Femoral hernia

Overview

•Femoral canal is the most medial compartment of the femoral sheath, bounded by rigid, unyielding structures (inguinal, pectineal, lacunar ligaments) - this rigidity explains the high strangulation risk

•Hernia passes through femoral ring → down femoral canal → emerges at saphenous opening (fossa ovalis)

•Femoral vein forms the lateral border of the femoral ring - at risk during repair

Risk Factors

Presentation

•Lump below and lateral to the pubic tubercle - key landmark distinguishing from inguinal hernia (which lies above and medial to the pubic tubercle)

•Cough impulse may be absent - narrow neck limits transmission

•Strangulation signs: hard, tender, irreducible lump, overlying skin changes, disproportionate pain, systemic sepsis

•Bowel obstruction features (vomiting, distension, obstipation) when obstructed or strangulated

🚨
An elderly woman with small bowel obstruction and NO prior abdominal surgery - always examine the groins. A strangulated femoral hernia is the classic cause and is easily missed if the groin is not examined.

💡
Richter's hernia: only the antimesenteric bowel wall herniates - no complete luminal obstruction so classic bowel obstruction signs may be absent, yet that segment can still strangulate and perforate. Particularly associated with the femoral canal.

Investigations

🥇 First-line

•Ultrasound - differentiates hernia from lymph node, lipoma, or vascular lesion; dynamic scanning (cough/Valsalva) increases sensitivity

•Bloods (FBC, U&E, CRP, lactate, G&S) - in suspected strangulation for pre-operative preparation

🥈 Second-line

•CT abdomen and pelvis - investigation of choice when bowel obstruction or strangulation suspected; shows hernial contents, bowel wall thickening, free fluid

Differential Diagnosis

Femoral vs inguinal hernia
FeatureFemoral herniaInguinal hernia
Position relative to pubic tubercleBelow and lateralAbove and medial
Relation to inguinal ligamentBelow/emerges belowAbove/originates above
Sex predominanceFemale > maleMale >> female
Strangulation riskVery high (~22% at 3 months)Lower
Watchful waitingNot recommendedMay be appropriate

Feature	Femoral hernia	Inguinal hernia
Position relative to pubic tubercle	Below and lateral	Above and medial
Relation to inguinal ligament	Below/emerges below	Above/originates above
Sex predominance	Female > male	Male >> female
Strangulation risk	Very high (~22% at 3 months)	Lower
Watchful waiting	Not recommended	May be appropriate

Management

⚠️
Watchful waiting is NOT recommended for femoral hernias. Strangulation risk is approximately 22% at 3 months and approximately 45% at 21 months. Early elective repair is always preferable to emergency surgery.

•All femoral hernias should be repaired promptly once diagnosed - elective repair carries low morbidity and mortality

•Emergency repair (strangulation) carries substantially higher risk, especially in elderly patients; bowel resection required when ischaemia/necrosis present

Complications

•Strangulation and bowel necrosis - most feared; may require bowel resection

•Richter's strangulation - partial bowel wall ischaemia; presentation deceptively subtle

•Femoral vein injury during repair - lateral border of femoral ring

•Wound infection, haematoma, seroma, recurrence