Femoral hernia

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Overview
A hernia is caused by the protrusion of a viscus (in the case of groin hernias, an intraabdominal organ) through a weakness in the containing wall. This weakness may be inherent, as in the case of inguinal, femoral and umbilical hernias. On the other hand, the weakness may be caused by surgical incision through the muscles of the abdominal/thoracic wall. Hernias occurring through these are called incisional hernias.

Femoral hernias occur just below the inguinal ligament, when abdominal contents pass through a naturally occurring weakness called the femoral canal.

Anatomy
The femoral canal is located below the inguinal ligament on the lateral aspect of the pubic tubercle (note: inguinal hernias are above and medial to the pubic tubercle; femoral are below and lateral). It is bounded by the inguinal ligament anteriorly, pectineal ligament posteriorly, lacunar ligament medially, and the femoral vein laterally. It normally contains a few lymphatics, loose areolar tissue and occasionally a lymph node called Cloquet's node. The function of this canal appears to be to allow the femoral vein to expand when necessary to accommodate increased venous return from the leg during periods of activity.

Symptoms
Femoral hernias are more common in women, usually elderly and frail (although they can happen in children). They typically present as a groin lump. They may or may not be associated with pain. Often, they present with a varying degree of complication ranging from irreducibility through intestinal obstruction to frank gangrene of contained bowel. The incidence of strangulation in femoral hernias is high. A femoral hernia has often been found to be the cause of unexplained small bowel obstruction.

Signs
The obvious finding may be a lump in the groin. Cough impulse is often absent and should not be relied on solely when making a diagnosis of femoral hernia. The lump is more globular than the pear shaped lump of the inguinal hernia. The bulk of a femoral hernia lies below an imaginary line drawn between the anterior superior iliac spine and the pubic tubercle (which essentially represents the inguinal ligament) whereas an inguinal hernia starts above this line. Nonetheless, it is often impossible to distinguish the two preoperatively.

Differential Diagnoses

 * Inguinal hernia
 * Enlarged inguinal lymph node
 * Aneurysm of the femoral artery
 * Saphena Varix
 * Psoas abscess

Management
Femoral hernias like most other hernias need operative intervention. This should ideally be done as an elective procedure. However, because of the high incidence of complications femoral hernias often need emergency surgery.

Investigations
The diagnosis is largely a clinical one. However, in the difficult (obese) patient imaging in the form of ultrasonography, CT or MRI may aid in the diagnosis. An abdominal x-ray showing small bowel obstruction in a female patient with a painful groin lump needs no further investigation.

Surgery
Surgery may be performed under general or regional anaesthesia. Three approaches have been described.
 * Lockwood’s infra-inguinal approach
 * Lotheissen‘s trans-inguinal approach
 * McEvedy’s high approach

The infra-inguinal approach is the preferred method for elective repair. The trans-inguinal approach involves dissecting through the inguinal canal and carries the risk of weakening the inguinal canal. McEvedy’s approach is preferred in the emergency setting when strangulation is suspected. This allows better access to and visualisation of bowel for possible resection. In any approach care should be taken to avoid injury to the urinary bladder which is often a part of the medial part of the hernial sac.

Repair is either performed by suturing the inguinal ligament to the pectineal ligament using strong non-absorbable sutures or by placing a mesh plug in the femoral ring. With either technique care should be taken to avoid any pressure on the femoral vein.

Postoperative Outcome
Patients undergoing elective repair do very well and may be able to go home the same day. However, emergency repair carries a greater morbidity and mortality rate and this is directly proportional to the degree of bowel compromise. Patient's other co-existing medical conditions also influence outcome.