General Surgery
Final Professional MBBS — General Surgery. Explanation-first answers that teach the reasoning behind every fact, with classifications, comparison tables, drug doses, clinical pearls and key-point recaps from Bailey & Love and SRB's Manual.
THE CONCEPT
An inguinal hernia is a protrusion of abdominal contents through the inguinal canal, and it is by far the commonest hernia. The whole topic rests on the anatomy of the canal and on distinguishing the two types — indirect (which passes through the deep ring along the canal) and direct (which pushes forward through the weak posterior wall). Getting this distinction clear makes the clinical examination and the surgery logical.
ANATOMY OF THE INGUINAL CANAL
The inguinal canal is an oblique passage about 4 cm long lying just above the inguinal ligament, running from the deep (internal) ring — a defect in the transversalis fascia lateral to the inferior epigastric vessels — to the superficial (external) ring in the external oblique aponeurosis. Its anterior wall is the external oblique aponeurosis, its posterior wall the transversalis fascia and conjoint tendon, its roof the arching internal oblique and transversus, and its floor the inguinal ligament. It transmits the spermatic cord (or round ligament in women) and the ilioinguinal nerve.
INDIRECT VS DIRECT
Indirect Direct Route Through the deep ring, along the canal Through the posterior wall (Hesselbach's triangle) Relation to inferior epigastric vessels Lateral Medial Cause / age Congenital (patent processus vaginalis); younger Acquired (weak wall); older Into scrotum? Often Rarely Deep-ring occlusion test Controlled Not controlled Hesselbach's triangle (the site of direct hernias) is bounded by the inferior epigastric vessels laterally, the rectus sheath medially, and the inguinal ligament inferiorly.
CLINICAL FEATURES & EXAMINATION
The patient reports a groin swelling with a cough impulse and dragging discomfort, often reducible on lying down. The patient is examined standing to demonstrate the swelling, and the examiner determines its reducibility, cough impulse, whether it descends into the scrotum, and its relation to the pubic tubercle. The crucial landmark is that an inguinal hernia lies above and medial to the pubic tubercle, whereas a femoral hernia lies below and lateral.
COMPLICATIONS & MANAGEMENT
Like any hernia it may become irreducible, obstructed or strangulated. Treatment is surgical repair: herniotomy (excision and ligation of the sac — sufficient in children), and in adults a hernioplasty with tension-free mesh (Lichtenstein repair), performed open or laparoscopically (TEP or TAPP).
💡CLINICAL PEARL: Two facts anchor the topic. Indirect hernias pass lateral to the inferior epigastric vessels through the deep ring (and can reach the scrotum); direct hernias push medially through Hesselbach's triangle. And an inguinal hernia is above and medial to the pubic tubercle, distinguishing it at the bedside from a femoral hernia (below and lateral).MECHANISM OF THE CANAL — NATURE'S SAFEGUARDS
The inguinal canal has built-in protective mechanisms that normally prevent herniation, and their failure explains adult hernias. The obliquity of the canal means a rise in intra-abdominal pressure presses its anterior and posterior walls together (a 'flap-valve'); the shutter mechanism of the arching internal oblique and transversus flattens down onto the inguinal ligament on straining; and the deep ring is pulled laterally by the transversalis fascia sling. With ageing, chronic straining or muscle weakness these safeguards fail, allowing a direct hernia to push through the weakened posterior wall — which is why direct hernias are a disease of the older, straining patient.
CLINICAL EXAMINATION IN DETAIL
A thorough examination follows a set routine. The patient stands so the hernia is demonstrated, and the examiner notes the swelling, feels for an expansile cough impulse, and assesses reducibility. The relationship to the pubic tubercle separates inguinal (above and medial) from femoral (below and lateral). After reduction, the deep-ring occlusion test distinguishes indirect (controlled) from direct (not controlled), and whether the hernia descends into the scrotum is noted (favouring indirect). One must also confirm one can 'get above' a scrotal swelling to exclude a hydrocele, and examine the other side.
A NOTE ON HERNIAS IN CHILDREN
Inguinal hernia in children is almost always indirect and congenital, resulting from a patent processus vaginalis (the peritoneal tube that accompanies testicular descent and normally obliterates). Because the abdominal wall itself is sound, treatment is a simple herniotomy — excision and high ligation of the sac — without any need for wall repair or mesh. The same patent processus explains the association of congenital inguinal hernia with an undescended testis and with a hydrocele, and why repair is advised even in infancy given the risk of obstruction in a narrow infantile canal.
💊KEY POINTS / NUMBERS (viva)- Indirect = lateral to inferior epigastric vessels, through deep ring, congenital, can reach scrotum; direct = medial, through Hesselbach's triangle, acquired.
- Inguinal hernia lies above & medial to the pubic tubercle (femoral: below & lateral).
- Repair: herniotomy (child); tension-free mesh hernioplasty (Lichtenstein) or laparoscopic (TEP/TAPP) in adults.
🔑KEY POINTS TO REMEMBER- Commonest hernia; protrusion through the inguinal canal; indirect (through deep ring) vs direct (through posterior wall/Hesselbach's triangle).
- Indirect: lateral to inferior epigastric vessels, congenital, younger, can reach scrotum, controlled by deep-ring pressure.
- Direct: medial to inferior epigastric vessels, acquired, older, rarely into scrotum, not controlled by deep-ring pressure.
- Inguinal hernia is above & medial to the pubic tubercle; examine standing for cough impulse, reducibility, scrotal descent.
