The association between indications for cesarean delivery and surgery time

We aimed to determine risk factors for prolonged surgery time of cesarean delivery (CD).

significant benefits such as improving surgery availability and ensuring appropriate operating time for surgeons. 3Several innovative techniques have been developed to improve operating room efficiency 4 including machine learning models. 5Determining the mean length of a specific surgery and a priori projection of potentially prolonged surgeries is crucial as it can improve scheduling and improve the efficient use of hospital resources. 3 ensure maternal and neonatal safety, recent studies have investigated the risk factors for prolonged decision-to-incision time and incision-to-delivery interval in CD. 6,7 However, the obstetrical risk factors for prolonged CD have not yet been thoroughly investigated.
Thus, the aim of the current study was to determine the risk factors for prolonged operation time during CD.

| Study population
We conducted a retrospective cohort study of all women who underwent CD in a single, university-affiliated tertiary medical center between January 2011 and April 2022.
Those who had missing data regarding the surgery time were excluded.All deliveries were categorized into two groups according to the surgery time: (a) surgeries that lasted ≥90 min, representing the 95th percentile of CD length in our cohort (prolonged CD, study group), and (b) surgeries that lasted <90 min (control group).
A comparison was made between the demographic and clinical characteristics as well as indications for CD between the two groups.

| Data collection
All medical charts were retrieved from computerized delivery room logbooks.The database encompassed demographic, obstetric, and clinical characteristics such as maternal age, body mass index (BMI), parity, gravidity, previous CD, gestational age at delivery, method of contraception, multiple pregnancies, and gestational diabetes (GD) in the index delivery.Moreover, CD features such as medical indications for the surgery were also included.
To ensure that all of the components that influence the total operating room time were accounted for, the surgery time was calculated from the patient's entry into the operating room until the completion of the surgery.Preterm delivery was determined as delivery prior to 37 weeks of gestation.Grand multiparity was defined as a history of five or more births (live or stillborn).Macrosomia was defined as an estimated newborn birth weight > 4000 g.Abnormal placentation was defined as one of the following: placenta previa, vasa previa, or placenta accreta spectrum.Patient request refers to cases in which there was no objective medical indication for CD.

| CD technique
At our university-affiliated hospital, we employ a modified Misgav Ladach method for performing CDs. 8These surgeries are carried out collaboratively by a team of residents and attending physicians.
Our standard protocol for abdominal closure is as follows: The uterus is meticulously closed using a double-layer technique with Vycril sutures.The closure of the abdominal fascia involves continuous suturing using either Vicril or PDS, while the subcutaneous layer is closed discontinuously if it measures >2 cm in depth.
The choice of skin closure, whether through subcuticular sutures, staples, or absorbable staples, is determined based on the surgeon's discretion.

| Statistical analysis
Univariate analysis techniques were used to identify differences between the groups.Two-tailed unpaired Student t test or Mann-Whitney test (in the case of nonnormally distributed variables) were used to assess the significance of continuous variables.In the same way, we used χ 2 test (or Fisher exact test, as needed) for categorical variables.A multivariable logistic regression model, controlling for variables that were found to be statistically different between groups, was used to determine the role of the independent variables.
The data were analyzed using SPSS software version 21.0 (IBM, Armonk, NY, USA).A P value <0.05 was considered significant.Data analysis was performed with an deidentified database.Therefore, informed consent was not needed.

| RE SULTS
During the study period, a total of 31 660 CDs were performed at our center, and 31 419 deliveries were eligible for analysis.Of these, 1397 (4.4%) lasted >90 min.The median length of time for CD in our study was 53 min (interquartile range, 44-64 min) with a 95th percentile of 90 min (Figure 1).
The demographic, obstetrical characteristics and surgery indications are detailed in Table 1.Women in the study group were older and had higher BMI compared with women in the control group (aged 35.5 vs. 34.4years and 24.8 vs. 22.9, respectively; P < 0.001).
In addition, women in the study group were more multiparous and had a higher prevalence of GD (2.8% vs. 1.1% and 23.1% vs. 17.1%, respectively; P < 0.001).
The main indication for CD was associated with the surgery time.

| Principal findings
In this study, we aimed to determine the risk factors for prolonged CD.Our principal findings were: (1) approximately 4.5% of CDs lasted >90 min; (2) no association was found between the degree of urgency and the duration of the surgery; (3) the main independent risk factors for prolonged surgery time are previous uterine scar and abnormal placentation; (4) preterm delivery, GD, and grand multiparity were also associated with prolonged surgery time; and (5) malpresentation, NRFHR, multiple gestation, and patient request for CD are indications that were found to be associated with surgeries that lasted <90 min.

