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Ultrasound guided in-plane approach to block the iliohypogastric/ilioinguinal nerves
The ilioinguinal nerve (IIN) typically emerges together with the iliohypogastric (IH) nerve from the lateral margin of the psoas major, descends laterally across the anterior side of the quadratus lumborum, pierces the posterior aponeurotic extension of the transversus abdominis, and runs medially together with the IH nerve sandwiched between the transversus abdominis and the internal oblique – first on top of the iliac crest, and then on top of the inguinal ligament
The IIN exits via the external inguinal ring and terminates as the anterior scrotal/labial branches
Together with the IH nerve the IIN innervates the inferior portions of the transversus abdominis and the internal oblique
The anterior scrotal branches innervate the skin proximal to the symphysis and the lateral parts of the male scrotum and the female labia majora
Ilioinguinal nerve (IIN, magenta), anterior scrotal branches (red arrow), IIN runs between the transversus abdominis and internal oblique on top of both the iliac crest and the inguinal ligament (blue and green arrows). Quadratus lumborum, transversus abdominis, psoas major, and iliacus (yellow, magenta, cyan & green asterixs).
– Identify the anterior superior iliac spine (ASIS) with palpation and ultrasound
– Place the high-frequency linear probe on the line connecting the ASIS and the umbilicus and with the lateral end of the probe just superior to the ASIS
– Identify the layers of the abdominal wall and the iliohypogastric and ilioinguinal nerves and the deep circumflex artery inside the neurovascular fascial plane between the transverse abdominis and the internal abdominal oblique (see next page)
– Insert the needle with in-plane technique from the lateral end of the probe and advance the needle tip to the neurovascular plane. Inject 15 mL of local anaesthetic
In-plane approach to block the ilioinguinal/iliohypogastric nerves with ultrasound guidance
Ca = caudad, cr = cranial
The iliohypogastric (IH) nerve emerges at the lateral margin of the psoas major – typically together with the ilioinguinal (II) nerve
The IH descends across the anterior surface of the quadratus lumborum and it pierces the posterior aponeurotic extension of the transverse abdominis; it runs along and on top of the iliac crest sandwiched between the transversus abdominis and internal oblique. It innervates the inferior portions of these two muscles
The lateral cutaneous branch innervates the iliac crest and the skin of the hip between the iliac crest and the greater trochanter
The IH/II nerve block does not anaesthetize the lateral cutaneous branch of the IH nerve
The anterior cutaneous branch pierces the anterior aponeurotic extension of the external oblique muscle and innervates the skin above the medial part of the inguinal ligament
Iliohypogastric (IH) nerve (magenta), lateral and anterior cutaneous branches (red and green arrows), IH nerve trajectory between the transversus abdominis and internal oblique (cyan arrow), quadratus lumborum (yellow asterix), transversus abdominis (magenta asterix), psoas major (cyan asterix), iliacus (green asterix)
