A femoral hernia refers to a hernia in which the hernial sac protrudes through the femoral ring, traverses the femoral canal, and emerges at the saphenous opening (fossa ovalis). Femoral hernias account for approximately 3% to 5% of external abdominal hernias, and they are more common in women over 40 years of age. The wider pelvis in women, combined with weaker pectineal and lacunar ligaments, results in a larger and more lax femoral canal opening, increasing susceptibility. Pregnancy is one of the main causes of increased intra-abdominal pressure.
Anatomical Overview of the Femoral Canal
The femoral canal is a narrow, funnel-shaped space measuring approximately 1–1.5 cm in length. It contains fat, loose connective tissue, and lymph nodes. The femoral canal has two openings. The upper opening, known as the femoral ring, is approximately 1.5 cm in diameter and is covered by the femoral septum. Its anterior boundary is the inguinal ligament, posterior boundary is the pectineal ligament, medial boundary is the lacunar ligament, and lateral boundary is the femoral vein. The lower opening is the saphenous opening (fossa ovalis), a weak area of the deep fascia of the thigh (fascia lata) covered by a thin layer called the cribriform fascia. At this point, the great saphenous vein passes through the cribriform fascia to join the femoral vein.
Pathological Anatomy
When intra-abdominal pressure increases, intra-abdominal organs push the peritoneum downward against the opening of the femoral canal, causing it to protrude through the femoral ring into the femoral canal, forming a femoral hernia. As the hernia progresses, it may emerge through the fossa ovalis, breaking through the cribriform fascia to reach the subcutaneous layer. The contents of the hernia often include the omentum or small intestine. Because the femoral canal is nearly vertical, the hernia forms an acute angle when turning forward at the saphenous opening. Additionally, the small size of the femoral ring, combined with the surrounding rigid ligaments, contributes to a high risk of incarceration. Among external abdominal hernias, femoral hernias exhibit the highest rate of incarceration, reaching up to 60%. Once incarcerated, they can rapidly progress to strangulated hernias.
Clinical Presentation
The hernial mass is often small and typically presents as a hemispherical protrusion at the saphenous opening below the inguinal ligament. Following reduction of the hernia's contents, a mass may persist due to the surrounding fatty tissue. In these cases, the hernial sac is not completely reduced. Due to the narrow neck of the sac, the cough impulse is often not prominent. Reducible femoral hernias usually present with mild symptoms and are often overlooked by patients, particularly those who are obese. When incarceration occurs, the patient may experience significant localized pain as well as symptoms of acute mechanical bowel obstruction. In severe cases, the local symptoms of the femoral hernia may be overshadowed by systemic symptoms.
Differential Diagnosis
The diagnosis of femoral hernias can be challenging and must be differentiated from the following conditions:
Inguinal Indirect Hernia
An inguinal indirect hernia is located above and medial to the inguinal ligament, whereas a femoral hernia is situated below and lateral to the inguinal ligament. In most cases, this distinction is straightforward. However, in larger femoral hernias, part of the hernial mass may extend above the inguinal ligament. Palpation of the superficial inguinal ring may help identify enlargement and assist in differentiation.
Lipoma
Femoral hernias are often accompanied by a thickened layer of fatty tissue surrounding the hernial sac. After reduction of the hernial contents, the residual mass formed by this fat may be mistaken for a lipoma. Unlike lipomas, which have mobile and non-fixed bases, femoral hernias feature fixed bases that cannot be displaced.
Enlarged Lymph Nodes
Incarcerated femoral hernias are sometimes misdiagnosed as inguinal lymphadenopathy or lymph node inflammation.
Varicose Nodules of the Great Saphenous Vein
Nodular enlargements of the great saphenous vein at the saphenous opening may enlarge during standing or coughing and disappear upon lying down, making them easily confused with reducible femoral hernias. Compression of the proximal femoral vein can cause the nodules to enlarge. Additionally, concurrent varicose veins in the lower limb can aid in the differential diagnosis.
Iliopsoas Tuberculous Abscess
Cold abscesses caused by tuberculous infection of the spine or sacroiliac joint may track along the psoas muscle to the inguinal region, presenting as a mass. These abscesses can also demonstrate a cough impulse and may temporarily reduce in size when the patient is supine, leading to potential confusion with femoral hernias. Careful examination often reveals that such abscesses are located laterally in the inguinal region or iliac fossa and exhibit fluctuations. Further examination of the spine may reveal signs indicative of lumbar vertebral involvement.
Treatment
Femoral hernias have a high likelihood of incarceration, and once incarcerated, they can quickly progress to strangulation. Timely surgical intervention is therefore emphasized once a diagnosis of femoral hernia is confirmed. Emergency surgery is particularly critical for incarcerated or strangulated femoral hernias.
Surgical treatment methods for femoral hernias include:
Tissue-Based Tension Repair
The McVay repair is commonly employed, as it not only strengthens the posterior wall of the inguinal canal for inguinal hernias but also closes the femoral ring to address femoral hernias.
Tension-Free Hernia Repair or Laparoscopic Hernia Repair
Laparoscopic procedures, including the totally extraperitoneal (TEP) and transabdominal preperitoneal (TAPP) techniques, are alternative methods for repair.