Surgery chapters
Abdominal wall, hernias and umbilicus
Anatomy of the inguinal and femoral canals, the types of abdominal wall hernia and their complications, how each is repaired, and the common umbilical conditions seen in surgery.
- An indirect inguinal hernia leaves through the deep ring lateral to the inferior epigastric vessels; a direct hernia bulges through Hesselbach's triangle medial to them.
- Femoral hernia lies below and lateral to the pubic tubercle, is commoner in elderly women and has the highest strangulation risk; it should always be repaired.
- Infant umbilical hernias mostly close on their own (repair if still present after 2 years); adult paraumbilical hernias have a narrow neck and are repaired.
On this page
Overview
A hernia is the protrusion of a viscus or part of a viscus through an abnormal opening in the wall of the cavity that contains it. Abdominal wall hernias are among the commonest operations a general surgeon performs; in adults about 80% of hernia repairs are for inguinal hernia.
The exam tests three things: anatomy (inguinal and femoral canals, Hesselbach's triangle), behaviour (which hernias strangulate) and management (when and how to repair). The umbilicus adds a short list of classic signs.
Basic terms
| Term | Meaning |
|---|---|
| Reducible | Contents go back into the abdomen on lying down or with gentle pressure |
| Irreducible (incarcerated) | Contents cannot be returned; risk of complications |
| Obstructed | Bowel in the sac is blocked, but its blood supply is intact |
| Strangulated | Blood supply cut off; painful, tender, no cough impulse; needs urgent surgery |
| Infarcted | Contents have become gangrenous; high mortality |
Sequence of strangulation: a tight neck first blocks venous return, the contents swell and become oedematous, rising pressure then stops arterial inflow, and the bowel becomes ischaemic, gangrenous and finally perforates.
The hernias with a narrow, rigid neck strangulate most: femoral, paraumbilical and obturator. Broad-necked direct inguinal hernias rarely do.
Anatomy of the inguinal canal
The canal is about 4 cm long and runs downwards and medially from the deep to the superficial ring.
| Wall | Formed by |
|---|---|
| Anterior | External oblique aponeurosis (plus internal oblique laterally) |
| Posterior | Transversalis fascia, with the conjoint tendon medially |
| Roof | Arching fibres of internal oblique and transversus abdominis (conjoint tendon) |
| Floor | Inguinal ligament (rolled-in lower edge of external oblique); lacunar ligament medially |
- Deep ring: a gap in the transversalis fascia at the midpoint of the inguinal ligament (halfway from the ASIS to the pubic tubercle), about 2-3 cm above the femoral pulse. It has the inferior epigastric vessels on its medial side.
- Superficial ring: a V-shaped gap in the external oblique aponeurosis, above and medial to the pubic tubercle.
- Contents: spermatic cord in men (vas, testicular artery, pampiniform veins, lymphatics) or round ligament in women, plus the ilioinguinal nerve and the genitofemoral nerve's genital branch. The iliohypogastric nerve runs close by.
Hesselbach's (inguinal) triangle, seen from inside: inferior epigastric vessels laterally, lateral border of rectus abdominis medially, inguinal ligament below. Here the wall is only transversalis fascia under the external oblique, so it is weak.
Inguinal hernia
Indirect vs direct
| Feature | Indirect (oblique, lateral) | Direct (medial) |
|---|---|---|
| Origin | Congenital: patent processus vaginalis | Acquired: weak posterior wall |
| Exit point | Deep ring, lateral to inferior epigastric vessels | Hesselbach's triangle, medial to the vessels |
| Age | Any age; all hernias in children | Older men |
| Descent into scrotum | Common | Rare |
| Deep ring occlusion test | Controlled (does not appear on coughing) | Not controlled; bulges medially |
| Shape and neck | Narrow neck, oblique | Broad, round, wide neck |
| Strangulation | Can strangulate | Rare |
| Relation to cord | Sac lies within the cord coverings | Sac lies behind the cord |
- Sliding hernia: part of the sac wall is formed by a viscus (sigmoid colon on the left, caecum on the right, or bladder). Take care not to open the bowel when opening the sac.
