Multidetector computed tomography features of linea arcuata (arcuate-line of Douglas) and linea arcuata hernias

The aim of the study was to estimate the prevalence of delineation of semi circular or linea arcuata (arcuate line of Douglas) (LA) during 64-row multidetector Computed Tomography (mdCT) of the abdomen and to illustrate the so-called linea arcuata hernia (LAH), a peculiar type of interstitial parietal hernia of the anterior abdominal wall consisting of an ascending protrusion of intraperitoneal structures under the LA. The mdCT abdominal wall anatomy of a continuous series of 315 unselected patients was retrospectively reviewed and explored with multiplanar reformations (MPR). Considering a grade 1 lesion (G1) as a single delineation of the LA due to minimal bulging of intraperitoneal fat, a grade 2 hernia (G2) as a substantial herniation under the LA and grade 3 hernia (G3) as a frank prominent herniation of peritoneal structures (essentially omental fat and/or intestinal loops), lesions of all types were found in 8.57% of patients with more than 81% of lesions being G1; this prevalence reached 14.97% in men but only 1.35% in women (M:F sex ratio 12.5:1); all lesions were found in patients older than 51 years and 76% of them were older than 71 years with a great majority of men. Most patients were absolutely free of symptoms related to theses abnormalities. The anatomy of the rectus abdominis sheath and LA are reviewed and the mdCT signs of LA and LAH are described and illustrated. In conclusion, 64-row mdCT can frequently delineate the linea arcuata (LA) and more rarely linea arcuata hernias (LAH), particularly in old men, but these abnormalities mostly represent fortuitous asymptomatic findings.