- Treat by surgical repair: herniotomy (child), tension-free mesh hernioplasty (Lichtenstein) or laparoscopic TEP/TAPP in adults.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT
A femoral hernia is a protrusion of abdominal contents through the femoral canal, emerging below the inguinal ligament into the upper thigh. Although less common than inguinal hernia, it is disproportionately important for two reasons captured in a single idea: it occurs through a narrow, rigid ring, so it is much more likely to strangulate, and it is commoner in women. These facts make it a hernia that should almost always be repaired promptly.
ANATOMY OF THE FEMORAL CANAL
The femoral canal is the small medial compartment of the femoral sheath, normally containing fat and a lymph node (the node of Cloquet) and allowing the femoral vein to expand. Its opening, the femoral ring, is bounded anteriorly by the inguinal ligament, posteriorly by the pectineal (Astley Cooper's) ligament, medially by the sharp, unyielding lacunar ligament, and laterally by the femoral vein. It is the rigid medial lacunar ligament that makes the neck so constricting.
WHY IT STRANGULATES
The clinical danger flows directly from this anatomy: the femoral ring is narrow and surrounded by rigid, unyielding structures, so once bowel enters, its neck is easily constricted, cutting off the blood supply. This is why a large proportion of femoral hernias present already obstructed or strangulated — a much higher rate than inguinal hernias.
CLINICAL FEATURES
A femoral hernia appears as a swelling in the groin/upper thigh that lies below and lateral to the pubic tubercle — the key contrast with an inguinal hernia (above and medial). It is often small, may be difficult to feel (especially in the obese), frequently irreducible, and has a poor cough impulse. Because it is easily overlooked, it is a classic cause of a missed strangulated hernia, and the groins must always be examined in a patient with unexplained intestinal obstruction.
MANAGEMENT
Because of the high risk of strangulation, a femoral hernia should always be repaired surgically, and promptly (a truss is not appropriate). Several approaches are used — the low (Lockwood), high (McEvedy) and trans-inguinal (Lotheissen) approaches — the principle being to reduce the contents and close the femoral canal (often narrowing the ring by suturing the inguinal ligament to the pectineal ligament, or with mesh). The McEvedy (high) approach is favoured in the emergency, strangulated case as it allows bowel resection.
💡CLINICAL PEARL: The exam essentials: a femoral hernia is below and lateral to the pubic tubercle, commoner in women, and carries a high risk of strangulation because of the narrow, rigid ring (especially the lacunar ligament medially). It should always be operated on, and the groins must be examined in any patient with intestinal obstruction to avoid missing one.DIFFERENTIAL DIAGNOSIS OF A GROIN LUMP
A femoral hernia must be distinguished from the several other causes of a lump in the groin, which is a common exam question. These include an inguinal hernia, an enlarged inguinal lymph node, a saphena varix (a dilatation of the saphenous vein that has a fluid thrill and disappears on lying down), a femoral artery aneurysm (pulsatile and expansile), a psoas abscess or bursa, a lipoma, and an ectopic or undescended testis. The position relative to the pubic tubercle, the cough impulse, reducibility and pulsatility help identify the femoral hernia among these.
EMERGENCY PRESENTATION & OPERATIVE PRINCIPLES
Because so many femoral hernias present as an emergency with strangulation, the operative principle is to gain adequate exposure to assess and, if needed, resect bowel. The McEvedy (high) approach is favoured in the strangulated case as it gives access above the inguinal ligament to deliver and inspect the bowel. In an elective repair the femoral canal is simply closed. Whatever the approach, the sac is opened with care (a Richter's-type strangulation is common in femoral hernias), viability is assessed, and the canal is obliterated to prevent recurrence.
A NOTE ON THE ANATOMY OF THE PUBIC TUBERCLE
The pubic tubercle is the single most useful landmark in groin hernias and deserves emphasis. An inguinal hernia (and the superficial ring) lies above and medial to it, whereas a femoral hernia (and the femoral canal) lies below and lateral. Reliably locating the pubic tubercle — by tracing the tendon of adductor longus up to its origin, or following the spermatic cord — therefore allows the two to be distinguished at the bedside, which matters because the femoral hernia's far higher strangulation risk makes it the more urgent diagnosis.
💊KEY POINTS / NUMBERS (viva)- Femoral hernia: below & lateral to the pubic tubercle; commoner in women.
- High strangulation risk (narrow, rigid ring — lacunar ligament medially) → always operate promptly.
- Femoral ring boundaries: inguinal ligament (ant), pectineal ligament (post), lacunar ligament (medial), femoral vein (lateral); Cloquet's node.
🔑KEY POINTS TO REMEMBER- Femoral hernia = protrusion through the femoral canal, below the inguinal ligament; commoner in women.
- Ring boundaries: inguinal ligament (anterior), pectineal ligament (posterior), lacunar ligament (medial, rigid), femoral vein (lateral).
- Lies below & lateral to the pubic tubercle (vs inguinal above & medial); often small, irreducible, poor cough impulse.
- High strangulation risk (narrow rigid ring) — often presents obstructed/strangulated.
- Always repair surgically and promptly (Lockwood/McEvedy/Lotheissen); examine the groin in any unexplained bowel obstruction.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT — A PROGRESSION
The complications of a hernia are best understood as a progression: a hernia moves from reducible → irreducible (incarcerated) → obstructed → strangulated. The single most important skill is recognising strangulation, because it means the blood supply of the contents is cut off — an emergency that leads to gangrene and death of the trapped bowel if not relieved.
1. IRREDUCIBILITY (INCARCERATION)
An irreducible hernia is one whose contents can no longer be returned to the abdomen, usually because of adhesions within the sac or a narrow neck. It is not, by itself, obstructed or strangulated, but it is the precondition for those more dangerous complications.
