Abdominal wall and groin hernias

• A hernia is the protrusion of an organ or tissue through a weakness in its surrounding wall: in the groin this usually means abdominal contents pushing through the inguinal or femoral canal.
• Inguinal hernias are extraordinarily common, with a lifetime occurrence of about 27 to 43% in men and 3 to 6% in women, and over 20 million people undergo repair each year worldwide.
• They are classed as indirect (through the deep inguinal ring, lateral to the inferior epigastric vessels), direct (through Hesselbach's triangle, medial to those vessels) or femoral (through the femoral canal), and the type dictates both examination and repair.
• Surgery is the only cure. Symptomatic hernias should be repaired; minimally symptomatic men may be managed with watchful waiting because the risk of a hernia emergency is low.
• The dangerous complications are incarceration, obstruction and strangulation, which need urgent surgical assessment.

By the end of this page you should be able to:

1. Describe the walls and contents of the inguinal canal and the neighbouring femoral canal.
2. Distinguish indirect, direct and femoral hernias on examination, and locate each relative to the inferior epigastric vessels and the pubic tubercle.
3. Outline the other abdominal-wall hernias and recognise Richter and Littre hernias.
4. Explain the risk factors and how raised intra-abdominal pressure and fascial weakness produce a hernia.
5. Examine a patient with a groin swelling safely and choose first-line investigations.
6. Recognise strangulation and outline emergency management.
7. Summarise the treatment options, including watchful waiting, Lichtenstein repair, laparoscopic TEP and TAPP, and low-resource practice.

Groin hernias are the commonest abdominal-wall hernias in adults. The hernia may contain omentum, small bowel, colon, bladder, ovary or fallopian tube, and the contents can change with posture. An inguinal hernia enters or leaves through the inguinal canal; a femoral hernia passes beneath the inguinal ligament through the femoral canal.

Memory aid: indirect hernias start lateral to the inferior epigastric vessels (through the deep ring); direct hernias push medial to them (through Hesselbach's triangle).

The inguinal canal is an oblique tunnel in the lower anterior abdominal wall. In men it transmits the spermatic cord and the ilioinguinal nerve; in women it transmits the round ligament of the uterus and the ilioinguinal nerve. Its four walls are easy to remember if you picture the canal as a trough created by the three flat muscles.

• Anterior wall: external oblique aponeurosis, reinforced laterally by fibres of internal oblique.
• Posterior wall: transversalis fascia, reinforced medially by the conjoint tendon and, in its whole, by the transversus abdominis.
• Roof: arching fibres of internal oblique and transversus abdominis.
• Floor: the inguinal ligament, with the lacunar ligament at its medial end.

Figure 1Indirect (oblique) inguinal hernia: the varieties

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Long description

Three line drawings. Complete oblique inguinal: the hernial sac descends into the scrotum in front of the tunica vaginalis. Complete congenital: the sac and the tunica vaginalis form one cavity because the processus vaginalis stayed open. Incomplete congenital: the sac lies above a closed-off tunica vaginalis.

Deep (internal) inguinal ring. This is an opening in the transversalis fascia, a U-shaped slit, located just lateral to the inferior epigastric vessels and about midway between the anterior superior iliac spine and the pubic symphysis. The spermatic cord or round ligament enters the abdomen here, carrying a sleeve of transversalis fascia (the internal spermatic fascia) with it.

Superficial (external) inguinal ring. This is a triangular split in the external oblique aponeurosis lying above and medial to the pubic tubercle. The spermatic cord or round ligament exits here.

Inferior epigastric vessels. These vessels run upward and medially behind the rectus sheath after arising from the external iliac vessels. They are the surgeon's landmark: lateral for indirect hernias, medial for direct hernias.

Figure 2Direct inguinal hernia seen at laparoscopy

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Long description

Laparoscopic view of the right groin. The hernia defect, labelled 1, bulges through the floor of the inguinal canal medial to the inferior epigastric vessels, labelled 2. The relation of the defect to these vessels separates direct from indirect inguinal hernias.

