Cesarean section (CS) is one of the most frequently performed surgical procedures globally, with rates exceeding 30% in many high-income countries and rising steadily in low- and middle-income regions [1]. Postoperative pain management following CS remains a critical clinical challenge, as inadequate analgesia can lead to prolonged recovery, impaired maternal-infant bonding, and increased risk of chronic pain syndromes [2]. Traditional multimodal analgesic regimens—combining systemic opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), and neuraxial techniques such as intrathecal morphine—have demonstrated variable efficacy and are often limited by opioid-related adverse effects, including nausea, sedation, and respiratory depression [3]. In this context, regional anesthesia techniques, such as the ilioinguinal-iliohypogastric (ILIH) nerve block, have emerged as promising adjuncts to conventional strategies, offering targeted analgesia while minimizing systemic opioid exposure [4].

The ILIH nerve block, first described in pediatric inguinal surgery, anesthetizes the sensory nerves supplying the lower abdominal wall-the ilioinguinal (L1) and iliohypogastric (T12–L1) nerves—which innervate the Pfannenstiel incision site commonly used in CS [5]. Unlike transversus abdominis plane (TAP) blocks, which require ultrasound guidance to deposit local anesthetic between the internal oblique and transversus abdominis muscles, the ILIH block can be performed using anatomical landmarks alone, rendering it accessible in resource-limited settings [6]. Its simplicity and potential for opioid-sparing analgesia have spurred interest in its applicability to post-cesarean pain control. However, evidence supporting its efficacy remains heterogeneous, with conflicting outcomes reported across randomized controlled trials (RCTs) and meta-analyses [7,8]. 

Post-cesarean pain arises from somatic, visceral, and inflammatory pathways. Somatic pain, localized to the abdominal wall incision, is transmitted via the ilioinguinal and iliohypogastric nerves, making them logical targets for regional blockade [9]. The ILIH block’s mechanism involves injecting local anesthetic (e.g., bupivacaine or ropivacaine) near these nerves as they traverse the inguinal canal, thereby blocking nociceptive signals from the surgical site [10]. By contrast, systemic opioids exert non-selective central nervous system effects, contributing to side effects that may interfere with early ambulation and breastfeeding [11]. 

Proponents of the ILIH block argue that its anatomical precision reduces opioid consumption and associated complications. A 2020 meta-analysis by Hussain et al. found that ILIH blocks reduced 24-hour morphine consumption by 35% compared to placebo in patients undergoing CS under spinal anesthesia. Similarly, a double-blind RCT by Aydın et al. reported significantly lower pain scores at rest and during movement in the ILIH group versus controls at 6, 12, and 24 hours postoperatively [12]. These findings align with the broader shift toward enhanced recovery after surgery (ERAS) protocols, which prioritize opioid minimization to accelerate discharge and improve patient satisfaction [13]. 

Despite encouraging results, the utility of the ILIH block remains debated. Critics highlight inconsistencies in trial design, including variability in local anesthetic volumes, concentrations, and timing of block administration (pre-incisional vs. postoperative) [14]. For instance, a 2021 Cochrane review by Hamid et al. concluded that ILIH blocks provided no significant reduction in pain scores beyond 6 hours post-CS when compared to sham blocks, attributing discrepancies to underpowered studies and heterogeneity in outcome measures. Furthermore, the block’s reliance on landmark techniques raises concerns about precision; ultrasound-guided approaches, while not always feasible, may improve consistency and success rates [15].

Another critical consideration is the interaction between ILIH blocks and intrathecal opioids. Many CS patients receive intrathecal morphine as part of spinal anesthesia, which provides potent analgesia but carries risks of pruritus and delayed respiratory depression [16]. Whether ILIH blocks confer additive benefits in this population—or merely redundant coverage—remains unclear. A 2022 RCT by Özmen et al. found no difference in pain scores or opioid use between ILIH and control groups when intrathecal morphine was administered, suggesting that the block’s utility may depend on institutional analgesia protocols [17]. 

This review evaluates the efficacy of the ILIH nerve block in controlling postoperative pain following cesarean delivery, synthesizing evidence from randomized controlled trials, systematic reviews, and mechanistic studies. Key outcomes include postoperative pain scores (at rest and during movement), opioid consumption, time to first analgesic request, and incidence of opioid-related adverse effects. Additionally, this analysis explores technical considerations (e.g., landmark vs. ultrasound-guided approaches), pharmacological variables (e.g., local anesthetic type and volume), and contextual factors (e.g., resource availability, ERAS protocols) that influence the block’s clinical relevance. By addressing these dimensions, this review aims to provide evidence-based recommendations for integrating ILIH blocks into post-cesarean pain management algorithms.

