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Correspondence Letters are published at the discretion of the Editor. Opinions expressed by correspondents are not necessarily those of the Editor. Unduly long letters may be returned to the authors for shortening. Letters in response to a paper may be sent to the author of the paper so that the reply can be published in the same issue.

Letters should be typed double spaced and should be signed by all authors personally. References should be given in the style specified in the Instruction to Authors at the front of the Journal.

THE SMALL BOWEL ENEMA MADE EASY

SIR - - I read with interest the paper by Nolan & Cadman (1987) on the small bowel enema and wish to make two points:

1 Why do the authors use plain water as a double contrast agent? Water washes the barium rapidly from the mucosa and excessive water leads to distintegration of the barium suspension. These difficulties may be easily overcome with a 0.5% aqueous solution of methylcellulose (Herlinger, 1978; Antes & Lissner, 1983). In our experience the technique with methylcellulose leads to a much better transparency of bowel loops than pure water.

2 It is really important, as the authors emphasize, to have the colon clean so that the barium column can flow freely into the caecum. However, the colon contains not only faeces, but also great amounts of gas, most of which is swallowed air, and which, like faecal material, may retard the passage of barium through the ileum. We routinely introduce a 40 cm long plastic rectosigmoidal catheter (9 gauge, two sideholes - Unoplast Co. Denmark) con- nected to a big empty plastic bag in order to facilitate the passage of flatus (Kinnunen et al., 1985).

J A A K K O KINNUNEN Department of Diagnostic Radiology Fourth Department of Surgery

Helsinki University Central Hospital Kasarmikatu 11

SF-O0130 Helsinki Finland

References

Antes, G & Lissner, J (1983). Double-contrast small-bowel ex- amination with barium and methylcellulose. Radiology, 148, 37-40.

Herlinger, H (1978). A modified technique for the double-contrast small-bowel enema. Gastrointestinal Radiology, 3, 201-207.

Kinnunen, J, Linden, H, Tervahartiala, P & RiJfenacht, B (1985). Diinndarmeinlauf mit Hilfe eines rektosigmoidalen Katheters. Fortschritte ROntgenstrahlen, 142, 351-352.

Nolan, DJ & Cadman, PJ (1987). The small bowel enema made easy. Clinical Radiology, 38, 295-301.

SiR - Nowhere in our paper did we advocate the use of water as a double contrast agent. We merely add water to maintain the flow of contrast medium during the final stage of the examination. The paper we published was a detailed description of the technique we use, based on Sellink's original method and it was not our purpose to discuss other small bowel enema examination techniques. We are not aware of colonic gas delaying the transit of barium through the ileum and we doubt that there is an indication for introducing a rectosigmoid catheter to facilitate the passage of flatus.

D. J. NOLAN Department of Radiology P. J. C A D M A N John Radcliffe Hospital

Headington Oxford

OX3 9D U

PERCUTANEOUS TRANSLUMINAL ANGIOPLASTY IN THE ~REATMENT OF PATIENTS HAVING ANGIOGRAPHY FOR ISCHAEMIC DISEASE OF THE LOWER LIMB

SIR - In a recent article on percutaneous transluminal angioplasty in the treatment of patients having angiography, by McLean et al. (1987), o n e of the conclusions was not well substantiated. The

authors concluded that 'since all our angiograms were abnormal, preliminary clinical and vascular laboratory assessment is shown to be a highly efficient screening procedure which ensures that angiography and subsequent treatment is offered only to patients with measurable arterial insufficiency'.

I am particularly concerned that information is not provided on the group of patients who as a result of screening were not referred for angiograms. It would be premature to comment on the efficiency of screening if data on this group were not analysed. An important question remains: what percentage of this group would have had abnormal angiograms?

Secondly, there was a group of patients mentioned who were not screened through the procedure under study and were, instead, admitted as emergencies. If this was a small number, then the effects would be insignificant; but if the number was large, credit for all abnormal angiograms could not be given to the efficiency of the screening methods alone.

PATRICIA WEAVER Community Medicine Clerkship Department of Community and

Occupational Health Meharry Medical College

1005 D.B. Todd Blvd. Nashville, Tennessee 37028, USA

References

McLean, L, Jeans, WD, Horrocks, M & Baird, RN (1987). The place of percutaneous transluminal angioplasty in the treatment of patients having angiography for ischaemic disease of the lower limb. Clinical Radiology, 38, 157-160.

SiR - I am grateful to Miss Weaver for her comments on our paper (McLean et al.,1987).

The purpose of the paper was to find out what happened to the patients having angiography in ischaemic disease of the lower limb, For this reason we have not examined the patients who did not come for angiograms, but previous papers have suggested that in England (MacPherson et al., 1980) 38% of requests for aortography were inappropriate. A similar study in Scandinavia (Christenson et al., 1978) found that 50% of angiograms were unnecessary. The steps in the argument are that:

(a) It is important to treat patients and not radiographs. (b) Intermittent claudication can be mimicked by spinal stenosis,

osteoarthritis and other more rare diseases. (c) If patients have symptoms or signs suggestive of diminished

blood flow then the appropriate test is to measure the ankle pressure before and after exercise.

(d) Angiography has a small but real risk and should not be performed unless it is going to lead to some benefit for the patient.

(e) Patients who have angiographic abnormalities which do not cause symptoms nor reduce ankle pressure would not be treated and therefore should not be examined. It is for this reason that the incidence of angiographic abnormalities in patients without symptoms or evidence of a fall in ankle pressure do not cause us any anxiety.

Eleven of our 226 patients (4.8%) were admitted as emergencies with acute ischaemia and were therefore not screened before angiography.

W. D. JEANS Department of Radiodiagnosis Bristol Royal Infirmary

Bristol BS2 8HW