Rectus sheath blocks for pediatric laparoscopic appendicectomy

Abstract

Background

Acute appendicitis is the leading cause of abdominal surgical emergencies, and appendicectomy is a commonly performed surgery. Although generally regarded as minor, appendicectomies can lead to significant postoperative pain. Rectus sheath blocks (RSB) can provide effective analgesia for 3-port laparoscopic appendicectomy.

Methods

A total of 145 patients aged between 8 and 18 years who underwent laparoscopic appendicectomy were included in this prospective observational study. The study cohort was analyzed in two groups: patients who received RSB (RSB group, n = 68) and control patients who did not receive any type of regional blocks (Control group, n = 77). Data on postoperative pain scores, total analgesic consumption, and the cutaneous sensory coverage of RSB in the port entry areas were collected.

Results

Postoperative pain scores at the 3rd hour were significantly lower in the RSB group compared to the controls (p < 0.001). Total paracetamol use in the first 24 h was also reduced in the RSB group (p < 0.001). The need for rescue analgesics was slightly lower in the RSB group (p = 0.047). Total procedural time showed no significant difference between the groups. In the postoperative 3rd hour assessment of the RSB blocks: all patients experienced visceral pain to varying degrees, three (4.4%) had pain at the umbilical port entry site, fourteen (20.6%) had pain at the left iliac fossa port entry site, and eight (11.8%) had pain at the suprapubic port entry site.

Conclusions

RSB can improve pain scores and reduce overall analgesic consumption in pediatric laparoscopic appendicectomies. However, RSB may miss the lateral trocar entry site, and suprapubic coverage can differ among individuals.

Trial registration

NCT06913205.

Introduction

Acute appendicitis is the leading cause of abdominal surgical emergencies globally, with appendicectomy being one of the most frequently performed surgeries [1]. Although appendicectomies are considered minor or minimally invasive surgeries, they can result in significant postoperative pain, regardless of whether the procedure is performed as laparoscopic or open surgery. A prior study assessed 70,764 patients across 105 hospitals in Germany. It revealed that high pain scores were recorded on the first day after appendicectomies, placing this procedure among the top 25 for the highest pain intensities out of 179 surgical operations. Furthermore, the study asserted that patients’ pain ratings after laparoscopic appendicectomy were comparable to those following knee joint replacement and sternotomy [2]. Another study involving 189 children who underwent laparoscopic appendicectomy revealed that median pain scores were ≥ 7 out of 10 (severe pain) in 5% of children and ≥ 4 out of 10 (moderate pain) in 25%. It was also noted that children experiencing moderate to severe pain on the first postoperative day had significantly higher pain severity in the following days during hospitalization [3]. Based on the results of the previously mentioned studies, pain scores during appendicectomy procedures were often unexpectedly high, even though the surgery is considered minor [4]. This may result from underestimating pain and consequently undertreating it due to the nature of the surgical procedure.

The rectus sheath block (RSB) is a regional anesthetic technique that targets the ventral rami of T7–T12, providing adequate analgesia for surgeries involving midline incisions or the umbilical region. In our institute, the 3-port laparoscopic appendicectomy for pediatric patients involves 2 port entries that remain in the midline (umbilicus and suprapubic). Furthermore, based on our general clinical experience, umbilical port entry tends to be more painful than other port entry sites in laparoscopic surgeries, regardless of whether the patient is adult or pediatric or the type of surgery. Therefore, this study aims to evaluate the effect of RSB on postoperative pain management in 3-port laparoscopic appendicectomy for pediatric patients. The primary objective was to assess postoperative pain scores, while secondary objectives focused on total analgesic consumption and the analysis of RSB's analgesic effect in the port entry areas.

Methods

After receiving approval from the institutional ethics committee for the study protocol (date: 25.08.2021, decree: 2011-KAEK-25 2021/08–20), this prospective observational study took place in a tertiary-level hospital, and registered on www.clinicaltrials.gov with the ID NCT06913205 (30 March 2025). The project described was conducted following the Helsinki Declaration in adherence to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines for observational studies. Informed consent to participate in the study were obtained from participants (or their parent or legal guardian in the case of children under 16).

