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Inguinal Hernias

This PatientPlus article is written for healthcare professionals so the language may be more technical than the condition leaflets. You may find the abbreviations list helpful.

This comprises a protrusion of abdominal contents through the fascia of the abdominal wall, through the internal inguinal ring. Hernias always contain a portion of peritoneal sac and may contain viscera, usually small bowel and omentum.

INGUINAL HERNIA (OM295a.jpg)

Epidemiology

Hernias comprise approximately 7% of all surgical outpatient visits.

  • Male:female ratio is 8:1.
  • Affect 1-3% of young children.
  • In men the incidence rises from 11 per 10,000 person years aged 16-24 years to 200 per 10,000 person years aged 75 years or above.1

Risk factors

Presentation

  • Swelling in the groin that may appear with lifting and be accompanied by sudden pain.
  • Indirect hernias are more prone to cause pain in the scrotum and cause a 'dragging sensation'.
  • An impulse (increase in swelling) may be palpable on coughing.
  • It may not be possible to see the hernia if it is reduced.
  • If a lump is present, it may be reducible

Congenital inguinal hernias are usually detected at birth, and all need urgent outpatient referral for surgical repair.
Inguinal hernias in older children and adults usually develop gradually, but can occur suddenly with an episode of heavy lifting causing 'rupture':

  • At first appearance, a hernia is usually easily reducible when the patient reclines, but it may require manual replacement if large.
  • With time, the hernia enlarges and becomes harder to replace, due to fibrous adhesions forming.
  • When it can no longer be reduced, it is irreducible or incarcerated. This can occur at any time, as can strangulation. This is when visceral contents of the hernia become twisted or entrapped by the narrow opening. This compromises the blood supply causing swelling, and eventually infarction.
    Strangulation usually leads to bowel obstruction.

There are two types of inguinal hernia:

  • Indirect: a protrusion through the internal inguinal ring passes along the inguinal canal through the abdominal wall. This is the more common form accounting for 80% of inguinal hernias, especially in children. It is associated with failure of the inguinal canal to close properly after passage of testis in utero or during the neonatal period.2
  • Direct: the hernia protrudes directly through the abdominal wall into the inguinal canal. It is more common in the elderly and rare in children.

There is NO clinical merit in distinguishing the two.

The less common form is the sliding hernia where a portion of viscera slides behind the peritoneal sac into the inguinal canal with the wall of the organ forming part of the hernial sac.

Assessment

  • Examine the patient both standing and lying and ask them to cough or strain.
  • Insert a finger through the top of the scrotum into the external inguinal ring and palpate for a lump when coughing - cough impulse.
  • Sliding hernias are probable with large scrotal hernias.

Differential diagnosis

See also separate article Lumps in the Groin and Scrotum.

  • Femoral hernia: this is seen in various forms, at simplest as a small swelling in the top of the inside of the thigh. Alternatively, it may be deflected to appear higher as an inguinal hernia. It is either irreducible or reduces only slowly with pressure.
  • Hydrocele (when differentiating from an inguinoscrotal hernia, note it is possible to get above a hydrocele on examination.
  • Spermatic cord hydrocele.
  • Lymph node swelling.
  • Abscess.
  • Saphena varix.
  • Varicocele.
  • Bleeding.
  • Undescended testis.

Investigations

Ultrasound is the less invasive method, if there is doubt.3 However, herniography with injection of X-ray contrast agent into the peritoneum is also used.

Management

Adults

If the hernia is small, the patient may only need reassurance. However, there is always the chance of its becoming a surgical emergency through obstruction and incarceration. Episodes of pain and tenderness suggest the need for urgent treatment, but when these become prolonged and severe then emergency surgery is indicated for possible strangulation.
The fundamentals of indirect inguinal hernia repair are the same regardless of the patient's age. Reduction or excision of the sac and closure of the defect with minimal tension are the essential steps in any hernia repair.