Conditions for Conducting this Study

This research is a clinical trial study conducted in 2025 on 66 full-term pregnant women undergoing cesarean section. The samples were selected using the convenience sampling method based on the inclusion criteria and then divided into two equal groups based on random allocation.

Data Collection and Sample Size

The sample size was calculated based on the sample size formula, and the total number of subjects studied was 66 people based on the formula. Inclusion criteria included full-term pregnant women; age between 18 and 45 years; according to the American Society of Anesthesiologists (ASA) II classification; no history of opioid, alcohol, or any substance abuse. Exclusion criteria included preeclampsia, eclampsia, renal, hepatic, or cardiac disorders, history of sensitivity to the study drugs, history of chronic pain and chronic analgesic use, or any infection in the area of the nerve block. Randomization was performed in a double-blind manner, and the patients were divided into two groups.

Study design

To conduct this study, informed consent was first obtained from the patient. Information about the purpose of the study and its methodology, the injected drugs, and their possible side effects was explained to them. A checklist containing the patient's demographic information and medical history was completed, and all steps of anesthesia preparation were performed. After induction of general anesthesia with the closed-envelope technique, the patients were randomly divided into two equal groups. After antagonizing the neuromuscular block with intravenous neostigmine 0.04 mg/kg and atropine 0.02 mg/kg, before extubation, a II-IH nerve block was performed in group I (II-IH block), and patients received a sham block with saline solution at the corresponding puncture site in group II (sham block). A mark was made approximately 2 cm from the midpoint and superior to the anterior superior iliac spine. A 22G needle is inserted into the skin and, after piercing the external oblique fascia, one-sixth of 10 ml of 5% ropivacaine is injected after a negative aspiration test. The needle is then advanced until resistance is felt between the internal oblique and transverse muscles. Another one-sixth of the local anesthetic solution is injected. The needle is withdrawn, and the procedure is repeated by changing the needle inward and then outward at a 15-degree angle in the same horizontal plane and in a fanning manner. The same procedure is performed on the opposite side, and a total volume of 20 ml of local anesthetic is administered for both injection sites. A sham block with the same volume of saline is performed using the technique described by Bell et al. in the sham block group. Close monitoring of vital signs continues throughout the surgery, and the severity of postoperative pain is recorded in both groups of patients.

Ethical considerations

All ethical considerations were considered in the study process. Permission was obtained from Tehran University of Medical Sciences. Written informed consent was obtained from patients to participate in the study, and freedom to enter and exit the study, as well as the anonymity of the questionnaires and emphasis on confidentiality and privacy of information.

Statistical Analysis

All statistical analyses were performed using SPSS (Statistical Package for Social Sciences) for Windows, version 25. Data are presented as mean and standard deviation. A p-value of less than 0.05 was considered statistically significant.

The study demonstrated that intraoperative vital signs such as heart rate and oxygen saturation did not differ significantly between the nerve block and sham groups, nor across different age and BMI subgroups, underscoring the safety of the procedure during surgery. the high percentage of participants was found in the 36 - 45-year group, which reached 40.9%. While the low percentage of participants was found in the 16 - 25-year group, which reached 13.6%. all participants were female, representing 100.0%. the high percentage of participants’ BMI was found in the 30 - 34.9 Obese class I group, which reached 48.5 %while the low percentage of participants’ BMI was found in the 35 - 39.9 Obese class II group, which reached 6.1 %. the high percentage of participants’ type of anesthesia was found in the general anesthesia group, which reached 68.2% while the low percentage of participants’ Spinal anesthesia group was found to reach 31.8%. the highest of participants’ Analgesia consumption was found in the 62.1% group Tramadol, which reached to while, while the lowest of participants’ Morphine group was found to reach (37.9 %).

The highest of participants’ Analgesia consumption was found in (62.1%) Tramadol group, which reached to while, while the lowest of participants’ Morphine group was found, which reached 37.9 %. the high percentage of participant’s group allocation according to BMI was found in 30-34.9 Obese group that reach to ((27.3%)) in Group II (Sham Block) while, the low percentage of participant’s 35 - 39.9 Obese class II group was found in Group I (II-IH Block) that reach to (1.5%). the high percentage of participants’ group allocation according to age was found in Group II (Sham Block), which reached 30.3% in 30.3% years group, while the low percentage of participants’ Group II (Sham Block) was found in the (25-30) years group, which reached 1.5%. showed the mean of heart rate before and during anesthesia. The heart rate before general anesthesia was 72 ± 10 bpm, while during anesthesia, the mean heart rate was 70 ± 8 bpm. There were no significant (p≤0.05) differences in the heart rate before and during anesthesia. The postoperative assessment after anesthesia. The Pain score rate after anesthesia was 5 in 6 h Time Post-Surgery, which amounted to 47.0%. On the other hand, the least common Pain score rate after anesthesia was 3 in 1 h Time Post-Surgery, which amounted to 22.7%. showed the adverse effects after anesthesia. The bleeding rate after anesthesia was 40.9% and it’s the most common complication, followed by nausea, which reached 16.7% of patients after anesthesia. On the other hand, the least common complication in patients after anesthesia was bradycardia, which amounted to 10.6% Table 1.

