Imaging Findings:

The examination revealed a hernia between the rectus abdominis and transversus abdominis muscles at the level of the anterior superior iliac spine – a lateral, ventral hernia or Spigelian hernia. The dimension of the hernial orifice was 1.3 x 0.7 cm and the hernia contained preperitoneal fat without any bowel loops. There was no change in size or content of the hernia on standing or Valsalva.

Discussion:
The Spigelian fascia is located lateral to the rectus abdominis muscle along the semilunar line.^1–3 Spigelian hernias penetrate through this fascia and are very rare (approximately 1% of all abdominal hernias¹). The location of the hernia gives the diagnosis. Cicatricial hernia are located in scars from previous surgery, inguinal hernia are located in the groin and umbilical hernia in the umbilicus.

In some cases, the Spigelian hernia only penetrates the transverse abdominal aponeurosis, but since this is tightly bound to the internal oblique muscle, the hernia usually penetrates both³. In addition to the hernias often being obscured by at least one aponeurotic layer, they tend to be small, and they can therefore be very difficult to see and feel³. If doubt persists after radiological examinations with ultrasound or CT then a diagnostic laparoscopy is usually performed due to the high risk of strangulation².

Teaching points:
Although Spigelian hernias are very rare, it is important to remember them when dealing with a patient with vague symptoms and recurring lower abdominal pain. Diagnosis from clinical presentation is often problematic, but can be made by ultrasound or CT with high accuracy^1,2.

REFERENCES:

1. https://radiopaedia.org/articles/spigelian-hernia-1
2. Mittal T, Kumar V, Khullar R et al. Diagnosis and management of Spigelian hernia: A review of literature and our experience. J Minim Access Surg. 2008;4:95-8.
3. Spangen L. Spigelian hernia. World J Surg. 1989;13:573-80.