Spigelian Hernia

A Spigelian hernia protrudes through the Spigelian fascia along the lateral border of the rectus abdominis, adjacent to the semilunar line.

Most occur in the lower abdomen near the arcuate line.

The hernia often develops between abdominal wall muscle layers while the external oblique aponeurosis remains intact. This interparietal position explains why a clinically significant hernia may produce pain without an obvious external lump.

The defect is frequently narrow, creating a relatively high risk of incarceration.

Presentation may be a focal lateral abdominal swelling, localised pain or intermittent symptoms without a visible lump.

The swelling may be easier to identify standing or during Valsalva.

Acute incarceration can present with focal severe pain or small bowel obstruction.

Because the external oblique can conceal the sac, physical examination can be falsely reassuring.

Ultrasound: useful for a dynamic examination of a suspected superficial defect.

CT abdomen: most useful when examination is inconclusive; demonstrates a defect through the Spigelian fascia and defines the hernia contents.

Once confidently diagnosed, repair is generally preferred because the narrow fascial defect carries appreciable incarceration risk, even when symptoms are limited.

Open and minimally invasive repairs are effective.

Laparoscopic TAPP, TEP or intraperitoneal approaches allow direct identification of occult defects and are particularly useful when the diagnosis is uncertain or the hernia is interparietal.

Mesh reinforcement is preferred for most adult repairs.

Small defects may occasionally undergo primary closure, but mesh reduces recurrence risk and is generally favoured when the operative field is clean.

Acute irreducibility, obstruction or strangulation requires emergency operation with assessment of bowel viability.

Minimally invasive repair is associated with shorter hospitalisation in elective disease, while open surgery remains common in emergency presentations.