Hesselbach's (inguinal) triangle is the weak area of the posterior wall through which a direct hernia exits. Its boundaries are the lateral edge of the rectus sheath medially, the inguinal ligament inferiorly, and the inferior epigastric vessels laterally and superiorly. Its floor is the transversalis fascia alone, which is why acquired weakness here is enough to bulge forward.

The conjoint tendon (inguinal aponeurotic falx) is the fused aponeurosis of internal oblique and transversus abdominis. It inserts onto the pubic crest and the pectineal line and buttresses the posterior wall medially, just lateral to the superficial ring. If it is poorly developed or stretched, the medial canal weakens and a direct hernia results.

The femoral canal is the small medial compartment of the femoral sheath, lying just below the inguinal ligament and medial to the femoral vein. Its boundaries are the inguinal ligament anteriorly, the pectineal (Cooper's) ligament posteriorly, the femoral vein laterally and the lacunar ligament medially. It normally contains lymphatic tissue and a lymph node (of Cloquet). Because the canal's neck is rigid and cannot expand, a femoral hernia that becomes tight is easily strangulated.

Groin hernias are among the commonest conditions a general surgeon sees. The lifetime occurrence of groin hernia is 27 to 43% in men and 3 to 6% in women; more than 20 million hernia repairs are performed worldwide each year. ^[1] Recurrences needing reoperation occur in 10 to 15% over a lifetime, and surgically successful repairs still leave 10 to 12% with chronic pain, about 1 to 3% severe. ^[1]

Children differ: inguinal hernia affects roughly 0.8 to 4.4% of all children and is a common paediatric surgical condition. ^[3] It arises almost always from a patent processus vaginalis (see below).

A hernia is best thought of as the balance between raised intra-abdominal pressure and a weak wall. Some defects are acquired, some congenital, and many factors interact.

Risk factors for adult inguinal hernia (HerniaSurge summary): ^[1]

• Family history, especially a first-degree relative; the effect is larger in women.
• Male sex (repair is roughly 8 to 10 times more common in men).
• Age (peaks at about 5 years and again at 70 to 80 years).
• Collagen metabolism (a diminished collagen type I to III ratio) and rare connective-tissue disorders such as Ehlers-Danlos syndrome.
• Open radical prostatectomy.
• Low body mass index (inguinal hernia is inversely related to body weight in adults).
• Chronic constipation.
• Prior contra-lateral hernia.
• Rarely chronic pulmonary disease with cough, which may increase risk.

Factors the evidence is weaker on or mixed: race (hernias are less common in black adults in some studies); heavy lifting; social and occupational factors. Liver disease, renal disease and alcohol have not been adequately studied. ^[1]

The obesity puzzle. Basic teaching often lists obesity as a risk factor, but the HerniaSurge review of adult epidemiology found body mass index inversely related to inguinal hernia incidence, while abdominal-wall (ventral) hernias are clearly promoted by excess weight. ^{[1] [2]} Treat the contribution of weight cautiously and remember that obesity still worsens postoperative wound and respiratory complications.

Other relevant factors

• Prematurity and undescended testis in children; hernia incidence is much higher in premature infants.
• Pregnancy and multiparity promote groin swelling, much of which is self-limited round-ligament varicosity rather than a true hernia.
• Previous abdominal surgery and wound infection predispose to incisional hernias.
• Smoking damages healing and is a clear risk factor for incisional (not strong for primary inguinal) hernias.
• Ascites, chronic cough and straining at stool increase intra-abdominal pressure in susceptible patients.
• Collagen disorders (Ehlers-Danlos, Marfan) and, in young patients, mutations such as PRKAR1A-association conditions.

Everything in a hernia follows from two mechanisms: a raised-pressure event and a weak wall.

1. Congenital. In fetal life the testis or round ligament descends with a peritoneal outpouching, the processus vaginalis. If it fails to close, abdominal contents can follow it into the canal: an indirect hernia. This explains why hernias are common in boys and why descent into the scrotum or labium occurs.
2. Acquired. Chronic pressure on the transversalis fascia (cough, constipation, straining, heavy work) stretches Hesselbach's triangle and thins the conjoint tendon, producing a direct hernia in older adults.
3. Protrusion without resolution. A mobile sac of peritoneum contains omentum or viscera. At first it slides back when pressure falls. Repeated stretching enlarges the neck and sac so the contents may become irreducible.
4. Compromise. A narrow, rigid neck (especially femoral, but also a tight internal ring) can trap the contents and threaten their blood supply, producing strangulation.