| Our findings in the context of other observations
The length of a CD can vary and ranges from 30 to 60 min.It is influenced by several factors.Rottenstreich et al. reported a mean time of 30 to 66 min for repeat cesarean sections, 9 which is consistent with our findings.
Several risk factors, e.g., repeat procedures, adhesions, and obesity, have been investigated regarding cesarean surgery time in the context of time from incision to delivery, 7,10 due to its association with adverse neonatal outcomes.
In our study, we found that in-labor CD was not associated with a prolonged surgery time.However, we observed that urgent CD was linked to an increased rate of intraoperative complications, 11 and prolonged hospitalization following the procedure. 12This can be explained by the shorter preoperative surgical preparation.Nevertheless, intraoperative complications in such surgeries, including uterine atony, cystectomy, and need for intraoperative transfusion, lead to prolongation of the surgery in women with previous uterine scar who underwent urgent CD. 13 Regarding primary CD, no association was demonstrated between urgency and surgical complication. 14[17] Similarly, preterm CD is known to be associated with maternal complications such as infections, large blood loss, and even death, 18 probably due to surgical challenges caused by the thicker lower uterine segment that has a larger surface area of the transected myometrium.A recent review and meta-analysis by Cerra et al. reported a higher rate of intraoperative and postoperative complications in women who underwent preterm CD. 19 The described literature may explain the higher prevalence of prolonged CD in preterm deliveries in our study.
Spinal anesthesia has gained popularity for CD. 20Unlike in our study, no significant difference was found in the total operating room presence between spinal and general anesthesia for elective CD. 21General anesthesia is virtually exclusively used in emergency situations or when neuraxial anesthesia techniques have failed or are contraindicated. 22Moreover, in the case of women experiencing pain under neuraxial anesthesia, converting to general anesthesia is acceptable, especially in prolonged surgeries. 23This finding provides an explanation for the observed association between general anesthesia and prolonged CD time.
We also found some CD indications in the association with short surgery time.According to the American College of Obstetricians and Gynecologists (ACOG), maternal requests for CD and malpresentation account for about a fifth of the reasons for primary CD. 24,25Moreover, in our institution, CD is the initial mode of delivery for approximately 65% of multiple gestation pregnancies.Being in most cases an elective and primary indication for CD with favorable neonatal and maternal outcomes, it is reasonable that these two indications are associated with shorter CD times.

F I G U R E 1
The distribution of cesarean surgery time among the study population.

| Clinical implications
As mentioned above, CD has become one of the most popular surgeries in obstetrics.Surgery time has medical and economic implications.The risk assessment could allow for better identification of patients at risk for prolonged CD.In our institution, we have implemented a process to identify these patients, allowing us to effectively manage our operating room schedule.For example, we strategically schedule elective surgeries that are at risk for the prolonged duration during time slots when we have a more experienced surgical team available.Additionally, we make a conscious effort to avoid scheduling multiple surgeries with potentially prolonged durations simultaneously.In our view, in those patients, preoperative preparation and scheduling management may have an impact both medically and economically.

| Strengths and limitations
Our study has several strengths.First, as far as we know, this is the first study that investigated the risk factors for the prolongation of TA B L E 1 Demographic, obstetric, and labor characteristics of the studied population.total operating room time in CD.Second, the sample size allowed us to perform analysis with sufficient statistical power.Third, univariable analysis was performed to assess candidate variables as risk factors for prolonged CD, and multivariate logistic regression confirmed the independent associations of the different risk factors for that outcome.
However, it is important to note that our study is a retrospective cohort study, and as such, it has some limitations.For example, we were not able to control for all potential confounding factors, such as the experience and skill level of the surgeon.
In addition, our study was conducted at a single universityaffiliated tertiary medical center, and the results may not be generalizable to other settings.Furthermore, we investigated every indication as lone risk factor, not in combination with others as occurs in many CDs.In such cases, statistical interactions may be missed.
By utilizing the total operation time, we can consider the risk factors that could assist in scheduling the operating room time.
However, it is important to acknowledge that in certain cases, this approach may not accurately reflect the specific surgery time.For example, when patients have received prior anesthesia in the delivery room, it can introduce bias to our results, particularly when considering anesthesia time as a risk factor for prolonged CD.

| CON CLUS ION
This study identified general anesthesia, abnormal placentation, previous uterine scar, and preterm delivery as the main risk factors

CO N FLI C T O F I NTE R E S T S TATE M E NT
Authors state no conflicts of interest.
for prolonged surgery time during CD.By recognizing these risk factors, we hope to contribute to better decision-making and resource management, ultimately benefiting both patients and health care systems.Further research is needed to develop a risk score for prolonged surgery time.AUTH O R CO NTR I B UTI O N SDaniel Gabbai and Emmanuel Attali contributed equally, conducted the literature search, and drafted the manuscript.Yariv Yogev and Anat Lavie helped to conceptualize the study design and edited and revised the manuscript.All authors revised the article for important intellectual content and approved the final version submitted for publication.