Spigelian Hernia - A Diagnostic Dilemma

Introduction

Spigelian hernias (SHs) are not very common. They comprise around 1–2% of all the hernias presenting to the emergency department.¹ Spigelian hernia is a multifactorial disease, involving both congenital and acquired factors. Spigelian hernias can occur spontaneously via the semilunar line at the lateral border of the rectus abdominis muscle. This line demarcates the transition from muscle to aponeurosis in the transversus abdominis muscle. Most Spigelian hernias are observed to be caudal and lateral from the umbilical level at the junction of semilunar and semicircular lines. Spigelian hernias are believed to be a surgical rarity. Due to the position of the obscure intraparietal sac, sometimes it becomes difficult to determine the correct diagnosis.²

The clinical diagnosis of Spigelian hernia is challenging because of the lack of specific clinical features³ and the wide differential diagnosis for lower abdominal pain. Generally, patients present with localized pain that becomes diffuse. Abdominal computed tomography (CT) establishes the diagnosis and laparoscopic or open surgical repair is the definitive treatment.²

We report a case of SH in a 24-year-old woman who presented with recurrent abdominal pain.

Case Presentation

A 24-year old female who presented with recurrent abdominal pain for one year was referred to our emergency OPD (Figure 1). Physical examination revealed mild tenderness over the left lumbar region.

Swelling could not be appreciated. Ultrasonography guided (USG) examination of the abdomen showed a left para-umbilical defect measuring 4.7 cm with bowel as hernia content (Figure 2).

After left oblique incision and on the opening of the external oblique, a hernia was seen sticking out from the lateral margin of the rectus abdominis (Figure 3). The hernia sac was dissected off the external oblique and contained a part of the omentum (Figures 4 & 5), which was reduced.

A non-absorbable suture was used to secure the fascial defect in layers with onlay mesh (Figure 6). The patient's recovery was uneventful and is now symptom-free.

Discussion

Spigelian hernias were first mentioned by Adrian van der Spiegel, an anatomist from Brussels. It occurs secondary to a defect in the transversus abdominis muscle and rectus sheath aponeurosis, which permits abdominal contents to bulge through the linea semilunaris (Spigelian line or belt). “Spigelian hernia” normally refers to hernias located cranially to the inferior epigastric vessels. Based on the location, few hernias cross the strip of Spigelian at the triangle of Hasselbach, are caudal and medial to the vessels, referred to as “low”.

Most hernias occur just below the umbilicus where the aponeurosis is wide and weak. Spigelian hernia is commonly constituted by small intestine, but it can also include caecum, appendix causing, sigmoid colon or omentum.^4,5 There are many diverse factors and etiology which deteriorate the abdominal wall and are considered as predisposing factors such as collagen disorders, changes in body weight, aging, chronic pulmonary disease, trauma, and previous abdominal surgery.^6,7 It is challenging to diagnose Spigelian hernia clinically because the symptoms can be erratic and non-specific. The most common symptom observed is pain which is usually specified to that side of the abdomen.⁸ The best diagnostic test is abdominal CT scan with contrast, even though the hernia might be evident on ultrasound (US) or by clinical examination in some patients.⁹

There are many differential diagnoses of SH in children including appendicitis and appendiceal abscess, tumor of the abdominal wall, ventral or inguinal hernia, and spontaneous hematoma of the rectus sheath. SHs are usually minor in size but the danger of strangulation is very high, so they should be repaired.

The main indication for surgery is fibrous bands of Spigelian fascia which form a rigid neck making incarceration and strangulation.¹⁰ A gridiron incision over the mass is recommended in the surgical repair of a Spigelian hernia. The external oblique aponeurosis is incised in the direction of its fibers, exposing the hernial sac. The sac is divided and sutured after its contents are returned. The internal oblique muscle and external oblique aponeurosis are reapproximated in layers. Recently, laparoscopic approaches for diagnosing and repairing Spigelian hernia have been reported.¹⁰ Laproscopy can identify the exact location of the hernia, the reduced size of hernia sac and the defect patched with non-absorbable mesh. Laparoscopy may afford a safe and minimally invasive surgery without prolonged recovery.¹¹

Spigelian hernia is non-specific clinically and is insidious in nature which makes its diagnosis difficult. Spigelian hernias are clinically elusive often until strangulation occurs. If diagnosed, operation should always be advised as early as possible.

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Conflict of Interest

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