Background SMA Syndrome is characterised by a decreased acuity of the angle between aorta and SMA due to the loss of mesenteric fat between the SMA and aorta resulting in compression of the third portion of the duodenum and consequent partial or total obstruction.

Aims To present two patients with SMA syndrome, in order to promote knowledge of this condition and aid early diagnosis.

Methods History, clinical examination and imaging.

Results Patient 1 is a 14 year old girl who presented with a history of eating disorder and features of bulimia and anorexia nervosa. She had persistent vomiting and weight loss of 18 Kg. She strongly denied inducing vomiting. The diagnosis of SMA syndrome was made by the clinical history, ultrasound, and an upper GI contrast study.

Patient 2 is a teenager with severe learning difficulties, autism, epilepsy, and tuberous sclerosis. He also had refractory ulcerative colitis and at age of 17.6 years he underwent sub-total colectomy and ileostomy formation. He required further surgical procedures including a two stage illeo-anal pouch formation and stoma closure. He had a turbulent clinical course over the following year with multiple episodes of vomiting, diarrhoea, abdominal pain and features suggestive of intestinal obstruction resulting in admissions. The stoma was re-formed despite no adhesions nor anatomical reason being seen. His stoma losses subsided but he continued to vomit. He had a 12 Kg weight loss over 14 months. A CT Scan performed was suspicious of SMA syndrome and an upper GI contrast study showed external occlusion of the third part of Duodenum.

Both the above cases improved after a period of parenteral nutrition initially and jejunal feeding later. On follow-up they gained weight and tolerated gastric feeding.

Conclusion The most common risk factor for SMA syndrome is significant weight loss for any reason. Patients with learning difficulties or mental health problems may not give a clear history, or their history may not be believed due to their concurrent health problems.