The femoral ring is the proximal or abdominal/pelvic opening of the femoral canal.
- Anterior: inguinal ligament
- Posterior: pectineal ligament and muscle
- Medial: lacunar ligament
- Lateral: medial border of the femoral vein
The femoral canal is a cylindrical space, making up the medial compartment enclosed within the femoral sheath.
- Same boundaries as the femoral ring
- Extends 1–2 cm into the thigh
- Contains loose areolar tissue, lymphatic vessels, and lymph nodes
- The femoral sheath is a fascia that encloses the contents of the femoral triangle (except the femoral nerve), each within its own compartment.
The femoral triangle is located on the medial aspect of the anterior thigh.
- Lateral: sartorius muscle
- Medial: adductor longus muscle
- Superior (base): inguinal ligament
- Apex: continuous with the adductor canal
- Floor: pectineus and adductor brevis medially, and iliopsoas laterally
- Roof: fascia lata, superficial fascia, and skin
- Fascia lata overlies the femoral triangle; the saphenous opening here allows entrance of lymphatic vessels and the greater saphenous vein; the femoral hernia protrudes through this opening
The femoral hernia is the protrusion of intra-abdominal contents under the inguinal ligament, through the femoral ring, and into the femoral canal, producing a “bulge” or swelling in the femoral triangle.
To remember the borders of the femoral triangle—SAIL:
- S: Sartorius muscle
- A: Adductor longus muscle
- IL: Inguinal Ligament
To remember the contents of the femoral triangle (from lateral to medial)—NAVEL:
- N: femoral Nerve
- A: femoral Artery
- V: femoral Vein
- E: Empty space (femoral canal)
- L: deep inguinal Lymph nodes
Epidemiology and Etiology
- More common in women, with a female-to-male ratio of 3:1
- Represents < 5% of all hernias
- Any condition that increases intra-abdominal pressure and enlarges/weakens the ligamentous structures of the pelvis (e.g., the femoral ring)
- Risk factors:
- Increased intra-abdominal pressure
- Chronic cough
- Recurrent, regular, or violent vomiting (e.g., eating disorder)
- Prostatic hypertrophy (causes straining during micturition)
- Enlarged/weakened femoral ring
- Female gender (wider pelvis)
- Advanced age
- Previous surgical repair of inguinal hernias
- Increased intra-abdominal pressure
- Globular, subcutaneous swelling or “bulge” in the groin that may or may not be tender
- Located inferior to the inguinal ligament and medial to the femoral vein
- Swelling or “bulge” enlarges with Valsalva maneuvers
Types of femoral hernias
Depending on the location and contents of the protrusion, several subtypes of femoral hernias have been described:
- Serafini’s hernia: The hernial sac lies behind the femoral vessels.
- Velpeau’s hernia (or prevascular): The hernial sac lies in front of the femoral vessels, which can lead to this type being mistaken for a femoral aneurysm.
- Laugier’s hernia: The hernial sac transverses the lacunar ligament or the pectineal ligament of Cooper.
- Hesselbach’s hernia: The neck of the sac lies lateral to the femoral vessels.
- Cloquet’s hernia: The hernial sac descends deep to the femoral vessels through the pectineal fascia.
- De Garengeot’s hernia: The hernial contents include the vermiform appendix, which often leads to incarceration of the hernia and requires an appendectomy as part of the surgical repair.
- Incarceration: Hernia becomes irreducible.
- Strangulation: Constriction by femoral ring partially or completely obstructs the blood supply to the herniated part of the bowel, leading to ischemic necrosis. Clinical manifestations of strangulation:
- Cardinal signs of inflammation (erythema, swelling, pain, warm to touch)
- Nausea, vomiting, and severe abdominal pain
- Signs of mechanical bowel obstruction (colicky abdominal pain, nausea, bilious or fecal vomiting, constipation, abdominal distension)
- Signs of peritonitis, followed by paralytic ileus (due to intestinal perforation)
Diagnosis and Management
- Mainly a clinical diagnosis
- If palpation is difficult (e.g., obesity), diagnosis can be confirmed by an ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) of the groin area, which will show signs of small bowel obstruction.
- Inguinal hernia
- Swollen femoral lymph node
- Aneurysm of the femoral artery
- Dilation of the saphenous vein
- Abscess of the psoas muscle
- Due to the high risk of complications because of the small size of the canal/ring, all femoral hernias should be surgically repaired.
- Non-complicated hernias: early elective surgical repair with mesh hernioplasty
- Complicated hernias: herniorrhaphy within 4 hours of the onset of symptoms in order to prevent bowel ischemia and necrosis
Femoral vascular access: The femoral artery and vein are easily accessed within the femoral triangle for interventional procedures.
The following conditions are included in the differential diagnoses of femoral hernias:
- Inguinal hernias: a protrusion of intra-abdominal contents through the deep inguinal ring, producing an indirect inguinal hernia, or through a weakness in the posterior wall of the inguinal canal, producing a direct inguinal hernia. Presents with similar clinical manifestations as the femoral hernia; however, inguinal hernias are located above the inguinal ligament. In some cases, the 2 types may be indistinguishable during physical examination.
- Aneurysm of the femoral artery: an arterial dilation caused by weakness of the wall of the femoral artery, located in the medial aspect of the thigh. Aneurysm of the femoral artery is the 2nd-most common peripheral aneurysm. May present as painless, pulsatile swelling with a palpable thrill and a continuous murmur at the mid-inguinal point. Femoral aneurysms can rupture, which may cause life-threatening, uncontrollable bleeding.
- Drake, R.L., Vogl, A.W., & Mitchell, A.W.M. (2014). Gray’s Anatomy for Students (3rd ed.). Philadelphia, PA: Churchill Livingstone.
- Goethals, A., Azmat, C.E., & Adams, C.T. (2020). Femoral Hernia. NCBI/StatPearls Publishing LLC. https://www.ncbi.nlm.nih.gov/books/NBK535449/