2. OBSTRUCTION
When the herniated bowel is kinked or compressed, its lumen is blocked and the patient develops intestinal obstruction — colicky pain, vomiting, distension and absolute constipation — combined with a tense, tender, irreducible hernia that has lost its cough impulse. At this stage the blood supply may still be intact, but obstruction commonly precedes strangulation.
3. STRANGULATION
Strangulation means the blood supply to the contents is compromised, leading to ischaemia → gangrene → perforation and peritonitis. It is a surgical emergency. The pathophysiology is sequential: the tight neck first obstructs venous return, causing congestion and oedema, which then compromises the arterial supply, producing ischaemia. Clinically there is sudden severe pain, a tense, tender, irreducible hernia with overlying redness, an absent cough impulse, features of obstruction, and systemic toxicity (tachycardia, fever). Femoral and indirect inguinal hernias strangulate most often.
SPECIAL TYPES
- Richter's hernia — only part of the bowel circumference is trapped, so it strangulates without causing intestinal obstruction (a dangerous trap).
- Maydl's hernia — a 'W'-shaped double loop in which the strangulated segment is the connecting loop lying inside the abdomen.
- Littre's hernia — a hernia containing a Meckel's diverticulum.
MANAGEMENT
A strangulated hernia requires emergency surgery: resuscitate the patient, then explore the hernia, assess the viability of the contents, resect any non-viable bowel, and repair the defect. A cardinal rule is never to forcibly reduce a strangulated hernia, because this risks returning dead bowel into the abdomen ('reduction en masse'), causing peritonitis.
💡CLINICAL PEARL: Strangulation = ischaemia = emergency. The warning signs are a painful, tense, tender, irreducible hernia with no cough impulse, overlying redness and features of obstruction. Two traps to remember: a Richter's hernia strangulates without obstruction, and one must never forcibly reduce a strangulated hernia (reduction en masse).REDUCTION EN MASSE & OTHER PITFALLS
Two pitfalls deserve emphasis. Reduction en masse occurs when forcible reduction pushes the hernia, still trapped within its constricting neck, back into the abdomen as a whole — so the bowel remains strangulated but is now hidden inside, delaying diagnosis with disastrous consequences. This is why forcible reduction is forbidden. The second is the Richter's-type strangulation, where only part of the bowel wall is caught, so obstruction is absent and the ischaemia is silent — a reminder that a tender irreducible hernia is an emergency even without obstructive symptoms.
ASSESSING BOWEL VIABILITY
At operation, judging whether strangulated bowel is viable or must be resected is a critical skill. Viable bowel regains its pink colour and sheen, shows visible peristalsis, and has pulsation in the mesenteric arcade after the constriction is released and the segment is wrapped in warm packs for a few minutes. Bowel that remains dark, dull, flaccid and non-peristaltic, with no mesenteric pulsation, is non-viable and is resected with restoration of continuity. Erring towards resection of doubtful bowel is safer than returning dead bowel to the abdomen.
PREVENTING PROGRESSION
An understanding of the progression underlies the advice to repair symptomatic hernias electively before they complicate. A reducible hernia can be repaired safely and easily as a planned procedure, whereas an emergency operation for a strangulated hernia — on an unwell, often elderly patient, frequently requiring bowel resection — carries far greater morbidity and mortality. This is the rationale for offering repair of an uncomplicated hernia (particularly a femoral hernia) rather than waiting, and for teaching patients the warning signs that should prompt urgent attention.
💊KEY POINTS / NUMBERS (viva)- Progression: reducible → irreducible → obstructed → strangulated.
- Strangulation (emergency): sudden pain, tense/tender/irreducible, no cough impulse, overlying redness, obstruction, toxicity → emergency surgery.
- Never forcibly reduce a strangulated hernia (reduction en masse); Richter's strangulates without obstruction.
🔑KEY POINTS TO REMEMBER- Hernia complications progress: reducible → irreducible (incarcerated) → obstructed → strangulated.
- Obstruction: features of intestinal obstruction + tense, tender, irreducible hernia with no cough impulse.
- Strangulation (emergency): blood supply compromised → ischaemia/gangrene; severe pain, tender irreducible tense hernia, overlying redness, systemic toxicity.
- Special types: Richter's (partial wall — strangulates without obstruction), Maydl's (W-loop, dangerous loop intra-abdominal), Littre's (Meckel's).
- Strangulation → resuscitate + emergency surgery (assess viability, resect non-viable bowel, repair); never forcibly reduce (reduction en masse).
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT
Besides the groin hernias, several important hernias occur through the midline and acquired weaknesses of the anterior abdominal wall. They are grouped here because they share the same principles of assessment and repair, but each has a characteristic patient, site and behaviour worth knowing.
UMBILICAL HERNIA (INFANTILE)
A true umbilical hernia protrudes through the umbilical cicatrix and is common in infants, resulting from incomplete closure of the umbilical ring. Reassuringly, the great majority resolve spontaneously by the age of 2–3 years as the ring closes, so treatment is usually conservative. Surgical repair is reserved for a hernia that persists beyond about 3–4 years, is very large, or develops complications.
PARAUMBILICAL HERNIA (ADULT)
A paraumbilical hernia occurs in adults through a defect in the linea alba just above or below the umbilicus, typically in obese, multiparous, middle-aged women. Unlike the infantile type it does not resolve, often contains omentum and bowel, is frequently irreducible, and carries a real risk of strangulation — so it is repaired surgically (classically Mayo's 'vest-over-pants' repair, now usually with mesh).
