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Stercoral obstruction in a young woman with disseminated phaeochromocytoma was diagnosed and treated successfully using an enema of isosmolar iohexol (Omnipaque) and 1% polysorbate 80 (Tween 80) without complication. Surgical intervention was thus avoided. A low osmolality water-soluble contrast medium (iohexol 150 mg I/ml) with a wetting agent (1% Tween 80) was used because a barium suspension would have inspissated, exacerbating the constipation and a hyperosmolar contrast medium might have precipitated a hypertensive crisis and destabilized her critical salt and water balance.

The radiographic demonstration of vessels in an organ by injecting the vessels with a contrast medium is an anatomic technique which has been recognised for many years (LEXER et coll. 1904). It was not until after the work of BARCLAY (1951) and BELLMAN (1952), that the technique became widely used.Microarteriography, in which only the arterial side of the vascular bed is examined, can provide the radiologist or anatomist with useful information concerning the number, size and distribution of arteries within the organ if all, or nearly all, the arteries and arterioles are demonstrated. Micropaque (Damancy) is a contrast medium of suitable attenuation and fluidity which does not cross the normal capillary bed (BROOKES 1971). It is, therefore, useful in microarteriography because venous filling does not occur per viam of the normal capillary bed.In excised organs better microarteriographic results are obtained if the injected arterial system to the organ is of the single, end-arterial type, such as is found in the kidney or testis, than if it is an anastomotic arterial system, such as is found in muscle or stomach (HARRISON 1951). The intra-arterial perfusion of Micropaque into a whole limb or the whole body results in filling also of the veins (BELLMAN, SEVITT 1964, BERGLJUNG 1968, ROTHMAN et coll. 1975). This process, microangio graphy, is anatomically less precise than microarteriography because it is im-The author is now