- Pantaloon hernia: direct and indirect sacs on both sides of the inferior epigastric vessels, straddling them like trouser legs.
The indirect inguinal hernia is the commonest hernia in both men and women. Femoral hernia is commoner in women than in men, but it is still less common than inguinal hernia in women.
The only certain way to classify an inguinal hernia is at operation, by its relation to the inferior epigastric vessels. Clinical tests are often wrong.
Clinical examination
- Examine standing. An inguinal hernia appears above and medial to the pubic tubercle; a femoral hernia below and lateral.
- A groin swelling with a cough impulse that you cannot get above extends into the scrotum (hernia), unlike a hydrocele.
- Deep ring occlusion test: reduce the hernia, press over the deep ring, ask the patient to cough. If held back, it is indirect.
- About 10% of patients present with bilateral hernias, and more have an occult hernia on the other side.
Investigations
Diagnosis is clinical. Ultrasound helps with an uncertain groin lump or occult hernia; MRI or CT for difficult cases.
Management
- Repair most symptomatic hernias in fit patients. A small, symptomless direct hernia in an older man may be watched.
- Correct contributing factors first: chronic cough, constipation and prostatic obstruction (treat BPH before or with the hernia).
- Children: herniotomy (excise the sac only) without delay, because of the risk of incarceration.
| Repair | Key points |
|---|---|
| Lichtenstein | Open, tension-less mesh onlay over the posterior wall; commonest elective adult repair; local anaesthesia possible |
| Shouldice | Open, multilayer tissue (sutured) repair of the transversalis fascia; very low recurrence in expert hands |
| Bassini | Older sutured repair of conjoint tendon to inguinal ligament; largely replaced |
| TEP | Laparoscopic, totally extraperitoneal: mesh placed without entering the peritoneum |
| TAPP | Laparoscopic, transabdominal preperitoneal: enters the peritoneal cavity, opens a peritoneal flap |
Laparoscopic repair suits bilateral and recurrent hernias (recurrence after open repair: go through a fresh plane).
Complications: haematoma, wound infection, urinary retention, recurrence, chronic groin pain from nerve entrapment (ilioinguinal, iliohypogastric, genitofemoral), testicular atrophy from damage to testicular vessels (ischaemic orchitis), and injury to the vas.
Numbness of the scrotum or labium and the upper medial thigh after open repair points to the ilioinguinal nerve. Loss of the cremasteric reflex points to the genital branch of the genitofemoral nerve.
Femoral hernia
Femoral canal (the medial compartment of the femoral sheath) normally holds fat, lymphatics and the lymph node of Cloquet.
| Boundary of the femoral ring | Structure |
|---|---|
| Anterior | Inguinal ligament |
| Posterior | Pectineal (Cooper's) ligament on the pubic bone |
| Medial | Lacunar (Gimbernat's) ligament: sharp, unyielding edge |
| Lateral | Femoral vein |
- Commoner in women (wider pelvis), especially thin, elderly women. Also seen after inguinal repair.
- Lies below and lateral to the pubic tubercle. A large sac can turn upwards over the inguinal ligament and be mistaken for an inguinal hernia.
- Often small, irreducible and with no cough impulse; easily missed, especially in an obese patient with bowel obstruction.
- Around half present as an emergency. The tight ring makes it the hernia most likely to strangulate, often as a Richter type.
- Differential diagnosis: inguinal hernia, enlarged lymph node, saphena varix (soft, bluish, disappears on lying, has a cough thrill), femoral artery aneurysm, psoas abscess, lipoma.
Repair: every femoral hernia should be repaired. Approaches: low (Lockwood, crural) for elective cases, high (Lotheissen, inguinal) through the posterior wall of the inguinal canal, or McEvedy (high extraperitoneal), preferred in emergencies because bowel can be resected. TEP and TAPP are also used. If the ring must be widened, cut the lacunar ligament medially and watch for an abnormal obturator artery running near it.