EPIGASTRIC HERNIA
An epigastric hernia protrudes through the linea alba between the xiphisternum and the umbilicus. It is usually small and often contains only extraperitoneal fat, but can be surprisingly painful (from nipping of the fat). Symptomatic hernias are repaired.
INCISIONAL HERNIA
An incisional hernia protrudes through the weakened scar of a previous surgical incision. Its risk factors are highly examinable and include wound infection (the most important), obesity, poor surgical technique, raised intra-abdominal pressure, steroids, malnutrition, and emergency surgery. It presents as a swelling with a cough impulse at or near a scar, and may become very large. Repair is by mesh reinforcement, sometimes requiring component separation for large defects.
PRINCIPLES OF MANAGEMENT
For all of these the principles are the same: reduce the contents, repair the defect, and reinforce with mesh where appropriate, while addressing the underlying risk factors (weight, cough, straining) to reduce recurrence.
💡CLINICAL PEARL: Contrast the two umbilical types: the infantile umbilical hernia usually resolves spontaneously and is watched, whereas the adult paraumbilical hernia does not resolve, tends to strangulate, and needs surgery. For incisional hernia, the number-one preventable risk factor to quote is wound infection.EXOMPHALOS & GASTROSCHISIS — THE CONGENITAL CONTRAST
It is worth contrasting the ordinary umbilical hernia with the serious congenital anterior-wall defects seen at birth. Exomphalos (omphalocele) is a herniation of abdominal viscera into the base of the umbilical cord, covered by a membrane, and is associated with other anomalies. Gastroschisis is a defect lateral to the umbilicus through which uncovered bowel protrudes, with no covering membrane. Both are neonatal surgical emergencies requiring urgent protection of the viscera and staged closure — quite different from the benign, self-resolving umbilical hernia of infancy.
PREVENTING INCISIONAL HERNIA
Because incisional hernia is common and largely preventable, its prevention is emphasised. Good surgical technique — a mass closure of the abdominal wall with a suture length at least four times the wound length, using slowly absorbable or non-absorbable material — reduces the risk, as does preventing wound infection (the chief risk factor) and optimising the patient (weight loss, nutrition, diabetic control, stopping smoking, treating a chronic cough). When repair is needed for a large defect, mesh reinforcement and sometimes component separation are used, since simple suture repair has a high recurrence rate.
RARER VENTRAL HERNIAS
A few rarer ventral hernias complete the picture. A divarication of the recti is a midline bulge from stretching (not a true defect, and not needing repair). A parastomal hernia occurs alongside a stoma. A Spigelian hernia arises at the lateral rectus edge. These, together with the umbilical, paraumbilical, epigastric and incisional hernias, are all managed on the same principles — reduce, repair, reinforce with mesh where needed, and correct the raised intra-abdominal pressure driving them.
💊KEY POINTS / NUMBERS (viva)- Infantile umbilical hernia: usually resolves spontaneously by 2–3 years (repair if persists >3–4 y, large, or complicated).
- Adult paraumbilical hernia: does not resolve, strangulation risk → surgical (mesh) repair.
- Incisional hernia risk factors: wound infection (chief), obesity, poor technique, raised intra-abdominal pressure, steroids, malnutrition.
🔑KEY POINTS TO REMEMBER- Infantile umbilical hernia (through umbilical cicatrix) usually resolves spontaneously by 2–3 years; repair if persists/large/complicated.
- Adult paraumbilical hernia (obese multiparous women) does not resolve, often irreducible with strangulation risk → surgical (mesh) repair.
- Epigastric hernia: through the linea alba between xiphoid and umbilicus, often extraperitoneal fat, may be painful.
- Incisional hernia: through a previous scar; risk factors — wound infection (chief), obesity, poor technique, raised intra-abdominal pressure, steroids, malnutrition.
- Principles: reduce, repair the defect, reinforce with mesh, and treat underlying risk factors.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.DEFINITION & PARTS
A hernia is the abnormal protrusion of a viscus, or part of a viscus, through a weakness or defect in the wall of its containing cavity into an abnormal position. Every hernia has three components: the sac (a pouch of peritoneum, with a mouth, neck, body and fundus), the coverings (the layers of the wall it pushes in front of it), and the contents — most often omentum (an 'omentocele') or bowel (an 'enterocele').
AETIOLOGY — TWO INGREDIENTS
Hernias form from the combination of raised intra-abdominal pressure and a weak abdominal wall. Pressure is raised by chronic cough (COPD), chronic straining (constipation or prostatism), ascites, pregnancy, heavy lifting and obesity; the wall is weakened by congenital defects, ageing, previous incisions and collagen disorders. Recognising these factors matters because treating them is part of preventing recurrence.
CLASSIFICATION
Hernias are classified by site (inguinal, femoral, umbilical, incisional, epigastric and rarer types), by their contents, by whether they are reducible or irreducible, and as external (through the abdominal wall) or internal (through a defect within the abdominal cavity). This framework organises an otherwise long list.
PRINCIPLES OF TREATMENT
- Conservative — a truss is rarely used, only for a patient unfit for surgery, and does not cure the hernia.
- Herniotomy — excision and ligation of the sac at its neck; sufficient in children, whose wall is otherwise sound.
- Herniorrhaphy — herniotomy plus repair/reconstruction of the weakened wall.
- Hernioplasty — reinforcement of the wall with a prosthetic mesh, giving a 'tension-free' repair (Lichtenstein) with the lowest recurrence; increasingly done laparoscopically (TEP/TAPP).
