Hesselbach triangle

**Boundaries (mnemonic: "REI")** - **R**ectus abdominis: lateral border (medial boundary) - **E**pigastric vessels, inferior: lateral boundary - **I**nguinal ligament: inferior boundary (base)

**Floor:** transversalis fascia and aponeurosis of the transversus abdominis. This is an area of relative weakness with no muscle layer.

**Clinical significance** - **Direct inguinal hernia:** Abdominal contents push directly through the weak floor of the triangle, **medial** to the inferior epigastric vessels. It is **acquired**, usually in older men, and is associated with heavy lifting, chronic cough, constipation or straining, obesity, and connective tissue weakness. The hernia passes through the **external (superficial) inguinal ring** but does **not** enter the deep ring. It usually does not descend into the scrotum and is **not covered by the internal spermatic fascia** (the sac is outside the spermatic cord). It is **less likely to strangulate** because of its wide neck. - **Indirect inguinal hernia:** Passes through the **deep inguinal ring, lateral** to the inferior epigastric vessels, and so is outside the triangle. It is **congenital**, caused by a patent processus vaginalis. It is the **most common hernia in both sexes**. It follows the course of the spermatic cord, is covered by the internal spermatic fascia, and can reach the scrotum. It has a higher risk of incarceration and strangulation. - **Landmark:** The inferior epigastric vessels (branches of the external iliac artery and vein) separate direct from indirect hernias. This distinction is made at surgery, since it is hard to tell clinically.

**Key points for boards** - Direct hernias are **medial** to the inferior epigastric vessels, and indirect hernias are **lateral**. - Do not confuse the Hesselbach triangle with the **triangle of Doom** (laparoscopic repair: vas deferens and gonadal vessels, with risk to the external iliac vessels) or the **triangle of Pain** (inguinal nerves: lateral femoral cutaneous, femoral branch of the genitofemoral). Both are laparoscopic hernia repair landmarks. - **Femoral hernia** is **below and lateral to the pubic tubercle**, inferior to the inguinal ligament. It is more common in women and has a high strangulation risk. - **Pantaloon hernia** is a combined direct and indirect hernia straddling the inferior epigastric vessels. - **Conjoint tendon (falx inguinalis)** reinforces the medial part of the area. - Repair is most commonly done with mesh (Lichtenstein open repair or laparoscopic TEP/TAPP). - Embryology: the indirect hernia sac is the persistent processus vaginalis. The direct hernia is an acquired defect of the transversalis fascia.