Look carefully for a femoral hernia in any elderly woman with small bowel obstruction; examine below the inguinal ligament.
Ventral hernias and the umbilicus in children and adults
| Hernia | Key facts |
|---|---|
| Infant umbilical | Defect in the umbilical scar; conical bulge increasing with crying; up to 10% of infants, commoner in premature and black infants and in congenital hypothyroidism; rarely strangulates; 95% close spontaneously; repair if still present after 2 years |
| Paraumbilical (adult) | Defect in the linea alba next to (usually above) the umbilicus; obese, multiparous women, cirrhosis with ascites; umbilicus pushed into a crescent shape; narrow neck so obstruction and strangulation are common; repair (Mayo "vest over pants" or mesh) |
| Epigastric | Small defect in the linea alba between xiphoid and umbilicus; usually contains only extraperitoneal fat (no sac); tender pea-sized lump; may cause pain out of proportion; may coexist with other upper GI disease |
| Divarication of recti | Separation of the recti along the linea alba after pregnancy or in obesity; a midline ridge on raising the head; no fascial defect, no strangulation; reassurance or abdominoplasty |
| Incisional | Through a previous scar; after 10-50% of laparotomies and 1-5% of port sites; risk factors: wound infection (main), obesity, poor closure, steroids, malnutrition, cough; wide neck usually, so obstruction more than strangulation |
| Parastomal | Around a stoma; very common (up to half of patients) |
Preventing incisional hernia
- Close the midline with a continuous, slowly absorbable or non-absorbable suture, taking small bites close together.
- Jenkins' rule: suture length should be at least 4 times the wound length.
- Bring drains out through separate stab incisions, not through the wound.
Wound length 20 cm
Minimum suture length = 4 × 20 = 80 cm
A closure using only 50 cm (ratio 2.5:1) means bites are too far apart or pulled too tight.
Burst abdomen (fascial dehiscence) usually appears around the end of the first postoperative week, often heralded by a serosanguinous (pink) discharge from the wound. Cover the bowel with warm, moist sterile packs, give analgesia and return to theatre for closure.
Rare hernias
| Hernia | Site and clue |
|---|---|
| Spigelian | Through the spigelian fascia at the lateral edge of rectus, usually at the level of the arcuate line; lies deep to external oblique, so lump is hard to feel; ultrasound or CT |
| Lumbar | Inferior triangle of Petit (iliac crest, latissimus dorsi, external oblique) or superior triangle of Grynfeltt |
| Obturator | Through the obturator canal; thin elderly women (about 6 times commoner); small bowel obstruction plus pain down the medial thigh to the knee (obturator nerve, Howship-Romberg sign); often Richter type; felt on vaginal or rectal examination; CT diagnosis |
| Gluteal and sciatic | Through the greater or lesser sciatic foramen; very rare |
Named hernia contents
| Name | What is trapped |
|---|---|
| Richter | Only part of the circumference (antimesenteric wall) of the bowel; can strangulate and perforate without bowel obstruction; common in femoral and obturator hernias |
| Littre | A Meckel's diverticulum in the sac |
| Maydl (W hernia) | Two loops in the sac; the middle loop inside the abdomen strangulates; check it at surgery |
| Amyand | Appendix in an inguinal sac |
| De Garengeot | Appendix in a femoral sac |
Reduction en masse: forcing back a strangulated hernia can push the whole sac, still gripping the bowel, back into the abdomen. The lump disappears but pain and obstruction continue. Treat as strangulation.
Strangulated hernia: management
- Resuscitate: IV fluids, nasogastric tube, urinary catheter, analgesia, antibiotics.
- Operate urgently. Open the sac first at its fundus (away from the neck) to inspect the contents and release toxic fluid before dividing the constricting neck.