THE ROLE OF MESH & TREATING THE CAUSE
Tension-free mesh repair has become standard for adult hernias because suturing tissue under tension is painful and has a higher recurrence rate, whereas mesh bridges and reinforces the defect. Equally important is correcting precipitating factors — treating a chronic cough, relieving constipation or prostatic obstruction, and encouraging weight loss and smoking cessation — otherwise the same forces that produced the hernia will cause it to recur.
💡CLINICAL PEARL: The surgical principles distil to a sequence: reduce the contents, deal with the sac (excise and ligate), repair and reinforce the defect (tension-free mesh), and treat the precipitating cause. Remember the three named operations — herniotomy (child), herniorrhaphy, and hernioplasty (mesh) — and the laparoscopic options (TEP/TAPP).COMPLICATIONS OF HERNIA SURGERY
Hernia repair, though common and safe, has recognised complications that must be included for consent. Early complications include haematoma, seroma, wound infection, and urinary retention. Specific to groin surgery are injury to the ilioinguinal or genitofemoral nerve (causing chronic groin pain or numbness), ischaemic orchitis or testicular atrophy (from damage to the cord vessels), and damage to the vas. Late complications are chronic pain, mesh infection, and recurrence. Awareness of these guides careful technique and honest pre-operative discussion.
LAPAROSCOPIC VS OPEN REPAIR
The choice between open (Lichtenstein) and laparoscopic (TEP/TAPP) repair is a practical decision. Laparoscopic repair offers less post-operative pain and a quicker return to work and is particularly favoured for bilateral or recurrent hernias, but it needs general anaesthesia and greater expertise. Open mesh repair can be done under local anaesthesia and is well suited to the frail patient or a large scrotal hernia. Both are tension-free mesh techniques with low recurrence rates, so the decision is individualised to the hernia and the patient.
FACTORS AFFECTING RECURRENCE
Recurrence is the yardstick of a hernia repair, and understanding what drives it ties the topic together. Recurrence is increased by tension in the repair (hence the move to tension-free mesh), infection, poor tissue quality, and — crucially — uncorrected precipitating factors such as a persistent cough, constipation, prostatism or obesity. This is why the modern repair combines a tension-free mesh with treatment of the underlying cause, and why patient optimisation (smoking cessation, weight loss, treating a chronic cough) is considered part of the operation rather than an afterthought.
💊KEY POINTS / NUMBERS (viva)- Hernia = abnormal protrusion of a viscus through a defect in its containing wall; parts = sac (mouth/neck/body/fundus), coverings, contents.
- Aetiology = raised intra-abdominal pressure + weak wall (treat the cause to prevent recurrence).
- Operations: herniotomy (child), herniorrhaphy, hernioplasty (tension-free mesh, Lichtenstein; laparoscopic TEP/TAPP).
🔑KEY POINTS TO REMEMBER- Hernia = abnormal protrusion of a viscus through a defect in its containing cavity's wall; parts = sac, coverings, contents (omentocele/enterocele).
- Aetiology = raised intra-abdominal pressure (cough, straining, ascites, pregnancy, obesity) + weak wall (congenital, ageing, incisions).
- Classify by site, contents, reducible vs irreducible, external vs internal.
- Treatment: truss (rarely, if unfit); herniotomy (child); herniorrhaphy; hernioplasty (tension-free mesh — Lichtenstein/laparoscopic TEP/TAPP).
- Reduce contents, excise/ligate sac, repair & reinforce with mesh, and treat precipitating factors to prevent recurrence.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT
Both direct and indirect inguinal hernias emerge in the groin, but they take different routes through the abdominal wall, and distinguishing them is a classic clinical and surgical exercise. The single defining anatomical difference is their relationship to the inferior epigastric vessels: an indirect hernia passes lateral to them (through the deep ring), while a direct hernia bulges medial to them (through the weak posterior wall).
THE COMPARISON
Feature Indirect Direct Route Through the deep ring, along the canal Through the posterior wall (Hesselbach's triangle) Inferior epigastric vessels Lateral to them Medial to them Cause / age Congenital (patent processus vaginalis); younger Acquired (wall weakness); older Descends into scrotum Often Rarely Occluding the deep ring Controls the hernia Does not control it Strangulation More likely Less likely CLINICAL DISTINCTION
After reducing the hernia, the examiner occludes the deep ring (just above the mid-inguinal point) and asks the patient to cough: an indirect hernia is controlled (does not reappear), whereas a direct hernia bulges forward medially. Both, however, lie above and medial to the pubic tubercle (distinguishing either from a femoral hernia). In practice the definitive distinction is often made at operation by seeing the relationship to the inferior epigastric vessels.
SURGICAL RELEVANCE OF THE DISTINCTION
Distinguishing the two matters at operation because it affects the repair. An indirect sac is dissected off the cord and its neck ligated at the deep ring; a direct hernia bulges through a weak posterior wall that must be reinforced. In practice, both are now repaired with a tension-free mesh (Lichtenstein or laparoscopic) that reinforces the whole posterior wall, so the distinction is less critical to the repair than it once was — but it remains a key anatomical and examination concept.
THE BOTTOM LINE
The essence is that indirect hernias are lateral to the inferior epigastric vessels (through the deep ring, often congenital and scrotal) and direct hernias are medial (through the posterior wall, acquired), both lying above and medial to the pubic tubercle.
A NOTE ON MIXED (PANTALOON) HERNIA
Occasionally both types coexist — a 'pantaloon' or saddlebag hernia — where sacs straddle either side of the inferior epigastric vessels, one medial (direct) and one lateral (indirect), draped over the vessels like a pair of trousers. This is a reminder that the two types are not mutually exclusive, and that a mesh repair reinforcing the whole posterior wall deals with both simultaneously.
