Inguinal hernias

1. What a hernia is

2. The anatomy you need

• Deep (internal) inguinal ring: a defect in the transversalis fascia, midway between the anterior superior iliac spine and the pubic tubercle. The inferior epigastric vessels lie just medial to it.
• Superficial (external) ring: an inverted V-shaped gap in the external oblique aponeurosis, just above the pubic tubercle.
• Anterior wall: external oblique aponeurosis.
• Posterior wall: transversalis fascia.
• Roof: the conjoint tendon, formed from internal oblique and transversus abdominis.
• Floor: the inguinal ligament.
• Contents: in men, the spermatic cord (vas deferens, testicular vessels, lymphatics, cremasteric muscle). In women, the round ligament. The ilioinguinal nerve, the iliohypogastric nerve and the genital branch of the genitofemoral nerve also pass through. These nerves matter because surgery can injure them and cause chronic pain.
• The weak area: the muscle arches over the deep ring. Below that arch there is no muscle, only transversalis fascia and aponeurosis. This is where hernias tend to occur. - Bailey and Love, p. 1087

3. The two main types

• laterally by the inferior epigastric artery,
• medially by the lateral edge of rectus abdominis,
• inferiorly by the inguinal ligament.

• Pantaloon hernia: a direct and an indirect hernia on the same side, draped over the inferior epigastric vessels.
• Femoral hernia: not an inguinal hernia. It comes out below the inguinal ligament, medial to the femoral vein. It is more common in women, has a high strangulation risk, and is easily confused with an inguinal hernia.
• Bubonocele, incomplete, complete: these describe how far the hernia has descended. A bubonocele stays within the canal. An incomplete hernia exits the superficial ring but does not reach the scrotum. A complete hernia reaches the bottom of the scrotum. - S Das, A Manual on Clinical Surgery, 13th Edition, p. 607

4. Hernia terminology

• Reducible: the contents go back in, spontaneously or with gentle pressure.
• Irreducible (incarcerated): the contents cannot be pushed back, but the blood supply is intact.
• Obstructed: bowel is trapped and blocked. The patient has colicky pain, vomiting and constipation.
• Strangulated: the blood supply is cut off, so the contents die (ischaemia, then gangrene). This is a surgical emergency.

5. Why they happen

• Male sex, older age, and family history
• Chronic cough (COPD, smoking)
• Straining at stool (chronic constipation) or at urination (prostatic obstruction)
• Heavy lifting
• Obesity, or pregnancy and ascites
• Connective tissue weakness (collagen abnormalities). A 2024 systematic review in genetic and biologic risk factors for hernia supports this.
• Previous lower abdominal surgery, such as an appendicectomy that damaged nerves

6. Symptoms

• A lump in the groin that appears on standing, coughing or straining and disappears on lying down. This is the classic presentation.
• A dragging or aching discomfort in the groin, worse at the end of the day or with exertion.
• Many hernias cause no pain at all.
• Warning signs of complications: a tense, tender, irreducible lump, severe pain, vomiting, abdominal distension, constipation, and red or purple skin over the lump.

7. Examination

1. Inspection: look for a swelling in the groin or scrotum, and for an impulse on coughing.
2. Palpation: find the pubic tubercle. An inguinal hernia lies above and medial to it. A femoral hernia lies below and lateral.
3. Reduce the hernia. Then use the deep ring occlusion test: press over the deep ring (midway between the anterior superior iliac spine and the pubic tubercle) and ask the patient to cough.
   • If the hernia stays controlled, it is indirect.
   • If it bulges out, it is probably direct. S Das describes this as a confirmatory test to differentiate the two. - S Das, p. 598
4. Zieman's technique, the finger invagination test, and the "cough impulse" test are further bedside methods you may meet. The deep ring test is the one most often taught.
5. In practice the type is often decided at surgery. Classification does not change the repair much.
6. Always examine the testes and the other groin.
7. Transillumination is positive for a hydrocele, not for a hernia. Examining the scrotum helps you separate a hernia from a hydrocele, varicocele or testicular tumour.

8. Investigations

• Ultrasound: when the diagnosis is unclear, such as a small or occult hernia, an obese patient, or the groin lump differential.
• CT: if there is suspected obstruction or strangulation, or to check for other abdominal pathology.
• MRI or dynamic ultrasound: for occult hernias in athletes or for chronic groin pain.
• Blood tests: if complicated (lactate, white cell count, electrolytes, urea).

9. Differential diagnosis of a groin lump

• Femoral hernia
• Enlarged lymph nodes
• Hydrocele of the cord, or a hydrocele
• Undescended or ectopic testis
• Lipoma of the cord
• Saphena varix
• Femoral artery aneurysm
• Psoas abscess or psoas bursa

10. Management

Adults

1. Open mesh repair (Lichtenstein): a mesh is placed over the posterior wall of the canal, usually under local anaesthetic. It is a good choice for low-resource settings.
2. Laparoscopic or endoscopic repair: the TEP (totally extraperitoneal) or TAPP (transabdominal preperitoneal) approach places mesh behind the defect. Both are recommended as evidence-based options, provided the surgeon is experienced. These suit bilateral and recurrent hernias well. They usually mean less early pain and a faster return to normal activity. They need general anaesthesia.
3. Tissue repairs without mesh: the Shouldice repair is the first choice if a non-mesh repair is chosen. Recurrence is higher than with mesh, so it is used in selected cases such as infection risk or patient preference.
4. Robot-assisted repair: a newer minimally invasive option, with the same principles as laparoscopic repair.

• Resuscitation: IV fluids, analgesia, nasogastric tube if obstructed, antibiotics.
• Operate urgently. Inspect the bowel for viability. Resect if necrotic.
• Mesh use is individualised. Contaminated fields increase the risk of mesh infection.
• Avoid forceful taxis (manual reduction), which can push dead bowel back into the abdomen.

Children

• Infants are at high risk of incarceration because the ring is narrow.
• An incarcerated hernia can usually be reduced with gentle pressure, sometimes with light sedation. Operate within about 24 hours after reduction.
• If it cannot be reduced, or there are signs of strangulation, operate as an emergency. - Schwartz, p. 1771

Truss

11. Complications

• Irreducibility and obstruction
• Strangulation (a risk of bowel necrosis, perforation and peritonitis)
• Testicular ischaemia in infants if the cord vessels are compressed
• Richter's hernia (only part of the bowel wall is trapped, so obstruction may be absent despite strangulation)

• Haematoma, seroma, wound infection
• Chronic groin pain, which is the most important long-term complication (nerve injury or mesh-related)
• Recurrence
• Urinary retention
• Testicular atrophy or ischaemic orchitis
• Injury to the vas deferens, bladder or bowel
• Mesh infection or migration

12. Prevention and advice

• Treat chronic cough, constipation and urinary obstruction.
• Stop smoking, lose weight if overweight, and lift with proper technique.
• After surgery, most people return to light activity within days. Heavy lifting is usually restricted for a few weeks, but advice differs by surgeon.

13. Key points to remember

1. The inferior epigastric vessels separate indirect (lateral) from direct (medial) hernias.
2. Indirect hernias are the most common type, they are the only type seen in children, and they come through the deep ring.
3. Direct hernias are acquired and pass through Hesselbach's triangle.
4. Inguinal hernias lie above and medial to the pubic tubercle. Femoral hernias lie below and lateral.
5. A tender, irreducible lump with vomiting means strangulation until proven otherwise, so operate urgently.
6. Mesh repair is standard for adults. Children get a high ligation of the sac without mesh.