Patient selection

Children who underwent appendicectomy surgery between August 2021 and August 2022 were evaluated for study eligibility. Patients under 8 or over 18 years old, those whose laparoscopy was converted to open abdominal surgery, individuals who underwent an open appendicectomy, those who received only non-steroidal anti-inflammatory analgesics other than paracetamol, patients lost to follow-up, individuals receiving various types of regional blocks other than RSB (such as transversus abdominis plane (TAP) block or quadratus lumborum block) and those who did not consent to participate were excluded from the study. The study cohort was analyzed in two groups: patients who received RSB (RSB group, n = 68) and control patients who did not receive any type of regional blocks (Control group, n = 77).

The choice between open and laparoscopic appendicectomy was made based on the senior surgeon’s discretion. Open appendicectomy was selected for complicated cases, patients with intra-abdominal abscess, and those with a history of previous surgery. Also, the surgeon’s limited experience with laparoscopic techniques influenced this decision. None of the patients received preoperative analgesics.

Anesthesia method

Following standard monitoring, intravenous propofol was given at a dosage of 2–3 mg/kg to induce general anesthesia, accompanied by fentanyl at 1 μg/kg and rocuronium at 0.8 mg/kg. After intubation, anesthesia was maintained with a mixture of inhaled sevoflurane, oxygen, and air. Paracetamol was given at a dose of 10 mg/kg before the surgery ended.

Laparoscopic appendicectomy method

Surgery was performed using a 3-port laparoscopic appendicectomy technique by either a senior surgeon or pediatric surgery residents, under the supervision and assistance of the senior surgeon. A 12-mmHg pneumoperitoneum was established using a Veress needle through an infraumbilical incision. A 10-mm optical port was inserted through the same incision. Two 5-mm working ports were then placed from the left iliac fossa and suprapubic region under direct endoscopic vision. The mesoappendix was dissected with a vessel sealing device (LigaSure™, Covidien™). The base of the appendix was ligated with 2/0 Vicryl™ using intracorporeal knots. The appendix was resected, placed into a sterile glove and removed via the 10-mm infraumbilical port. The umbilical entry site and fascia were closed with 2/0 Vicryl™, while the other trocar sites were closed with 4/0 Vicryl Rapide™.

Rectus sheet block and incision-site infiltration

The decision on whether to use regional blocks was left to the anesthesiologist. Anesthesiologists chose to employ regional blocks for analgesia based on their knowledge, skills, and experience without interference in their judgment. The rationale for utilizing RSB was the surgical incisions along the midline of the abdomen, such as trocar insertion sites in laparoscopic appendicectomies.

RSB were placed either by the senior anesthesiologist or by the residents under the supervision and guidance of the senior anesthesiologist at the conclusion of surgery. The ultrasound-guided RSBs were performed after the conclusion of surgery and prior to extubation. A high-frequency linear probe was placed in the transverse orientation on the midline, 2–3 cm below the umbilicus, where the linea alba was identified. The probe was then moved laterally to identify the rectus abdominis muscle and the two-layered view of the posterior rectus sheath. After confirming the correct placement of the needle with a test injection and negative aspiration, local anesthetic was injected (Fig. 1). This procedure was repeated on the other side. In the preparation phase for the RSB, a total dose of 0.5 mL/kg of 0.25% plain bupivacaine was prepared, and this amount was distributed equally for each side (0.25 mL/kg of 0.25% bupivacaine for each side). For children weighing more than 60 kg, a standard dose of 15 mL was applied to each side. Following the block, the spread of the local anesthetic along the rectus abdominis muscle was confirmed with a post-block ultrasound scan.

Fig. 1.

A Pre-block scanning illustrates the rectus abdominis muscle and the posterior rectus sheath. B The ultrasound-guided rectus sheath block demonstrates hydro-dissection of the rectus abdominis muscle from the posterior rectus sheath. White arrows indicate the direction of the needle

Before inserting trocars at three locations, the surgeon injected approximately 1 mL of 0.5% plain bupivacaine at each incision point for all patients, including those who were going to receive regional blocks. The main reason for the surgeon injecting local anesthetic into surgical incisions was to suppress the sympathetic response to trocar placement.

