**Abstract**

Pain management after a surgical intervention is one of the fundamental pillars for optimal patient recovery. In obstetric patients, this management may affect the mother and the newborn. The gold standard for analgesic management is the use of intrathecal morphine due to its long-lasting effect; however, adverse effects related to the use of opioids are evidenced, whether administered intrathecally or systemically in case of contraindication to the neuraxial approach or if a long-acting opioid is not available. Cesarean sections have been associated with moderate-tosevere postoperative pain. Multimodal analgesic management seeks to minimize the undesirable effects on the mother-newborn binomial in order to increase maternal satisfaction. The most studied regional blocks for this surgery are the transversus abdominis plane block and the ilioinguinal-iliohypogastric block, which shows contradictory evidence at the time of evaluate pain where there is no significant difference compared with intrathecal morphine, but there were fewer side effects with the TAP block group when assessing pruritus, nausea, and vomiting. Quadratus lumborum and erectus spinae plane block demonstrate its usefulness with better pain management compared with TAP block regardless of them having a higher level of complexity due to the visceral pain control; but there is no evidence with methodologic quality enough that demonstrates better outcomes compared with intrathecal morphine.

**Keywords:** post-Cesarean pain, TAP block, ilio-inguinal, iliohypogastric block, ESP block, quadratus lumborum block

### **1. Introduction**

Proper pain management after a surgical intervention is the fundamental pillar for optimal recovery, as in obstetric patients this aspect affects not only the mother but also the newborn. The gold standard for postoperative analgesic management is the use of intrathecal morphine since it has a long duration. However, adverse effects related to the use of opioids are evidenced, whether administered intrathecally or systemically in case of contraindication to the neuraxial approach, or if a long-acting opioid is not available. Cesarean sections have been associated with moderate-to-severe postoperative pain; therefore, improper management of analgesia would lead to chronic post-surgery pain, problems in breastfeeding, and

the mother-newborn relationship, and it has even been considered a trigger for postpartum depression. Based on the foregoing, multimodal analgesic management seeks to minimize the undesirable effects on the mother-newborn binomial in order to increase maternal satisfaction and that the relationship between the mother and her newborn is not altered, since the regional analgesia techniques have gained territory by reducing the consumption of analgesics in the immediate postoperative period, and also are easy to perform procedures. Among the most studied we will review the more important aspects of the abdomen transverse plane (TAP), quadratus lumborum and erectus spinae plane blocks [1–7].

### **2. Transversus abdominis plane block**

The TAP block had been described for the first time as an abdominal wall block based on anatomical landmarks to introduce local anesthetic (LA) into the TAP through the Petit triangle using the loss of resistance technique. The first ultrasound-guided TAP was described in 2007, since then it uses have become popular in upper and lower abdominal surgeries, although it has not been fully integrated into routine clinical practice [8].

The anterolateral abdominal wall consists of four muscles: rectus abdominis, external oblique, internal oblique, and transversus abdominis. The innervation of the abdominal wall and the underlying parietal peritoneum depends on the intercostal nerves (T7–T12) and the first lumbar root (L1). After their spinal emergence, the spinal nerves give a posterior branch and a lateral branch (which usually emerges at the level of the mid-axillary line) and ends in an anterior branch that joins in the linea alba with the anterior branches of the contralateral hemi body. The terminal branches of these nerves travel in the abdominal wall within a neurofascial plane located between the internal oblique muscle and the transversus abdominis muscle, and this space is named the transversus abdominis plane (TAP) [9].

The use of ultrasound allowed the development of new approaches, such as the subcostal, lateral, posterior or combinations such as dual TAP in which the possibilities of TAP block use have been increased [8].

There are three reported TAP block approaches: the posterior one, by anatomical landmarks in Petit's triangle, described by Rafi and McDonnell for analgesia of the lower abdominal quadrants (dermatomes from T11 to L1); the ultrasoundguided subcostal approach, described by Hebbard in 2008 for periumbilical and upper-quadrant analgesia of the abdomen (T10 to T6 dermatomes), and the lateral approach [10].

The subcostal approach targets the compartment of the transverse plane of the abdomen in the anterior abdominal wall, below the costal margin, anywhere between the xiphoid process and the anterior superior iliac spine. The lateral approach is directed to the compartment of the transverse plane of the abdomen in the lateral abdominal wall between the mid-axillary and anterior axillary lines. Finally, the posterior approach is directed to the compartment of the transverse plane of the abdomen at the level of Petit's lumbar triangle or the anterolateral aspect of the quadratus lumbar muscle (**Figures 1**–**3**) [11].

To perform these interfascial blocks, the abdomen is exposed between the ribs margin and the iliac crest, and it is recommended to use the high-frequency linear transducer (6–15 MHz), because the anatomical structures are relatively shallow [12].

