Describe the femoral canal and femoral hernia. Differentiate it from an inguinal hernia.

Definition

• Accounts for about 5% of all hernias, but a disproportionate share of strangulations
• Three times commoner in women, because of the wider pelvis and larger femoral ring; nonetheless an inguinal hernia is still the commoner hernia in women

Anatomy of the Femoral Canal

• The medial compartment of the femoral sheath, about 1.25 cm long
• Contains fat, lymphatics and the node of Cloquet
• Normally allows the femoral vein to expand during increased venous return
• Its upper opening is the femoral ring, closed by the femoral septum

Course of the Hernia

• The characteristic direction of travel is down, forward and then up, which is why the sac may appear to lie above the inguinal ligament in a large hernia and be mistaken for an inguinal hernia

Distinguishing Femoral from Inguinal Hernia

Complications and Treatment

• Strangulation is the great danger — the narrow rigid ring obstructs venous return, then arterial supply, and gangrene follows within hours
• Richter hernia — only part of the circumference of the bowel wall is trapped; the bowel is not obstructed, so there is no vomiting or distension, yet gangrene occurs. Femoral hernia is the commonest site
• All femoral hernias should be repaired, and urgently, given the risk
• Approaches — low (Lockwood), high (McEvedy, preferred if bowel resection may be needed), or inguinal (Lotheissen)

Applied Aspects

• An abnormal obturator artery runs along the lacunar ligament in about 30% of people — historically called the "artery of death", because dividing the ligament blindly to release a strangulated hernia could cause fatal haemorrhage
• A femoral hernia may be mistaken for an enlarged inguinal lymph node, a saphena varix (which has a fluid thrill on coughing and disappears on lying down), a psoas abscess, or a lipoma
• Elderly women with unexplained intestinal obstruction should be examined for a femoral hernia — it is small, easily missed, and a classic cause