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Each year, more than 45 million surgical procedures are performed in the U.S.

Acute postoperative pain will develop into persistent postoperative pain (PPP) in an estimated 10-50% of individuals after common operations. PPP can be severe in up to 10% of these patients, affecting more than 450,000 patients each year.

PPP is typically associated with iatrogenic neuropathic pain caused by surgical injury to a major peripheral nerve, such as the ilioinguinal and illohypogastric nerves. Certain surgeries are at higher risk of PPP, such as inguinal hernia repair, leg amputation, breast and thoracic surgery, and coronary artery bypass surgery. A patient’s emotional health may increase their likelihood of developing PPP.


The Ilioinguinal And Illohypogastric Nerves

The ilioinguinal and illohypogastric nerves arise from the first lumbar nerve (L1) on each side of the body and run together from the spine, through the abdominal wall muscles along the lower part of the abdomen where it reaches the pelvis. The iliohypogastric nerve supplies sensation to the skin over the lower abdomen where it joins the pelvis, on the front and back side. The ilioinguinal nerve provides sensation to the upper pelvis along the middle portion of the thigh, on both sides.

Because of where these nerves are located, they are at risk of being injured during lower abdominal surgery, such as appendectomy, inguinal herniorrhaphy, or laparoscopic surgery.


Benefits of an Ilioinguinal and Illohypogastric Nerve Block

This type of nerve block can provide intraoperative and postoperative analgesia for the following types of inguinal surgeries:

  • Inguinal hernia repair
  • Orchidopexy
  • Hydrocoele repair
  • Varicocoele surgery

The ilioinguinal and illohypogastric nerve block can be used in combination with T11 and T12 intercostal nerve blocks to provide postoperative pain relief after a renal transplant.

The nerve block can also be used to:

  • Relieve inguinal post-herniorrhaphy pain
  • Diagnose and treat groin and genital pain mediated by the ilioinguinal nerve
  • Provide surgical anesthesia for groin and genital surgery, when combined with iliohypogastric and genitofemoral nerve block
  • Provide postoperative analgesia for cesarean section surgeries

Side Effects and Complications

The risks of an illoinguinal and illohypogastric nerve block include block failure, colon puncture, small bowel puncture, pelvic retroperitoneal haematoma, bowel haematoma and transient femoral nerve palsy with transient quadriceps paresis.

The success of the procedure largely depends on the physician’s knowledge of the anatomy of the nerves. Procedures performed under X-ray guidance or ultrasound have much lower risk of complications.

What to Expect During the Procedure

The patient lies down on their back and the abdomen and thigh are cleaned with an antiseptic. The physician uses ultrasonographic guidance to visually identify the nerves that need to be blocked. This visual confirmation is critical to ensure the drug is injected into the right location and to prevent complications such as bowel perforation and femoral block.

Local anesthetic is injected in the layers between (1) the internal oblique muscle and transversus abdominis muscles and (2) the external oblique muscle and the internal oblique muscles.

The physician then injects the drug (steroid) using an out-of-plane approach, which involves inserting the needle at the side of the probe and aiming towards the plane of sound.