Effective postoperative pain control is crucial following lower segment cesarean sections (LSCS), not only for enhancing maternal comfort but also for facilitating early mobility, breastfeeding initiation, and mother-infant bonding [1]. Traditionally, postoperative pain in LSCS is managed with opioids delivered through systemic or neuraxial routes, which, while effective, are often associated with adverse effects including nausea, vomiting, constipation, and respiratory depression. These side effects can impair recovery, increase healthcare costs, and ultimately reduce patient satisfaction with their care [1,2,3].

The Transversus Abdominis Plane (TAP) block is an evolving regional analgesic technique that provides targeted pain relief for lower abdominal procedures, such as LSCS, by anesthetizing the sensory nerves from T6 to L1. By delivering a local anesthetic within the fascial plane between the internal oblique and transversus abdominis muscles, the TAP block produces a reliable myocutaneous sensory blockade that may be comparable in efficacy to systemic opioids but with a reduced risk of complications [4]. This technique is particularly advantageous for minimizing postoperative opioid consumption and its associated side effects [5].

While ultrasound-guided TAP blocks are considered safe and effective, their use is often limited by the availability of ultrasound equipment and trained practitioners.[6] To overcome these barriers, modified techniques such as the surgeon-assisted TAP block have been introduced, allowing anesthetic to be precisely delivered even in higher BMI patients. This approach not only reduces the risk of peritoneal or visceral injuries but also enables less experienced practitioners to perform the TAP block safely [6,].

The TAP block was first introduced in 2001 by Rafi as a single-pop technique [7] and has since evolved by Later on, it was modified by McDonnell who described it as a “two pop” technique using regional anesthesia via a blunt needle perpendicular to the skin, just superior to the iliac crest and behind the mid-axillary line.[7]  The success rate of this technique is found to be around 85% among experienced practitioners.[7]  It has a high margin of safety and is technically easy to perform. Some other modifications are ultrasound-guided methods, depending on the clinician's expertise and available resources [8]. Studies consistently show that TAP blocks, as part of multimodal analgesic regimens, effectively decrease additional analgesic needs, delay the onset of breakthrough pain, and enhance overall patient satisfaction during the postoperative period [9].

In LSCS, postoperative pain has both somatic and visceral components, frequently rated as moderate to severe. Addressing this pain promptly is essential for maternal well-being, early ambulation, and optimal newborn care [10]. Given its proven efficacy and ability to reduce opioid requirements, the TAP block represents a valuable option in obstetric analgesia, aligning with current efforts to improve postoperative outcomes in cesarean deliveries [9].

A range of local anesthetic (LA) agents has been employed for postoperative analgesia using a transversus abdominis plane (TAP) block. [11,12,13] While both ropivacaine and levobupivacaine have comparable pKa values and plasma protein-binding characteristics, and are frequently utilized in TAP blocks, their relative effectiveness has not been directly compared. This study aimed to determine whether ropivacaine, with its inherent benefits—such as high anesthetic potency, extended duration of action, and a favorable toxicity profile—outperforms levobupivacaine in providing postoperative analgesia for patients undergoing cesarean section.

The study was a prospective, randomized, double-blind, controlled clinical trial conducted over a six-month period. Following Institutional Review Board (IRB) approval and informed patient consent, 60 participants from the Department of Anesthesiology were enrolled and assessed for eligibility. A comprehensive pre-anesthetic evaluation determined inclusion or exclusion based on the following criteria:

Inclusion Criteria

Eligible participants were aged 20-35 years, consented to participate, and were pregnant patients scheduled for elective or non-urgent lower-segment cesarean sections, with an American Society of Anesthesiologists (ASA) physical status of I or II.

Exclusion Criteria

Participants were excluded if they declined consent or had contraindications to spinal anesthesia, such as localized lumbar infections, bleeding disorders, thrombocytopenia, intracranial space-occupying lesions, spinal anatomical abnormalities, hypovolemia, or allergies to local anesthetics or NSAIDs. Additionally, patients on analgesic therapy or with a body mass index (BMI) ≥ 25 kg/m² were excluded.

Study Groups and Blinding

Patients were randomly assigned to two groups of 30, using a computer-generated randomization sequence. Both the investigator administering the drug and the observer were blinded to group assignments and drug details. Group L (n=30) received a bilateral transversus abdominis plane (TAP) block with 15 ml of 0.25% Levobupivacaine, while Group R (n=30) received the same volume of 0.25% ropivacaine.