Postoperative follow-up

All patients were transferred to pediatric surgery ward after the surgery. Pain levels were evaluated with the Wong-Baker Faces Pain Rating Scale, where zero indicates no pain, and 10 represents the worst imaginable pain. In the postoperative period, paracetamol was routinely given at 10 mg/kg three times a day. The regular analgesic dose was omitted if the patient's pain score was below 4; ibuprofen served as a rescue analgesic for those still experiencing pain despite paracetamol treatment. At the end of the first 24 h, the need for rescue analgesics and the total paracetamol consumption were recorded. At the postoperative 3rd hour, incisional pain at the trocar sites was evaluated. The staff in the follow-up unit were blinded to the study.

Sample size

The sample size was calculated using G*Power (v.3.1.9.4) analysis software. The power analysis was calculated using the pain scores of 10 children who had previously undergone laparoscopic appendicectomy at the study institute and did not receive RSB. The mean postoperative pain scores at the 3rd hour for these children were 3.7 ± 1.33 out of 10. With the expectation that RSB blocks will reduce postoperative pain scores at the 3rd hour by 20%, a total of 138 patients were needed to achieve a power of 85% with an alpha value of 0.05, considering a 0.5 effect size.

Statistical analysis

Statistical analysis was performed using SPSS version 25.0 (IBM SPSS Statistics for Windows, v. 25.0, Armonk, NY: IBM Corp., 2017). The normality of the distribution was assessed using the Kolmogorov–Smirnov test. Continuous variables were examined with the Mann–Whitney U test, while categorical variables were evaluated using Pearson chi-square tests. Descriptive statistics for continuous variables were presented as median (25–75 percentiles), and for categorical variables as counts and percentages. A P value of less than 0.05 was considered statistically significant.

Results

Three hundred ninety-one children who underwent appendicectomy were assessed for eligibility. A total of 231 children were excluded, including 227 who had open appendicectomy and four who were converted from laparoscopy to open surgery. Subsequently, two patients with a paracetamol allergy and 13 who received regional blocks other than RSB (9 TAP blocks and 4 quadratus lumborum blocks) were excluded from the study. Consequently, 145 children underwent statistical analysis (Fig. 2).

Fig. 2.

The flowchart of the study

The demographics of patients are shown in Table 1. There was no significant difference in the general characteristics between the patients who received RSB and the controls. Postoperative pain score at the 3rd hour was significantly lower in children who received RSB compared to the controls (p < 0.001) (Table 2). Additionally, in the RSB group, six patients required no analgesics in the first 8 h postoperatively, and three patients needed none in the first 12 h postoperatively. However, there were no differences in the pain scores at the 8th and 24th postoperative hours. Subsequently, the total cumulative paracetamol dose within the first 24 h was significantly lower in the RSB group (p < 0.001). Furthermore, the need for rescue analgesics was slightly higher in the controls than in the patients receiving RSB (p < 0.047) (Table 2). No opioid analgesics were administered during the postoperative period for any children.

Table 1.

Demographics of children undergoing laparoscopic appendicectomies

	RSB (n = 68)	Control (n = 77)	p
Age; years	12.8 (9.4–14.8)	13.2 (10.6–15.5)	0.192
Sex, male; n	44 (64.7)	49 (63.6)	0.839
Weight; kg	45.0 (35.0–55.0)	50.0 (39.0–55.5)	0.182
BMI; kg/m2	18.6 (17.1–20.7)	18.1 (16.9–21.6)	0.683
Duration of anesthesia; hour	1.3 (0.8–1.8)	1.5 (1.0–1.9)	0.293
Perforated; n	11 (16.2)	14 (18.2)	0.750

Data are presented as counts (percent) for sex (male) and perforation rates, and as median (25–75 percentiles) for other variables

BMI Body Mass Index

Table 2.

Postoperative pain scores and analgesic consumption in children who underwent laparoscopic appendicectomy

	RSB (n = 68)	Control (n = 77)	p
Pain score 3rd hour	3.0 (2.0–3.8)	4.0 (3.0–5.0)	< 0.001
Pain score 8th hour	3.5 (3.0–4.0)	4.0 (2.0–5.0)	0.964
Pain score 24th hour	2.0 (1.0–2.0)	2.0 (1.0–3.0)	0.344
Total paracetamol consumption; mg	20.0 (10.0–30.0)	30.0 (20.0–30.0)	< 0.001
Rescue analgesic; n	2 (2.9)	9 (11.7)	0.047

Data are presented as counts (percent) for rescue analgesic and median (25–75 percentiles) for other variables

