Abstracts

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E1999. Spontaneous Isolated Visceral Artery Dissection: An Unusual Cause For Acute Abdomen
Authors
  1. Shuyi Guo; Changi General Hospital
  2. Karen Fernandes; Changi General Hospital
  3. Ranu Taneja; Changi General Hospital
Background
Acute abdomen is a common emergency presentation. Most patients undergo MDCT scans. An unusual cause for abdominal pain is spontaneous isolated visceral artery dissection (SIVAD). This exhibit aims to discuss diagnostic features of this uncommon condition to enable early diagnosis and appropriate patient management.

Educational Goals / Teaching Points
1. Introduction to SIVAD 2. Familiarise with MDCT findings in SIVAD 3. Discuss briefly the treatment options for this condition

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Isolated arterial dissection, which occurs without aortic dissection, has been reported in carotid and renal arteries but rarely in visceral arteries. Spontaneous dissection of the superior mesenteric artery is most common, followed by celiac artery. It is seen most often in males in the fifth decade. Patients may be asymptomatic or present with acute abdominal pain. The reported risk factors include hypertension, cystic medial necrosis, abdominal aortic aneurysm, fibromuscular dysplasia, trauma, pregnancy and connective tissue disorders. Most of the patients are however healthy with no underlying disease. Complications include occlusion with end organ ischaemia, aneurysm formation and rupture. The visceral arterial dissection typically begins a few centimeters from the ostium. It has been suggested that the SMA is more susceptible to shear stress in the transition zone between the fixed retropancreatic and relatively mobile segment in the mesenteric root [1]. Intimal flap, thrombosed false lumen, and aneurysmal dilatation are the most common CT findings of SIVAD [2]. Because intimal flap is not always visible, mural thrombus may be the only clue to the presence of dissection. In such instances, misdiagnosis of dissection as thromboembolic occlusion can lead to unnecessary pharmacologic thrombolysis [3]. Infiltration of the fat surrounding the dissected arteries may also be seen [4]. Although less common, this finding may be predictive of the acuity of dissection and predisposition toward extension of dissection into adjacent vessels. Initial conservative medical management with or without anticoagulation and close imaging follow-up may be effective for patients without signs of intestinal infarction or bleeding. Bowel ischemia, aneurysmal dilatation three times the normal arterial diameter, and progression of dissection indicate the need for endovascular stent insertion [5]. Open surgical management is only very rarely used and most patients respond to conservative management or endovascular therapy [6].

Conclusion
SIVAD is an uncommon condition which presents acutely with abdominal pain, often in the middle aged male patient. Knowledge of this condition and timely and accurate diagnosis is imperative for appropriate management.