**3. Ilioinguinal/iliohypogastric block**

Both the iliohypogastric (IH) and ilioinguinal (II) nerves arise from L1 and emerge from the upper part of the lateral border of the psoas major muscle. Nerve II is smaller and runs caudal to nerve IH. Both nerves pass obliquely anterior to the quadratus lumbar and the iliac muscle and pierce the transverse abdominis muscle near the anterior part of the iliac crest. In the anterior abdominal wall, both nerves travel in the transverse abdominal plane. The IH nerve provides skin sensitivity to the groin region, and the II nerve provides skin sensitivity on the upper medial aspect of the thigh.

#### **3.1 Blocking technique**

The patient is placed in a supine position exposing the lower abdomen, the iliac crest and the groin area are the margins to be located, and the anterior superior iliac spine (ASIS) is marked. A high-frequency linear transducer is used, which is located obliquely along a line that joins the ESIA and the umbilicus, immediately superior and medial to the ESIA, to obtain a cross-sectional view of the nerves, performing an inspection from the iliac crest to the lower abdomen.

An attempt should be made to identify the three muscle layers: external oblique, internal oblique, and transverse abdominis, finding nerves II and IH inside the plane between the internal oblique, and the transverse abdominis on the ASIS. Many times, at this level the external oblique is visualized as a thin aponeurotic layer (**Figure 4**).

**Figure 4.** *Ilioinguinal/iliohypogastric nerve [19].*

There is conflicting evidence when IL and IH nerve blocks are compared with TAP blocks. One study found significantly higher cumulative mean consumption of tramadol in 24 hours (63 mg vs. 27 mg) in the combined ILIH group compared with the TAP blocks, but there was no difference in time to first request for analgesia or in postoperative pain scores between groups. In a prospective non-randomized trial combining nerve blocks were associated with a reduction in cumulative consumption of tramadol in 24 h (37.25 mg vs. 52.45 mg) and a prolonged time to first analgesic request (14.09 h vs. 10, 71 h) compared with TAP blocks after elective Cesarean section. In both studies, there were no significant differences in pain scores between the groups at any time [19]. According to the study by Jin et al. [20], the score and cumulative morphine consumption were compared between the two groups (TAPB, transverse abdominal plane block; IHINB, iliohypogastric/ilioinguinal nerve block). Regarding the VAS score, there was no significant difference between the two groups in the first 12 h (all p > 0.05). However, the VAS score of the IHINB group was significantly lower than that of the TAPB group at 24 and 48 h after surgery (p < 0.001 for each). Similar to the VAS score, the cumulative total morphine consumption in the two groups was comparable at 12 h, while it was significantly lower for the IHINB group at 24 and 48 h after surgery (p < 0.05 and p < 0.001, respectively).