- Assess bowel viability after warm packs: colour, sheen, peristalsis, mesenteric pulsation. Resect non-viable bowel.
The umbilicus
| Condition | Clue |
|---|---|
| Umbilical granuloma (infant) | Moist, pink, raspberry-like tissue after cord separation; treat with silver nitrate |
| Umbilical adenoma (polyp) | Raspberry-like lesion of retained intestinal mucosa from the vitellointestinal duct; excision |
| Patent vitellointestinal duct | Faecal or mucous discharge from the umbilicus; remnant may form a band causing obstruction |
| Patent urachus | Urine from the umbilicus; in adults look for bladder outlet obstruction |
| Omphalitis | Infection of the umbilical stump; risk of portal vein thrombosis |
| Chronic infection, pilonidal sinus | Poor hygiene, obesity, deep umbilicus |
| Sister Mary Joseph nodule | Hard nodule = metastasis, usually from stomach, colon, ovary or pancreas, spreading along the falciform ligament or lymphatics; very advanced disease |
| Caput medusae | Dilated veins radiating from the umbilicus in portal hypertension (paraumbilical veins) |
Femoral hernia = 3 Fs: Female, Fixed (irreducible) and Fatal if missed (strangulates).
MDs don't LIe: Medial to the inferior epigastric vessels = Direct; Lateral = Indirect.
Abdominal wall conditions
- Rectus sheath haematoma: sudden painful mass after coughing or straining, especially on anticoagulants; rupture of the inferior epigastric vessels; does not cross the midline; CT confirms; usually conservative (reverse anticoagulation).
- Desmoid tumour: locally aggressive fibrous tumour of the rectus, commoner in women, often after pregnancy, linked to familial adenomatous polyposis; does not metastasise but recurs; wide excision.
- Necrotising infections (Meleney's synergistic gangrene) of the abdominal wall need radical debridement.
Expect: walls of the inguinal canal and the position of the deep ring; Hesselbach's triangle; telling direct from indirect by the inferior epigastric vessels; commonest hernia in women (indirect inguinal); femoral canal boundaries, saphena varix and the high strangulation risk of femoral hernia; Richter, Littre, Maydl and sliding hernia definitions; obturator hernia with medial thigh pain; infant umbilical hernia resolving by 2 years; paraumbilical crescent sign; Jenkins' 4:1 rule; nerve injury after hernia repair; and umbilical discharges (urine, faeces, Sister Mary Joseph nodule).
Quick revision
- Indirect = deep ring, lateral to inferior epigastric vessels, congenital, commonest in both sexes.
- Direct = Hesselbach's triangle, medial, acquired, broad neck, rarely strangulates.
- Femoral = below and lateral to pubic tubercle, women, strangulates, always repair; lacunar ligament medial.
- Richter = part of wall trapped, no obstruction; Littre = Meckel's; Maydl = W loop.
- Obturator = elderly thin woman, obstruction plus knee pain.
- Infant umbilical hernia: wait until 2 years. Adult paraumbilical: repair.
- Incisional hernia: wound infection is the main cause; prevent with 4:1 small-bite closure.
- Umbilical urine = urachus; faeces = vitellointestinal duct; hard nodule = metastasis.
Written by The House Job from standard references (Bailey & Love).
FAQ
Which hernia is commonest in women?
The indirect inguinal hernia. Femoral hernia is relatively commoner in women than in men, but inguinal hernias still outnumber it.
Why does a femoral hernia strangulate so often?
Its neck is a small, rigid ring bounded medially by the sharp lacunar ligament, so swollen contents quickly lose their blood supply.
What is a Richter hernia?
A hernia in which only part of the bowel wall is trapped, so it may become gangrenous without causing intestinal obstruction.
When should a baby's umbilical hernia be repaired?
Most close by themselves; operate if it persists beyond about 2 years of age or causes symptoms.
What is the commonest cause of an incisional hernia?
Wound infection after laparotomy, helped by obesity, poor closure technique, steroids and raised abdominal pressure.