A novel injection technique for ilioinguinal nerve block for post-operative pain relief in caesarean delivery – a randomized, double-blind, placebo-controlled trial

Summary

Aim: To determine whether the novel method is successful in blocking both ilioinguinal nerves to lessen postoperative pain following caesarean surgery. Materials and methods: Between January 2022 and January 2023, 300 patients were enrolled in this study at the Obstetrics and Gynaecology Departments of the Faculty of Medicine at Al-Azhar University. About 150 of these patients received bupivacaine infiltration on both sides close to the anterior superior iliac spine, and 150 received a normal saline injection at the same locations. Results: The study compared the two groups and discovered significant differences in the timing of analgesic requests, interval before the patient’s first ambulation, length of hospital stay, postoperative pain score, and incidence of postoperative nausea and vomiting, with group A performing better. Conclusion: After a caesarean section, the local anaesthetic “bupivacaine” injection used to block the ilioinguinal nerves bilaterally is an efficient way to lessen postoperative discomfort and analgesic use.

Keywords:

Pain – ilioinguinal nerve block – bupivacaine – caesarean delivery

Introduction

For women having caesarean deliveries, effective pain management should be a top priority. Suboptimal perioperative pain control is linked to postpartum depression, chronic pain, higher opioid use, delayed functional recovery, reduced maternal foetal attachment, and delayed functional recovery. Strong links exist between chronic pain following a caesarean delivery and severe acute postoperative pain. The fundamental idea behind managing pain during caesarean delivery is multimodal analgesia [1]. All women having caesarean deliveries under neuraxial anaesthesia are advised to take neuraxial morphine and opioid-sparing adjuncts like acetaminophen and scheduled non-steroidal anti-inflammatory drugs, unless it is contraindicated [2].

Inguinal skin is supplied with cutaneous sensation by the iliohypogastric (IH) nerve, while the skin across the upper medial side of the thigh is supplied with sensation by the ilioinguinal (II) nerve. Since L1 supplies the dermatomal distribution where the Pfannenstiel incision is located, combined II and IH (combined IIIH) nerve blocks provide anterior abdominal wall analgesia after caesarean delivery (CD) [3]. After CD under general anaesthesia (GA), studies have compared bilateral II nerve blocks to a control group that did not get a block and have evaluated pain levels and opioid usage postoperatively. Patients who received II blocks reported lower pain levels and narcotic usage [4,5].

In one study, patients receiving CD under GA exhibited lower papaveretum needs (four hours postoperatively) in the II nerve block group when compared to controls at eight hours (6.2 vs. 13.3 mg) and 12 hours (3.8 vs. 13.9 mg), but not at 24 hours postoperatively [4].

Materials and methods

Study setting and design

This study was a prospective randomized double-blind controlled study that was performed in Al-Azhar University maternity hospitals.

Study participants

Eligibility: 300 patients in this study had undergone elective caesarean sections. The patients were divided into two groups at random:

• 150 patients in Group A (cases) received 10 mL of bupivacaine (0.5%) in a three-layer infiltration 2 cm above and medial to the anterior superior iliac spine, as well as under the skin to block the anterior cutaneous branch of the II nerve.
• 150 individuals in Group B (controls) received 10 mL of ordinary saline subcutaneously and 2 cm above the anterior superior iliac spine on each side.

Sample size: The normal approximation approach was applied, and the significance level of the test was set at 0.05 (5% error) to achieve 80% power (error 20%). It was done using a 2-sided Z-test with pooled variance. It was observed that each group’s sample size was 150. To determine the sample size, we used PASS 15 Power Analysis and Sample Size Software, version 2017 (NCSS, LLC. Kaysville, Utah, USA, ncss.com/software/pass).

Randomization and allocation: A ran­- dom table created by a computer was used to perform simple randomization. The participants were divided into two groups, each with 150 participants. A different technique of allocation was used with a ratio of 1: 1 to ensure equal distribution. Closed opaque envelopes carrying a card with the intended intervention helped to maintain secrecy. We did not alter the allocation for envelope openers.

Selection standards: Patients with Elective Caesarean Section, Full Term Pregnancies, Singleton Pregnancies, and First Caesarean Section were between the ages of 20 and 40.