Understanding why older men get direct hernias and why premature infants get indirect ones guides both examination and the operation you choose.

Patients usually report a groin swelling or lump, often first noticed on standing or lifting, that aches or drags and disappears on lying down. Ask about:

• Onset, whether the bulge appeared with strain or appears only on standing.
• Reducibility: does it go back in lying down or with gentle pressure?
• Pain quality: dull ache, heaviness, sharp pain on straining, or severe constant pain suggesting incarceration.
• Aggravating and relieving factors, cough, constipation, occupation.
• Gastrointestinal symptoms (nausea, vomiting, colic, constipation) suggesting obstruction.
• Genitourinary or fertility problems.
• Previous abdominal surgery or mesh repair, smoking, ascites, chronic lung disease.
• In children: prematurity, undescended testis, intermittent scrotal swelling.

A hernia can be entirely asymptomatic and found incidentally. That is the setting where watchful waiting is discussed.

Examine standing and supine, with the groin fully exposed, and compare sides.

1. Inspection. Look for an asymmetric bulge, scars, skin changes, localised swellings in the scrotum/labium majus.
2. Cough impulse. Place a finger over the superficial ring (just above and medial to the pubic tubercle) or over the femoral triangle; ask the patient to cough. A transmitted expansive impulse supports a hernia. A femoral hernia may not produce an obvious cough impulse once it is tight.
3. Palpation and reduction. Palpate from above downwards. Try to reduce the swelling gently (never force). Note the site of origin relative to the pubic tubercle and the impulse felt on coughing. An indirect hernia descends to the scrotum/labium; a direct one rarely does.
4. Relation to pubic tubercle (the single most useful clinical distinction). An inguinal hernia presents above and medial to the pubic tubercle; a femoral hernia presents below and lateral to it. (Use this to separate them at the bedside; ultrasound is used when the examination is uncertain.)
5. Transillumination. Shine a light through a swelling. A hydrocele transilluminates; a hernia generally does not (omentum or bowel blocks light), and a hydrocele of the cord or an encysted cord may mimic a hernia. Transillumination is therefore used to exclude a hydrocele.
6. Assessment for complications. Is it reducible, irreducible, tense or tender? Is there overlying erythema? Ask about vomiting and bowel habit.
7. Abdomen and testes. Feel the testes for descent and for masses; examine the abdomen for incisional hernias and ascites.

• Hydrocele (transilluminates; testis cannot be felt separately when large).
• Saphena varix and venous dilatation.
• Lymphadenopathy or abscess.
• Undescended testis or tumour.
• Psoas abscess or pelvic mass presenting in the groin.
• Sportsman's groin / athletic pubalgia (no true hernia defect on examination).

A small, occult or atypical bulge is where imaging helps settle the diagnosis.

Diagnosis is clinical in most patients. ^[1]

• Physical examination confirms the vast majority of groin hernias with typical signs and symptoms.
• Ultrasound is the usual first imaging test when the diagnosis is uncertain, when the swelling is intermittent or occult, or to distinguish a femoral hernia. Dynamic sonography with Valsalva can show fascial defects and reduce the need for surgery that is not needed.
• Computed tomography (CT) is used when the presentation is atypical, when other abdominal-wall or groin masses are suspected, in recurrent hernia, in suspected strangulation with intra-abdominal sepsis, or in patients with a complex abdominal wall.
• Magnetic resonance imaging (MRI) (sometimes a dynamic herniogram) is reserved for difficult cases, athletes' groin pain, and preoperative mapping of large or recurrent hernias.
• Plain radiographs only if bowel obstruction is suspected.

