This descriptive cross-sectional retrospective study conducted from August 2024 to May 2025, used data from the medical records of 1986 eligible pregnant patients who required tracheal intubation during elective or emergency cesarean section at Women’s Wellness and Research Center Hamad Medical Corporation between January 1, 2016 and December 31, 2023.

Inclusion criteria were all pregnant patients aged $\ge$18 years, with American Society of Anesthesiologists (ASA) class II or III, undergoing tracheal intubation for cesarean section in our operating rooms. Patients were excluded if they were under 18 years of age, had an ASA class of IV or higher, or were intubated prior to entering the operating room.

Data were collected from the electronic medical records after approval from the institutional review board. Key variables included: (1) Demographic information including age, gestational age (GA), gravidity, parity, body mass index (BMI), comorbidities (anemia [10], hypertension and pre-eclampsia [11], thyroid issues [12], multiple sclerosis [13], anti-phospholipid syndrome [14], asthma [15], chronic obstructive pulmonary disease [COPD] [16], and diabetes mellitus [DM] [17]), categories of C-section, and indications for C-section including abruption, fetal distress, no progress, and previous C-section; (2) Preoperative assessment parameters such as ASA score, Mallampati score, Cormack Lehane score, and thyromental distance; and (3) Airway management data including training degree of the anesthetist. The training level of the intubator was categorized as trainee (resident/registrar) in anesthesiology undergoing supervised clinical training or senior (consultant/attending) anesthesiologist with independent practice. The number of intubation attempts, use of video laryngoscope or direct laryngoscope, laryngoscope blade number, use of stylet/bougie, drugs for general anesthesia, and intra-operative data including peripheral oxygen saturation (SpO₂), baseline, 5 and 15 minutes post endotracheal intubation heart rate (HR), 5 and 15 minute post endotracheal intubation mean arterial pressure (MAP) and end-tidal carbon dioxide (EtCO₂), peak airway pressure (PAP) after intubation, high-dependency unit, and intensive care unit (ICU) durations were also recorded.

The ASA Physical Status Classification System is a standardized tool used to assess and communicate a patient’s pre-anesthesia medical comorbidities. It categorizes patients as follows: ASA I—a normal healthy patient; ASA II—a patient with mild systemic disease or a normal pregnancy; ASA III—a patient with severe systemic disease; ASA IV—a patient with systemic disease that is a constant threat to life; ASA V—a moribund patient not expected to survive without the operation; and ASA VI—a declared brain-dead patient whose organs are being removed for donor purposes [18]. The Mallampati classification and Cormack–Lehane grading system are both used to assess airway difficulty. The Mallampati score is a preoperative bedside assessment based on the visibility of oropharyngeal structures, helping predict ease of endotracheal intubation. Class I—full visibility of the soft palate, uvula, and tonsillar pillars; Class II—soft palate and part of the uvula; Class III—base of the uvula; and Class IV—only hard palate [19]. The Cormack–Lehane grading system, used during direct laryngoscopy, classifies the laryngeal view. Grade I—full view of the glottis; Grade II—partial view of the glottis; Grade III—only the epiglottis visible; and Grade IV—neither glottis nor epiglottis visible [20]. Clinically, higher Mallampati classes and Cormack–Lehane grades indicate increasing difficulty in intubation and airway management.

The categories of C-section were defined according to hospital guidelines. Category 1 was defined as C-section is required as there is an immediate threat to maternal or fetal life. Category 2 was defined as C-section is required as there is a maternal or fetal compromise but not immediately life threatening. Category 3 was defined as C-section is required as there is a need for early birth, but no maternal or fetal compromise. Category 4 was defined as C-section is required at a time suitable for woman and the C-section team [21].

A standardized Case Report Form (CRF) was provided to the data collection team, who extracted information from the Hospital Cerner System. Under the direct supervision of the Principal Investigator (PI), the team recorded clinical data in the CRFs. All CRFs were anonymized using a coded system that excluded patient identifiers. The coded data sheet was stored exclusively on a secure, non-networked computer located in the PI’s locked office. The data were entered into a Microsoft Excel sheet on this secure, non-networked computer, specifically allocated for the study. Patient names were not recorded at any stage; instead, a unique alphanumeric code was assigned to each case.

Operating rooms in the Women’s Wellness and Research Center were categorized into Level 2 and Level 3, each assigned a specific letter code for anonymization:

Level 2:

• Women’s Wellness Level 2 C-section 01 $\to$ Code A.

• Women’s Wellness Level 2 C-section 02 $\to$ Code B.

Level 3:

• Women’s Wellness Level 3 C-section 01 $\to$ Code C.

• Women’s Wellness Level 3 C-section 02 $\to$ Code D.

• Women’s Wellness Level 3 gynecology (Gyne) 01 $\to$ Code E.

• Women’s Wellness Level 3 Gyne 02 $\to$ Code F.

• Women’s Wellness Level 3 Gyne 03 $\to$ Code G.

In the coding system, a unique nine-digit alphanumeric code was generated by combining six digits representing the day, month, and year of the procedure, followed by the operating room designation and the patient’s numerical sequence for that 24-hour period (00:00 to 23:59 hours). For example, the code 010718A06 represents the sixth patient in Room WW Level 2 C-Section 01 on July 1, 2018.