Procedure

In the pre-anesthetic preparation room, standard monitoring was established, including heart rate (HR), peripheral oxygen saturation (SpO₂), and non-invasive blood pressure (NIBP). Baseline vitals were recorded, and an 18G intravenous line was placed in the non-dominant hand. Patients were preloaded with Ringer's lactate (10 ml/kg) before surgery and received a subarachnoid block with 2 ml of 0.5% hyperbaric bupivacaine via a 23G spinal needle in the L3-L4 interspinous space. After achieving adequate sensory and motor block, surgery commenced. Upon completion of the procedure, a TAP block was administered bilaterally. In the supine position, the iliac crest was palpated to locate the triangle of Petit, bordered anteriorly by the external oblique, posteriorly by the latissimus dorsi, and inferiorly by the iliac crest. A 22G, 9-cm blunt-tip needle was inserted into the triangle at a perpendicular angle to the coronal plane until the first resistance (indicating penetration of the external oblique muscle) was felt. Advancing the needle produced a "pop" sensation, signalling entry into the fascial plane between the external and internal oblique muscles. A second "pop" indicated the transverse abdominis plane was reached. Negative aspiration was confirmed before administering 15 ml of 0.25% bupivacaine or ropivacaine in 5-ml increments on each side.

Post-Operative Care and Analgesia

An incision site pressure dressing was applied, and the patients were transferred to the Post-Anesthesia Care Unit (PACU), where they received standard analgesia per obstetric department protocol, including 75 mg intravenous diclofenac every eight hours, beginning at the end of surgery.

Pain and Outcome Assessment

Pain levels at rest and during passive hip and knee flexion were measured immediately upon PACU transfer and at multiple time points (30 minutes, 2, 4, 6, 8, 10, 12, 16, 20, and 24 hours post-surgery) using a Visual Analog Scale (VAS; 0 = no pain, 10 = worst pain). If VAS scores reached or exceeded 4, intravenous paracetamol (1 g) was administered as a rescue analgesic.

Visual Analog Scale (VAS) for Pain:

The VAS is a continuous scale, often represented by either a horizontal (HVAS) or vertical (VVAS) 10-centimeter line. The respondent self-completes the scale by marking a point along the line that best reflects their current pain intensity.

Scoring:
Using a ruler, the score is calculated by measuring the distance (in centimeters) along the 10-cm line:

• 0 — No Pain
• 1-3 — Mild Pain
• 4-6 — Moderate Pain
• 7-9 — Severe Pain
• 10 — Worst Possible Pain

Outcome Measures:

The primary outcomes included the VAS pain score, total dosage, and frequency of rescue analgesics used within the first 24 hours post-surgery and surgeon and patient satisfaction score. Secondary outcomes were the effects on hemodynamic parameters (such as heart rate, mean arterial pressure, and oxygen saturation), as well as the occurrence of any side effects or complications.

Statistical Analysis:

The primary outcome was the time to the first request for analgesia, while secondary outcomes included the number of patients requesting analgesia within specific time intervals and the incidence of side effects such as sedation, nausea, and vomiting. A clinically significant difference was defined as a 180-minute variation in the time to first analgesia request between the levobupivacaine and ropivacaine groups. Based on a pilot study with nine patients, the sample size was calculated with a 5% α error and 80% power, requiring 28 participants per group. To account for potential dropouts, 30 patients were included in each group. Data analysis was performed using GraphPad software version 3.06, with results expressed as mean ± standard error of the mean (SEM) for normally distributed data. An unpaired Student’s t-test was applied, with statistical significance set at P < 0.05.

All 60 patients enrolled successfully completed the study and no patient had a primary block failure. Patient characteristics in terms of age, gender, weight and were comparable among the two groups.

Table 1: Demographic data of study participants

Table 1 presents the age and weight distributions for the ropivacaine and levobupivacaine groups. The mean age in the ropivacaine group was 24.27 ± 0.62 years, compared to 24.4 ± 0.78 years in the levobupivacaine group, with no statistically significant difference (P = 0.625). Similarly, the mean weight in the ropivacaine group was 60.08 ± 0.82 kg, while in the levobupivacaine group, it was 59.64 ± 0.48 kg, also showing no significant difference (P = 0.770). These results suggest comparable baseline characteristics between the two groups in terms of age and weight, as indicated by the P-values greater than 0.05. The two groups were comparable with regard to cardiovascular and respiratory status.Patient

Table 2: VAS Score

*=p<0.05 by unpaired t test.

