34. Inguinal hernias: types, anatomy, diagnosis, complications and treatment

Inguinal hernias: types, anatomy, diagnosis, complications and treatment

The inguinal canal is an oblique passage in the lower anterior abdominal wall, approximately 4 cm long, above the medial half of the inguinal ligament.
Anterior wall: external oblique aponeurosis, reinforced laterally by internal oblique. Posterior wall: transversalis fascia, reinforced medially by conjoint tendon. Roof: arching fibres of internal oblique and transversus abdominis. Floor: inguinal ligament, with lacunar ligament medially.
Deep ring is an opening in transversalis fascia lateral to inferior epigastric vessels. Superficial ring is an opening in external oblique aponeurosis. The spermatic cord traverses the canal in males; the round ligament does so in females.
Key relations: inferior epigastric vessels distinguish direct from indirect hernias. Hesselbach triangle is bounded by rectus abdominis medially, inferior epigastric vessels laterally and inguinal ligament inferiorly.

Indirect inguinal hernia enters through the deep ring lateral to inferior epigastric vessels, follows the canal and may descend into the scrotum. It is associated with a patent processus vaginalis and may be congenital or acquired.
Direct inguinal hernia protrudes through a weakness in the posterior wall of the canal within Hesselbach triangle, medial to inferior epigastric vessels. It is usually acquired and less likely to descend into the scrotum.
Pantaloon hernia combines direct and indirect components on either side of the inferior epigastric vessels. Sliding hernia has an organ forming part of the sac wall.

Patients describe a groin lump or discomfort on lifting, coughing or straining; indirect hernias may extend into the scrotum.
Examine standing and supine, inspect both groins, ask the patient to cough/strain, palpate the swelling and assess reducibility. Examine testes and scrotum.
Clinical distinction between direct and indirect hernias by bedside manoeuvres is imperfect; imaging is not routinely required when the diagnosis is clear.
Ultrasound is useful for occult or equivocal hernia. CT/MRI may be used for atypical pain, recurrence or complex anatomy.

Complications include irreducibility, bowel obstruction, strangulation, inflammation and recurrence after repair.
Femoral hernia, lymph node, saphena varix, hydrocele of the cord, varicocele, undescended testis, lipoma and vascular aneurysm are important differentials.
Sudden pain, irreducibility, vomiting, abdominal distension, fever or overlying erythema suggests incarceration/strangulation and requires emergency surgical assessment.

Offer elective repair for symptomatic hernias. Watchful waiting can be considered for selected asymptomatic or minimally symptomatic men after discussion; femoral hernias should generally be repaired because of their higher complication risk.