  • Conventional surgery is based on Bassini's operation; this consists of apposition of the transversus abdominis and transversalis fascia and the lateral rectus sheath to the inguinal ligament. The Shouldice technique uses 2 layers of running suture in a similar fashion.
  • However, the Lichtenstein technique is widely used, where a piece of open-weave polypropylene mesh is used to repair and reinforce the abdominal wall.4 This operation is easier to learn, gives earlier mobility and has a very low recurrence rate.5,6 The standard repair now uses prostheses, usually polypropylene mesh. It is, however, associated with a slightly increased risk of infection.7
  • Laparoscopic repair is usually reserved for recurrences and bilateral hernias. There is less postoperative pain, full recovery is better, and return to work is faster.8 However, the price is increased compared with the conventional approach,9 and there appears to be a higher number of serious complications of visceral (especially bladder) and vascular injuries.8
  • There are 2 approaches: either the transabdominal preperitoneal (TAPP) or the totally extraperitoneal (TEP) procedure. In TAPP the surgeon goes into the peritoneal cavity and places a mesh through a peritoneal incision over possible hernia sites. TEP is different as the peritoneal cavity is not entered and mesh is used to seal the hernia from outside the peritoneum. The mesh, where used, becomes incorporated by fibrous tissue.
  • Surgery can be performed on a day-case basis and for 7 days afterwards the patient should avoid driving and lifting. The patient should be able to resume normal activities over the next 2-3 weeks, but, with a heavy job, it can take up to 6 weeks to return to work.
  • A truss may be required where surgery is inadvisable or refused; however, it can be difficult for patients to manage and cannot be recommended as a definitive form of treatment.

Children

The incidence of incarcerated or strangulated hernias in paediatric patients is 10-20%. 50% of these occur in infants aged younger than 6 months:7

  • Paediatric surgeons will repair soon after diagnosis, regardless of age or weight, in healthy full-term infant boys with asymptomatic reducible inguinal hernias.
  • Premature infants with inguinal hernias are usually repaired prior to discharge from the neonatal intensive care unit (NICU), but this practice is changing, as infants are now being discharged home at much lower weights. Some surgeons prefer to postpone the surgery in these very small babies for 1-2 months to allow further growth.
  • Herniotomy is all that is required with ligation and excision of the patent processus vaginalis.

Complications

These include:

  • Recurrence: 0.5-1.0% - most happening within 5 years of operation. The recurrence rate increases in:
    • Children aged younger than 1 year.
    • Elderly patients.
    • After incarcerations.
    • In those with ongoing increased intra-abdominal pressure.
    • Growth failure.
    • Prematurity.
    • Chronic respiratory problems.
    • In girls with sliding hernias.
  • Infarcted testis or ovary with atrophy.
  • Wound infection.
  • Bladder injury.
  • Intestinal injury.
  • A hydrocele from fluid accumulation in the distal sac usually resolves spontaneously but sometimes requires aspiration.

Prognosis

This is generally very good, depending on comorbidity.

Document references

  1. Jenkins JT, O'Dwyer PJ; Inguinal hernias. BMJ. 2008 Feb 2;336(7638):269-72.
  2. van Wessem KJ, Simons MP, Plaisier PW, et al; The etiology of indirect inguinal hernias: congenital and/or acquired? Hernia. 2003 Jun;7(2):76-9. Epub 2003 Mar 18. [abstract]
  3. Lilly MC, Arregui ME; Ultrasound of the inguinal floor for evaluation of hernias. Surg Endosc. 2002 Apr;16(4):659-62. Epub 2001 Dec 17. [abstract]
  4. Sakorafas GH, Halikias I, Nissotakis C, et al; Open tension free repair of inguinal hernias; the Lichtenstein technique. BMC Surg. 2001;1:3. Epub 2001 Oct 15. [abstract]
  5. No authors listed; Repair of groin hernia with synthetic mesh: meta-analysis of randomized controlled trials. Ann Surg. 2002 Mar;235(3):322-32. [abstract]
  6. Bisgaard T, Bay-Nielsen M, Christensen IJ, et al; Risk of recurrence 5 years or more after primary Lichtenstein mesh and sutured inguinal hernia repair. Br J Surg. 2007 Aug;94(8):1038-40. [abstract]
  7. McCrudden Erickson K; Abdominal Hernias, eMedicine, Apr 2010
  8. McCormack K, Scott NW, Go PMNYH, Ross S, Grant AM, the EU Hernia Trialists Collaboration. Laparoscopic techniques versus open techniques for inguinal hernia repair. Cochrane Database of Systematic Reviews 2000, Issue 4. Art. No. CD001785. DOI: 10.1002/14651858.CD001785
  9. Hernia - laparoscopic surgery, NICE (2004)

Internet and further reading

Acknowledgements

EMIS is grateful to Dr Hayley Willacy for writing this article. The final copy has passed scrutiny by the independent Mentor GP reviewing team. ©EMIS 2011.
Document ID: 2324
Document Version: 25
Document Reference: bgp295
Last Updated: 26 Aug 2010
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