Spigelian hernias (alternative plural: herniae), also known as lateral ventral hernias, are a type of abdominal hernia along the semilunar line, resulting in herniation between the muscles of the abdominal wall.
They are rare and account for ~1% (range 0.1-2%) of ventral hernias . The incidence is thought to peak around the 4to 7decades. There may be a slightly increased female predilection with a male to female ratio of 1:1.18 .
They may be congenital or acquired.
A Spigelian hernia is associated with ipsilateral cryptorchidism among 75% male infants .
Two hypotheses have been proposed to explain the association, but the exact mechanism is still in debate
- Spigelian-cryptorchidism syndrome (failure in the development of a gubernaculum)
- Raveenthiran syndrome (ectopic testis from a potential hernia sac)
The hernial orifice of a Spigelian hernia is located in the Spigelian fascia, that is, between the lateral border of the rectus abdominis muscle and the semilunar line, through the transversus abdominis aponeurosis, close to the level of the arcuate line. The majority of Spigelian hernias are found in a transverse band lying 0-6 cm cranial to a line running between both anterior superior iliac spines referred to as the Spigelian hernia belt.
Most Spigelian hernias occur in the lower abdomen where the posterior sheath is deficient.
The diagnosis of a Spigelian hernia at times presents greater challenge than its treatment. The clinical presentation varies, depending on the contents of the hernial sac and the degree and type of herniation. The pain, which is the most common symptom, varies, and there is no pain typical to a Spigelian hernia. Findings to facilitate diagnosis are a palpable hernia and a palpable hernial orifice. It should be stressed, though, that since the hernia lies deep to a muscle, it commonly does not cause a noticeable bulge in the abdominal wall.
Ultrasound can be recommended for verification of the diagnosis in both palpable and nonpalpable Spigelian hernia.
The hernial orifice and sac can be well demonstrated by computed tomography, which gives more detailed information on the contents of the sac than does ultrasound scanning.
Treatment and prognosis
The treatment is often surgical and the risk of recurrence is small.
History and etymology
It is named after Adriaan van der Spieghel (1578-1625), Flemish anatomist , who first described the semilunar line. However the hernia is thought to have been first described by a Czech anatomist Josef Tadeas Klinkosch (1734–1778) in 1764 .