Chapter 60: Genitofemoral Nerve Block

INTRODUCTION

Perhaps because much of its path is intra-abdominal, the genitofemoral nerve (GFN) nerve is an under-recognized cause of abdominal and pelvic pain.

INDICATIONS

• The diagnosis and treatment of:

  • Groin pain

  • Inguinal pain, especially after inguinal hernia repair using mesh and/or staples

  • Pelvic pain

  • Suprapubic pain (mimicking interstitial cystitis)

  • Vaginal or penile pain

• Used with ilioinguinal and iliohypogastric nerve blocks for inguinal herniorrhaphy

• Used with femoral nerve block for saphenous vein stripping

• Used to diagnose genitofemoral neuralgia

RELEVANT ANATOMY

Genitofemoral Nerve

• Branch of the L1 and L2 nerve root

• Pierces the psoas muscle at the level of the third and fourth lumbar vertebra behind the ureter and divides into 2 branches (Figures 60-1 and 60-2)

  • The genital branch provides the efferent and afferent components of the cremasteric reflex

  • The femoral branch, which supplies the anterior skin in the femoral triangle

    • Accompanies the external iliac artery in the femoral sheath lateral to the artery

  • The genital branch, which travels along the medial pelvic ring, enters the inguinal canal through the deep (ventral) inguinal ring in 97% of patients,¹ passing lateral to the pubic tubercle

    • In males, the genital branch travels through the inguinal canal within the spermatic cord and supplies the cremaster muscle and the scrotal skin.

    • In females, the genital branch travels with the round ligament and supplies sensation to the mons pubis and labia majora.²

BASIC CONCERNS AND CONTRAINDICATIONS

• Large volumes of local anesthetic are often used for blind anesthetic blocks for surgery, but diagnostic injections need to be low volume.

• Contraindications

  • Absolute

    • Infection

    • Severe anxiety to needle sticks

    • Severe scarring over entire area to be injected

    • Coagulopathy

  • Relative

    • Psychogenic pain

    • Inability to communicate with the patient

    • Anticoagulant or nonaspirin antiplatelet therapy (for the superficial injections, there is little risk of bleeding, since these are small gauge needles)

Because of its intra-abdominal as well as abdominal wall location, the genitofemoral nerve can be injured by conditions such as:

• Psoas abscess

• Postoperative intra-abdominal scarring

• Any laparoscopic abdominal procedures

• Transpsoas lateral interbody fusion³

• Femoral branch

  • Trauma to the groin

• Genital branch

  • Inguinal hernia repair, especially mesh repairs, when the mesh is secured to the Poupart ligament at the symphysis pubis^4,5

Pain pathology is usually distal; however, occasionally it is necessary to address the nerve proximally at L1.

PREOPERATIVE CONSIDERATIONS

• Informed consent and proper explanation of risks, complications, and benefits must be performed.

• Anticoagulation does not necessarily ...