Spigelian hernia

AKA lateral ventral hernia

Herniation through the Spigelian fascia, which lies between the rectus muscle medially and semilunar line laterally, at the level of the arcuate line

Anatomy/pathophysiology

• Protrusion of intra-abdominal contents through a congenital or acquired defect in the Spigelian aponeurosis
  • Most commonly occurs just below the arcuate line (which is found just above the level of the ASIS)
  • Two subtypes:
    • Interstitial/interparietal - does not protrude past the external oblique
    • Subcutaneous - protrudes through external oblique into subcutaneous tissue
  • Typically 1-2cm in size
• Linea semilunaris - a curved line on the lateral side of rectus abdominis, extending between 9th costal cartilage to the pubic tubercle
  • First described by Adrian van der Spieghel
• Spigelian aponeurosis - aponeurosis of transversus abdominis - limited laterally by linea semilunaris and medially by rectus abdominis
• Spigelian fascia is a combination of TA and IO aponeuroses

Presentation

• Typically middle aged, slightly more common in females
• The usual hernia risk factors, also multiple pregnancies
• Hernia only palpable in a third of them
• Differential - haemangioma, tumour
• CT/USS will often be required
• Incarceration and strangulation will be present at diagnosis in one third

Management

• No universal consensus on treatment, but most would say repair should be done once diagnosed because of risk of strangulation
• Procedure choice:
  • Open anterior repair best in emergency cases - direct muscle re-approximation +/- mesh
  • Laparoscopic IPOM is superior in elective cases, especially in interstitial hernias - don't need to breach external oblique. Also good for large cases.
  • TEP is good for easily reducible hernias <3cm in diameter and positioned inferior to umbilicus

Technique

• Open anterior
  • Transverse skin incision over protrusion
  • Dissect down to EO
    • Usually need to open EO to see the hernia, and will see the sac or pre-peritoneal fat in the inter-parietal plane
    • If EO is exposed and it's unclear where the hernia is, palpate for the defect, then incise EO and bluntly open the plane between EO and IO to find the hernia
    • If EO is fibrotic from previous repair, open it in a separate area and then dissect towards the defect from normal to abnormal
  • Dissect sac down to hernia neck
  • To place mesh between EO and IO:
    • Separate external oblique from internal oblique for a 3cm circumference
    • Close internal oblique defect with running absorbable
    • Synthetic mesh between internal and external obliques (suture to rectus medially with nonabsorbable sutures)
  • To place pre-peritoneal mesh:
    • Just treat it like a standard sub-lay Ventralex repair, creating a pre-peritoneal pocket
  • Close external oblique
• TAPP/IPOM
• TEP
  • Dissecting balloon superficial to posterior rectus sheath
  • Keep inferior epigastrics anterior to balloon to avoid tearing
  • Insufflate 12mmHg
  • 5mm trocars placed in midline between umbilicus and pubic symphysis
  • Reduce sac, approximate edges, place mesh
• Open intra-peritoneal