Inguinal Hernia


DEFINITION
An abnormal protrusion of an abdominal tissue or organ through a defect in the surrounding abdominal wall of the inguinal area, possibly leading to entrapment and strangulation.

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INCIDENCE

Age
Up to 25% of men, 2% women.
Up to 4% of infants.
Refer hernia (paeds) card for this age group.

Sex
M>F 10:1
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AETIOLOGY

Pathogenesis
Besides congenital defect of patent processes vaginalis in the indirect hernia, both occur when normal integrity of inguinal canal fails.

Integrity maintained by:


1) Deep inguinal ring shutter
Tough U-shaped condensation of transversalis fascia surrounds ring.
When transversus abdominis contracts (eg during straining), the U sling is pulled up and out, causing ring to close around cord.

2) I.O & T.A. Shutter
Roof of inguinal canal formed by arching fibres of internal oblique and transversus abdominis.
When these contract, the arch is flattened.

3) Posterior Wall
Formed mainly by transversalis fascia.
- depends on conjoint tendon laterally and transversalis fascial medially.

4) Ring positions
Superficial ring is medial and inferior to the deep ring.
Keeps canal oblique.

Aetiology

Predisposing factors:
i) Anything that impairs integrity of above factors.
ii) Anything that increases intraabdominal pressure.

Integrity
Patent processus vaginalis due to incomplete obliteration (indirect).
Congenital structural predisposition.
Connective tissue disorders.
Widening and weakening of deep ring occurs in adulthood; not fully explained.
-
Degeneration; muscle wasting with age.
Smoking.

Pressure
Obesity (stretches c.t. and abdo muscles, weakening wall).
Heavy straining, lifting, coughing (then its covered by ACC)
Intraabdominal tumours.
Gross organomegaly.
Peritoneal dialysis.
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BIOLOGICAL BEHAVIOUR

Classification

Indirect
Descend through inguinal ring.
Hernial sac is a patent processes vaginalis.
(20% M have this at autopsy).
Lateral to inf epigastric vessel.
Usually lateral and anterior to spermatic cord.
- may be bubonocele (limited to within canal).
- funicular through sup ring, but not further.
- complete into scrotum or labium.

Direct
Protruding through a weakness of the anterior abdominal wall (through the transversalis fascia).
Ie, within Hesselbach's triangle (lateral margin of rectus sheath (linea similunaris), inferior epigastric vessels, inguinal ligament)
- this area is only composed of fascia; transversalis and aponeurotic fibres of transversus abdominus; no true muscle covering
Medial to inferior epigastric vessel.

Pathophysiology

Behaviour and clinical manifestations depend on:
i) composition of the hernia.
ii) state of the hernia.

Composition
Consider 3 parts: sac, coverings and abdo contents.
Sac
Diverticulum of the peritoneum.
Coverings
Layers of abdo wall surrounding the sac.
Abdo contents
Most often small bowel & omentum.
May be only a knuckle of one wall of small bowel (Richter's hernia).
May be other structures - ovary, fallopian tubes.
Rarely large bowel, appendix, Meckel's.

States
Reducible
Irreducible
Obstructed
- ie bowel obstructed.
--> Usually leads to... Strangulated
- once intraluminal pressure rises greater than venous pressure, ischaemia starts
---> gangrene, eventually perforation.
- peritonitis ensues.
- abscess, fistula, necrotising fasciitis possible.
- omentum may strangulate, leads to local peritonism, not sepsis.
Inflamed
Rare, eg appendicitis in a hernial sac.

NB - 'incarcerated' historically applied to an irreducible hernia, with colonic contents and faecal impaction.
Now is often used interchangeably for 'irreducible'.

Sliding herniae are technically those composed of viscous retroperitoneal structures with peritoneum.
Sigmoid or caecum are typical contents.
They 'slide' back and forth.
Are age-related and much more common in males.

Natural History

Indirect
4x more common than DIH.
Despite being a partly congenital problem, occur at any age.
Precipitated by failure of integrity (above).
May commonly strangulate due to narrow neck.

Direct
Rare in females, never in children.
Rarely strangulate due to wide neck.
Rarely reach a large size or to the scrotum.
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MANIFESTATIONS

Symptoms
Local

Indirect
Typically present as groin pain +/- lump.
May disappear on lying down - "only present during the day, Dr."
Possibly pain in testes (referred along ilioinguinal nerve) or dragging sensation (stretching of contents).

Often recent hx of heavy lifting prior to presenting
Severe pain indicates something more serious (obstruction / strangulation).

Direct
Similar to indirect.
Discomfort & a lump.

Systemic
Suspect strangulation if systemic symptoms present.

Complications

Obstruction
Beware features of intestinal obstruction.
Eg colic, vomiting, constipation, distension.

Strangulation
1-5% of indirect herniae present strangulated.
Severe pain in groin, spreading to central abdo, often within a few hours.
If worse, may perforate with peritonitis & septicaemia.

Inflammation
Depends on aetiology, same as particular symptoms, but localised to hernial sac.

Richter's hernia
May mimic gastroenteritis, with no local pain.
Perhaps no vomiting, but vague abdo pain. Often normal stools, ie no obstruction.


Signs
See card

Observe
Examine standing to show lump, and any cough impulse.
- diffuse bulge on coughing is not a hernia.
- cough impulse should be discrete and confined to one area.
Lye down, check if reduces spontaneously.
Examine overlying skin
- skin erythema and oedema are signs of strangulation.

