Richter-type spigelian hernia

Clinical History

An 83-year-old woman presented at the emergency room showing abdominal pain, vomiting and poor deposition. She had no previous history of abdominal surgery and no previous radiological images. Bowel sounds were increased. Blood tests showed increased inflammatory parameters (elevated acute phase reactants, leukocytosis and neutrophilia). The main clinical suspicion was acute diverticulitis.

Imaging Findings

In abdominal radiography, distended small bowel loops were observed. Distal aeration was present, existing air bubbles in the rectum. Diagnosis of subocclusive or progressive occlusive ileus was established.

Computed tomography showed dilated small bowel loops without affecting the colon. There was a transition point in the ileum. In that place the antimesenteric side of the ileum was herniated (Richter's hernia) through a defect in the abdominal wall located in the inferior third of the left semilunar line (Spigelian hernia).

Herniated ileum showed wall oedema and surrounding free fluid. Contrast enhancement was preserved or even increased, indicating that there was no arterial compromise, but only venous.

As an incidental finding a liquid collection in left inguinal region was found. It measured about 5 cm and was related with previous left inguinal hernia repair.

Taking into account these findings, surgery department performed laparoscopic ventral hernia repair. The evolution of the patient was appropriate.

Discussion

Although considered individually they are two relatively common entities, the fact that both phenomena occur simultaneously (Richter’s herniation through Spigelian line) is very unusual. A literature review conducted in 2014 found only six cases since 1978 [1].

Spigelian hernias occur through a defect in the linea semilunaris, a fibrous union of the rectus sheath with the aponeuroses of the transverse abdominal and abdominal internal oblique muscles that extends from the level of the ninth rib cartilage to the pubic symphysis. Usually wall defects are secondary to acquired weakness of the abdominal wall, often related to surgical incisions [2].

This is a rare type of abdominal wall hernia. A literature review found that 479 cases were reported between 1970 and 2000 [3].

The clinical diagnosis of Spigelian hernia is difficult because it produces nonspecific symptoms [4]. The most common one is pain in the location of the hernia. Herniation may be apparent on clinical examination or ultrasound in some patients. Nevertheless, abdominal CT with intravenous contrast is the imaging test of choice because it allows to know if there is vascular compromise or some other underlying pathology.

It is recommended to perform treatment immediately because of the high risk of incarceration, approximately 24% of cases, and the low risk of recurrence if the procedure is properly done [5].

On the other hand, Richter’s hernia strangulation is produced when the antimesenteric wall of the intestine protrudes through a defect in the abdominal wall. It occurs more commonly in the femoral region. It is more frequent in women and usually involves a segment of the distal ileum.

Since only one side of the intestine is affected, the obstruction is rare. This type of hernia is usually found as an incidental finding, but intestinal necrosis and perforation can occur.

The treatment of choice for Spigelian and Richter’s hernias is laparoscopic mesh repair of the abdominal wall defect [6]. If intestinal necrosis is established, the affected segment must be resected.

Differential Diagnosis List

Final Diagnosis

Herniation of antimesenteric portion of the bowel through semilunar line.

URL:	https://www.eurorad.org/case/14878
DOI:	10.1594/EURORAD/CASE.14878
ISSN:	1563-4086