The HerniaSurge guidelines note that examination alone confirms the diagnosis in the vast majority; ultrasound is only occasionally needed and dynamic MRI, CT or herniography less often still. ^[1]

Preoperative assessment. Check cardiorespiratory fitness for surgery, and investigate comorbidity (cough, constipation, ascites, urinary retention) that could be corrected before elective repair. In patients at higher cardiac risk having major surgery, consider a coronary assessment. Urine and electrolytes and a full blood count are standard. Anaesthesia choice (local, regional or general) depends on patient and technique.

The European Hernia Society (EHS) classification records whether a hernia is primary or recurrent, lateral (indirect) or medial (direct), femoral, and its maximum diameter. Its purpose is to standardise treatment, research and audit; it is optional but useful in specialist practice. ^[1]

• Incarceration: the contents cannot be reduced. The swelling is tense and may be tender; bowel, if trapped, causes colic.
• Obstruction: a loop of bowel within the sac obstructs, with colicky pain, vomiting, distension and constipation.
• Strangulation: the blood supply to the sac contents is compromised. This is a surgical emergency: severe constant pain, a tense irreducible tender mass, overlying skin erythema, fever, tachycardia and systemic signs. Ischaemia progresses to necrosis, perforation and peritonitis within hours.
• Richter hernia: only part of the bowel wall (the antimesenteric border) enters the sac. Because the lumen is not occluded, there is no obstruction until late, yet the wall can necrose and perforate: a hidden strangulation without obstruction. It is more common in femoral and small hernias.

Risk factors for incarceration or strangulation include female sex, femoral hernia and a history of hospitalisation for groin hernia. ^[1]

• Femoral hernia. Small, firm, irreducible swelling below and lateral to the pubic tubercle. Because the femoral ring is unyielding, strangulation risk is high; repair should be timely. ^[1]
• Obturator hernia. Passes through the obturator canal. It occurs in frail elderly women and presents with medial thigh pain radiating to the knee (Howship-Romberg sign), often with bowel obstruction. It is notoriously diagnosed late and carries high mortality.
• Umbilical (and para-umbilical) hernia. Midline defect at the umbilicus. Common and usually harmless in infants; in adults it associates with multiparity, raised abdominal pressure, obesity and ascites (especially in cirrhosis). Small defects with a narrow neck carry strangulation risk.
• Incisional (ventral) hernia. Defect through a previous surgical scar. Watch for recurrence, wound infection, mesh exposure and skin ulceration; repair should treat the defect and reduce intra-abdominal pressure.
• Epigastric hernia. Small midline defect between the xiphoid and the umbilicus, often containing pre-peritoneal fat. It causes severe localised pain disproportionate to size.
• Spigelian hernia. Through the spigelian fascia at the lateral border of the rectus sheath, usually below the arcuate line. Often occult; CT or ultrasound clinches it.
• Parastomal hernia. Protrusion beside a stoma; manage with stoma appliances, support belts and elective repair when troublesome.
• Sliding hernia. Part of the hernia sac wall is formed by the herniated organ (sigmoid colon, caecum, bladder). Recognise this at operation to avoid injuring the viscus when the sac is ligated.
• Littre hernia. A hernia containing a Meckel diverticulum; repair it without leaving the diverticulum in place if it is inflamed or ectopic.
• Hiatal hernia. Protrusion through the diaphragmatic hiatus; gastric cardia sliding hernias are discussed in the reflux and oesophagus topic. (They are outside the scope of groin repair, but the same principle of a sliding hernia applies.)
• Richter hernia. See above.

• Reduce a simple incarceration safely. In a recent, clean incarceration without signs of strangulation, gentle taxis (knee-chest position, sedation/analgesia, then sustained gentle pressure) may reduce the contents; admit for observation and arrange prompt repair, because recurrence is likely.
• Emergency surgery is indicated for strangulation, irreducible hernia with obstruction, any signs of peritonitis or sepsis, and usually for femoral hernias (which have a high strangulation risk). Tailor the operation (open or laparoscopic) to patient factors, contents and local expertise. ^[1]
• Do not reduce and forget: an incarcerated hernia, even if reduced, should be repaired during the admission.

