A femoral hernia is a protrusion of peritoneum through the femoral canal. It may contain abdominal contents or extraperitoneal fat. Femoral hernias are the third most common type of groin hernia, after indirect and direct inguinal hernias and account for approximately 6 per cent of all abdominal wall hernias. They are twice as common on the right side as on the left. Although they are four times more common in women than in men, overall, the most common abdominal wall hernia in females remains the indirect inguinal hernia.

The aetiology of femoral hernias is unclear, although elevated intra-abdominal pressure and/or laxity of groin tissues is implicated. Femoral hernias are more common in parous than in nulliparous women and the incidence increases with advancing years, especially with those with weight loss, chronic cough, or constipation. Ten per cent of patients with femoral hernia have undergone previous groin surgery for inguinal hernia repair.

Femoral hernias may be described as reducible, irreducible, or strangulated. The higher incidence of irreducibility and strangulation in femoral hernias compared with inguinal hernias is related to the anatomy of the femoral canal.

The femoral canal provides a conduit by which the femoral structures leave the abdomen and enter the upper thigh. The canal is bounded anteriorly by the inguinal ligament, posteriorly by the pectineal (Cooper's) ligament, medially by the unyielding lacunar ligament, and laterally by the iliopsoas muscle (Fig. 1) 1430. The contents of the canal consist of (from lateral to medial) the femoral nerve, the genitofemoral nerve, the femoral artery, and the femoral vein. Medial to the femoral vein lies the femoral ring, which contains loose areolar tissue, lymphatics, and the lymph node of Cloquet. The laxity of this tissue allows distension of the femoral vein during periods of increased venous return during exercise. The femoral vessels, but not the femoral nerve, are encased in the fibrous femoral sheath which is an extension of transversalis fascia. This forms a funnel extending down to the fossa ovalis where the long saphenous vein joins the deep femoral vein through the cribriform fascia.

The common site of a femoral hernia is through the femoral ring, in the loose areolar tissue medial to the vein. As the hernia enlarges within the femoral sheath, it emerges at the fossa ovalis (Fig. 2) 1431 and, by necessity, turns proximally into the loose subcutaneous tissue of the thigh. Distal progression is blocked by the fusion of the femoral sheath with the deep fascia of the thigh.

Although a femoral hernia may enlarge in the thigh, the femoral neck is bounded by the unyielding lacunar ligament medially. Any associated oedema of the hernial contents makes spontaneous reduction of the hernia unlikely, and progression to strangulation is common.

A reducible femoral hernia may present as an asymptomatic lump or as localized intermittent discomfort. If it becomes irreducible, the lump and localized discomfort become constant features. A mild pyrexia with localized discomfort suggests strangulated omentum within the hernial sac; if obstruction is also present strangulated small bowel is likely.

Richter's hernias are common in femoral hernias and result in strangulation of the antemesenteric intestinal wall without obstruction. Signs and symptoms are confusing and the diagnosing may be delayed.

Femoral hernias occasionally present with visible distension of the long saphenous vein. That indicates that the hernia has extended through the fossa ovalis and is compressing the sapheno-femoral junction.

The differential diagnoses of a femoral hernia include inguinal hernia, groin lymph nodes, varicocele, maldescended testis, cyst of the canal of Nuck, or a hydrocele of the spermatic cord. The major feature distinguishing a femoral from an inguinal hernia is that the former lies below and lateral to the pubic tubercle.

Femoral hernias should not be treated conservatively: it is impossible to control the hernial neck with a truss and the incidence of strangulation is high, especially in elderly women. A non-tender femoral lump may be reduced by taxis in the short term but if any local tenderness suggesting strangulation is present, operative intervention is mandatory. Emergency repair of femoral hernias is ten times more common than elective operation. Elective repairs should not be delayed unduly.

The principles of femoral hernia repair, whether elective or emergency, are excision or reduction of the hernial sac, and narrowing of the stretched femoral opening.

Three approaches to femoral hernia repair are described, none of which is universally applicable.

This is suitable only for the uncomplicated small elective hernia in a thin patient. The incision is placed directly over the hernia, parallel to the inguinal ligament. The fundus of the sac often lies over the inguinal ligament, where it has turned proximally back on to itself. The various fascial layers are dissected and the neck freed circumferentially from the boundaries of the femoral canal. The fundus is opened and any contents of the sac inspected and returned to the abdomen. The sac is transfixed at its neck with an absorbable suture (Fig. 3) 1432 and redundant sac excised and allowed to recede into the abdomen.

The stretched femoral opening is narrowed by placing one or two non-absorbable sutures medial to the femoral ring, apposing the inguinal and pectineal ligaments (Fig. 4) 1433. A single figure-of-eight suture may also be used. This manoeuvre is most easily performed using a ‘J’-shaped needle. The placement of these sutures is critical to the success of the procedure, as the femoral opening must be sufficiently narrowed to prevent hernial recurrence, without compromising the femoral vein. On completion, the narrowed femoral opening should allow only the entry of the little finger of the hand. Further reinforcment of the apposed inguinal and pectineal ligaments has also been advocated, achieved by suturing an aponeurotic flap from the surface of pectineus muscle to the external oblique aponeurosis (Fig. 5) 1434.

This is useful when a concomitant inguinal hernia needs to be repaired. It is obligatory when a femoral hernia is misdiagnosed as an inguinal hernia. The incision is the same as for an inguinal hernia. The femoral canal is approached through transversalis fascia on the back wall of the inguinal canal (Fig. 6) 1435. The femoral sac is delivered into the wound above the inguinal ligament and transfixed and excised (Fig. 7) 1436. The sutures to appose the inguinal and pectineal ligaments and narrow the canal are inserted on the pelvic aspect of the femoral opening. Closure of the tissue layers is then completed as for an inguinal hernia.

The preperitoneal approach

This is mandatory for the emergency treatment of femoral hernia with obstruction or strangulation. It also allows better access for the elective repair of large or long-standing hernias, especially in obese patients. If, when using the low approach, a femoral hernia is found to be strangulated, an additional ipsilateral preperitoneal incision may facilitate inspection of the viscera or resection of the bowel. The rectus muscles are retracted through a pararectal or oblique incision (Fig. 8) 1437 to expose the extraperitoneal space. This is enlarged to identify the hernial sac entering the femoral canal. By sharp and blunt dissection, using external pressure on the hernial lump if necessary, the sac is returned to the pelvis (Fig. 9) 1438. The unyielding lacunar ligament often requires disruption to facilitate this manoeuvre, especially if strangulation is present.

The sac is opened and its contents are inspected. If bowel resection is necessary, exposure through this preperitoneal approach is more than adequate. The neck of the sac is transfixed and the redundant portion excised. As with the inguinal approach, the inguinal and pectineal ligaments are apposed by interrupted non-absorbable sutures on the pelvic aspect of the femoral canal (Fig. 10) 1439.

Devlin HB. Management of Abdominal Hernias. London: Butterworth and Co, 1988.

Nyhus LM, Condon RE, eds. Hernia. 3rd edn. Philadelphia: JB Lippincott Co, 1989.