Spigelian hernia is a rare condition accounting for 0.1–2% of abdominal wall hernias in adults [1]. It is often responsible for an abdominal mass next to the Spiegel line [2]. The generally narrow hernial ring is the cause of complications with the onset of bowel obstruction by incarceration [3]. We report the case of an incarcerated Spigelian hernia without palpable abdominal mass diagnosed by computed tomography (CT) scan.

This was a 63-year-old male, obese with a body mass index (BMI) of 34 without surgical history. He consulted to the emergency department for intestinal obstruction consisting of abdominal pain, vomiting evolving for three days. The blood pressure was at 130/80 mmHg, the temperature was at 37.7 °C, and the respiratory rate at 25 breaths/min. Physical examination showed no visible or palpable mass. There was no tenderness and the rest of the exam was unremarkable. The usual laboratory tests were normal. An abdominal CT scan was performed. It revealed a dilatation of small bowel, measured at 38 mm with a flat colon (Figure 1). On the right side of the anterior abdominal wall at 30 mm below the umbilicus, at the outer edge of the rectus muscle, a parietal defect between the internal and external oblique muscles was visualized, corresponding to an interstitial Spigelian hernia (Figure 2). The hernial ring was measured at 15.5 mm and the hernial sac contained flat small bowel and epiploic fat (Figure 3). The CT scan did not find any sign of digestive ischemia or extra digestive air.

Elective surgical exploration centered on the mass confirmed the diagnosis of incarcerated Spigelian hernia, containing a viable content (small bowel). Reduction of the hernia and a parietal repair with an aponeurorrhaphy using Merseture 0 was performed. The postoperative course was uneventful. There was no recurrence after four months of follow-up.

Spigelian hernia, also called lateral ventral hernia, is an acquired or congenital dehiscence of the anterolateral abdominal wall. It is rare, representing between 0.1% and 2% of abdominal hernias in adults [1]. It occurs most often in obese people aged around 50 years [4],[5]. The other risk factors are the causes of intra-abdominal hyper pressure (chronic cough, intense and repeated pushing efforts) and repeated pregnancy.

In our patient, the risk factors found were advanced age and obesity. There was no chronic cough, heavy labor, or signs of prostatic disease.

The clinical presentation of Spigelian hernias is often a swelling with a mass on the semilunar line [2]. Moreover, in 36% of cases, there is no mass visible or palpable at clinical examination [6]. This was the case in our patient and this could be explained by the fact that the hernia was interstitial and its contents were not dilated. With this presentation, CT scan plays a key role for a positive diagnosis. Some authors attribute to it a specificity and a sensitivity greater than 90% [7]. In addition, CT scan also makes the diagnosis of viability of the hernial contents. Some authors attribute to it a specificity and a sensitivity greater than 90% [7]. In addition to the positive diagnosis CT scan also makes the diagnosis of viability of contents of a hernial sac.

Spiegel hernias are asymptomatic in 9 out of 10 cases, but the risk of strangulation is high. This risk is greater when the hernial neck is narrow with interstitial situation of the hernia [8]. In our patient these two factors were combined.

Spigelian hernia is a rare type of ventral abdominal wall hernia. Its diagnosis can often be evoked with clinical examination when there is a swelling on the semilunar line. But in the absence of this parietal mass, CT is the key examination both for a positive diagnosis and for assessing the nature and viability of the contents of the hernial sac.