Inguinal hernia

More than 20 million groin hernia repairs are performed worldwide every year — it is the most frequent operation in general surgery — and yet the candidate who cannot quote the watchful-waiting trials, the mesh evidence and the femoral numbers will lose the viva. This page is those numbers, organised the way an examiner asks for them.^[1][15]

Definition, anatomy and classification

A groin hernia is a protrusion of peritoneal contents through the myofascial layers of the groin. The three types a candidate must separate on examination and at operation are the indirect inguinal hernia (through the deep inguinal ring, lateral to the inferior epigastric vessels, travelling the inguinal canal), the direct inguinal hernia (through the posterior wall of the canal, medial to those vessels), and the femoral hernia (below the inguinal ligament, through the femoral canal into the upper thigh). The distinction is not academic: the type drives the urgency — femoral hernias are the strangulation-prone ones.^[11]

For description and audit, the European Hernia Society classification (2007) — a simple system derived from the Aachen classification — grades groin hernias as primary or recurrent, medial (direct) or lateral (indirect), by defect size, and HerniaSurge suggests using it to stratify patients for tailored treatment, research and audit.^[2][1] Its one piece of living vocabulary on this page: M3 hernias — large medial defects — are the exception in which mesh fixation is recommended even in laparo-endoscopic repair.^[1]

Named content variants deserve a line each. A Richter hernia (partial enterocele) is protrusion or strangulation of only part of the circumference of the bowel's antimesenteric border through a small rigid defect — comprising about 10% of strangulated hernias, progressing to gangrene faster than other strangulated hernias while obstructing less often, which is exactly why it hides.^[21] A de Garengeot hernia is the appendix incarcerated in a femoral hernia sac (see the mined CT in Figure 3); and the obturator hernia is the great femoral mimic — an uncommon cause of small-bowel obstruction in elderly women whose nonspecific presentation delays diagnosis (Figure 4).^[22][23]

Epidemiology and risk factors

The classic life-table figures remain the ones examiners quote: the lifetime risk of undergoing inguinal hernia repair is 27% for men and 3% for women; in the Oxford data behind that estimate, 30,675 repairs over a decade ran at an all-ages annual incidence of 13 per 10,000 population, with 9% of operations performed as emergencies and emergency rates rising exponentially with age beyond 50.^[3] HerniaSurge lists the risk factors: family history, previous contralateral hernia, male gender, age, abnormal collagen metabolism, prostatectomy, and low body mass index — the collagen item is the answer to "why do hernias happen at all" at fellowship depth.^[1]

^{[1] [3] [4]}

Diagnosis — a clinical diagnosis with rare exceptions

HerniaSurge is explicit: inguinal hernia diagnosis can be confirmed by physical examination alone in the vast majority of patients with appropriate signs and symptoms; ultrasound is rarely necessary, and dynamic MRI, CT or herniography less commonly still.^[1] The imaging question in the exam is therefore not "which scan?" but "who scans?" — the obese patient with groin pain and no lump, the recurrent-bulge-after-repair dilemma, and the acute abdomen where the hernia was never looked for. That last group is lethal: in the Danish emergency-mortality series, 41% of patients who died after emergency hernia surgery had not been examined for a hernia at admission, and over 60% had symptoms for 48 hours or more before arrival.^[10]

Watchful waiting — the four studies to quote

Fitzgibbons (JAMA 2006). 720 minimally symptomatic men at five North American centres randomised to watchful waiting versus open tension-free repair. Two-year primary outcomes were statistically indistinguishable: pain limiting activities 5.1% versus 2.2% (P = .06), physical-component score change 0.29 versus 0.13. Crossover ran both ways — 23% of the watchful-waiting arm elected surgery (rising pain the commonest reason) and 17% of the surgical arm declined surgery. The safety number every candidate must carry: acute incarceration occurred at 1.8 per 1000 patient-years — one incarceration without strangulation within 2 years, one with obstruction at 4 years. Conclusion: watchful waiting is acceptable; delaying repair is safe because acute incarcerations are rare.^[4]

The long-term follow-up (Ann Surg 2013) delivers the honesty the counselling needs: with up to 11.5 years of follow-up, the estimated cumulative crossover reached 68% — 79% in men over 65 versus 62% in younger men — with pain the reason in 54%. Three patients required an emergency operation; nobody died. The authors' sentence is the consent form: watchful waiting is reasonable and safe, but symptoms will likely progress and an operation will be needed eventually.^[5]

The British pair. O'Dwyer (Ann Surg 2006) randomised 160 men over 55 with painless hernias: no significant pain-score difference at 12 months, but the observation arm suffered 3 serious hernia-related adverse events versus none in the operated arm, and crossover was higher than predicted.^[6] Its 7.5-year follow-up (Chung, Br J Surg 2011) found an estimated conversion rate of 72% — 16% at 1 year, 54% at 5 years — and concluded that most patients with a painless inguinal hernia develop symptoms over time, so repair is recommended for medically fit patients.^[7]