Palpate
Is it doughy like omentum, squishy like bowel, indenting like faeces?
If tense and exquisitely tender, suspect strangulation.
May not be able to differentiate obstructed from strangulated.
If in scrotum, is it discernable from testes? Can you get above it?
Doesn't transilluminate.

Indirect hernia
Protrusion along line of inguinal canal.
Extends varying distance from superficial inguinal ring, depending on type.
Passes inferomedially to scrotum on coughing.

Direct hernia
Usually easily reducible.
Rarely extends down into scrotum.

Type of hernia
Determine if it is inguinal or femoral.
Then if inguinal, is it direct or indirect.

Inguinal or Femoral?
Distinguished by position relative to inguinal ligament.
(Line between ASIS and pubic tubercle).
If it originates above, it is inguinal.
If below, it is femoral.

Indirect or direct?
Reduce hernia, pushing upwards and laterally.
Place fingers firmly over surface marking deep ring.
If it appears, it is direct.
If it is absent assume indirect.
Difficult and not essential
- though indirect herniae are worth operating sooner, higher likelihood of irreducibility.

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INVESTIGATIONS
Clinical diagnosis
Erect CXR, supine abdomen as necessary.
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MANAGEMENT

Conservative
A truss may be used for uncomplicated herniae in elderly debilitated pts.
And in those declining surgery.
Pretty ineffective however.

Acute Complication
<8% of acute presentations are strangulated
- attempt to reduce hernia.
Treat any obstruction
If strangulation suspected
- resuscitate
- broad spectrum ABs (eg triples)
Any acutely tender and irreducible hernia should receive an operation.

Surgical Repair
Advise no lifting for 6-8 wks.
2-4 wks off work.
'Herniotomy' = excision of the sac.
'Herniorrhaphy / hernioplasty' = repair & strengthening of posterior wall.

When to repair?
Groin pain alone (in absences of hernia / lump) is not a good indication for surgery; will make it worse.
RCTs show watchful waiting in asymptomatic hernias is safe and does not increase morbidity or mortality
- this is relevant to the older population with comorbidities.
- close to 25% of these patients will become symptomatic though and will require repair within 2y
Repair symptomatic hernias and those in fit people.

Pre-operative work-up
Correct cough if possible, lessens recurrence risk.

Surgical Options

Nonmesh Repair
Now only done in cases of strangulated bowel requiring resection
- another option is biological meshes but unproven.
Tissue to tissue repairs: Bassini, McVeigh and Shouldice
Bassini: suturing internal oblique and transversus abdominus and transversalis fascia to iliopubic tract / inguinal ligament
Shouldice similar but done in layers;
- continuous nonabsorbable suture; even distribution of tension
- transversalis fascia opened from internal ring to pubic tubercle; flap of muscle sewn to the ligament; then EO aponeurosis to medial flap;
- in total reinforced with suture lines
- tension can be relieved by relaxing incision medially at rectus fascia

Standard Tension-free Open Mesh Repair
(Lichtenstein Repair)
Gold standard repair
Onlay mesh repair; mesh fixed to inguinal ligament and overlapping pubic tubercle by 2cm.
Slit in mesh for cord structures; lateral wings overlapped and fitted to mesh as new internal ring and shutter mechanism.
Polypropylene mesh (8x16cm) and e.g. 2-0 prolene suture

Laparoscopic Repair

- increasingly popular, with reduced pain and earlier return to work (1-2 wks).
- however costs more and takes longer.
- recurrence rates appear similar, though longer trials needed.

Outcomes
Five measures used to judge success:
1. Recurrence rates
- 1-2% considered standard
2. Technical difficulty
3. Rehabilitation time
4. Complication rates
5. Cost to healthcare system and employment environment.
- cost of lap repair means it is best justified for bilateral or recurrent hernias, particularly in older people.

Complications
Wound infection (1%).
Recurrent hernia (<2%)
Nerve injury (ilioinguinal most commonly), with numbness resulting
Chronic pain (uncommon), perhaps due to nerve entrapment / neuroma formation, pressure.
- rates of 0.5% should be achievable.
- usually resolves spontaneously with expectant watching and analgesia
- In nerve distributions, patient should be taken back to theeatre to release suspected nerve entrapments
- if long term (6-12mo, series of steroid injections, local anaethetics, pain clinic or perhaps RFA.
- persistent troubling pain warrent exploration with triple neurectomy and possible mesh removal, after excluding other causes and recurrence.
Testicular ischaemia - rare but serious.
Hydrocele formation
Vas injury - should be avoided.

Note on Female groin hernias
Uncommon; mainly indirect.
Significantly higher rates of chronic pain
Round ligament ligation usually required to reduce sac, then mesh can be laid on to preperitoneal space.

Note on Recurrent Inguinal Hernias
Complication rate is higher:
- chronic pain
- scrotal haematoma, testicular atrophy (3-5%)
- re-recurrence in up to 20%
--> higher if older, smoker, COPD, prostate disease, heavy work, obesity, retired or unemployed.
--> in women need to consider if a femoral hernia was there all along but misdiagnosed.
Diagnosed by physical exam, primarily, to distinguish chronic groin pain.
- US, CT, MRI all used, no clear evidence for one over another.
- do a Valsalva maneuvre during imaging
Generally delay repair for 6 weeks after primary repair in early recurrence.
- can use a mesh plug in the hernia defect in big defects
Prior mesh should be left in-situ if possible as high risk of complications with removal.
Laparoscopic approach preferred
- virgin tissue planes, less risk / fewer complications to testis, vas and nerves, better outcomes (stay, return to work). lower re-recurrence




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References
Current Surgical Therapy 8th.
Operative Surgery Manual 1st.