Femoral hernia

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. Femoral hernias are a relatively uncommon type, accounting for only 3% of all hernias. While femoral hernias can occur in both males and females, almost all of them develop in women because of the wider bone structure of the female pelvis.^[1] Femoral hernias are more common in adults than in children. Those that do occur in children are more likely to be associated with a connective tissue disorder or with conditions that increase intra-abdominal pressure. Seventy percent of pediatric cases of femoral hernias occur in infants under the age of one.^[1]

A reducible femoral hernia occurs when a femoral hernia can be pushed back into the abdomen, either spontaneously or with manipulation, but most likely, spontaneously. This is the most common type of femoral hernia and is usually painless.

An irreducible femoral hernia occurs when a femoral hernia becomes stuck in the femoral canal. This can cause pain and a feeling of illness.

An obstructed femoral hernia occurs when a part of the intestine becomes intertwined with the hernia, causing an intestinal obstruction. The obstruction may grow and the hernia can become increasingly painful. Vomiting may also result.

A strangulated femoral hernia occurs when a femoral hernia blocks blood supply to part of the bowel - the loop of bowel loses its blood supply. Strangulation can happen in all hernias, but is more common in femoral and inguinal hernias due to their narrow "necks". Nausea, vomiting, and severe abdominal pain may occur with a strangulated hernia. This is a medical emergency. A strangulated intestine can result in necrosis (tissue death) followed by gangrene (tissue decay). This is a life-threatening condition requiring immediate surgery.^[2]

A femoral hernia may be either reducible or irreducible, and each type can also present as either (or both) obstructed or strangulated.

The term incarcerated femoral hernia is sometimes used, but may have different meanings to different authors and physicians. For example: "Sometimes the hernia can get stuck in the canal and is called an irreducible or incarcerated femoral hernia."^[3] "The term 'incarcerated' is sometimes used to describe an [obstructed] hernia that is irreducible but not strangulated. Thus, an irreducible, obstructed hernia can also be called an incarcerated one."^[4] "Incarcerated hernia: a hernia that cannot be reduced. May lead to bowel obstruction but is not associated with vascular compromise."^[5] However, the term "incarcerated" seems to always imply that the femoral hernia is at least irreducible.

Anatomy

The femoral canal is located below the inguinal ligament on the lateral aspect of the pubic tubercle. 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. Femoral herniae are more common in females than in males.

Classification

Several subtypes of femoral hernia have been described.^[6]

Signs and symptoms

They typically present when standing erect as a groin lump or bulge, which may differ in size during the day, based on internal pressure variations of the intestine. The bulge or lump typically is smaller or may not be visible in a prone position.^[7]

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.

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.

Diagnosis

The diagnosis is largely a clinical one, generally done by physical examination of the groin. However, in obese patients, 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.

Several other conditions have a similar presentation and must be considered when forming the diagnosis: inguinal hernia, an enlarged inguinal lymph node, aneurysm of the femoral artery, saphena varix, and an abscess of the psoas.

Management

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

Surgery

Some surgeons choose to perform "key-hole" or laparoscopic surgery (also called minimally invasive surgery) rather than conventional "open" surgery. With minimally invasive surgery, one or more small incisions are made that allow the surgeon to use a surgical camera and small tools to repair the hernia.^[8]

Either open or minimally invasive surgery may be performed under general or regional anaesthesia, depending on the extent of the intervention needed. Three approaches have been described for open surgery.

• 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 surgical 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.

Epidemiology

Femoral hernias are more common in multiparous females which results from elevated intra-abdominal pressure that dilates the femoral vein and which in turn stretches femoral ring. Such a constant pressure causes preperitoneal fat to insinuate in the femoral ring consequence of which is development of femoral peritoneal sac.^[9]

References

External links

• Surgery Encyclopaedia