“Classifications for Cesarean Section: A Systematic Review” (2011), by Maria Regina Torloni, Ana Pilar Betran, Joao Paulo Souza, Mariana Widmer, Tomas Allen, Metin Gulmezoglu, and Mario Merialdi

Maria Regina Torloni and colleagues published “Classifications for Cesarean Section: A Systematic Review,” hereafter “Classifications for C-sections,” in 2011 in the journal PLOS One. A Cesarean section, or C-section, is a surgical birth through an incision in the pregnant person’s abdomen and uterus. Across the world, medical professionals use many different C-section classification systems to group the procedures according to particular features of the medical situation, such as the person undergoing the C-section or their specific medical needs. The authors of “Classifications for C-sections” systematically review the various available classification systems and evaluate them to identify their strengths and weaknesses. In “Classifications for C-sections,” the authors stress the need for a standardized classification system that experts can use to communicate internationally and address the health needs of pregnant people seeking C-sections.

1. Background
2. Article Contents
3. Impacts

Background

The authors of “Classifications for C-sections” primarily work in obstetrics and gynecology, with many of them working for the World Health Organization, or WHO. Torloni has a medical degree and doctorate and, as of 2025, works as a researcher in the Department of Obstetrics, the field of medicine concerned with pregnancy, labor, and delivery, at São Paulo Federal University in São Paulo, Brazil. Ana Pilar Betran, a co-author of the article, works in the Department of Reproductive Health and Research for the WHO. After writing “Classifications for C-Sections,” Torloni and Betran co-authored the “WHO Statement on Caesarean Section Rates” in 2015, which documents the rise of international C-section rates. In that paper, Torloni and Betran argue that physicians should only perform C-sections when necessary. Of the other authors of “Classifications for C-sections, Joao Paulo Souza, Mariana Widmer, Metin Gulmezoglu, and Mario Merialdi also work in the WHO Department of Reproductive Health and Research. Tomas Allen works in the WHO Department of Knowledge Management and Sharing.

Article Contents

“Classifications for C-sections” has four sections. In the first section, “Introduction,” the authors argue that there is a need for a C-section classification system that physicians and public health authorities internationally can use. They state that the objective of their study is to identify the C-section classification systems that, at the time, were available and compare the benefits and drawbacks of each system. In the second section, “Methods,” the authors explain how they gathered the classification systems they reviewed and how they created the evaluation tool they used to rate the characteristics of each system. In the third section, “Results,” the authors discuss that they can group existing classification systems by whether they focus on conditions that call for C-section, urgency, patient characteristics, or other aspects of a C-section. They examine the benefits and drawbacks of each type of system and discuss how some work better than others in different situations. In the fourth section, “Discussion,” the authors explain the qualities of classification systems that make them easier to use and apply in-depth and that there is no system that, at the time, currently exists to meet the needs of medical professionals internationally.

In the “Introduction,” the authors explain that C-sections are common internationally but that there is no standard classification system to describe the surgeries. They explain that different countries have different rates of C-sections and that a standardized classification system can help gather and compare C-section data from around the globe. The authors express that such a system would allow healthcare professionals around the world to make decisions on ways to increase or decrease C-section rates depending on the needs of the area. Torloni and colleagues state that the objectives of their article include identifying the available classification systems and comparing how useful classification systems are for medical professionals based on expert criteria.

In the “Methods” section, the authors explain that they surveyed C-section experts to create an evaluation tool to assess the classification systems. The authors asked forty-six experts to grade a series of characteristics based on what they think the most important features of a classification system are. The experts rated characteristics across four broad groups. The first group included characteristics, such as how easy the classification was to understand, how reproducible it was, meaning whether different physicians would classify different situations in the same way, and how clearly defined the classification system’s categories were. The second group of characteristics had to do with how easy a classification system might be to use, including whether using the classification system required training or extra equipment to apply the system to real patients. The third group of characteristics had to do with how useful a classification system might be to different groups of people, from medical professionals to public health researchers. The fourth group of characteristics had to do with the number and content of categories in a classification system.

In the second part of the “Methods” section, the authors explain that they found classification systems from multiple databases that classified low-risk and general C-sections and tested the classification systems according to how well they could be applied to real-life scenarios. The systems also had to be detailed enough that anyone using them could understand how to classify patients. The authors searched through multiple databases to find classification systems from around the world in all different languages. Two investigators screened all the papers with potentially relevant classification systems that they found in the database. They selected only the classification systems that fit the criteria above and graded them on how well they fulfilled the criteria as well as how easy they were to use. The researchers created twelve hypothetical scenarios of different people getting C-sections for different reasons to test each classification system further. Then, the two reviewers categorized the twelve scenarios according to each classification system, which allowed the researchers to see if each of the twelve cases fit into categories defined by the classification systems as well as if both reviewers classified the scenarios in the same way.

In the “Results” section, the authors describe what they found as the most helpful and detrimental aspects of each classification system. The experts rated the characteristics from one to nine, nine being the most essential for a quality classification system. The characteristics the experts rated most highly were that the system helps physicians make clinical decisions and the system has clearly defined, straightforward categories. The authors used the expert responses to create an evaluation system that they used to determine the effectiveness of the twenty classification systems they studied.