All statistical analyses were performed using SPSS version 22.0 (IBM Corp., Armonk, NY, USA). Continuous variables were presented as mean $\pm$ standard deviation (SD) for normally distributed data or as median with interquartile range [IQR] for non-normally distributed data, while categorical variables were summarized as frequencies and percentages. For inter-group comparisons, the t-test was applied to normally distributed continuous variables, and the Mann–Whitney U test was used for non-normally distributed continuous variables. Chi-square tests were employed to compare categorical variables. Logistic regression was used for categorical predictors, and reference category comparisons were reported using regression p-values. Correlation analyses were conducted using Spearman’s correlation method. All statistical tests were two-tailed, and a p-value 0.05 was considered statistically significant.

Table 1 summarizes the baseline characteristics of the 1986 eligible pregnant patients included in this study. The median age was 31 years, and the median BMI was 31 kg/m². The median gestational age was 38 weeks, whereas the median gravidity and parity were 3 and 1, respectively. Although the majority of patients (84.4%) reported no comorbidities, the most commonly reported condition was thyroid-related issues (6.8%), followed by anemia (4.6%) and hypertension (1.9%). Most patients had no history of asthma or COPD. Regarding DM, 73.2% had no history of the disease, while 26% had gestational DM (GDM).

Table 2 summarizes the preoperative assessment and intubation data of the study participants. The median thyromental distance was 6 cm (IQR 2–8 cm). Most patients were Mallampati class II (75.5%), followed by class III (14.9%), class I (6.9%), and class IV (2.7%); when grouped, 82.5% were Mallampati class I–II. Similarly, most patients were Cormack–Lehane grade II (70.3%) or grade I (22.7%), with only 7.0% classified as grade III–IV.

The majority of patients were ASA II (85.2%), whereas 14.8% were ASA III. Regarding urgency, more than half of C-section deliveries were Category 1 (51.1%), followed by Category 2 (23.2%), Category 4 (19.9%), and Category 3 (5.7%). The most common indications for C-section were previous C-section delivery (23.9%) and fetal distress (18.3%).

Most intubations were performed by senior anesthesiologists (86.1%). The median number of intubation attempts was 1 (IQR 1–4). A video laryngoscope was used in only 39 patients (2.0%), whereas direct laryngoscopy was used in the remaining 98.0%. Among laryngoscope blades, size 3 was most frequently employed (94.3%), followed by size 4 (5.2%) and size 2 (0.5%). Stylets or bougies were used in 7.7% of cases.

As shown in Table 3, among the 1986 patients, only 39 were intubated using a video laryngoscope. The mean gestational age was lower in patients who underwent video laryngoscope intubation. Following intubation, the mean peak airway pressure was slightly higher in this group compared to those intubated with a direct laryngoscope. Its use also varied based on the induction agent, with higher usage observed in patients receiving propofol. Furthermore, the percentage of Category 3 cases in whom video laryngoscope was used was higher than that of Category 1 cases.

A stylet or bougie was used in 153 patients, who had a lower mean gestational age. Its use was associated with higher post-intubation peak airway pressure as well as lower lowest SpO₂ during intubation. Stylet or bougie usage differed significantly by patient category, with higher usage in Category 3. Usage was also significantly greater among trainees compared to senior practitioners. Additionally, significant variation was observed based on medication type, with increased use among patients receiving propofol or other medications.

Among the study cohort, emergent cases (Categories 1–2) included 1015 patients in Category 1 (51.1%) and 461 in Category 2 (23.2%), totaling 1476 patients (74.3%), while non-emergent cases (Categories 3–4) comprised 114 patients in Category 3 (5.7%) and 396 in Category 4 (19.9%), totaling 510 patients (25.7%). Emergent cases accounted for approximately 74% of the cohort and demonstrated similar number of difficult intubations as non-emergent cases. Overall, VL and adjunct use remained rare in both groups, with slightly higher usage rates in non-emergent cases and higher post-intubation airway pressures (Table 4).

The number of intubation attempts was negatively correlated with the lowest SpO₂ during both intubation and extubation (Table 5). By contrast, PAP after intubation showed a significant positive correlation. Additionally, a significant difference in the number of attempts was found based on the induction agent used with patients receiving thiopental requiring a higher number of intubation attempts compared to those receiving propofol (p = 0.031).

While this study provides valuable insights, it had several limitations. First, the descriptive cross-sectional study design precludes any conclusions regarding causality. Second, the single-institution setting may limit generalizability of the findings to other settings or populations. Third, reliance on electronic medical records for data collection may result in missing or incomplete data, potentially affecting the accuracy of the results. Fourth, the study, by nature, did not account for possible confounding factors, such as variations in surgical technique or the presence of other comorbidities, which could influence the outcomes. The relatively small sample size for certain subgroups, such as those with a history of DM or those using specific medications, may limit the statistical power of the analyses. Further prospective, multicenter studies are needed to validate these findings and explore additional factors that may influence neonatal and maternal outcomes.

As this was a single-center retrospective study, the generalizability of our findings is limited. Variations in institutional resources, operator expertise, and patient populations across different centers may influence airway management practices and outcomes. Future multicenter, prospective studies with larger sample sizes are warranted to validate these findings. In addition, adjustment for potential confounding factors such as maternal comorbidities, GA, indication for cesarean section, anesthetist experience, and time of procedure would strengthen causal inferences. Incorporating multivariate analyses in future research could help clarify the independent contribution of each of these factors.