The evaluation at the 3rd hour postoperatively revealed that almost all the patients experienced visceral pain to varying degrees, majorly at the right lower abdominal quadrant. Three (4.4%) of the patients who underwent RSB experienced somatic pain at the umbilical port entry site, while the other port entry sites were numb. This result was attributed to a failed block caused by inadequate distribution of the local anesthetic. Fourteen (20.6%) patients reported somatic pain at the left iliac fossa port entry site, and eight (11.8%) patients had somatic pain at the suprapubic port entry site. Three out of eight children who reported pain at the suprapubic trocar entry site also experienced discomfort in the same area immediately after surgery in the recovery room. The remaining five children had numbness at the suprapubic trocar entry site right after surgery in the recovery room, although they reported pain at that site at the 3rd hour postoperatively.

Regarding RSB complications, injury to the inferior epigastric artery and vein is rare but possible and can cause serious issues such as rectus sheath hematoma. In this series, no block-related complications were observed.

Discussion

The main finding of this study is that ultrasound-guided RSB effectively reduces pain during the early postoperative hours, resulting in a significant decrease in overall analgesic consumption following 3-port laparoscopic appendicectomies in children. If the left iliac port is placed more laterally than usual, the RSB will not sufficiently cover this area. Furthermore, the efficacy of RSB in the suprapubic region can vary based on the distribution of the local anesthetic and the recovery of its analgesic effects.

Abdominal wall blocks have gained popularity due to their effectiveness in reducing postoperative pain across various surgeries. TAP blocks and quadratus lumborum blocks have been studied for laparoscopic appendicectomy in both adult and pediatric patients; however, they are not currently recommended by guidelines due to a lack of sufficient procedure-specific evidence [5]. Additionally, some of these studies showed contradictory results. Tanggaard et al. performed bilateral dual TAP on adults, revealing improved postoperative pain scores, although opioid consumption did not significantly decrease [6]. Conversely, a study by Tupper-Carey et al. reported no notable enhancement in postoperative analgesia outcomes [7]. Sertcakacilar et al. demonstrated comparable effectiveness of lateral quadratus lumborum blocks to TAP blocks in adults undergoing laparoscopic appendicectomy [8]. Moreover, a study by Sandeman et al. revealed that TAP blocks provided no significant benefits compared to local anesthetic port-site infiltration, and they even extended the procedural time for pediatric patients undergoing laparoscopic appendicectomy [9].

RSB has been most commonly used in pediatric umbilical hernia surgeries to date [10–14]. When considering the trocar entry site for laparoscopic appendicectomy, the RSB may be a logical choice as it offers midline analgesia; however, there are only a limited number of studies on RSB for laparoscopic appendicectomy in children. Maloney et al. compared ultrasound-guided RSB with local anesthetic infiltration for single-port appendicectomy in children with nonperforated appendicitis, demonstrating that RSB resulted in lower pain scores and reduced opioid consumption without significantly prolonging the procedure [15]. Additionally, Hamill et al. demonstrated a clinically meaningful reduction in pain with ultrasound-guided RSB compared to placebo in children, although no opioid-sparing effect was noted [16]. Furthermore, RSB can be performed by both surgeons and anesthesiologists. Kim et al. carried out RSB surgically under semi-blind conditions at the conclusion of the operation in adult patients undergoing single-port laparoscopic appendicectomy, demonstrating a reduction in postoperative pain [17]. Little et al. also reported that RSB, conducted by both surgeons and anesthesiologists, was sufficient for postoperative analgesia in a small cohort of children undergoing laparoscopic appendicectomy [18]. Also, our study findings indicate that ultrasound-guided RSB notably alleviated postoperative pain three hours after surgery, but this effect was not significant at the eighth and 24th hours following the procedure. Additionally, total analgesic consumption was lower in children who received RSB. When considered together, RSB can offer temporary postoperative analgesia and reduce the overall need for analgesics.

The RSB primarily exhibits an analgesic effect by targeting the ventral rami from T7 to T12, and it also shows no effectiveness on visceral pain, as highlighted in this study. Furthermore, injections administered at the umbilicus level have a restricted craniocaudal spread, necessitating multiple injections to match anesthetic dispersion with the surgical incision's length. Visoiu et al. investigated the spread of local anesthetic following RSB in children, observing a spread of 6.9 ± 2.2 cm on the right and 6.5 ± 1.9 cm on the left side with a volume of 0.2 mL/kg of local anesthetic. The authors also emphasized that approximately 1.2 mL of local anesthetic would cover 1 cm, noting that half of the medication spread is above the umbilicus, a quarter below it, and a quarter at the level of the umbilicus when RSB is placed at umbilicus level [19].