Continuing in the “Results” section, the authors describe that they sorted the twenty classification systems into four categories, including indication-based, urgency-based, women characteristics-based, and “other” systems. Indication-based systems grouped C-sections based on the patient’s indication, or the reason the patient needs a C-section. The authors list that one of the main benefits of indication-based systems is that a hospital's patient information typically includes the types of indications necessary to classify them, which makes the necessary information easily accessible. The drawbacks that the authors identify are that there are no strict definitions for the indications, which makes them confusing, and that some of the indications are not mutually exclusive. Patients could fit into more than one category.

The second category they identified was a degree of urgency-based systems, which classify C-sections based on when it is necessary to perform them. Torloni and colleagues express that the pros of such a system are that it could improve communication between physicians. However, the staff would need to be trained and they would need clear definitions and distinctions between terms like “urgent” and “emergent.”

The third category the authors found was women-based classification systems, which focus on who is undergoing the C-section. Women-based systems consider whether the woman has been pregnant previously and whether it is her first C-section. The benefits of women-based systems are that the categories include most patient types and are less prone to overlap. Additionally, the authors report that the information needed to use the classification system is easily accessible, and the categories are easily comprehensible and clearly defined. The main drawback identified is that women-based classification systems do not list the reason for C-sections.

The authors call the final category “other” classification systems, which include various systems that reveal who may be performing the C-section, or specific circumstances for the procedures. Some of the benefits include that such systems can contain some information about contributing factors that affect the pregnant person and fetus that are overlooked by the other classification systems. One potential drawback is that the data necessary for classifying the patient might not be easily accessible. Some need more clearly defined categories.

In the “Discussion” section, the authors explain that the experts most highly rated the scoring systems that were clear and understandable to help the professionals who use them and they can standardize terms and characteristics to aid in international research. In the indication-based classification systems, expert disagreements in classifying the twelve theoretical scenarios caused the reproducibility to be low. In the degree of urgency systems, the timing difference between each category was difficult to compare and therefore difficult to reproduce. The authors found that the women-based characteristics classification systems could change the way practitioners admit and classify patients. They could classify a patient upon admission and increase understanding among all the physicians involved. The authors argue that the “other” classification systems could not apply to all situations and were too specific to standardize.

Continuing in the “Discussion” section, the authors rated indication-based and women-based classification systems the highest. The best-scoring indication-based systems had clearly defined categories and specific rules on how to classify each case. The best-scoring women-based systems were also easily adaptable to different medical settings. The authors suggest they could be useful to increase or decrease C-section rates. They explain that their overall findings were that no perfect classification system exists that can fulfill the needs of all different types of healthcare professionals that might need it. However, the Robson classification system, a women-based system, had the highest scoring characteristics based on the expert criteria. The authors articulate that in the future, researchers could develop a hybrid system that includes the Robson model for many international needs.

Impacts

As of 2025, different authors researching C-sections have cited “Classifications for C-sections” over 580 times. Other researchers of the WHO used the article to determine the best existing classification system for their needs. Other researchers investigating rising C-section rates internationally have also cited the article. According to the WHO, the rise in C-section rates has caused concern among health professionals and organizations across the world. The authors of “Classification of C-Sections” worked toward finding a way to standardize terms and classifications that can be used for C-sections worldwide.

The authors of “Classifications for C-sections” identified a need for a standardized international classification system for C-sections. Through their research, Torloni and colleagues identified the most useful characteristics of a C-section classification system, including straightforward categories and usefulness in physician decision-making. Additionally, the researchers proposed adopting something similar to a women-based C-section classification system to work as a standardized, international system. The authors express that accessible to all healthcare professionals, leading to more comprehensive and wide-ranging research about C-sections and C-section rates.

Sources

1. Betran, A. P., M. R. Torloni, J. J. Zhang, A. M. Gülmezoglu, and the WHO Working Group on Caesarean Section. “WHO Statement on Caesarean Section Rates.” British Journal of Obstetrics and Gynaecology 123 (2015): 667–70. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5034743/ (Accessed March 31, 2025).
2. Boerma, Ties, Carine Ronsmans, Dessalegn Y. Melesse, Aluisio J. D. Barros, Fernando C. Barros, Liang Juan, Ann-Beth Moller, Lale Say, Ahmad Resa Hosseinpoor, Mu Yi, Dácio de Lyra Rabello, and Marleen Temmerman. “Global Epidemiology of Use of and Disparities in Caesarean Sections.” The Lancet 392 (2018): 1341–8. https://researchonline.lshtm.ac.uk/id/eprint/4649993/1/Boerma_etal_2018_The%20global%20epidemiology.pdf (Accessed March 31, 2025).
3. Johns Hopkins Medicine. “Cesarean Section.” Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/cesarean-section (Accessed March 31, 2025).
4. Torloni, Maria Regina, Ana Pilar Betran, Joao Paulo Souza, Mariana Widmer, Tomas Allen, Metin Gülmezoglu, and Mario Merialdi. “Classifications for Cesarean Section: A Systematic Review.” PLoS One 6 (2011): e14566. https://pmc.ncbi.nlm.nih.gov/articles/pmid/21283801/ (Accessed March 31, 2025).