Strangulated Spigelian Hernia

A 72-year old man presented to the emergency department with a five-day history of left lower quadrant abdominal pain accompanied by nausea, bilious vomiting, abdominal distention, and obstipation. He had noted a new left-sided abdominal mass coincident with symptom onset. A similar episode several years prior had resolved spontaneously. Physical examination revealed a palpable tender mass in the left lower quadrant, measuring approximately 8×12 cm, midway between the umbilicus and the pubis in the mid-clavicular line. Computed tomography (CT) scan depicted a small-bowel obstruction caused by a spigelian hernia (Fig. 1). The patient was explored via an oblique incision in Langer lines directly over the mass, identifying an abdominal wall defect measuring approximately 3×5 cm; within the hernia sac was infarcted omentum and a loop of viable small bowel. After omentectomy, herniorraphy was performed with a bioprosthesis (Surgisis Gold®, Cook Biotech, Inc., West Lafayette, IN). The mesh was placed in the preperitoneal space, and the defect was closed over the mesh with absorbable sutures. In this case, biologic mesh was chosen because of the presence of strangulated bowel in the field and the high risk of postoperative infection. The patient recovered promptly and was discharged to home.

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FIG. 1.

Representative image of abdominal computed tomography scan showing incarcerated spigelian hernia with resultant small bowel obstruction.

Adriaan van der Spieghel (c. 1578–1625) was a Flemish anatomist who first described the semilunar line, but who published nothing in his lifetime. His eponymous hernia was first characterized by Josef T. Klinkosh in 1764 [1]. This hernia develops as a defect in the area of the transversus abdominis aponeurosis, lateral to the edge of the rectus abdominis but medial to the spigelian line, which is the point of transition of the transversus abdominis to its aponeurotic tendon [2]. Spigelian hernias occur most commonly at the arcuate line, the point at which the posterior lamina of the internal oblique and the aponeurosis of the transversus abdominis fuse to form the anterior rectus sheath, leaving only the transversalis fascia to envelop the rectus abdominis posteriorly; laterally at the semilunar line, sites of perforating vessels are common sites for herniation [2,3].

Spigelian hernias account for approximately 0.1–2% of all abdominal wall hernias [2]. These hernias may afflict children or adults as congenital or acquired defects. Adult patients are usually aged 40–70 years. The incarceration rate of spigelian hernia has been reported to be about 20% at the time of surgery [4] (overall incidence of incarceration 2–4/10,000 hernias of all types). Complications (e.g., intestinal obstruction) are rarer still. Spigelian hernias contain greater omentum most commonly, but involvement of the small intestine, colon, gallbladder, Meckel diverticulum, appendix, ovary, or testis has been reported. Risks for incarceration include factors that increase intra-abdominal pressure or weaken the abdominal wall, such as obesity, ascites, trauma, prior surgery, rapid weight loss, and chronic constipation [2].

Diagnosis of spigelian hernias from the history and physical examination can be challenging, owing to the small size of the hernia or to overlying fascia and fat. Plain radiographs are of little utility. Ultrasonography or CT with oral contrast probably are the most useful imaging modalities, but many spigelian hernias are identified only at surgery. Reported rates of accurate preoperative diagnosis differ widely, ranging from 20–93% [4].

Despite the rarity of incarcerated spigelian hernias, they account for 2% of hernia cases that require emergency surgery. Classically, the repair is performed open with re-approximation of tissues or with placement of mesh if the hernia is large. Recurrence rates after primary repair have been reported to be between 2% and 14% [2]. Laparoscopic extra-peritoneal and intra-peritoneal methods of repair have been described [5]. Repairs with mesh have better results than primary repairs, with reported recurrence rates as low as 0.7% [4].