VAS score was significantly less in ropivacaine group as compared to bupivacaine after LSCS at 6,8, and 10 hours. (P<0.05).

Table 3: -Patient Satisfaction Score.

P<0.05 as compared to levobupivacaine by using unpaired t test.

Table 3 summarizes the patient satisfaction scores for the ropivacaine and levobupivacaine groups. The mean satisfaction score in the ropivacaine group was 2.5 ± 0.21, while in the levobupivacaine group, it was 2.01 ± 0.44. Statistical analysis using an unpaired t-test revealed a significant difference between the two groups, with the ropivacaine group achieving a higher satisfaction score (P < 0.05). This indicates that patients who received ropivacaine reported greater satisfaction compared to those who received levobupivacaine.

Table 4: -Surgeons Satisfaction Score.

P<0.05 as compared to levobupivacaine by using unpaired t test.

Table 4 presents the satisfaction scores given by surgeons for the ropivacaine and levobupivacaine groups. The mean satisfaction score for the ropivacaine group was 2.4 ± 0.37, while for the levobupivacaine group, it was 2.2 ± 0.24. An unpaired t-test indicated a statistically significant difference between the two groups (P < 0.05), with higher satisfaction scores in the ropivacaine group. This suggests that surgeons were more satisfied with the operative conditions when ropivacaine was used compared to levobupivacaine.

Rescue analgesia was needed early in the Levobupivacaine group as compare to ropivacaine group. Patients in both the group not reported nausea and vomiting. There was no local complication attributed to TAP block in either group.

Figure 1 Rescue analgesia

Managing postoperative pain after a cesarean section presents unique challenges, requiring an approach that is not only effective but also safe and free from significant side effects. Recently, there has been increased interest in regional nerve block techniques, which have shown promising results by effectively reducing the need for additional analgesics [14]. Among these, the transversus abdominis plane (TAP) block is a relatively recent abdominal nerve block technique that has demonstrated excellent efficacy in various abdominal surgeries, including cesarean sections. Notably, because the TAP contains fewer blood vessels, the risk of systemic toxicity from local anesthetics—typically caused by vascular puncture and a common concern with other peripheral nerve blocks—is minimized. This procedural simplicity also enhances its clinical utility.

Racemic bupivacaine is a widely used local anesthetic for nerve blocks. [15] However, at high doses or with inadvertent intravascular injection, it may cause severe cardiovascular [16]  and central nervous system toxicity[17,18], primarily due to the R(+) enantiomer in bupivacaine[16,17]. This risk led to the development of levobupivacaine, the S(+) enantiomer, which exhibits fewer toxic effects while maintaining a similar clinical efficacy profile to racemic bupivacaine. Levobupivacaine has a lower tendency for cardiac toxicity because R(+) bupivacaine has a 2.4-fold greater affinity for cardiac sodium channels and dissociates more slowly than the S(+) enantiomer[19]. Additionally, levobupivacaine has a plasma protein binding affinity of over 97%, compared to bupivacaine's 95%, meaning that less free drug is available to cause adverse effects [18,20]. Its inherent vasoconstrictive properties also contribute to an extended duration of action and reduced systemic toxicity. Numerous studies have investigated levobupivacaine’s effectiveness as a local anesthetic, assessing parameters such as onset time, duration, and analgesic quality.[21]

McDonnell et al. [11] reported that administering a TAP block with 0.75% ropivacaine at 1.5 mg/kg (up to a maximum of 150 mg) significantly reduced the total dose of morphine required via IV-PCA in patients undergoing cesarean sections over a 48-hour postoperative period compared to controls. In our study, 0.25% ropivacaine was utilized for postoperative analgesia and hemodynamic monitoring. Analgesia was effectively maintained for 24 hours without any discomfort, and hemodynamic parameters remained stable throughout this period.

In 2012, Bhavna et al. [22] conducted a study involving fifty women who underwent bilateral TAP block with either 0.5% ropivacaine (N=25) or a placebo (N=25). In our study, the duration of analgesia with 0.5% ropivacaine was 24 hours, which aligns with the findings of Bhavna et al., where the analgesic effect also lasted for 24 hours.