Criteria for exclusion included sensitivity to opiates and local anaesthetics, diabetes, hypertension, neurologic conditions, substance abuse, and emergency caesarean sections. Patients that chose not to take part in the trial, had infections at the injection sites, had previous abdominal or pelvic surgery, or had any surgical complication were not included.

Intervention procedures

After checking that there was no bleeding from the uterine incision and before sealing the peritoneum, we had executed an II nerve block utilising the blind three-layer technique. The procedure involves making a single puncture site 2 cm above and medial to ASIS with a 23-G, 1.5-inch long needle. The needle is pointed at ASIS at an angle of 45° to 60°.

Between the transverse abdominalis muscle and the external oblique muscle, 8 mL of 0.5% bupivacaine were injected. To prevent harm to the internal organs, the left hand was used to guard the needle while it moved into the tissues and spread the local anaesthetic. To block the anterior cutaneous branch of the II nerve, 2 cm were subcutaneously injected. Diclofenac potassium 75 mg was given to all patients intramuscularly every 12 hour to control visceral pain.

Statistical analysis

For data analysis, IBM Corp., Armonk, NY, USA, provided SPSS version 25 (Statistical Package for the Social Sciences). The normal distribution of the variables was examined using the Kolmogorov--Smirnov test. With the Student T-test, continuous variables were compared after being expressed as the mean and standard deviation. The chi-square test was used to compare categorical data, which were shown as frequencies and percentages. P-values under 0.05 were regarded as significant. The impact of several parameters on the likelihood of pregnancy was assessed using a univariate regression analysis.

Outcome

Utilizing the standard 10 cm visual analogue scale for pain scoring, which was described to patients as a 100 millimetre horizontal line with verbal anchors at both ends during the preoperative visit, postoperative pain was assessed at 0.5, 2, 4, 6, 8, 12, 24 and 36 hours after the operation. The score is the measurement in millimetres from the left side of the scale to the mark with the words “no pain” on the left end and “worst pain conceivable” on the right. The patient was instructed to mark the line. A visual analogue scale (VAS) score of 70 or higher indicates severe pain, whereas a score of 0 to 5 indicates no pain, 5 to 44 indicates mild pain, and 45 to 74 indicates moderate pain.

These rating systems have the advantages of being quick and easy to use, allowing for a variety of ratings, and avoiding imprecise descriptive phrases (Fig. 1).

Additionally, the interval between requests for the first analgesic, length of time spent walking, length of stay in the hospital, and adverse effects of the medications administered were evaluated.

Based on patients’ assessments of the impact of their sickness on their postoperative recovery and the frequency of their vomiting, the intensity of the nausea and vomiting were quantified using a postoperative nausea-vomiting impact scale that was simplified. Vomit count was used to score the severity of the vomiting (0–2 or 3 if three or more vomiting episodes).

Results

The mean mother age in groups A and B, respectively, was 26.67 + 7.4 and 27.45 + 6.3 years, respectively, according to Tab. 1. Between the two study groups, there was no statistically significant difference in the mother’s age. The mean body mass index (BMI) for group A was 23.45 ± 1.8, while for group B it was 23.87 ± 1.9. Regarding BMI, there was no statistically significant difference between the two study groups. Between the two groups, there was no statistically significant difference in terms of gestational age or foetal presentation.

In Tab. 2, the mean systolic blood pressure for groups A and B was 121.4 ± ± 7.6 and 120.8 ± 8.1, respectively. Between the two groups, there was no statistically significant difference in systolic blood pressure. In group A, the mean diastolic blood pressure was 80.2 ± 7.2, while in group B it was 79.8 ± 5.1. Between the two study groups, there was no statistically significant difference in diastolic blood pressure. In terms of pulse, group A’s mean was 79.5 ± 5.2 and group B’s was 82.1 ± 3.9; there was no statistically significant difference between the two study groups in terms of pulse. Between the two groups, there was no statistically significant difference in Hb or platelet count.

Regarding VAS at 6, 8, 12, 24, and 36 hours, group A’s score was statistically significantly lower than group B’s in Tab. 3. At other times, there was no statistically significant difference between the two study groups in terms of VAS score.

The length of hospital stay was statistically lower for group A than for group B, as indicated in Tab. 4, but there was no statistically significant difference in the length of the surgery between the two groups. The time for the first analgesic request was statistically significantly shorter in group B than in group A. When compared to group B, group A’s ambulation time was statistically significantly shorter.