🔑KEY POINTS TO REMEMBER- Indirect: lateral to inferior epigastric vessels, through the deep ring/canal, congenital, younger, can reach scrotum, controlled by deep-ring pressure, strangulates more.
- Direct: medial to inferior epigastric vessels, through Hesselbach's triangle (posterior wall), acquired, older, rarely scrotal, not controlled by deep-ring pressure, strangulates less.
- Both lie above & medial to the pubic tubercle (vs femoral, below & lateral).
- Deep-ring occlusion test controls an indirect but not a direct hernia; the definitive distinction (relation to inferior epigastric vessels) is often made at surgery.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
A strangulated hernia is one in which the blood supply to the contents of the sac is cut off, and it is the most feared complication of any hernia — a surgical emergency. Without prompt relief, the trapped bowel proceeds through ischaemia → gangrene → perforation → peritonitis, which is life-threatening.
PATHOPHYSIOLOGY
The mechanism is sequential and worth stating. The tight neck of the sac first obstructs the low-pressure venous and lymphatic return, so the contents become congested and oedematous; this swelling further tightens the neck until the arterial supply is occluded, producing ischaemia and, if unrelieved, infarction (gangrene). Femoral and indirect inguinal hernias, with their narrow necks, strangulate most readily.
CLINICAL FEATURES
The hernia becomes suddenly painful, tense, tender and irreducible, with an absent cough impulse and often redness of the overlying skin. There are usually accompanying features of intestinal obstruction (colicky pain, vomiting, distension) and, as ischaemia advances, systemic toxicity — tachycardia, fever and signs of sepsis.
MANAGEMENT
Treatment is emergency surgery: resuscitate the patient (fluids, analgesia, nasogastric tube, antibiotics), then explore the hernia, assess the viability of the contents, resect any non-viable bowel, and repair the defect. A cardinal rule is to never forcibly reduce a strangulated hernia — doing so can push dead bowel back into the abdomen ('reduction en masse'), converting a localised problem into fatal peritonitis.
💡CLINICAL PEARL: A painful, tense, tender, irreducible hernia with no cough impulse is strangulated until proven otherwise — a surgical emergency. Never attempt forcible reduction (risk of reducing gangrenous bowel), and always examine the groins in a patient presenting with intestinal obstruction, as a small femoral hernia is easily missed.EXAMINE THE GROINS IN OBSTRUCTION
A recurring clinical lesson is that a small, easily-missed hernia — especially a femoral hernia in an obese elderly patient — is a classic cause of unexplained intestinal obstruction. Therefore the groins and hernial orifices must always be examined in any patient presenting with intestinal obstruction. Overlooking a strangulated femoral hernia hidden in the groin folds is a well-recognised and avoidable error.
THE BOTTOM LINE
A strangulated hernia is a surgical emergency of compromised blood supply — painful, tense, tender, irreducible, no cough impulse — treated by resuscitation and emergency surgery, and never by forcible reduction.
A NOTE ON TAXIS
The only situation in which gentle reduction ('taxis') may be attempted is an obstructed but not yet strangulated hernia of recent onset, performed gently and once only; forceful or repeated attempts are dangerous and any suspicion of strangulation (tenderness, redness, toxicity, or a long history) is an absolute contraindication. When in doubt, the safe course is surgical exploration rather than attempted reduction.
🔑KEY POINTS TO REMEMBER- Strangulated hernia = blood supply to contents cut off → ischaemia → gangrene → perforation/peritonitis (emergency).
- Mechanism: tight neck obstructs venous return → oedema → arterial occlusion → infarction; femoral & indirect inguinal strangulate most.
- Sudden painful, tense, tender, irreducible hernia, no cough impulse, overlying redness, features of obstruction + toxicity.
- Emergency surgery: resuscitate → explore, assess viability, resect non-viable bowel, repair.
- Never forcibly reduce (reduction en masse); examine groins in any bowel obstruction.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
A Richter's hernia is a special and dangerous type in which only part of the circumference of the bowel wall — the antimesenteric border — becomes trapped and strangulated in the sac, while the rest of the bowel lumen remains in continuity. The defining and treacherous feature follows directly: because the full lumen is not occluded, the bowel strangulates without causing intestinal obstruction.
WHY IT IS DANGEROUS
This absence of obstruction is exactly what makes Richter's hernia perilous. The usual warning symptoms of a strangulated hernia — colicky pain, vomiting and distension from obstruction — are missing, so the diagnosis is easily delayed while the trapped portion of bowel wall silently becomes gangrenous and perforates. It occurs most often in hernias with a small, tight neck, classically the femoral hernia.
MANAGEMENT
A Richter's hernia requires surgical exploration: the strangulated portion of the bowel wall is assessed for viability and, if non-viable, the affected segment is resected (or the involved wall repaired) and the hernia repaired. Awareness of the entity is the key clinical lesson — a localised, tender, irreducible groin lump (especially femoral) may be a strangulating Richter's hernia even without any features of bowel obstruction.
A NOTE ON THE FEMORAL LINK
The strong association of Richter's hernia with the femoral hernia is not coincidental: the femoral ring's narrow, rigid neck is exactly the kind of small defect that can catch just a portion of the bowel wall while allowing the rest of the lumen to remain patent. This is why a tender, irreducible femoral lump — even in a patient who is passing stool and flatus normally — must be treated as a surgical emergency and not reassured on the basis of absent obstruction.
THE BOTTOM LINE
Richter's hernia is partial-circumference strangulation that occurs without obstruction — a dangerous, easily-missed trap, classically femoral, needing exploration.