The arrangement of the aponeurosis of the abdominal muscles that forms the rectus sheath varies along the length of the rectus abdominis muscle. The posterior rectus sheath is complete at the upper levels but absent below the arcuate line, situated about a third of the way from the umbilicus to the pubis. Below this line, the rectus abdominis muscle lies directly on the transversalis fascia and peritoneum [20]. Therefore, this anatomical arrangement can also influence the extent of local anesthetic spread in RSB. Although we performed the blocks 2–3 cm below the umbilicus, eight patients experienced pain at the suprapubic trocar site. In three patients, the RSB did not cover this area, and in five out of eight cases, the block duration in this area was shorter than at the other port entry sites. Furthermore, the spread of local anesthetic in RSB is limited by the linea semilunaris laterally and the linea alba medially. Consequently, RSB does not cover the surgical incision, which is placed more laterally than the linea semilunaris, as indicated by our study results, where RSB did not cover the lateral trocar entry site in 14 patients. In such cases, an additional TAP block may be administered.

This study has some limitations. Firstly, the lack of randomization may have introduced selection bias, as allocation depended on the general skills of anesthesiologists in regional anesthesia and their choices regarding the use of conventional systemic analgesia. However, all patients received anesthetics and analgesics intraoperatively with the same protocol, and each group was balanced and comparable in general characteristics. Secondly, the lack of proper blinding of anesthesiologists may also have contributed to bias; however, this issue was largely mitigated by blinding the staff in the follow-up unit (which included ward nurses and pediatric surgery physicians) who collected pain scores and administered analgesics without interrupting their daily routine. Thirdly, the impact of RSB on hemodynamic responses to incision pain could not be assessed because the blocks were placed after the conclusion of the surgery. Moreover, the extent of local anesthetic spread, visualized with ultrasound, was not documented. Therefore, a potential discrepancy between the local anesthetic spread and the cutaneous sensory block, as previously noted, could not be evaluated [19]. Furthermore, since our institute serves as a training and education center, most regional blocks were performed by anesthesiology residents with varying levels of experience in regional anesthesia. Another limitation of this study is that the precise duration of performing RSB, which could be affected by varying levels of experience, was not accurately documented. Moreover, the total hospital stay was not recorded. However, the minimum hospitalization time was one day, which enabled us to evaluate the pain scores at the 24th hour postoperatively. This study also did not evaluate perforated and non-perforated patients separately; however, this variable was also comparable in the statistical analysis. Lastly, a restrictive approach to opioid administration in pediatric clinics was adopted at our institute following health ministry guidelines that indicate contraindications and restrictions on tramadol use for patients under 18 years of age. Consequently, baseline analgesia was not provided with opioids, in contrast with many previously published studies.

Conclusions

In conclusion, RSB can improve pain scores in pediatric laparoscopic appendicectomies and can also reduce total analgesic consumption. For a 3-port laparoscopic appendicectomy, the lateral trocar entry site may be missed by RSB if the incision is positioned more laterally than usual. Suprapubic coverage of RSB may also differ among individuals.

Abbreviations

RSB

Rectus sheath block

TAP

Transversus abdominis plane

Authors’ contributions

H.G. helped with study design, data collection, analysis, and manuscript preparation. D.K. helped with study design, data collection, and manuscript preparation. A.K.D. helped with data collection. N.K. helped with study design and data collection. All authors reviewed the manuscript.

Funding

The authors have no sources of funding to declare for this manuscript.

Data availability

The data sets used in this research may be made available upon reasonable request to the corresponding author.

Declarations

Ethics approval and consent to participate

This study was approved by the Research Ethics Committees of Bursa Yuksek Ihtisas Training and Research Hospital (date: 25.08.2021, decree: 2011-KAEK-25 2021/08–20) and was registered on www.clinicaltrials.gov with the ID NCT06913205 (30 March 2025). Informed consent to participate in the study were obtained from participants (or their parent or legal guardian in the case of children under 16). All experiments were performed in accordance with relevant guidelines and regulations.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.