1. Introduction
Over several decades, there was a steady increase in the percentage of completed births by cesarean section globally [
1]. Pain following cesarean section is somatic and visceral in nature and its inadequate treatment has both short- and long-term possible consequences, such as reluctance to feed the newborn, impaired early ambulation, reduced willingness for future pregnancies, or symptoms of chronic pain in the abdomen and pelvis [
2]. Therefore, the optimal control of pain remains an important aspect of postoperative care in cesarean section [
3]. Regional blocks in the anterolateral abdominal wall performed under ultrasound guidance are currently an important pillar in multimodal analgesia after cesarean section [
4]. The most commonly performed regional fascial plane blocks are the transversus abdominis plane block (TAPB) and the quadratus lumborum block (QLB) [
5]. Multiple randomized controlled trials and meta-analyses concerning the use of these fascial blocks and wound infiltration techniques have shown a reduction in opioid consumption in the first 24–48 h following a cesarean delivery [
6]. Other tools used to evaluate the effectiveness of analgesic therapy are postoperative pain scores, such as the Visual Analogue Scale (VAS) or Numerical Rating Score (NRS), which assume that a result of up to 3 points in an 11-point scale suggests analgesia is appropriate [
7]. However, a good NRS or VAS result does not prompt health care providers to reflect on whether the therapy is satisfactory and could be better managed in the future. To date, few authors of randomized, controlled studies in the field of regional anesthesia for cesarean section evaluated patient satisfaction or conducted a survey of the effectiveness of their actions as seen through the eyes of the patients [
8]. Moreover, few authors attempted to assess the incidence and severity of chronic postsurgical pain (CPSP) in this group of patients [
9].
We hypothesized that QLB type I, as part of a multimodal analgesic treatment, would result in higher patient satisfaction and would decrease the incidence of chronic postsurgical pain, as assessed by the questionnaires taken after 48 h following a cesarean section and at 6 months from surgery in comparison to patients who did not receive a block. The aim of this study was to test these hypotheses and to observe any additional positive effects in postoperative pain treatment in patients undergoing elective cesarean section under spinal anesthesia.
4. Discussion
Parturients undergoing cesarean section are a unique group of patients in terms of optimizing postoperative pain relief [
3]. On the one hand, the surgical technique induces acute somatic and visceral pain with an intensity reported by patients as moderate to severe, and on the other hand, there is a risk associated with the use of analgesic techniques on breastfeeding the newborn, as well as the need for early ambulation [
14]. Additionally, there is a concern regarding chronic postsurgical pain with new interest in the effect of regional blocks on its incidence and severity [
15].
For decades, both opioid and non-opioid analgetic drugs were the mainstay in the treatment of postoperative pain after cesarean section [
16]. However, taking into account a series of clinical studies, as well as meta-analyses, the clinician planning pain treatment should limit the amount of opioid administered in accordance with multimodal strategies [
17]. Techniques implementing local anesthetics were used as part of this therapy, such as intravenous infusions, wound infiltration or, above all, ultrasound-guided regional blocks independent of the surgical incision [
18]. Currently, as reported by multiple randomized controlled trials and meta-analyses, the QLB block, regardless of the approach and with the possible exception of the intramuscular block, is a very effective tool in combating postoperative pain seen in the reduction in opioid consumption and pain intensity following cesarean section [
19].
In our study, we investigated whether QLB type I was effective in improving satisfaction with postoperative pain treatment among parturients after cesarean section and its effect on the incidence of postsurgical chronic pain. In the year 2014, when the study was designed, QLB type I with a lateral approach technique was the first described point of injection by Blanco et al. and was, therefore, chosen by the authors [
10]. Since then, several new approaches of QLB have been described, but the exact mechanism of the analgesic effect of quadratus lumborum block remains under anatomical, radiological, and neurophysiological investigation [
20]. The main focus of most studies assessing the effectiveness of QLB and intrathecal morphine (ITM) is opioid consumption, time to first analgesia, and pain severity in standardized pain scores (NRS, VAS, or NPSI—Neuropathic Pain Symptom Inventory) [
1,
2,
3,
4,
21]. These studies indicate that most effective method in postoperative pain control after cesarean section remains the administration of ITM also when compared with QLB. Its advantages over ultrasound-guided regional blocks are the ease of use, time needed for administration when performing a spinal block, and the minimum amount of additional equipment and materials used. However, one should remember the possible side effects of intrathecally administered morphine, such as delayed respiratory depression (up to 24 h after administration), pruritus, sedative effect, nausea, and vomiting [
22]. Limited numbers of clinical trials evaluate patient satisfaction with the chosen method of postoperative pain control, such as ITM following a cesarean section and its impact on persistent pain [
8,
23].
