Introduction
Cesarean delivery is a common surgical procedure, accounting for over 30% of births in the United States.[ 1 ] Of these, 22% involved primary cesarean deliveries (first cesarean delivery in the parturient’s lifetime), while 78% were repeated cesarean deliveries.[ 1 ] Primary cesarean delivery was associated with higher odds of developing persistent pain at 3 and 6 months compared to repeat cesarean delivery.[ 2 ] Persistent pain is defined as new onset pain that is localized to the surgical area and persists beyond three months after the exclusion of other potential causes of the pain.[ 3 ] It is present in approximately 30% of women after childbirth[ 4 ] and significantly impacts general activities, mood, and enjoyment of life.[ 2 , 5-7 ]
Although it is unclear why parturients who underwent primary cesarean delivery are at elevated risk of persistent pain, it is possible that the presence of pain and psychological vulnerability risk factors may predispose them toward persistent pain development. There is an accumulating body of evidence that increased maternal pain catastrophizing, central sensitization, pre-existing pain, anxiety, and depression are associated with the development of persistent pain after childbirth.[ 8 , 9 ] However, few studies have investigated whether these risk factors were associated with primary cesarean delivery, which may in turn provide insight into the etiology underlying the increased risk of persistent pain development in these parturients. Hence, our objective was to determine whether pre-operative maternal pain and psychological vulnerability factors such as pain catastrophizing (primary association variable), depressive symptoms, central sensitization, anxiety, anticipated pain intensity, and anticipated analgesic requirement are associated with primary cesarean delivery (primary outcome measure).
Materials and Methods
This is a secondary analysis of a prospective cohort study to identify pain and psychological vulnerability factors associated with maternal emesis following cesarean delivery. After ethical approval, this study was conducted between May 2018 and April 2019 at a local specialist maternity hospital. Written informed consent was obtained from all parturients. We included parturients aged 21–50 years old, above 36 gestational weeks, American Society of Anesthesiologists physical status 2, and undergoing elective cesarean delivery under neuraxial anesthesia. Parturients with a history of intravenous drug or opioid abuse, previous history of chronic pain syndrome, undergoing emergency cesarean delivery or general anesthesia, and those who were unable to communicate in English were excluded. This article adheres to the Strengthening the Reporting of Observational studies in Epidemiology guidelines.
Pre-operative data collected include PCS scores, a validated tool to evaluate negative and catastrophizing thoughts regarding anticipated or experienced pain that consists of 13 questions evaluating three aspects of catastrophizing: rumination, magnification, and helplessness.[ 10 ] We also administered the hospital anxiety and depression scale (HADS), a validated assessment for anxiety and depression[ 11 ] ; central sensitization inventory (CSI), a validated modality to evaluate central sensitization symptoms[ 12 ] ; and Edinburgh postnatal depression scale (EPDS), a self-reporting screening tool for depressive symptomatology.[ 13 ]
Additionally, the following questions were assessed, as previously described[ 14 ] : (1) self-reported anxiety about upcoming surgery: “on a scale of 0–100, with 0 being not anxious at all and 100 being extremely anxious, how anxious are you about your upcoming surgery?”; (2) anticipated pain score: “on a scale of 0–100, with 0 being no pain at all and 100 the most severe pain that you could imagine, how much pain do you anticipate experiencing after your upcoming surgery?”; and (3) anticipated pain medication requirement: “on a scale of 0–5, with 0 being none at all, and 5 being much more than average, how much pain medication do you anticipate needing after your upcoming surgery?” Parturients who scored higher with these three questions were associated with greater acute pain scores after cesarean delivery[ 14 ] and increased risk of developing persistent pain.[ 8 ] Pain score (numerical rating scale, 0: no pain; 10: worse pain imaginable) with local anesthetic infiltration with lignocaine prior to spinal needle insertion for spinal anesthesia was also assessed.[ 15 ]
Clinical management for cesarean delivery was standardized across all parturients. In brief, all parturients received antacids pre-operatively for aspiration prophylaxis. Spinal anesthesia to T4-5 dermatomal level was achieved with intrathecal 0.5% hyperbaric bupivacaine 11–12.5 mg, fentanyl 15 µg, and morphine 100 µg. All parturients received a Pfannenstiel skin incision and transverse uterine incision. Paracetamol and mefenamic acid were administered on a scheduled basis for postoperative analgesia, with tramadol available upon request for additional analgesia.
The primary outcome measure of “primary” or “repeat cesarean delivery ” was treated as a binary variable. Categorical and continuous variables were summarized as frequency (proportion) and mean with standard deviation (SD). All association variables were summarized in terms of the primary outcome measure. Univariate and multivariable logistic regression analyzes were performed to identify variables associated with the primary outcome. Quantitative associations from logistic regression were expressed as odds ratio (OR) with corresponding 95% confidence intervals (95% CI). Variables with a P -value of <0.05 in the univariate analysis were chosen for multivariable regression analysis, followed by a stepwise variable selection method to finalize the multivariable model. The area under the curve (AUC) of the receiver operating characteristics curve based on the final multivariable model was used to evaluate its overall performance. P -values <0.05 were considered statistically significant, and all tests were two-tailed. SAS version 9.4 software (SAS Institute, Cary, North Carolina) was used for all analyzes.
