Are all antral follicles the same? Size of antral follicles as a key predictor for response to controlled ovarian stimulation

Do we overlook predictive factors in Poseidon 1 patients? A retrospective analysis co-evaluating antral follicle counts & diameters

BACKGROUND

An unexpected impaired ovarian response pertains to an insufficient reaction to controlled ovarian hyperstimulation. This deficient reaction is identified by a reduced count of mature follicles and retrieved oocytes during an IVF cycle, potentially diminishing the likelihood of a successful pregnancy. This research seeks to examine whether the characteristics of antral follicles can serve as predictive indicators for the unexpected impaired ovarian response to controlled ovarian stimulation (COS).

METHODS

This retrospective cohort study was conducted at a tertiary university hospital. The electronic database of the ART (assisted reproductive technologies) center was screened between the years 2012-2022. Infertile women under 35 years, with normal ovarian reserve [anti-Müllerian hormone (AMH) > 1.2 ng/ml, antral follicle count (AFC) > 5] who underwent their first controlled ovarian stimulation (COS) cycle were selected. Women with < 9 oocytes retrieved (group 1 of the Poseidon classification) constituted the group A, whereas those with ≥ 9 oocytes severed as control (normo-responders) one (group B). Demographic, anthropometric and hormonal variables together with COS parameters of the two groups were compared.

RESULTS

The number of patients with < 9 oocytes (group A) was 404, and those with ≥ 9 oocytes were 602 (group B). The mean age of the group A was significantly higher (30.1 + 2.9 vs. 29.4 + 2.9, p = 0.01). Group A displayed lower AMH and AFC [with interquartile ranges (IQR); AMH 1.6 ng/ml (1-2.6) vs. 3.5 ng/ml (2.2-5.4) p < 0.01, AFC 8 (6-12) vs. 12 (9-17), p < 0.01]. The number of small antral follicles (2-5 mm) of the group A was significantly lower [6 (4-8) vs. 8 (6-12) p < 0.01), while the larger follicles (5-10 mm) remained similar [3 (1-5) vs. 3(1-6) p = 0.3] between the groups.

CONCLUSION

The propensity of low ovarian reserve and higher age are the main risk factors for the impaired ovarian response. The proportion of the small antral follicles may be a predictive factor for ovarian response to prevent unexpected poor results.

Volume-based follicular output rate improves prediction of the number of mature oocytes: a prospective comparative study

OBJECTIVE

To test whether volume-based follicular output rate (FORT-V) is superior to diameter based follicular output rate (FORT-D) in predicting the number of mature oocytes. The follicular output rate (FORT) is the ratio between preovulatory follicle count (PFC) and antral follicle count (AFC) and has been proposed as a better predictor of the ovarian response compared with AFC alone.

DESIGN

A prospective observational study of 215 consecutive women (80 oocyte donors and 135 in vitro fertilization [IVF] patients) undergoing ovarian stimulation for IVF.

SETTING

University affiliated private IVF center.

PATIENT(S)

Women undergoing ovarian stimulation between May 2018 and September 2021.

INTERVENTION(S)

Manual two-dimensional ultrasound and computer-generated (three-dimensional ultrasound, [3D]) AFCs were performed at baseline. During ovulation induction, follicular growth was monitored in each patient using both two-dimensional and 3D ultrasound. Preovulatory follicles were defined as those with a mean diameter of 16-22 mm. The trigger was based on the follicular volume according to our standard protocol: at least 2 follicles with a volume of >2 cc with 70% of the follicles having a volume of >0.7 cc.

MAIN OUTCOME MEASURE(S)

The primary outcome was the difference between FORT-V and FORT-D in their ability to predict the mature oocyte output rate.

RESULT(S)

In both IVF patients and oocyte donors, the computer-generated AFC was greater than the manual AFC. The FORT-V was higher than the FORT-D for both computer-generated (the difference was 35 [95% CI {confidence interval}, 32-45] in oocyte donors and 21 [95% CI, 5-46] in IVF patients) and manual FORT (the difference was 38 [95% CI, 32-45] in oocyte donors and 15 [95% CI, 3-43] in IVF patients) and was closer to the mature oocyte output rate. There was a direct correlation between the computer-generated AFC and the PFC based on volume and between PFC based on volume and the number of mature oocytes in oocyte donors and IVF patients.

CONCLUSION(S)

In this prospective study of 215 women, the FORT based on 3D ultrasound derived follicular volume (FORT-V) was superior to the FORT-D in determining the ovarian response in both oocyte donors and IVF patients. Moreover, our results support the non-inferiority of the computer-generated method compared with the manual method for the determination of AFC. Further studies on the role of computer-generated antral follicle characteristics may be useful in evaluating follicle stimulation regimens.