54. Femoral hernia

1. Definition

• Femoral hernia → protrusion of abdominal contents through the femoral ring into the femoral canal, below the inguinal ligament
• Emerges at the saphenous opening and turns up over the inguinal ligament

2. Epidemiology

• About 5% of groin hernias; third commonest primary hernia
• Women : men about 4 : 1; still, inguinal hernia is more common than femoral hernia in women
• About 20% of hernias in women, 5% in men
• Older age, multiparous women
• Right side more common
• 30–40% present as an emergency (incarceration or strangulation); up to half of these need bowel resection
• Rare in children

3. Aetiology and risk factors

Anatomy (revision)

• Femoral sheath → three compartments: lateral (femoral artery), intermediate (femoral vein), medial (femoral canal)
• Femoral canal → about 1.25 cm long; contains fat, lymphatics and the lymph node of Cloquet
• Femoral ring (upper opening) → boundaries:
  • Anterior → inguinal ligament
  • Posterior → pectineal (Cooper's) ligament, pectineus fascia, pubic bone
  • Medial → lacunar ligament
  • Lateral → femoral vein
• Three sides are rigid → narrow, unyielding neck
• Abnormal (accessory) obturator artery → branch of the inferior epigastric crossing the lacunar ligament in about 25–30% → bleeding if the lacunar ligament is cut blindly ("corona mortis")

Causes

• Acquired → raised abdominal pressure on a weak area
• Wider female pelvis and femoral canal
• Pregnancy, obesity, constipation, chronic cough
• Age → loss of muscle bulk around the canal
• Previous inguinal hernia repair (missed or new femoral hernia)

4. Pathogenesis

1. Extraperitoneal fat pushed into the femoral ring
2. Fat drags peritoneum → sac
3. Sac passes down the canal (medial to the femoral vein)
4. Exits at the saphenous opening (cribriform fascia)
5. Turns upwards and forwards over the inguinal ligament (looks like an inguinal hernia)
6. Narrow rigid neck → contents trapped → strangulation
7. Richter's hernia common → part of the bowel wall trapped; may strangulate without obstruction

5. Classification

• By course → typical; prevascular (in front of the vessels); retrovascular; Laugier's (through the lacunar ligament)
• EHS → F (femoral)
• By state → reducible, irreducible, obstructed, strangulated
• Special contents → appendix (De Garengeot's hernia), bladder, ovary

6. Clinical picture

Symptoms

• Small groin lump; often no symptoms until it complicates
• Many first present with bowel obstruction or a painful, tender lump
• Elderly woman with small bowel obstruction → always examine the groins
• Richter's → vague pain, vomiting, tender lump, but bowel may still work

Signs

• Lump below and lateral to the pubic tubercle, in the upper medial thigh
• Lies medial to the femoral pulse
• Small, firm, round; often irreducible (fat, narrow neck)
• Cough impulse often absent
• Strangulated → tender, tense, red, irreducible; signs of obstruction

7. Diagnosis

• Clinical
• Ultrasound → confirms and separates from nodes, varix, aneurysm
• CT → obstruction, obese patients, uncertain lump
• Emergency → FBC, U&E, lactate, group and save; abdominal X-ray (dilated small bowel)
• If in doubt → explore (risk of strangulation)

8. Differential diagnosis

• Inguinal hernia → above and medial to the pubic tubercle
• Inguinal (femoral) lymph node → Cloquet's node, lymphadenitis
• Saphena varix → soft, disappears on lying down, cough thrill, varicose veins
• Femoral artery aneurysm → pulsatile
• Psoas abscess → lateral to the femoral artery, fluctuant, back pain
• Lipoma
• Ectopic testis, hydrocele of a femoral sac (canal of Nuck in women)

9. Treatment

Conservative

• No place → every femoral hernia is repaired (high strangulation risk); no truss
• Emergency → resuscitate first: IV fluids, NG tube, catheter, analgesia, antibiotics

Surgical

• Principles:
  1. Reduce or excise the sac, deal with the contents
  2. Close the femoral canal → suture the inguinal ligament to the pectineal ligament, or place a mesh plug
  3. Do not narrow the femoral vein (laterally)
• Low (infrainguinal, Lockwood) approach:
  • Incision in the groin crease below the inguinal ligament
  • Simple; good for elective repair
  • Poor access for bowel resection
• High (inguinal, Lotheissen) approach:
  • Through the inguinal canal, opening its posterior wall
  • Access to the femoral ring from above; weakens the inguinal floor
• High (McEvedy) approach:
  • Vertical or oblique incision over the femoral canal, extended above the inguinal ligament; preperitoneal approach
  • Best for emergencies → can open the peritoneum and resect bowel
• Laparoscopic (TEP or TAPP) → elective repair; mesh covers the femoral ring with the inguinal orifices
• Strangulation:
  • Do not let the contents slip back unseen → open the sac first
  • Tight neck → divide the inguinal ligament or carefully the lacunar ligament (watch for an abnormal obturator artery)
  • Non-viable bowel → resection via the preperitoneal space or laparotomy
  • Contaminated field → sutured repair rather than mesh

10. Complications

• Strangulation, bowel gangrene, perforation, peritonitis; mortality higher than inguinal hernia
• Bleeding → abnormal obturator artery, femoral vein injury
• Femoral vein compression or thrombosis (repair too tight)
• Recurrence (about 2–10%)
• Wound infection, haematoma
• Bladder injury (medial)