Results
A total of 220 parturients were included in this secondary analysis, with 75 (34%) having undergone primary cesarean delivery and 145 (66%) repeat cesarean delivery. All parturients completed the pre-operative assessments and were included in multivariable model development [Figure 1 ]. Among those who underwent primary cesarean delivery, 14 (18.7%) were multiparous. No significant difference in baseline characteristics was noted between parturients who underwent primary versus repeat cesarean delivery [Table 1 ].
Figure 1:: Study flow diagram
Table 1:: Univariate analysis of baseline parturient characteristics
Univariate associations of primary cesarean delivery are summarized in Table 2 . Increased pre-operative total PCS scores (OR 1.04, 95% CI 1.01–1.08), in addition to increased rumination (OR 1.09, 95% CI 1.02–1.16), magnification (OR 1.12, 95% CI 1.02–1.27), and helplessness (OR 1.10, 95% CI 1.03–1.16) sub-scale scores were significantly associated with primary cesarean delivery.
Table 2:: Univariate analysis of pre-operative pain and psychological factors associated with primary versus repeat cesarean delivery
Multivariable analysis of pre-operative pain and psychological vulnerability factors identified higher PCS helplessness sub-scale scores (adjusted OR (aOR) 1.10, 95% CI 1.03–1.17) and absence of medical comorbidity (defined as absence of chronic medical conditions at the time of assessment, aOR 1.87, 95% CI 1.00–3.50) as independent association factors with primary cesarean delivery, with an AUC of 0.67.
Discussion
This study comparing primary versus repeat cesarean delivery identified higher pre-operative PCS helplessness sub-scale scores and absence of maternal medical comorbidity as independent association factors with primary cesarean delivery. Higher pre-operative PCS total score and higher PCS rumination and magnification sub-scale scores were associated with primary cesarean delivery only in univariate analysis.
Pain catastrophizing has been described as the rumination of exaggerated negative cognitions and emotions pertaining to pain.[ 16 ] The etiology underlying the association between higher pre-operative pain catastrophizing and primary cesarean delivery is unclear, although it was shown that parturients with high catastrophizing preferred cesarean over vaginal delivery, likely due to fear of pain and the childbirth process.[ 17 ] It is also possible that prior favorable experience with cesarean delivery may have mitigated this fear of pain, therefore resulting in lower PCS scores with repeat surgery. Given that higher pain catastrophizing was associated with the development of persistent postsurgical pain and may therefore contribute to increased risk of developing persistent pain following primary cesarean delivery, early identification of catastrophizing and pre-emptive management of parturients’ pain expectations may be beneficial.[ 8 , 18 , 19 ]
The absence of medical comorbidity was found to be independently associated with primary cesarean delivery. Although parturients with obesity and diabetes are more likely to require cesarean delivery,[ 20 ] few studies compared primary versus repeat cesarean delivery in terms of pre-operative maternal comorbidity. Nonetheless, the absence of comorbidity is unsurprising given that fetal malpresentation, and not medical comorbidity, is the one of the most common indications for elective primary cesarean delivery.[ 21 ]
Our study contributes to the limited body of evidence pertaining to the association of pain and psychological vulnerability factors with primary cesarean delivery. Nonetheless, we acknowledge several limitations. First, our analysis included only parturients who underwent elective cesarean delivery, and the results may not be applicable to unscheduled or emergency cesarean delivery. Also, our study design precluded analysis of other potential confounders such as poor social support, unplanned pregnancy, and pre-existing pain.[ 22 ] To address these limitations, a larger prospective study evaluating a wide range of potential pain and psychological risk factors should be performed to elucidate their associations with primary cesarean delivery.
Conclusion
Increased pain catastrophizing and absence of medical comorbidity are independently associated with primary cesarean delivery. Parturients undergoing cesarean delivery for the first time may therefore benefit from early identification of pain catastrophizing and pre-emptive counseling of pain expectations to optimize perioperative analgesia.
Acknowledgement
We would like to thank Ms Agnes Teo (Senior Clinical Research Coordinator) for her administrative support in this work. This study received approval by SingHealth Centralized Institutional Review Board (Ref: 2017/2381) on June 22, 2017, with retrospective registration on Clinicaltrials.gov (NCT03645239) on August 24, 2018.
Financial support and sponsorship
This work was supported by the funding from the SingHealth Duke-NUS Academic Medical Centre, Anesthesiology and Perioperative Science Academic Clinical Program Pilot Research Grant (Grant no. ANAESPRG18/02). The aforementioned sponsors were not involved in the study activities.
Conflicts of interest
There are no conflicts of interest.
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