Nigerian Journal of Clinical Practice

ORIGINAL ARTICLE
Year
: 2022  |  Volume : 25  |  Issue : 4  |  Page : 473--477

Shoulder tip pain after cesarean section: General versus spinal anesthesia


F Simsek1, U Kara1, ME Ince1, E Sir2, S Eksert1, G Ozkan1, S Senkal1,  
1 Department of Anesthesiology and Reanimation, Gulhane Training and Research Hospital, University of Health Sciences, Ankara, Turkey
2 Department of Algology and Pain Medicine, Gulhane Training and Research Hospital, University of Health Sciences, Ankara, Turkey

Correspondence Address:
Dr. F Simsek
Department of Anesthesiology and Reanimation, Gulhane Training and Research Hospital, Ankara - 06010
Turkey

Abstract

Background and Aim: Shoulder tip pain is a common but overlooked complication during the postoperative cesarean section. In this study, we aimed to investigate the relationship between the anesthesia method and the incidence of shoulder tip pain. Patients and Methods: In this randomized clinical study, 117 patients who underwent cesarean section were divided into two groups as spinal anesthesia and general anesthesia. The demographic characteristics, the presence, the severity of shoulder tip pain, and also analgesic consumption in the first 24 hours were compared. Results: The incidence of shoulder tip pain was significantly higher in the spinal anesthesia group than in the general anesthesia group (p = 0.032). While there was no statistically significant difference in terms of the number of patients who needed opioid treatment within the first 24 hours between patients with and without STP, a statistically significant difference was observed in terms of the use of nonsteroidal anti-inflammatory drugs (p < 0.001). Conclusions: This study shows that the frequency and severity of shoulder pain are higher in women who have had cesarean section under spinal anesthesia, compared to those who had received general anesthesia.



How to cite this article:
Simsek F, Kara U, Ince M E, Sir E, Eksert S, Ozkan G, Senkal S. Shoulder tip pain after cesarean section: General versus spinal anesthesia.Niger J Clin Pract 2022;25:473-477


How to cite this URL:
Simsek F, Kara U, Ince M E, Sir E, Eksert S, Ozkan G, Senkal S. Shoulder tip pain after cesarean section: General versus spinal anesthesia. Niger J Clin Pract [serial online] 2022 [cited 2022 Jul 7 ];25:473-477
Available from: https://www.njcponline.com/text.asp?2022/25/4/473/343453


Full Text



 Introduction



Cesarean section (CS) is one of the most common surgical interventions conducted on women worldwide.[1] As it is an invasive procedure, it can result in a number of complications such as hemorrhage, postoperative pain, atelectasis, nausea, vomiting, and wound infection.[1],[2] Shoulder tip pain (STP) is also a common complication that occurs after CS, but is often overlooked and not properly treated.[3] The reported incidence of STP following laparoscopic surgery is between 35% and 65%.[4] The mechanism of STP has not been fully elucidated. However, the most frequently blamed mechanism is the physical and chemical stimulus on the diaphragmatic muscles and the phrenic nerve caused by CO2, which is used during the laparoscopic method.[5],[6] Accordingly, STP after CS has an incidence between 30% and 50% and has been described as a sharp pain by affected patients.[7] It is believed that blood or amniotic fluids leaking into the abdomen during cesarean section and accumulating under the diaphragm may be responsible for STP.[8] There are some studies showing that the anesthesia method applied to the patient is also effective in the development of STP.[3],[8] These studies reported that the incidence of shoulder pain is higher in pregnant women who underwent general anesthesia when compared to spinal anesthesia. However, considering the limitations of these studies, we thought that the results might be different, so we decided to investigate this issue again with similar methods.

This study aimed to investigate the relationship between STP development and anesthesia method in patients undergoing cesarean section with general anesthesia versus spinal anesthesia.

 Methods



This single-center, prospective, randomized clinical study was conducted in line with the Helsinki Declaration and the regulations of Gülhane Training and Research Hospital, Ankara, Turkey, between January 2018 and January 2019. The study protocol was approved by the Ethics Committee of the Keciören Training and Research Hospital, Ankara, Turkey (KAEK-15/1557). Parturient women (≥38 gestation weeks), who were scheduled for an elective CS, were included in this study after obtaining their verbal and written informed consent. Patients who had a severe systemic or chronic disease, under opioid treatment, emergency cases, younger than 18 years, changed position after the start of surgery, and who did not consent to participate in the study were excluded. Power analysis was performed before the study. In the pilot study, we accepted an alpha error of 5% and a beta error of 20% during the assessment of the incidence of shoulder tip pain following a cesarean section and calculated that a minimum of 56 patients should be included in each group. Taking the possibility of exclusions and dropouts, we decided to include 60 patients in each group. A total of 117 parturient women were randomized with the help of a computer-generated randomization list to receive either general anesthesia (group G, n = 56) or spinal anesthesia (group S, n = 61).