In other words, the results of this study showed in summary that pain scores increased over time, with the highest severity observed at 6 hours post-surgery, where nearly half of the patients experienced moderate pain (score of 5). The distribution of pain scores suggests that the nerve block did not significantly alter the pain trajectory compared to the control group. Adverse effects were frequently observed, with bleeding being the most common complication (about 41%), followed by nausea (17%), hypotension, and headache. The incidence of bradycardia remained low, around 10%. Analgesic use was predominantly with Tramadol, and the groups were evenly balanced in terms of demographic and clinical characteristics, supporting the validity of the comparison. Overall, the results indicate that while the nerve block is safe, its efficacy in reducing postoperative pain remains inconclusive in this study Table 1.

This study investigated the efficacy of the ilioinguinal-iliohypogastric nerve block in managing postoperative pain among women undergoing cesarean sections. The demographic profile revealed that most participants were aged between 36 and 45 years, aligning with the typical reproductive age group. The exclusive female composition of the sample reflects the study's focus on cesarean  deliveries.  Notably,  a  significant  proportion of participants had a BMI in the overweight and obese ranges, particularly in the 30-34.9 BMI category, which is consistent with global trends indicating rising obesity rates among women of reproductive age. This demographic distribution underscores the importance of considering BMI as a factor influencing anesthesia and analgesia outcomes. 

Table 1: Results of some parameters in patients

In terms of anesthesia types, the majority of patients received general anesthesia (68.2%), which is often preferred in cesarean sections for rapid induction and airway control. The analgesic modality predominantly involved tramadol, used by about 62% of participants, indicating reliance on opioid analgesics for postoperative pain relief. Participants were evenly allocated into two groups—one receiving the nerve block and the other a sham procedure, ensuring balanced comparison. The intraoperative vital signs remained stable across groups, with no significant differences in heart rate or oxygen saturation, indicating that the nerve block did not adversely affect intraoperative hemodynamics or respiratory parameters.

Postoperative pain assessments demonstrated a progressive increase in pain scores over time, with the highest reported pain (score of 5) at six hours post-surgery, affecting nearly half of the patients. Interestingly, the nerve block did not significantly reduce postoperative pain compared to the sham, suggesting limited efficacy in this setting. The pain trajectory indicates that additional or alternative analgesic strategies may be necessary for optimal pain control after cesarean section.

Adverse effects observed were common but generally manageable. Bleeding was the most frequent complication, affecting approximately 41% of patients, followed by nausea (16.7%), hypotension, and headache. Importantly, serious adverse events like bradycardia were infrequent, highlighting the safety profile of the techniques used. The high incidence of bleeding may be related to surgical or anesthesia-related factors, and further investigation could clarify this association.

Overall, the findings suggest that while the ilioinguinal-iliohypogastric nerve block is safe and well-tolerated, its effectiveness in reducing postoperative pain in cesarean section patients was not demonstrated in this study. Future research should consider larger sample sizes, different timing of nerve block administration, or combining multiple analgesic approaches to optimize postoperative pain management.

The findings indicate that the ilioinguinal-iliohypogastric nerve block did not produce a statistically significant reduction in postoperative pain scores compared to the sham procedure. Intraoperative vital parameters remained stable, indicating the safety of the block. Although the intervention appears to be safe with minimal adverse effects, its clinical efficacy in controlling postoperative pain after cesarean section requires further investigation. Larger sample sizes and possibly different techniques or timing may be necessary to establish its true benefits. Currently, the data suggest that this nerve block may not significantly improve postoperative analgesia in cesarean section patients.

Conflict of Interest

There are no conflicts of interest related to this study. There are no financial, personal, or professional interests that might influence the course or results of the research.

Ethical Approval

The ethical committee at Tehran University of Medical Sciences approved the study's ethical permission (IR.TUMS.SPH.REC.1404.110). Group data were published for all the information that was gathered (rather than individually). A name, ID number, country code, or any other identity data is missing from the required data.

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