The postoperative nausea and vomiting (PONV) was statistically considerably lower in group A than group B, as seen in Tab. 5.

There has never been a documented instance of the approach failing or the medications or techniques employed becoming problematic.

Discussion

The preferred method for pain treatment following a caesarean section is a bilateral II block and an IH block. Regarding the adverse effects of analgesics that enter breast milk, it is seen as favourable following caesarean section. In order to develop an early link between the mother and her infant, post-operative analgesia is necessary for an awake and alert mother to get adequate pain relief [6]. The major goal of this study was to evaluate the effectiveness of injecting “bupivacaine” local anaesthetic into both sides near ASIS with the intention of blocking the II and IH nerves bilaterally to lessen postoperative pain following caesarean section.

The gynaecology and obstetrics departments of Al-Azhar University hospitals participated in this prospective, randomised, double-blind controlled trial. About 300 people who underwent elective caesarean sections participated in the study, and they were randomly assigned to one of two groups: 150 patients in Group A received a local anaesthetic (10 mL bupivacaine 0.5%) in the area close to ASIS. Group B: As the control group, 150 patients in this group received normal saline injections in the same places.

Similar to our study, El Rasheedy et al evaluated a new analgesic technique for post-caesarean section pain through a local bupivacaine injection. They enrolled 150 patients, 50 of whom received saline infiltration at both angles of the rectus sheath incision, 50 of whom received bupivacaine infiltration at both angles of the rectus sheath incision, and 50 of whom received saline injection, but the age differences between the two study groups were not statistically significant [7].

In addition, Nigatu et al (2017) investigated the analgesic effectiveness of bilateral II and IH nerve blocks for post-caesarean delivery under spinal anaesthesia. They enrolled 80 participants, 39 of whom received a 0.25% bupivacaine II-IH nerve block in Group B and 41 in Group C (received no block). Regarding age, sex, and BMI, there was no statistically significant difference between the two groups [8].

The Wagh study (2017) also looked at the effectiveness of bupivacaine against ropivacaine for bilateral II and IH nerve blocks for postoperative pain following caesarean section. They enrolled 60 patients for the study, who were split into Group A and Group B. Patients in group A ranged in age from 26.63 to 4.12 years to 25.00 to 3.03 years. Age, weight, and ASA status of the patients’ demographic profiles were equivalent in both groups (P-value > 0.05), and it appears that this had no statistically significant difference in the study’s conclusion [6].

According to El Rasheedy et al, which supports our findings, there is no statistically significant difference between the studied groups’ VAS scores at 30 minutes post-op and a statistically significant difference between the studied groups after 12 hours post-op. Despite this, there was a statistically significant difference in the study groups’ VAS scores at 2, 4, 6, and 8 hours, which contradicts our findings [7].

The study by Nigatu et al. found that immediately following the patient’s transfer to the ward, NRS pain severity scores were similar between the II-IH block group and the control group. This can be due to the long-lasting analgesic effects of spinal anaesthesia. Even while the II-IH block group’s pain intensity was different from the control group’s at 4 hours and 8 hours of rest, this difference was not clinically significant [8]. According to the study conducted by Sakalli et al. in 2010, the mean VAS was noticeably lower in the intervention group than in the control group at 6, 8, 12, 16 and 24 hours. The mean VAS score at 0 hour and 2 hours in their investigation, however, did not differ. This may be because the treatment was carried out under general anaesthesia, and the block may take some time to induce analgesia [9].

In the study by Wagh, lower VAS scores were reported than ours. It was also stated that there was no statistically significant difference between the studied groups regarding VAS scores at 0, 0.5, 1, 1.5, 2, 3, 4, 5, 6 and 12 hours, but there was a statistically significant difference between the studied groups regarding VAS scores 7 and 8 [6].

Additionally, a randomised control trial was conducted by Krishnegowda et al in 2020 on the effectiveness of bilateral iliac-iliac-IH nerve block and local infiltration for post-caesarean delivery analgesia. They discovered that while no patients in the II-IH nerve block group had a VAS score of more than 4 at 4 hours after surgery, more than 80% (40 patients) of the patients in the control group did. Additionally, they discovered significantly lower VAS scores in the II-IH nerve block group compared to the control group at 4, 6, and 12 hours after surgery (P-values = 0.001, 0.010, and 0.011, respectively). At 4 hours after surgery, the II-IH nerve block group considerably outperformed the local infiltration group in terms of VAS scores (P-value = 0.001). At 12 hours after surgery, 11 patients in the group that received an II-IH nerve block had a VAS score of less than 4 [10].