Pulse oximetry, electrocardiography, and noninvasive arterial pressure monitoring were implemented according to the standards of the American Society of Anesthesiologists (ASA).

In group G, rapid sequence anesthesia was induced with propofol (2 mg/kg) and succinylcholine (1.5 mg/kg) after 3 minutes of pre-oxygenation via a face mask. Endotracheal intubation was performed by applying cricoid pressure. After delivery, rocuronium (0.3 mg/kg) and fentanyl (2 mcg/kg) were administered. Anesthesia was maintained with 1% sevoflurane in a 50–50% air/nitrous oxide mixture. The tidal volume was adjusted to maintain the end-tidal CO2 level at 35–40 mmHg. All patients were ventilated via volume-controlled ventilation with 5 cm H2O-positive end-expiratory pressure. Patients were not moved from the supine position during the surgery. After the completion of the surgery, rocuronium was reversed with IV sugammadex (2 mg/kg), and the patients were extubated.

In group S, spinal anesthesia was implemented in a sitting position with the midline approach at the L3-L4 intervertebral space, with a 25 G pencil-point needle. Spinal anesthesia was achieved with intrathecal 0.5% hyperbaric bupivacaine (12.5 mg) and fentanyl (15 mcg). The desired level of sensory block was between T4 and T6. After the implementation of spinal anesthesia, patients were put in the supine position and not moved from the supine position during the surgery. In cases of hypotension, a bolus injection of ephedrine (5 mg) was administered. CS was performed using the same technique and by the same surgical team for all patients.

All cesarean sections were performed by the same surgical team and using a similar cesarean section technique. Following the surgery, patients were transferred to the post-anesthesia care unit. When the Aldrete recovery score of the patients who underwent cesarean section under general anesthesia was above 9, they were sent to the obstetrics ward from the post-anesthesia care unit. Similarly, patients who underwent cesarean section under spinal anesthesia were transferred to the obstetrics ward when their block level decreased below the L4 level. Intramuscular diclofenac (75 mg) was administered to all patients with a visual analog scale (VAS) score >3 for the management of postoperative pain. If the visual analog scale (VAS) score >3 despite intramuscular diclofenac administration, the same dose was repeated for persisting pain. In patients who complained of pain despite two doses of diclofenac (2 × 75 mg) and had a VAS score >3, pethidine (1 mg/kg) was administered as rescue analgesia.

Patients' demographic information such as additional disease, age, height, weight, body mass index (BMI), gravidity, parity, and gestational age was recorded. Twenty-four hours after the surgery, one member of the study team, who was blinded to the implemented anesthesia method, evaluated the presence of shoulder tip pain. If STP presence was confirmed, the localization of STP (right/left/bilateral), the severity of shoulder pain evaluated with VAS (0–10 scale; 0 = no pain; <3 mild, 3–7 moderate, >7 severe pain), nonsteroidal anti-inflammatory drugs (NSAIDs) consumption, and supplemental opioid requirement were recorded.

Statistical analysis

Power analysis was performed before the study. In the pilot study, we accepted an alpha error of 5% and a beta error of 20% during the assessment of the incidence of shoulder tip pain following a cesarean section and calculated that a minimum of 56 patients should be included in each group. Taking the possibility of exclusions and dropouts, we decided to include 60 patients in each group (a total of 120 patients). We used IBM version 25 (IBM Corporation, Armonk, New York, USA) software for the statistical analysis. The normal distribution of continuous variables was analyzed using the Shapiro–Wilk test. Continuous variables were expressed as a mean ± standard deviation, and categorical variables were expressed as numbers (n) and percentages (%). A comparison of the continuous variables was made using the Mann–Whitney U test (for nonparametric) and t test (for parametric), and a comparison of the categorical variables was made using Pearson's Chi square test or Fisher's exact test. For all analyses, a P value of <0.05 was considered statistically significant.