Who fails watchful waiting? The ACS-trial prediction analysis: pain with strenuous activity (OR 1.3 per 10 mm on the visual analogue scale), chronic constipation (OR 4.9), prostatism (OR 2.9), being married (OR 2.3), and good health (ASA 1 versus 2, OR 3.0) predict crossover.^[8] And once a watched patient does come to surgery, the delay costs nothing: immediate versus delayed repair showed comparable operating time, complications, recurrence and satisfaction — no penalty for the wait.^[9]

The guideline synthesis (HerniaSurge): symptomatic groin hernias should be treated surgically; asymptomatic or minimally symptomatic men may be managed with watchful waiting since their risk of hernia-related emergencies is low — with the explicit caveat that the majority will eventually require surgery, so the strategy must be discussed, not imposed.^[1]

The repair landscape — mesh first, one size fits nobody

Mesh is the default. HerniaSurge recommends mesh repair as first choice, by open or laparo-endoscopic technique — and immediately adds that one standard repair technique for all groin hernias does not exist, so services should provide both anterior and posterior approach options.^[1] The effect size underneath: Cochrane's open mesh versus non-mesh review found mesh associated with a reduction in recurrence risk of between 50% and 75%.^[15]

Shouldice is the sanctioned exception. When mesh is declined or unavailable, the tissue-repair first choice is Shouldice — and its evidence is precise: recurrence is higher than with mesh (OR 3.80) but lower than with other non-mesh techniques (OR 0.62), making it the best non-mesh operation, at the price of longer operating time and stay.^[16][1]

Open versus laparo-endoscopic — quote both trials of the trade. The 2019 meta-analysis with trial sequential analysis (12 RCTs, 3,966 patients, laparoscopic versus Lichtenstein) found no difference in recurrence (OR 1.14) but significantly less acute pain and less chronic pain with laparoscopy (chronic pain OR 0.41) — and trial sequential analysis says further trials are unlikely to change the recurrence answer.^[18] The older Cochrane review (41 trials, 7,161 participants) frames the cost side: return to usual activity about 7 days earlier with laparoscopy, less persisting pain (OR 0.54) and numbness, no recurrence difference between laparoscopic and open mesh — but longer operations and a higher rate of rare serious complications, visceral (especially bladder) and vascular injuries.^[17] HerniaSurge's balanced sentence: provided resources and expertise exist, laparo-endoscopic techniques have faster recovery, lower chronic-pain risk and are cost-effective.^[1]

The learning curve is part of the answer. Probably about 100 supervised laparo-endoscopic repairs are needed to achieve the same results as open mesh surgery like Lichtenstein — a number examiners expect when the candidate advocates TEP.^[1]

TEP versus TAPP details that score marks. In almost all cases mesh fixation in TEP is unnecessary; in both TEP and TAPP, mesh should be fixed in M3 hernias to reduce recurrence risk. During TAPP, after consent, the contralateral side should be inspected for an occult hernia — this is not suggested during unilateral TEP. Antibiotic prophylaxis is not recommended for average-risk open repair in low-risk environments, and never for laparo-endoscopic repair.^[1]

Mesh selection and fixation. Lightweight mesh offers less chronic pain (OR 0.72) and less foreign-body sensation (OR 0.50) with a marginal 12-month recurrence signal — but HerniaSurge's position is that lightweight mesh gives slight short-term benefits without better long-term recurrence or chronic-pain outcomes, so mesh should not be selected on weight alone.^[19][1] Plug techniques are discouraged (erosion signal versus flat mesh).^[1] In Lichtenstein repair, glue fixation reduced chronic pain by 37% versus sutures (OR 0.63) with unchanged recurrence — the benefit concentrated in the heavyweight-mesh subgroup.^[20]

Chronic postoperative inguinal pain — the real complication

Recurrence is the complication candidates quote; CPIP is the complication patients live with. HerniaSurge puts clinically significant chronic pain at 10–12%, decreasing over time, with debilitating pain affecting daily activities or work in 0.5–6%. CPIP is defined as bothersome moderate pain impacting daily activities lasting at least 3 months postoperatively. Risk factors: young age, female gender, high preoperative pain, early high postoperative pain, recurrent hernia and open repair.^[1]

Prevention is an operative discipline — nerve recognition in open surgery, with prophylactic pragmatic neurectomy only in selected cases (planned resection is not suggested). Management belongs to multidisciplinary teams: pharmacological and interventional measures first, then — in selected cases — (triple) neurectomy and, where indicated, mesh removal.^[1]