In 2013, Priya Sharma et al. [23] conducted a study with sixty patients (mean age 36.2 ± 9.6 years) of either sex, classified as ASA grade 1 and 2, who underwent major gynecological or surgical procedures. These patients were randomly assigned to either receive standard care with patient-controlled tramadol analgesia (n = 30) or undergo a TAP block with 20 ml of 0.375% levobupivacaine (n = 30). The TAP block significantly reduced VAS pain scores at most time points (2, 4, 6, 12, and 24 hours), but not at the later time points (36 and 48 hours). Patients receiving the TAP block required less tramadol over 24 hours (P < 0.01) and 48 hours (P < 0.01), and had a longer time to the first PCA tramadol request compared to the control group (P < 0.001). This study concluded that TAP block provided superior analgesia compared to opioids or other intravenous medications. In our study, 0.25% levobupivacaine was used for the TAP block, which provided effective analgesia for 12 hours postoperatively, with a reduced need for intravenous analgesic medication.

In 2013, Sooyoung Cho, Youn-Jin Kim, Dong-Yeon Kim, and Soon-Sup Chung [24] conducted a study involving forty-four patients undergoing appendectomy. The patients were divided into two groups: one group received a right-sided TAP block (Group I, n = 22), while the other group received standard care (Group II, n = 22). All patients were administered standard anesthetic care, and the TAP block group received an ultrasound-guided right-sided TAP block using 20 mL of 0.5% levobupivacaine after anesthesia induction. The results showed that the TAP block group, compared to the control group, experienced a significant reduction in VAS scores up to 12 hours postoperatively, which aligns with the findings in our study.

In 2017, P. Raghunath et al. [25] conducted a study comparing the use of ropivacaine versus levobupivacaine for postoperative analgesia in patients undergoing lower abdominal surgeries. They found that the average duration of analgesia was 419.6 ± 49.95 minutes in the levobupivacaine group and 2140 ± 511.12 minutes in the ropivacaine group. The difference between the two groups was statistically significant (P < 0.05), which is consistent with the findings of our study.

In this study, when comparing analgesic efficacy, the VAS scores were similar between both groups, with a statistically significant difference observed at 6, 8, 10, and 12 hours (P < 0.05). These results are consistent with the findings of Uma Srivastava et al., [26] whose study showed significantly lower scores at all time points up to 24 hours in the study group, both at rest and with movement (P < 0.0001), when compared to the control group.

Maitreyi Gajanan Mankikar et al. [27] demonstrated that the VAS score was lower for the first 8–10 hours postoperatively in patients who received a TAP block with 0.5% ropivacaine, compared to those who received a placebo block.

In the current study, the number of patients needing rescue analgesics over time was significantly lower in the ropivacaine group compared to the levobupivacaine group. This finding aligns with a study by Uma Srivastava et al., [26] and study by Parmar Ravi et al., [28] which also reported a statistically significant reduction in rescue analgesia requirements in the study group compared to the control group (P < 0.0001). Additionally, when comparing mean satisfaction scores, patients in the ropivacaine group showed significantly higher satisfaction than those in the levobupivacaine group.

Prashant Parmar et al., in 2022 [29] conducted study on Transversus abdominus plane block with ropivacaine vs levobupivacaine for post-operative analgesia in patients undergoing LSCS and they found the surgeons satisfaction score and patient satisfaction score in  Levobupivacaine group  and Ropivacaine group were statistically significant. This difference between two groups was statistically significant (p<0.05) and they are compatible with our study.

A limitation of this study was the relatively small sample size, which restricted the assessment of safety parameters. Overall, the findings indicate that the analgesic effect of the TAP block with ropivacaine is more effective than with levobupivacaine. The TAP block technique is straightforward and beneficial for managing post-cesarean section pain. Our study suggests that both 0.25% levobupivacaine and 0.25% ropivacaine provide effective postoperative analgesia when used in TAP blocks, with comparable outcomes across demographic and other measured parameters. This block supports early ambulation, promotes infant care, and has minimal side effects for both mother and child. Previous studies have also shown that TAP blocks reduce intravenous opioid consumption, thereby decreasing opioid-related side effects. Limited evidence further suggests that TAP blocks or TAP catheters may offer analgesia and patient satisfaction comparable to epidural therapy.