P-771 Prospective comparison of different needle sizes (17G vs 18G) and aspiration pressures (110 vs 220 Hgmm) for egg collection in oocyte donors: randomized, pilot study
Authors: Rogel S , Bodri D , Reshota N , García Villalba A , Cañada I , García M , Aizpurua J 
Published: June 2023

Study question

How does higher aspiration pressure (220Hgmm) and thinner oocyte retrieval needle size (18G) affect egg retrieval rate, intervention duration, and post-operative pain in oocyte donors?

Summary answer

Egg retrieval rate and developmental potential did not vary according to needle thickness or aspiration pressure, whereas with higher aspiration pressure the intervention was shorter.

What is known already

Although transvaginal ultrasound guided egg collection has been successfully used for more than two decades, technical parameters of the egg collection are still not standardized and are often based on the manufacturer’s recommendations which have not been evaluated in a clinical setting. Only a handful of studies evaluated the use of thinner oocyte retrieval needle aiming at reducing ovarian trauma (Wikland 2011, Kushnir, 2013).

Study design, size, duration

After obtaining informed consent consecutive oocyte donors (n = 105) were prospectively assigned on the day of egg retrieval scheduling to three equal-sized groups (group 2: 17G needle, 220 Hgmm, group 1; 18G needle, 220 Hgmm, group 3: 17 G needle, 110 Hgmm) using two different oocyte retrieval needles (Kitazato, Japan) and two different aspiration pressures (Labotect, Germany). Oocyte donor age, BMI, baseline AMH, ≥14 mm and ≥10 mm follicular counts were not significantly different among groups.

Participants/materials, setting, methods

Oocyte donors were stimulated with GnRH antagonist protocol and oocyte maturation was triggered with GnRH agonist. Pre- and postoperative pain measured by visual analogue score (VAS:0-10) and duration of each egg collection performed under sedation was recorded. Retrieved mature eggs were assigned to previously matched recipients or electively vitrified for use in our centre’s egg bank. The developmental potential of retrieved eggs was evaluated by the fertilization and blastocyst formation rate of assigned, fresh oocytes.

Main results and the role of chance

As aspiration pressure and needle size decreased, the average duration of egg collection became longer (08:02, 09:36, 10:50 minutes, p = 0.002). Although postoperative pain scores were uniformly low, there was a marginally lower postoperative pain score in group 3, where a lower aspiration pressure was used (1.6±1.4, 1.9±1.9, 1±1.1, p &lt; 0.0001). No oocyte donor experienced any significant postoperative complication. The number of retrieved eggs (27.3±12, 26.8±13.6, 26.1±12), oocyte retrieval rate per number of ≥ 14 mm follicles (104, 103, 104%), and the proportion of damaged eggs with ruptured zona pellucida (3.8, 2.7, 3.7%) were not significantly different among groups. Fertilization (72, 73, 73%) and blastocyst formation (51, 53, 46%) rates of injected fresh mature oocytes were not significantly different.

Limitations, reasons for caution

Due to the lack of similar studies, the size of each study group (n = 35) was determined by convenience instead of a previous sample size calculation.

Wider implications of the findings

Precise calibration of technical parameters of egg collection merits further attention and continuous monitoring, especially in hyper-stimulated oocyte donors where an excellent oocyte yield should be balanced against a shorter intervention, maximally reduced postoperative pain, and the lowest possible rate of complications.

Trial registration number

Not applicable