The current study found that group A had statistically significantly shorter hospital stays than group B, although there was no statistically significant difference in the length of the surgeries between the two groups.

According to El Rasheedy et al, which supports our findings, there was no statistically significant difference between the studied groups regarding the length of their hospital stays, but there was no statistically significant difference between the studied groups regarding the length of their surgical procedures [7].

The study by Nigatu et al, which found no statistically significant variation in surgery time between the analysed groups, further confirmed our findings [8].

The study by Sakalli et al, which found no statistically significant difference between the analysed groups regarding surgical time and prior abdominal surgery, provided additional support for our findings [9].

Additionally, Abiy et al conducted a com­parison of bilateral II-IH nerve block versus transversus abdominis nerve block for postoperative pain management for expectant mothers having elective caesarean sections. They enrolled cases with no significant differences in age, BMI, previous C-sections, heart rate, blood pressure, and surgical time [11].

Our findings also showed that group A had a statistically significantly greater analgesic time than group B. When compared to group B, group A’s ambulation time was statistically significantly shorter.

According to El Rasheedy et al (2015), which supports our findings, there was a statistically significant difference between the analysed groups in terms of analgesic request time and ambulation time. Additionally, they discovered that local bupivacaine injection related with considerable analgesic or non-analgesic demand by group A was 74%, group B was 30%, and group C was 48% [7].

This was supported by Al-Hakim & Alidreesi (2010), who found that pre-emptive analgesia with 20 mL of 0.5% Bupivacaine infiltrated before skin closure lowered postoperative analgesia requests with Pethidine in patients undergoing elective LSCS via Pfannenstiel incision [12]. Additionally, Bamigboye & Hofmeyr (2010) showed that local anaesthetic infiltration and abdominal nerve blocks, used in conjunction with regional anaesthesia and general anaesthesia, are advantageous in CS by lowering the use of opioids [13].

The study by Nigatu et al found a statistically significant difference between the analysed groups in terms of the amount of time that had passed prior to the initial request for opioid analgesia and total tramadol intake, providing support for our findings [8].

The study by Krishnegowda et al, which found a significant difference in the analysed groups’ analgesic consumption and duration between the groups, provided more evidence for our findings [10].

According to the current findings, group A experienced statistically substantially less postoperative nausea and vomiting (PONV) than group B.

In line with our findings, El Rasheedy et al (2015) found a significant difference between the analysed groups in terms of the PONV scale, with group B exhibiting fewer side effects (nausea and vomiting) than the other groups [7].

According to a 2010 study by Amin and Tahir, direct local wound infiltration of bupivacaine offered effective pain management following CS and decreased the need for parenteral opioid analgesia with no significant side effects [14].

Contrary to our findings, the study by Abiy et al (2020) found no statistically significant difference in the incidence of side effects between the studied groups. They also found that transversus abdominis nerve block group had a higher incidence of side effects than II-IH nerve block group [11].

The negative effects of these medications typically rely on dosage, high plasma concentration brought on by unintentional drug vessel entry, patient tolerance being reduced, personal incompatibility, or excessive sensitivity. The rate of unintended side effects is additionally influenced by the injection site [15]. In our investigation, neither group experienced an injection site problem.

Conclusion

This study came to the conclusion that the local anaesthetic “bupivacaine” injected blindly in the three layers rather than one shot close to ASIS to block the bilateral II and IH nerves is an efficient way to lessen postoperative pain and analgesic consumption after caesarean section in patients receiving general anaesthesia as well as postoperative nausea and vomiting side effects.

Also, this technique is very simple and easily taught by juniors, proving to be effective in reducing patient suffering.

Submitted/Doručeno: 15. 3. 2023

Accepted/Přijato: 20. 3. 2023

Wael Khafagy, MD

Department of Obstetrics and Gynecology

Faculty of Medicine

Al-Azhar University

Al Mokhaym Al Daem

Gameat Al Azhar

4434003 Cairo Governorate

Egypt

karimabdel2013@outlook.com