• Surgical repair is the only cure. Mesh repair is recommended as first choice, open or laparo-endoscopic, depending on surgeon expertise, patient factors and resources. ^{[1] [2]}
• Open mesh repair (e.g. Lichtenstein) is reliable, widely available, teachable under local anaesthesia, and the mainstay where resources or expertise for laparoscopy are limited.
• Laparo-endoscopic repair (TEP or TAPP) offers faster recovery, lower chronic pain risk and cost-effectiveness where expertise exists; 100 or so supervised cases are needed to match open-mesh outcomes. ^[1]
• TEP vs TAPP. In TEP the mesh is placed in the preperitoneal space without entering the peritoneum; mesh fixation is almost always unnecessary, except in large medial (M3) hernias. During TAPP the contralateral side can be inspected through the peritoneum. ^[1]
• Tissue repair (Shouldice) is the preferred non-mesh technique and gives comparable one-year results to Lichtenstein/TEP/TAPP in selected patients with primary unilateral hernia, provided expertise and shared decision-making. ^[2]
• Plug repair techniques are not recommended, because erosion and chronic pain are more frequent. ^[1]
• Mesh details. Low-weight mesh may slightly reduce early pain and convalescence but does not improve longer-term recurrence or chronic pain; choosing on mesh weight alone is not recommended. ^[1]
• Femoral hernia should be repaired promptly, ideally laparo-endoscopically with mesh where expertise exists. ^[1]
• Women with groin hernias should be considered for laparo-endoscopic repair, which reduces chronic pain risk and is less likely to miss a femoral hernia. ^[1]
• Pregnancy: watchful waiting is suggested, as most groin swellings are self-limited round-ligament varicosities; repair, if needed, is deferred to after delivery. ^[1]
• Children: repair is undertaken promptly after diagnosis because the patent processus vaginalis can incarcerate or strangulate, and early repair in infants is preferred (avoids emergency presentation and anaesthetic morbidity). ^[3]
• Truss (external support): a holding measure for patients unfit or waiting for surgery, or where surgery is unavailable; not a cure.
• Watchful waiting is appropriate for asymptomatic or minimally symptomatic men, because the risk of a hernia emergency is low, but about 70% eventually need surgery within about five years, so risks and the strategy should be discussed. ^[1]
• Recurrent hernia: after an anterior repair, perform a posterior (laparoscopic/preperitoneal) repair; after a posterior repair, an anterior repair; after both have failed, refer to a specialist hernia surgeon. ^[1]
• Chronic postoperative inguinal pain (CPIP) is defined as bothersome moderate pain that impacts daily activities and lasts at least 3 months after operation, usually decreasing with time. It occurs in 10 to 12% overall, with severe pain in 1 to 3% and pain that limits activity in roughly 0.5 to 6%. Risk factors include young age, female sex, high preoperative pain, early severe postoperative pain, recurrent hernia and open repair. Management needs a multidisciplinary team, nerve recognition at operation (with prophylactic neurectomy only in selected cases), pharmacological and interventional measures, and, failing these, selected triple neurectomy or (in selected cases) mesh removal. ^[1]
• Antibiotics: not recommended for average-risk patients in low-risk environments for open repair, and never for laparo-endoscopic repair. ^[1]
• Anaesthesia: local anaesthesia has many advantages in open repair where the surgeon is experienced; general anaesthesia is suggested over regional in patients aged 65 or older (fewer myocardial infarction, pneumonia and thromboembolic complications). Regional and field/subfascial blocks are useful adjuncts. ^[1]
• Convalescence: patients should resume normal activities without restriction as soon as they feel comfortable; light activity early is encouraged, heavy lifting is increased gradually.
• Day surgery is recommended for most groin hernia repairs if aftercare is organised.

• Umbilical/para-umbilical (infant): many close spontaneously in early childhood; repair if large, symptomatic or persistent.
• Umbilical/para-umbilical (adult): repair if symptomatic, strangulated or progressively enlarging; eminently treatable, but optimise ascites, weight and constipation first.
• Incisional: non-operative care (belt, weight reduction) for very large defects or frail patients; definitive repair is mesh-based (often component separation or preperitoneal placement), with the lowest-tension closure possible.
• Epigastric: excision of the fat nodule and suture of the defect.
• Spigelian: repair, usually with mesh preperitoneally; laparoscopy helpful for occult cases.
• Obturator: emergency laparotomy or laparoscopy for obstruction, with repair of the canal.
• Hiatal: lifestyle and acid suppression first; fundoplication or hiatus repair for reflux/obstruction/volvulus.