Regarding the subcostal approach, initially a linear ultrasound probe with a sterile sheath is placed under the xiphoid process to view the linea alba. The probe is then directed obliquely down the costal margin while keeping the rectus

#### **Figure 1.** *Transversus abdominis plane block. Subcostal approach [11].*

**Figure 2.** *Transversus abdominis plane block. Lateral approach [11].*

**Figure 3.** *Transversus abdominis plane block. Posterior approach [11].*

abdominis muscle in view. The transverse abdominis muscle is seen below the rectus abdominis muscle. The probe is advanced further until the semilunaris (curved tendon intersection found on both sides of the rectus abdominis muscle) is seen. An echogenic needle is inserted into the plane until the tip of the needle reaches the fascia between the rectus abdominis and transverse abdominis muscles, while the local anesthetic is injected, the needle is advanced laterally, producing a lateral extension of the local anesthetic [13]. For the posterior approach TAP block, the linear transducer is positioned in the axial plane at the mid-axillary line and moved posteriorly to the most posterior limit of the TAP between the internal oblique and transverse abdominal muscles. The target is the rearmost end of the TAP. The needle is inserted in the mid-axillary line and advanced posteriorly until reaching the posterior end of the TAP [14].

The three muscle layers of the abdominal wall are identified: the external oblique muscle (most superficial), the internal oblique muscle (most prominent layer), and the transversus abdominis muscle. A 0.80 × 100 mm 21G short bevel needle is inserted in plane with the transducer. The insertion point is made slightly away from the transducer to allow better visualization of the needle. It is important to deposit the local anesthetic in a deep place in the fascia in such a way that it separates the internal oblique muscles from the transverse abdominis muscle, thus performing a "hydrodissection" (1–2 mL of saline solution or local anesthetic) that adequately exposes the plane. A total of 20 mL of local anesthetic is injected into the plane of each side [12].

Among RCTs comparing TAP versus intrathecal morphine, it has been demonstrated that there were no significant differences in VAS in pain at rest or in movement, nor any significant reduction in time to opioid rescue. It is well known that TAP prolonged the time to opioid rescue by 50%, increased early VAS at rest and on the move, and reduced PONV and pruritus in the TAP group. In the RCTs that compared TAP versus placebo TAP in Cesarean section with spinal anesthesia without intrathecal morphine, there is a decrease in opioid consumption in the first 24 h (18 mg vs. 13.5 mg; p < 0.05) and in the time to the first opioid rescue (2 h vs. 3 h, p = 0.019). However, no significant differences were found in VAS at rest or movement, as well as in the incidence of side effects of opioids. Baaj et al. demonstrated a significant reduction in opioid consumption in the first 24 h (25.89 mg vs. 62 mg, p > 0.05), as well as a 25% decrease in VAS at rest and in movement during the first 24 h, and a decrease in PONV [8].

In a study by Lopez et al. [9], 41 patients were included, 20 in the TAP group, and 21 in the group wound infiltration (WI). The analgesic efficacy obtained in both groups was similar, with a higher demand for additional analgesia in the postoperative period in the WI group at 10, 30, and 60 min, becoming statistically significant at 60 min. By means of a home telephone call at 24 h, a higher consumption of rescue analgesia was found in this group (p < 0.05). There were no differences in side effects or complications related to the ultrasound-guided regional technique. The degree of patient satisfaction with the anesthetic technique was similar for both groups. In the same way, Gao carried out a study where 100 patients who underwent Cesarean section were randomly classified into two groups. After surgery, one group underwent ultrasound-guided TAP block and the other group underwent patient-controlled intravenous analgesia (PCIA), and no significant differences were found in VAS scores between the groups (p > 0, 05). However, the incidence of postoperative complications in the TAP group was significantly lower than in the PCIA group (p < 0.05). Furthermore, patient satisfaction in the TAP group was significantly higher than in the PCIA group (p < .05) [15]. Also, in a study conducted by Dereu et al. [16], where patients undergoing Cesarean section were randomly assigned to one of two groups (quadruple blind): 100 mg of intrathecal morphine (ITM) was added to local spinal anesthetic or a bilateral TAP block with 20 ml of 0.375% ropivacaine +75 μg of clonidine on each side. About 24 hours after blocking, there was no significant difference between the ITM and TAP groups in the total number of patients who presented PONV: 17/92 patients and 27/88 patients in the TAP and ITM groups, respectively (p = 0.065). Pain scores at 6 h and cumulative morphine consumption at 24 h were lower in the ITM group (p < 0.0001 for morphine consumption at 24 h). The incidence of hypotension was higher in the TAP group. Maternal satisfaction was high and not different between the groups. As in the study by Ashok Jadon et al. [17], 139 mothers undergoing Cesarean section were randomized to receive a TAP block with 20 mL of 0.375% ropivacaine or 20 mL of saline. All subjects received a standard spinal anesthetic

*Ultrasound-Guided Regional Analgesia for Post-Cesarean Pain DOI: http://dx.doi.org/10.5772/intechopen.101465*

and diclofenac was administered for postoperative pain, found as a result that the median time to first analgesic request was prolonged in the TAP group compared with the control group (p < 0.0001); 11 h (8.12) and 4 h (2.5.6), respectively. The median doses of tramadol consumed in the TAP group was 0 (0.1) compared with 2 (1.2) in the control group (p < 0.0001). At all study points, pain scores both at rest and on movement were lower in the study group (p < 0.0001). Maternal satisfaction with pain relief was also higher in the study group (p = 0.0002).

Kakade and Wagh [18] evaluated the feasibility of TAP for postoperative analgesia after Cesarean section found that the duration of postoperative analgesia was significantly longer in the TAP block group compared with the control group (without block).