 Results



A total of 128 patients were evaluated for eligibility between January 2018 and January 2019. In total, 117 patients were included in the analysis [Figure 1]. The groups were comparable in terms of age, height, weight, BMI, number of gravities, presence of comorbidities, gestational age, number of primary CS, and neonate birth weights [Table 1]. There was a statistically significant difference only in the number of parity (p = 0.002).{Figure 1}{Table 1}

The overall incidence of STP was 49.5% in the study population. The incidence of STP was significantly higher in group S than in group G (59% and 39%, respectively; P = 0.032) [Table 2]. The location and severity of STP were statistically comparable between both groups [Table 2].{Table 2}

Patients with (n = 58) and without (n = 59) STP were compared in terms of opioid and NSAID use [Table 3]. There was no statistically significant difference between patients with and without STP, in terms of the number of patients who needed opioid treatment. However, patients with STP had higher NSAID consumption within the first 24 hours after the surgery than in patients without STP (p < 0.001). As a complication, hypotension developed due to high anesthesia level in five patients who were applied spinal anesthesia, and blood pressure values were brought to the normal range by applying ephedrine. No other complications were observed in the patients.{Table 3}

 Discussion



This study investigated the relationship between anesthesia type and STP in patients with CS. We found that the frequency of STP was higher in patients who underwent CS with spinal anesthesia. When the patients without STP were compared with patients with STP, similar characteristics in terms of opioid consumption were observed, but when evaluated in terms of 24-hour NSAID use, it was found that they needed less analgesics.

There is not enough research on the mechanism of shoulder pain, which is reported to occur in approximately one out of every two patients after cesarean section. Shin et al.[9] claimed that this pain could be due to diaphragm and peritoneum irritation caused by blood clots and amniotic fluid. However, in these studies, it was evaluated that STP was a complication related to surgery, and whether it was related to anesthesia method was not examined. In the study conducted by Zirak et al.,[3] it was suggested for the first time that the anesthesia method might have an effect on the occurrence of STP, and in this study, the incidence of STP was found to be higher in patients with general anesthesia compared to the spinal anesthesia group (40% and 19%, respectively). Likewise, Cift et al.[8] reported that STP after a CS was more common in the general anesthesia group than in the spinal anesthesia group (43.9% and 26.6%, respectively). However, in our study we found that STP after spinal anesthesia was more common than after general anesthesia. We think there are several mechanisms to explain this situation. Firstly, although Cift et al.[8] found the incidence of shoulder pain to be higher in the spinal anesthesia group, they reported that the development of shoulder pain may be related to the intraoperative patient position. Also, Kikuchi et al.[10] demonstrated that 2–5 degrees of head-up position during and after a CS reduces the incidence of shoulder pain in patients who underwent combined spinal and epidural anesthesia. In the current study, all patients were left in the supine position to eliminate the possible effect of patient position. The disappearance of the effect of patient position may have resulted in a higher incidence of shoulder pain in the general anesthesia group. As another mechanism, we think that with positive pressure ventilation under general anesthesia, fluid accumulation under the diaphragm may be less, which does not occur under spinal anesthesia. This may be the other possible mechanism explaining the result of our study.

Previous studies reported that STP after a cesarean section usually occurred in the right shoulder.[3],[8] It was also reported that only a minority of patients suffered from isolated left shoulder pain. Correspondingly, in our study, we observed the STP symptom only on the right shoulder, and we did not encounter left shoulder pain in any of our patients. Regarding the severity of STP, Cift et al.[8] described mild pain in the spinal anesthesia group and mostly moderate pain in the general anesthesia group. Zirak et al.[3] also reported similar results, finding that STP was relatively milder in the spinal anesthesia group and mostly moderate in the general anesthesia group. Unlike the previous studies, we found that the frequency and severity of STP were higher in patients undergoing spinal anesthesia. Our prediction on the subject is that the amount of amniotic fluid and air accumulated under the diaphragm due to the application of positive pressure ventilation in general anesthesia is less than in spinal anesthesia.

Nonsteroidal anti-inflammatory drugs are often used as part of multimodal analgesia in the treatment of postoperative pain.[11] We found that the postoperative 24-hour NSAID consumption was significantly higher in patients with STP. Accordingly, it can be said that patients in group S consume more NSAIDs than those in group G, due to the higher frequency and severity of STP in this group.

There were some limitations in the study. The presence and amount of amniotic fluid and hematoma, one of the reasons suggested for STP, could be measured postoperatively by ultrasound. Although the physicians who applied anesthesia were the same, only patients with the same surgical team could be included in the study to reduce the differences that may occur due to surgery. As another limitation, patient-controlled analgesia (PCA) could be used in patients to further evaluate postoperative analgesic consumption.

In conclusion, STP is observed more frequently after spinal anesthesia compared to those undergoing general anesthesia. Anticipating that STP may develop in these patients, it is recommended to plan postoperative analgesia follow-up attentively and to provide adequate analgesia support.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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