• Children: prompt elective repair after diagnosis, because incarceration risk is higher in infants and in girls, and early repair avoids emergency presentation. ^[3]
• Women: consider laparoscopic repair to avoid missing a femoral hernia and to reduce chronic pain. ^[1]
• Pregnancy: watchful waiting; repair deferred unless complications occur. ^[1]
• Older adults: optimise comorbidity; consider general over regional anaesthesia at 65 and above. ^[1]
• Low body weight/prematurity: repair after physiological stabilisation; coordinated neonatal and surgical care.

Delayed presentation and strangulation are common where access to surgery is limited. Priority is an overarching plan for safe inguinal hernia surgery that contains simple guidelines and a sustainability strategy independent of aid. In practice, focus on high-volume Lichtenstein repair under local anaesthesia using low-cost mesh, organised as day surgery, with trained non-specialist surgeons and registries. Mesh use varies from 0 to 5% in the lowest-resource settings to 95% in the highest; non-mesh (Shouldice) repair remains appropriate where mesh and sterility cannot be guaranteed. ^[1]

After uncomplicated repair: return to normal activity as comfort allows; inspect the wound at routine follow-up; review for persistent pain; reoperate with the appropriate approach if recurrence occurs. Send any unusual sac to histology. Long-term registries improve audit and outcomes. ^[1]

After elective repair prognosis is excellent: most patients are cured, recurrence is reduced by mesh, and day surgery keeps complications low. The dominant long-term morbidity is chronic pain (10 to 12%, severe 1 to 3%) rather than recurrence. ^[1] Mortality in elective repair is very low; the excess mortality sits in emergency surgery for strangulation, which is why timely repair and recognition of red flags matter.

There is no screening programme. Modifiable steps are treating cough and constipation, managing ascites, weight optimisation for abdominal-wall hernias, good wound care after laparotomy, and smoking cessation to support healing. Patients should seek early assessment of any new groin bulge, especially women and infants (where femoral or incarcerated hernias are more likely).

• Lifetime occurrence of groin hernia is 27 to 43% in men and 3 to 6% in women, with over 20 million repairs performed worldwide each year. ^[1]
• Diagnosis is clinical in most groin hernias, and ultrasound or cross-sectional imaging is only occasionally needed to confirm uncertain or complex cases. ^[1]
• Small, firm femoral hernias below and lateral to the pubic tubercle are managed with prompt repair because the unyielding femoral ring carries a high strangulation risk. ^[1]
• Strangulation, an irreducible hernia with obstruction, or signs of peritonitis or sepsis requires emergency surgery rather than taxis. ^[1]
• Surgery is the only cure, and mesh repair is the recommended first choice, whether performed open or laparo-endoscopically, depending on expertise and resources. ^{[1] [2]}
• Laparo-endoscopic repair (TEP or TAPP) offers faster recovery and lower chronic pain risk where expertise exists, requiring roughly 100 supervised cases to match open-mesh outcomes. ^[1]
• Watchful waiting is appropriate for asymptomatic or minimally symptomatic men, although about 70% eventually undergo surgery within roughly five years. ^[1]
• Women with groin hernias and those with femoral hernias are generally better served by laparo-endoscopic repair to avoid a missed femoral defect and reduce chronic pain. ^[1]
• Children undergo prompt elective repair after diagnosis because incarceration risk is greater in infants and in girls. ^[3]
• Chronic postoperative inguinal pain occurs in 10 to 12% overall, with severe pain in 1 to 3%, making nerve recognition and shared decision making important. ^[1]

Groin and hernia emergency surgery; gastro-oesophageal reflux disease (hiatal hernia); abdominal-wall reconstruction; chronic pain after groin surgery; inguinal hernia in children.