Evidence map›Paper›PMID 42630557›Full record

ArticleF&S reports2026

The Cardinal protocol: investigating a simplified, cost-conscious option for oocyte cryopreservation in a prospective noninferiority cohort study.

Esther H Chung, Natasha Raj-Derouin, Jiaqi Zhang, Victoria Harbour, Metabel Markwei, Arian Khorshid, Brindha Bavan, Lusine Aghajanova, Ruth B Lathi

Registry-linked trialAbstract read
In one paragraph

Article in F&S reports, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT05842070 (The Stanford Egg Freezing Study), which is not on this map. Not yet cited in PubMed.

0numbers the graph read from it
0cells of the map it votes in
0citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT05842070 nacompletednot on this map

The Stanford Egg Freezing Study: Investigating a Low-Cost, Low-Intensity Oocyte Cryopreservation Protocol

TypeinterventionalSponsorStanford UniversityRan2023 to 2025Enrolled168ConditionsFertility Issues, Reproductive IssuesArmsLow-Intensity Egg Freezing Protocol, High-Intensity Egg Freezing Protocol
3 · Its place in the literature

Who cites it

0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

9 authors.

Esther H ChungDivision of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
Natasha Raj-DerouinDepartment of Obstetrics and Gynecology, Kaiser Permanente, Los Angeles, California.
Jiaqi ZhangDepartment of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
Victoria HarbourDepartment of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
Metabel MarkweiDepartment of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
Arian KhorshidDivision of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
Brindha BavanDivision of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
Lusine AghajanovaDivision of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
Ruth B LathiDivision of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Objective: To determine if the novel cost-conscious and simplified Cardinal protocol could achieve noninferior clinical outcomes in planned oocyte cryopreservation (OC) cycles, compared with routine protocols. Design: Prospective noninferiority cohort study, nonrandomized. Subjects: Patients undergoing planned OC were prospectively recruited at a single academic institution between July 2023 and August 2024. Exposure: Participants self-selected between the routine protocols vs. the Cardinal protocol. All participants paid for their cycles out-of-pocket or using insurance. The Cardinal protocol is limited to 2 ultrasounds (baseline and stimulation day [SD] 9, no bloodwork, standardized follicle-stimulating hormone (FSH) dosing (antimüllerian hormone ≤ 4: 300 IU, antimüllerian hormone > 4: 225 IU), scheduled progestin start on SD6 in place of an antagonist, and autotrigger when ≥3 follicles are projected to be ≥18 mm. Routine protocols (antagonist, microdose flare) include up to maximum-dose gonadotropins, 5-6 ultrasounds, and 3-5 blood draws. Main Outcome Measures: The primary outcome was the number of mature metaphase II oocytes (MIIs) retrieved. Secondary outcomes included the total number of oocytes retrieved and cryopreserved, premature ovulation, ovarian hyperstimulation syndrome (OHSS), cycle cancellation, and postretrieval surgical complications. Total charges including the cost of medications were noted. A postcycle survey compared satisfaction and sociodemographic factors influencing patient choice between the Cardinal vs. routine protocols. Results: Of 118 total participants, 60 enrolled in Cardinal and 58 opted for routine. No significant differences (i.e., in age, body mass index, race/ethnicity) existed between groups. A total of 137 cycles (70 Cardinal and 67 routine) were compared. The mean difference in MIIs between groups was +1.08 (95% CI -1.1 to 3.27), demonstrating noninferiority of the Cardinal protocol. Premature ovulation did not occur in either group. The OHSS rates were lower in Cardinal (2.9% vs. 23%); no other significant differences in adverse events were noted. The median charge for a Cardinal cycle was $5,004 lower than that of routine protocols. Postcycle surveys (73% response rate) demonstrated higher satisfaction with Cardinal at 85% vs. 65%, driven by cost and convenience. Conclusions: The Cardinal protocol appears to be a noninferior option to routine protocols. It considerably reduced charges by $5,000 without a decrease in MIIs retrieved, making it a cost-conscious protocol that should be seriously considered for OC cycles. The Cardinal protocol was overall satisfactory for patients who selected this over the routine protocols, notably across diverse sociodemographic groups. Trial registration: NCT05842070; https://clinicaltrials.gov/study/NCT05842070.

Indexed as

access-to-careCardinal protocolLow-costoocyte cryopreservationprogestin protocol

Identifiers

PMID42630557
PMCPMC13494622

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Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.