see also:

• groin herniae
• hernia_hiatus

• abdominal herniae excluding groin or inguinal herniae:
  • ventral
    • incisional hernia
      • develop in 10-15% of sites of surgical incision in the abdominal wall as a result of failure of the fascial layers to close post-operatively
      • risk factors include obesity, slow wound healing (eg. smoking, corticosteroids, malnutrition, wound infection, etc), excessive wound tension, connective tissue (CT) disorders, midline incisions, compromised sutures or poor surgical technique
    • umbilical hernia
      • childhood herniae:
        • results from failure of the neonatal umbilical scar to heal fully
        • incidence 10-30% of children
        • do not usually cause problems
        • many close by 12-18 months of age
        • repair is rarely recommended under age 3 years
      • adult onset herniae:
        • result from increased intra-abdominal pressure such as pregnancy, ascites, obesity
        • 3x more common in women
        • adult hernia are more likely to present as incarcerated omentum or preperitoneal fat in men
    • epigastric hernia
      • defects are usually only ~1cm and although risk is low, they are prone to developing incarceration of preperitoneal fat and usually require surgical reduction and repair
    • Spigelian hernia
      • rare with only 1,000 cases reported in medical literature and account for 1% of ventral herniae.
      • may be congenital or acquired, but most present in the 4th to 7th decades
      • occurs along the semilunar line which is caudal-most extent of the posterior rectus sheath
      • present as a swelling in the mid to lower abdomen just lateral to the rectus muscle and usually 0-6cm cranially above the line connecting the two ASIS
    • diastasis recti
      • acquired condition in which the left and right rectus muscles have separated but as there is no fascial defect, there is no risk of incarceration or strangulation
• posterior herniae:
  • sciatic hernia:
    • rare hernia defined as protrusion of the peritoneal sac and its contents through the greater or lesser sciatic foramen
    • affects women more than men, can affect children
    • may entrap:
      • small bowel, resulting in gluteal mass, small bowel obstruction, and later, a gluteal abscess secondary to incarcerated and delayed diagnosis, or following intramuscular injection which inadvertently penetrates the hernial sac
      • omentum
      • ureter resulting in ureteric obstruction
      • ovary or Fallopian tube
      • colon
      • bladder
      • Meckel's diverticulum
    • the herniated sac may compress the sciatic nerve resulting in sciatica and atrophy of the gluteal muscles
    • usually requires CT scan +/- MRI scan for diagnosis
    • symptomatic sciatic hernia should be surgically treated as soon as possible, as the risk of strangulation of the bowel is high
  • lumbar herniae:
    • rare hernia occurring through the either the superior lumbar (Grynfeltt-Lesshaft) triangle, or less commonly, through the more superficial, inferior lumbar (Petit) triangle
    • 20% are congenital, rare and are often seen with other anomalies, such as undescended testes, bilateral renal agenesis, and lumbocostovertebral syndrome
    • 55% are primary acquired “spontaneous” usually due to increased intra-abdominal pressure but risk factors include:
      • age, extremes of body habitus, rapid weight loss, chronic disease, muscular atrophy, chronic bronchitis, wound infection, post-op sepsis, and strenuous physical activity
    • 25% are secondary acquired resulting from surgery, hepatic abscesses, pelvic bone infections, infected retroperitoneal haematoma, trauma, etc.
    • may present as:
      • posterolateral mass
      • back pain
      • small bowel obstruction
      • urinary obstruction if contents include ureter or kidney

• see groin hernias for Mx of inguinal or femoral herniae
• determine type of hernia
• if patient is not toxic, not unwell and has no signs of peritonitis, then try to reduce it
  • is it reducible or irreducible (incarcerated)?
• is it strangulated?
• if it is incarcerated or possibly strangulated then:
  • urgent general surgical consult
  • nil orally
  • iv fluids
  • FBE, U&E
  • NG tube if bowel is likely to be involved
  • consider erect/supine AXR and erect CXR to help exclude perforated bowel
  • consider contrast abdo CT scan if there is still concern of strangulation or incarceration
  • consider iv antibiotics if peritonitis
• if there is no evidence of strangulation of bowel and it is reducible:
  • children with umbilical herniae, can generally be reassured and followed by their LMO
  • other patients can be referred to general surgery outpatients
  • ensure patients are informed as to which symptoms necessitate emergent review.
  • if examination findings are difficult to assess, consider referral to ultrasound