RELATION TO OTHER PARTIAL-WALL PROBLEMS
Richter's hernia illustrates a wider surgical principle — that a portion of bowel wall can be ischaemic without the lumen being obstructed — which also applies to a partially trapped bowel loop elsewhere. The practical consequence is the same: never rely on the presence of obstruction to decide whether a tender, irreducible hernia is an emergency, because partial-wall strangulation can be silent until perforation occurs.
🔑KEY POINTS TO REMEMBER- Richter's hernia = only part of the bowel circumference (antimesenteric border) is trapped/strangulated; the lumen stays patent.
- Strangulates WITHOUT intestinal obstruction — the dangerous, easily-missed trap.
- Commonest in narrow-necked hernias, classically the femoral hernia.
- Delayed diagnosis → gangrene/perforation; treat by surgical exploration, resection of non-viable bowel, and repair.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT — TWO NAMED HERNIAS
Maydl's and Littre's hernias are two eponymous hernias defined by their unusual contents, and both are favourite viva topics because of the traps they set.
MAYDL'S HERNIA (HERNIA-IN-W)
A Maydl's hernia is a 'W'-shaped double-loop hernia: two loops of bowel lie within the sac, connected by a central loop that lies back inside the abdominal cavity. The danger is that the strangulation affects this connecting central loop — which is inside the abdomen, not in the visible sac. So the loops in the sac may look healthy while the intra-abdominal loop is gangrenous ('retrograde strangulation'). The lesson is that at operation for a strangulated hernia, the bowel inside the abdomen must also be inspected, not just the contents of the sac.
LITTRE'S HERNIA
A Littre's hernia is a hernia whose sac contains a Meckel's diverticulum. Because a Meckel's diverticulum can become inflamed or strangulated within the hernia, it may present with local features of strangulation, and, as with a Richter's hernia, may not cause complete intestinal obstruction. It is managed by surgical exploration with resection of the diverticulum and repair of the hernia.
THE TEACHING POINT OF EACH
Each hernia carries a distinct teaching point. Maydl's warns that the sac contents can look healthy while the real damage is in a loop hidden inside the abdomen, so the intra-abdominal bowel must always be checked at operation for a strangulated hernia. Littre's warns that a hernia can contain a Meckel's diverticulum which may strangulate or inflame without full obstruction. Both reinforce the general rule that a tender irreducible hernia demands exploration regardless of whether obstruction is present.
THE BOTTOM LINE
Maydl's (W-loop with the strangulated loop inside the abdomen) and Littre's (Meckel's-containing) hernias both teach that a tender irreducible hernia needs exploration and inspection of all the bowel, sac and intra-abdominal.
A NOTE ON RETROGRADE STRANGULATION
The term retrograde (or 'W') strangulation used for Maydl's hernia captures the paradox neatly: the loops you can see and feel in the sac may be perfectly healthy, while the connecting loop that has slipped back into the abdomen is the one being strangled. The operative discipline it teaches — to deliver and inspect the intervening intra-abdominal bowel — is the whole point of the eponym.
🔑KEY POINTS TO REMEMBER- Maydl's hernia = 'W'-loop: two loops in the sac with a connecting central loop inside the abdomen; the intra-abdominal loop strangulates ('retrograde strangulation').
- Lesson: inspect the intra-abdominal bowel too — the sac contents may look viable while the hidden loop is gangrenous.
- Littre's hernia = a hernia sac containing a Meckel's diverticulum (may strangulate without complete obstruction).
- Both managed by surgical exploration, resection of non-viable bowel/diverticulum, and repair.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
A Spigelian hernia is an uncommon hernia that protrudes through the Spigelian fascia — the aponeurotic layer at the lateral border of the rectus abdominis (the linea semilunaris) — most often just below the level of the umbilicus, near the arcuate line, where the posterior rectus sheath is deficient and the wall is weakest. Its importance lies less in its frequency than in how easily it is missed.
WHY IT IS DIFFICULT TO DIAGNOSE
A Spigelian hernia is characteristically interparietal — the sac lies between the muscle layers of the abdominal wall rather than emerging subcutaneously — so it often produces no obvious visible bulge, only vague localised pain or a poorly defined swelling. This concealed position, combined with a narrow neck, gives it a significant risk of strangulation, so it should not be dismissed.
DIAGNOSIS & MANAGEMENT
Because it is hard to feel, imaging (ultrasound or CT) is often needed to confirm the diagnosis and localise the defect. Treatment is surgical repair (open or laparoscopic, usually with mesh), which is generally recommended because of the strangulation risk of the narrow-necked defect.
A HIGH INDEX OF SUSPICION
The practical message is a high index of suspicion: a patient with localised abdominal-wall pain or a vague swelling at the lateral edge of the rectus, without an obvious visible hernia, may have a Spigelian hernia, and imaging should be requested rather than the symptom dismissed. Because the narrow neck risks strangulation, a confirmed Spigelian hernia is repaired rather than observed — the diagnosis, once considered, is readily confirmed on ultrasound or CT.
THE BOTTOM LINE
A Spigelian hernia is a concealed interparietal hernia at the linea semilunaris that is easily missed, needs imaging to diagnose, and is repaired because of its strangulation risk.
CONTRAST WITH DIVARICATION
A Spigelian hernia should be distinguished from the more benign causes of a lateral abdominal bulge, and imaging is what settles it — an ultrasound or CT demonstrates a genuine fascial defect with a sac, confirming a true hernia that warrants repair, rather than simple muscular bulging or a lipoma. This confirmation is important because the concealed Spigelian hernia is one that is repaired on diagnosis to pre-empt strangulation.
