg retrieval
Empty follicle rate	zero oocytes retrieved / follicles punctured	day of the egg retrieval
Procedure time	calculated from needle insertion to its withdrawal for each ovary	In seconds from needle insertion to its withdrawal for each ovary

Collaborators and Investigators

• Sponsor: Instituto Bernabeu

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2026
• Primary Completion (Actual): April 1, 2026
• Study Completion (Actual): April 1, 2026

Study Registration Dates

• First Submitted: November 17, 2025
• First Submitted That Met QC Criteria: December 4, 2025
• First Posted (Actual): December 8, 2025

Study Record Updates

• Last Update Posted (Actual): April 14, 2026
• Last Update Submitted That Met QC Criteria: April 13, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Poor responder; low ovarian reserve; Follicular flushing; Poseidon 3 and 4
• Other Study ID Numbers: MR47

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No