Cervical pessary plus vaginal progesterone in a singleton pregnancy with a short cervix: an experience-based analysis of cervical pessary’s efficacy

Abstract

Background

Several studies were published about cervical pessary, with controversial results. These studies demonstrated that the patient follow-up after pessary insertion is very different between the study centers and the number of pessary insertions per center was often <30 cases. This study aims to determine cervical pessary performance in singleton pregnancies with a short cervix based on a single center learning curve.

Methods

Between 2011 and 2018, 128 singleton pregnancies between 18 and 24 gestational weeks with a short cervix (<25 mm) were referred to our clinic. All cases were treated with progesterone, and when available in our supplies (due to low resources) cervical pessary was also offered. Three groups were created for statistical analysis: Group 1 (n = 33), treated with progesterone-only; Groups 2 and 3, treated with cervical pessary plus progesterone. Group 2 included the first cases (n = 30) of pessary, defined by a learning curve and cumulative sum analysis, while Group 3 included the subsequent 65 cases. The primary outcome was preterm birth (PTB) < 34 gestational weeks.

Results

The learning curve was performed with all cases of pessary plus progesterone, and 30 patients were obtained as the number needed for learning, in our study with two operators. The PTB rate < 34 weeks was 27.3, 20, and 4.6% in groups 1, 2, and 3, respectively. There was no significant difference between Group 1 and 2 (OR 1.1; 95% CI 0.066 − 18.45; p = .945). When comparing Groups 1 and 3 there was a significant difference in PTB rates (OR 0.08; CI95% 0.01–0.42; p = .003). Considering Kaplan-Meyer Survival analysis, we can observe that the performance of progesterone alone (Group 1) was similar to Group 2 (progesterone + first 30 cases of pessary) (p = .432), but the performance of Group 3 (progesterone + subsequent 65 cases of pessary) and Group 1 shows a statistically significant difference (p = .011).

Conclusion

Learning curve and cumulative sum analysis determined that the application and surveillance of at least 30 patients is required to see significant improvements in the primary outcome of PTB < 34 weeks.

Keywords:

• Preterm birth
• learning curve
• cervical pessary
• vaginal progesterone
• short cervix

Acknowledgments

We would like to thank Ingámed and Dr. Carlos Gilberto Almodin for offering without cost a part of the cervical pessaries used in this study. We would also like to thank the Health and Medical Equipment Division of Samsung Brazil for offering the WS80A ultrasound system we used to perform the exams during the study. We are also grateful to Mr. Rudolf Wiedemann for his support with the present article's English version.

Ethical approval

This study was approved by the Ethics Committee of The Federal University of São Paulo (Plataforma Brasil http://plataformabrasil.saude.gov.br) number CAAE 30873613.8.0000.5505, on 3rd Sep 2014, with an amendment on 8th Aug 2020.

Trial registry

Brazilian Clinical Trial Registry (ReBec) RBR-46rgjc, UTN: U1111–1254-6356, on 2nd Jul 2020.

Contribution to authorship

The authors’ contribution, the interpretation of the data, the article's writing, the critical review of the intellectual content, and the final approval of the version to be published were similar. All authors accept responsibility for the paper as published.

Disclosure statement

The authors report no conflict of interest: Including relevant financial, personal, political, intellectual, or religious interests.

Additional information

Funding

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001.