Define Femoral Hernia. Describe its clinical features, management and diagnosis.

The Concept

A femoral hernia is a protrusion of abdominal contents through the femoral canal, emerging below the inguinal ligament into the upper thigh. Although less common than inguinal hernia, it is disproportionately important for two reasons captured in a single idea: it occurs through a narrow, rigid ring, so it is much more likely to strangulate, and it is commoner in women. These facts make it a hernia that should almost always be repaired promptly.

Anatomy of the Femoral Canal

The femoral canal is the small medial compartment of the femoral sheath, normally containing fat and a lymph node (the node of Cloquet) and allowing the femoral vein to expand. Its opening, the femoral ring, is bounded anteriorly by the inguinal ligament, posteriorly by the pectineal (Astley Cooper's) ligament, medially by the sharp, unyielding lacunar ligament, and laterally by the femoral vein. It is the rigid medial lacunar ligament that makes the neck so constricting.

WHY It Strangulates

The clinical danger flows directly from this anatomy: the femoral ring is narrow and surrounded by rigid, unyielding structures, so once bowel enters, its neck is easily constricted, cutting off the blood supply. This is why a large proportion of femoral hernias present already obstructed or strangulated — a much higher rate than inguinal hernias.

Clinical Features

A femoral hernia appears as a swelling in the groin/upper thigh that lies below and lateral to the pubic tubercle — the key contrast with an inguinal hernia (above and medial). It is often small, may be difficult to feel (especially in the obese), frequently irreducible, and has a poor cough impulse. Because it is easily overlooked, it is a classic cause of a missed strangulated hernia, and the groins must always be examined in a patient with unexplained intestinal obstruction.

Management

Because of the high risk of strangulation, a femoral hernia should always be repaired surgically, and promptly (a truss is not appropriate). Several approaches are used — the low (Lockwood), high (McEvedy) and trans-inguinal (Lotheissen) approaches — the principle being to reduce the contents and close the femoral canal (often narrowing the ring by suturing the inguinal ligament to the pectineal ligament, or with mesh). The McEvedy (high) approach is favoured in the emergency, strangulated case as it allows bowel resection.

Differential Diagnosis of a Groin Lump

A femoral hernia must be distinguished from the several other causes of a lump in the groin, which is a common exam question. These include an inguinal hernia, an enlarged inguinal lymph node, a saphena varix (a dilatation of the saphenous vein that has a fluid thrill and disappears on lying down), a femoral artery aneurysm (pulsatile and expansile), a psoas abscess or bursa, a lipoma, and an ectopic or undescended testis. The position relative to the pubic tubercle, the cough impulse, reducibility and pulsatility help identify the femoral hernia among these.

Emergency Presentation & Operative Principles

Because so many femoral hernias present as an emergency with strangulation, the operative principle is to gain adequate exposure to assess and, if needed, resect bowel. The McEvedy (high) approach is favoured in the strangulated case as it gives access above the inguinal ligament to deliver and inspect the bowel. In an elective repair the femoral canal is simply closed. Whatever the approach, the sac is opened with care (a Richter's-type strangulation is common in femoral hernias), viability is assessed, and the canal is obliterated to prevent recurrence.

A Note on the Anatomy of the Pubic Tubercle

The pubic tubercle is the single most useful landmark in groin hernias and deserves emphasis. An inguinal hernia (and the superficial ring) lies above and medial to it, whereas a femoral hernia (and the femoral canal) lies below and lateral. Reliably locating the pubic tubercle — by tracing the tendon of adductor longus up to its origin, or following the spermatic cord — therefore allows the two to be distinguished at the bedside, which matters because the femoral hernia's far higher strangulation risk makes it the more urgent diagnosis.

• Femoral hernia: below & lateral to the pubic tubercle; commoner in women.
• High strangulation risk (narrow, rigid ring — lacunar ligament medially) → always operate promptly.
• Femoral ring boundaries: inguinal ligament (ant), pectineal ligament (post), lacunar ligament (medial), femoral vein (lateral); Cloquet's node.

Commoner in women and far more likely to strangulate.

• Femoral hernia = protrusion through the femoral canal, below the inguinal ligament; commoner in women.
• Ring boundaries: inguinal ligament (anterior), pectineal ligament (posterior), lacunar ligament (medial, rigid), femoral vein (lateral).
• Lies below & lateral to the pubic tubercle (vs inguinal above & medial); often small, irreducible, poor cough impulse.
• High strangulation risk (narrow rigid ring) — often presents obstructed/strangulated.
• Always repair surgically and promptly (Lockwood/McEvedy/Lotheissen); examine the groin in any unexplained bowel obstruction.