Salama et al. assessed satisfaction with analgesia in a three-point scale between patients receiving QLB, patients receiving no block, and a third group of patients receiving intrathecal morphine [
8]. In the QLB group, 100% of patients rated highly satisfied and satisfied. These findings are in line with our results which also add up to 100% satisfaction. In comparison, the percentage of patients dissatisfied with the pain treatment without a block in the study by Salama et al. was 16.6% and in our study, it was 13.3%. Despite the statistically significant lower consumption of morphine and NRS scores in the ITM group compared to the control, 30% of patients were dissatisfied with the postoperative pain management. Referring to the high efficacy of intrathecal morphine as seen in multiple published meta-analyses, the last result places the choice of intrathecal morphine under debate [
8,
24]. The three-point scale for assessing satisfaction with pain treatment was also used by other authors [
25,
26]. The assessment of postoperative pain therapy (based on the standard, most common criteria) does not necessarily correlate with the feeling of satisfaction among parturients with the proposed treatment. Therefore, according to the authors of this paper, not only the total amount of analgetic drugs used, but also the quality of the method of treating acute postoperative pain should be a priority.
We would like to underline the answers provided in the questionnaire after 48 h of treatment by a subgroup of parturients in our trial. All the patients in the QLB group who had a cesarean section in the past without an ultrasound-guided regional anesthetic block stated that they would like to have QLB performed again for a future cesarean section or other abdominal surgery.
Another rarely assessed, but important aspect of patient quality of life following surgery is the occurrence of chronic postsurgical pain (CPSP), which is considered one of the most common surgery-related complications [
23,
27]. The definition of CPSP involves postsurgical pain of more than 3-months duration that is new when compared to the preoperative status, and the cause is not secondary to an identifiable reason such as infection [
28]. The most important risk factors for developing CPSP in parturients undergoing cesarean section are female gender, young adult age, and the severity and duration of acute postoperative pain [
29]. The exact mechanism of CPSP is still under debate and no targeted treatment is available at this time [
30]. Although the occurrence of CPSP following cesarean section is lower than for other types of surgery [
2], the constant increase in the number of cesarean sections globally makes CPSP a possible growing problem [
31]. To date, few studies have been published assessing the possible effect of regional anesthesia on the occurrence of CPSP in patients after cesarean section [
2,
9,
23].
In our study, the incidence of CPSP in the surgical incision area after 6 months from the cesarean section was lower in the QLB I group when compared to the control group (1/28 to 5/30, respectively), but this was not statistically significant (
p = 0.102). This result correlates with those published by Borys et al., in which statistically significant differences between all groups were not seen after 3 and 6 months from the cesarean section, but such differences were noted only after 1 month [
2]. However, authors of the above-mentioned study showed a statistically significant difference in the assessment of chronic pain severity at 1 and 6 months when the QLB group was compared to the control group. We did not assess the intensity of CPSP in this study, which is one of our limitations [
2].
The presented study has other limitations. Failure to use patient-controlled analgesia (PCA) methods due to the lack of equipment at the time of the trial and subcutaneous morphine administration might have affected patient satisfaction. Another limitation was the fact that only staff taking care of the parturient after cesarean section (nurses and obstetricians) were blinded, which could have led to bias. A more direct comparison could have been made between the QLB I group and the control group if a sham block was administered. Statistical analysis of the answers to the questionnaire after 48 h from surgery was not performed due to the low number of answers provided by the involved participants.