Middle mesenteric artery: a rare variant

Clinical History

A 70-year-old male patient was referred to our emergency department for an urgent angiography. The angiography was performed to investigate a hemorrhage in the upper GI tract. It demonstrated, incidentally, a small vessel arising anteriorly from the abdominal aorta, between the origins of the renal arteries and the IMA, at the level of the L2-L3 intervertebral disk.

Imaging Findings

The 70-year-old male patient was referred to our emergency department for an urgent angiography to investigate an upper gastro-intestinal (GI) tract hemorrhage. A selective catheterization of the superior (SMA) (Fig.1a) and the inferior mesenteric artery (IMA) (Fig.1b) was performed with a 5 Fr. Cobra catheter, and demonstrated, incidentally, the presence of a small vessel between the origins of the renal arteries and the IMA (Fig.2). This vessel arose directly from the ventral aspect of the abdominal aorta at the level of the L2-L3 intervertebral disk and gave rise to two branches supplying the proximal segment of the descending colon.

Discussion

Embryologically, the viscera are supplied by the paired ventral segmental arteries arising from the paired dorsal aorta at every vertebra and are connected longitudinally via a ventral anastomosis. During the fourth week of intrauterine development, fusion of the paired dorsal aorta takes place. Subsequently, the paired ventral segmental branches also fuse and give rise to three mainly ventrally oriented vessels, namely, the celiac artery, the superior mesenteric artery (SMA) and the inferior mesenteric artery (IMA). Variations in the persistence or fusion of the paired ventral segmental arteries are the source of anomalies of the abdominal visceral arteries. The middle mesenteric artery (MMA) was identified by Benton and Cotter in 1963 and was named by Lawdahl and Keller in 1987. It is a very rare congenital variant resulting from the persistence of an additional ventral root between the thirteenth and the twenty-first segments. It may represent a variant of the accessory middle colic artery, and supplies a portion of the transverse and the descending colon. The recognition of various arteries supplying the colon has important diagnostic and therapeutic implications. Failure to do so may result in either a false-positive or a false-negative diagnosis in the supplied segment of the colon.

Differential Diagnosis List

Final Diagnosis

Middle mesenteric artery.

URL:	https://eurorad.org/case/3405
DOI:	10.1594/EURORAD/CASE.3405
ISSN:	1563-4086