🔑KEY POINTS TO REMEMBER- Spigelian hernia = protrusion through the Spigelian fascia at the lateral edge of the rectus (linea semilunaris), usually below the umbilicus near the arcuate line.
- Interparietal (lies between muscle layers) → often no visible bulge, only vague pain → easily missed.
- Narrow neck → significant strangulation risk.
- Often needs ultrasound/CT to diagnose; treat by surgical (usually mesh) repair.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
An obturator hernia is a rare hernia in which abdominal contents protrude through the obturator canal (the opening in the obturator foramen of the pelvis, transmitting the obturator nerve and vessels). It has a very characteristic epidemiology: it occurs almost exclusively in elderly, thin, emaciated women ('the little old lady's hernia'), in whom loss of the protective extraperitoneal fat allows the bowel to enter the canal.
CLINICAL FEATURES — THE HOWSHIP-ROMBERG SIGN
Because the hernia is deep within the pelvis and thigh, it produces no visible external swelling, and typically presents as unexplained intestinal obstruction in an elderly woman. The classic clue is the Howship-Romberg sign — pain referred along the inner aspect of the thigh to the knee, caused by pressure of the hernia on the obturator nerve, often worsened by extension, abduction or internal rotation of the hip.
DIAGNOSIS, MANAGEMENT & PROGNOSIS
The lack of an external lump means the diagnosis is often made late — on CT or at laparotomy for obstruction. Treatment is surgical reduction and repair of the defect, with resection of any non-viable bowel. Because of the delayed diagnosis and the frail, elderly patients affected, the mortality is relatively high — which is why the Howship-Romberg sign is emphasised as an early clue.
WHY MORTALITY IS HIGH
The relatively high mortality of obturator hernia results from a combination of factors: the frail, elderly, comorbid patients affected, the absence of an external sign leading to delayed diagnosis, and the frequent presence of strangulated bowel by the time of surgery. This is precisely why the Howship-Romberg sign is stressed — recognising inner-thigh pain as a clue to an obturator hernia in an elderly woman with obstruction can bring the diagnosis forward and save a life.
THE BOTTOM LINE
An obturator hernia is a rare hernia of thin elderly women presenting as obstruction with the Howship-Romberg sign, diagnosed late and carrying a high mortality, treated surgically.
A NOTE ON BILATERALITY & RECURRENCE
Obturator hernias may be bilateral, and because the affected patients are frail with weak pelvic tissues, the defect can be difficult to close durably. At operation the obstruction is relieved, non-viable bowel resected, and the canal repaired (with mesh where feasible). The combination of late presentation, frail patients and technically awkward repair is what keeps its mortality among the highest of the abdominal hernias.
🔑KEY POINTS TO REMEMBER- Obturator hernia = protrusion through the obturator canal; rare; classically elderly, thin, emaciated women.
- No external swelling → presents as unexplained intestinal obstruction.
- Howship-Romberg sign: pain along the inner thigh to the knee (obturator nerve compression) — the key clue.
- Often diagnosed late (CT/laparotomy); treat by surgical reduction and repair (± bowel resection); relatively high mortality.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
A sliding hernia (hernia-en-glissade) is a hernia in which a retroperitoneal organ forms part of the wall of the sac itself, rather than lying free within it as a content. As the organ is only partly covered by peritoneum, it 'slides' down behind the peritoneum along with the hernia, so one side of the sac is made up of the viscus. This is a structural definition, not a description of behaviour, and it matters chiefly at operation.
WHICH ORGANS SLIDE
The organ involved depends on the side: on the right it is typically the caecum, on the left the sigmoid colon, and in either the urinary bladder may form part of a medial (direct) sac. These are all partly retroperitoneal structures, which is why they can slide.
SURGICAL SIGNIFICANCE
The importance of recognising a sliding hernia is surgical safety: because part of the 'sac' is actually bowel or bladder, careless attempts to open or ligate the sac in the usual way risk injuring these viscera (opening the bowel or bladder). The surgeon must therefore be aware of the possibility, identify the sliding organ, avoid injuring it, and repair the hernia without resecting the viscus that forms the sac wall.
A NOTE ON PARTIAL PERITONEAL COVERING
The key to understanding sliding hernias is remembering that the involved organs (caecum, sigmoid, bladder) are only partly covered by peritoneum — their bare, retroperitoneal surface is dragged down to form the posterior wall of the sac. This is why the sac cannot simply be fully opened and ligated as usual: doing so on the organ's side would enter the bowel or bladder. Recognition and careful handling, not resection of the sliding viscus, are the essence of safe repair.
THE BOTTOM LINE
A sliding hernia has a retroperitoneal viscus (caecum, sigmoid or bladder) forming part of its sac wall, so its significance is the surgical risk of injuring that organ during repair.
A NOTE ON BLADDER INJURY
A particular hazard of the sliding hernia is injury to the urinary bladder, which may form the medial wall of a direct inguinal sac; an unexpected gush of urine or a thick, muscular 'sac' wall during dissection should alert the surgeon. Recognising the sliding component and staying on the correct plane avoids opening the bladder or bowel — the single most important safety point in these repairs.
🔑KEY POINTS TO REMEMBER- Sliding hernia (hernia-en-glissade) = a retroperitoneal organ forms part of the wall of the sac (not merely a content).
- Right side: caecum; left side: sigmoid colon; either: urinary bladder (medial/direct sac).
- Significance is surgical: part of the 'sac' is bowel/bladder → risk of injuring these viscera during sac dissection/ligation.
- Recognise it, protect the sliding organ, and repair without resecting the viscus forming the sac wall.
📚SOURCES: Bailey & Love's Short Practice of Surgery.