Recurrent hernia has its own rule, and it is beautifully logical: after an anterior repair, repair posteriorly; after a posterior repair, repair anteriorly; after failure of both, refer to a specialist hernia surgeon.^[1]

Femoral hernia — the dangerous one

The Swedish Hernia Register study (3,980 femoral repairs, 1992–2006) is the definitive femoral dataset:^[11]

• Femoral hernias account for 2–4% of all groin hernias, but 35.9% of femoral repairs were emergencies versus 4.9% of inguinal repairs — and women carried the higher emergency risk (40.6% versus 28.1% in men).
• Bowel resection: 22.7% of emergent femoral repairs versus 5.4% of emergent inguinal repairs.
• An emergency femoral operation carried a 10-fold increased mortality risk; elective femoral repair's risk did not exceed the general population's.
• The authors' instruction: femoral hernias should be operated with high priority to avoid incarceration, and repaired with mesh — in the elective setting, laparoscopic and open preperitoneal mesh gave fewer reoperations than suture repair.

HerniaSurge aligns: timely mesh repair by a laparo-endoscopic approach is suggested for femoral hernias where expertise exists, and the incarceration/strangulation risk factors are female gender, femoral hernia and a history of hospitalisation related to groin hernia.^[1] The contemporary acute-presentation cohort (6,165 acute groin hernias, nine NHS trusts) adds the modern numbers: 90.1% of acute femoral hernias were operated (55.1% of inguinal), bowel resection 14.7% versus 3.5%, and 30-day mortality 3.1% overall — with age, co-morbidity, obstruction and strangulation driving it.^[13]

The acute groin hernia — a delay-driven killer

Emergency groin hernia surgery kills not because the operation is hard but because the diagnosis and the knife come late. The Danish study of every death within 30 days of emergency hernia repair (mortality 7% — more than twice comparable countries) found median age 83, 80% with co-morbidity, over 60% symptomatic for 48 hours or more before admission, 41% never examined for a hernia at admission, and only 23% operated within 8 hours; laparotomy and bowel resection were needed in over half.^[10] The bedside rule it writes: examine the groins of every acute abdomen, and operate soon after admission.^[10] Primatesta's population data carry the same message from the elective side: mortality is significantly elevated after emergency operations, so elective repair should be undertaken soon after diagnosis.^[3]

Special populations

Women. Female groin hernia surgery is a different disease: the Danish database found a higher reoperation rate in women than men (4.3% versus 3.1%), and — the trap that explains it — 41.5% of female reoperations found a femoral hernia, versus 5.4% in males; case series of suspected incarcerated inguinal hernias in elderly women repeat the same lesson, finding femoral hernias that open repair easily overlooks.^[12][24] The femoral canal must be explored at the primary operation, which is why HerniaSurge suggests women undergo laparo-endoscopic repair where expertise exists: less chronic pain and no missed femoral hernia.^[1]

Pregnancy. Groin hernia in pregnancy is rare and almost never an emergency: in 20,714 pregnancies, primary ventral and groin hernias were registered in 0.08% and 0.12%, none required elective or emergency repair in pregnancy, several bulges (round-ligament varicosities) resolved after delivery — watchful waiting is recommended during pregnancy.^[14][1]

The elderly. HerniaSurge suggests general over regional anaesthesia at 65 and older (fewer cardiopulmonary complications), and the emergency-mortality data make the deeper point: the patient who dies of a groin hernia is an 83-year-old whose hernia was admitted 48 hours late.^[1][10]

Revision summary

• Diagnose on examination; image the exceptions. In the acute abdomen, the groin examination is not optional — 41% of fatal Danish cases were never examined.^[1][10]
• Symptomatic hernias get repaired; minimally symptomatic men may be watched — incarceration 1.8/1000 patient-years, but 68% cross over long-term (79% over 65).^[1][4][5]
• Mesh first, open or laparo-endoscopic; mesh halves-to-quarters recurrence versus non-mesh; Shouldice is the sanctioned tissue repair (OR 3.80 vs mesh, 0.62 vs other non-mesh).^[1][15][16]
• Laparo-endoscopic: same recurrence (OR 1.14), less chronic pain (OR 0.41), ~7 days faster recovery — against longer operations, rare visceral injury, and a ~100-case learning curve. No routine TEP fixation except M3; no prophylactic antibiotics laparo-endoscopically.^[18][17][1]
• CPIP 10–12% (debilitating 0.5–6%) is the complication to prevent: nerve recognition, MDT management, neurectomy/mesh removal in selected cases.^[1]
• Femoral hernias are never watched: 35.9% emergency, 22.7% resection, 10-fold emergency mortality — timely mesh repair. In women, think femoral; in reoperated women, it was femoral 41.5% of the time.^[11][12]

References24ShowHide

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