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pouchitis. I believe we should be cautious about the specificity of metronidazole for therapy. There are no trials that have compared steroids with metronidazole or metronidazole with ciprofloxacin. Such trials are urgently needed, but most patients with pouchitis present first to their doctor. Furthermore, the number of patients with pouchitis in any single centre would probably be insufficient to mount a trial to compare these various regimens. Despite this, multicentre trials are needed to identify the optimum treatment for true primary proctitis.

M. R. B. Keighley Department of Surgery Queen Elizabeth Hospital Edgbaston Birmingham B15 2TH UK

Antegrade enemas for the treatment of severe idiopathic constipation

Sir We found the paper by Mr Hill and colleagues very interesting (Br J Surg 1994; 81: 1490-1). The concept of antegrade colonic irrigation to achieve evacuation seems sound; however, we believe Hill et al. minimize the difficulties encountered when this technique is attempted in adults. We have recently described an operation whereby irrigation of the rectum through a continent sigmoid colonic conduit is used to produce rectal evacuation in patients with outlet obstruction constipation’. Irrigation through a 25-Fr rectal catheter with 2-3 pints of water instilled from an irrigation set effects evacuation with an increase in stool frequency and reduction in the time spent evacuating. The conduit may be constructed in the proximal transverse colon to treat slow-transit constipation.

We had previously considered the use of the appendix as an irrigation conduit, but felt that it had a number of disadvantages. The appendiceal lumen is too narrow to allow insertion of a catheter large enough to generate the flow required to produce rectal evacuation. In patients with outlet obstruction, irrigation in the proximal colon is unlikely to aid defaecation. We performed appendicostomy in one patient, but found that large volumes of fluid and phosphate enemas were required to produce evacuation, causing severe abdominal cramps. Also, the appendicostomy was incontinent to faeces and irrigation fluid.

We were therefore surprised that the authors achieved satisfactory results, particularly in the three patients with outlet obstruction, using a narrow catheter inserted into the appendix and small volumes of fluid via a bladder syringe. We found that the Nelaton (Surgicon, Brighouse, UK) catheters were too narrow and also rather firm, resulting in trauma to the mucosa. The authors do not comment on their experience with respect to continence of the appendicostomy to irrigation fluid.

We note that two patients utilize phosphate enemas to irrigate. This procedure is potentially dangerous in cases of constipation where evacuation may be delayed due to faecal loading. Rapid absorption of the phosphate may occur, resulting in hypocalcaemia2, particularly if the catheter is accidentally misplaced in the ileum. Phosphate absorption from the sigmoid colon is unlikely as the process of irrigation and evacuation takes just 15 min.

The incidence of stenosis at skin level of 50 per cent is not surprising as this has been observed in both appendicostomies for i r r i g a t i ~ n ~ . ~ and Mitrofanoff procedures for urinary diversion5. In our experience with the colonic conduit, stenosis at skin level was prevented by the construction of skin flaps, with only one of 21 patients requiring revisional surgery. Hill et al. attributed the stenosis to wound infection. An infection rate of 50 per cent for a clean contaminated wound is clearly greatly in

British Journal of Surgery 1995,82,564-570

excess of the accepted figures6. It is not clear from the paper whether bowel preparation was used, but it seems improbable as patients required a 2-week postoperative stay to clear the colon of faeces. Preoperative bowel preparation may improve the wound infection rate.

We appreciate that appendicostomy is a relatively minor procedure for the treatment of a condition which generally requires major ablative surgery. We are impressed with the symptomatic improvement, but it is difficult to explain how instilling 500ml saline into the caecum every 5 days results in resolution of incapacitating slow-transit constipation or outlet obstruction. As is often the case in outlet obstruction, there may be a psychological element to symptoms and the irrigation may be serving an elaborate behavioural therapeutic role. We believe that psychological assessment and comprehensive counselling before operating for constipation is essential.

S. F. Hughes N. S. Williams

Surgical Unit The Royal London Hospital Whitechapel London E l 1BB UK

Williams NS, Hughes SF, Stuchfield B. Continent colonic conduit for rectal evacuation in severe constipation. Lancet

Hunter MF, Ashton MR, Griffiths DM, Ilangovan P, Roberts JP, Walker V. Hyperphosphataemia after enemas in childhood: prevention and treatment. Arch Dis Child 1993; 68:

Malone PS, Ransley PG, Kiely EM. Preliminary report: the antegrade continence enema. Lancet 1990; 336: 1217-18. Squire R, Kiely EM, Carr B, Ransley PG, Duffy PG. The clinical application of the Malone antegrade continence enema. J Pediatr Surg 1993; 28: 1012-15. Smith ED. Follow up studies of 150 ileal conduits in children. J Pediatr Surg 1972; I : 1-10. Cruse PJE, Foord R. A five year prospective study of 23,649 surgical wounds. Arch Surg 1973; 107: 206-10.

1994; 343: 1321-4.

233-4.

Rehabilitation outcome 5 years after 100 lower limb amputations

Sir We were extremely concerned to read the article on rehabilitation outcome following major lower limb amputation by Mr McWhinnie and colleagues (Br J Surg 1994; 81: 1596-9). Their conclusion that below-knee amputation does not improwe the effective rehabilitation rate for major limb amputations needs to be examined critically. Our first immediate comment is that they have a poor fitting rate for primary amputees. In our unit, the fitting rate for final prostheses is almost 85 per cent. This compares with 57 per cent in the authors’ present series, which we would regard as rather low.

In the methodology, there is little indication as to how rehabilitation was achieved. Were these amputees rehabilitated at a Limb Fitting Centre in an appropriate environment with rehabilitation physicians, nurses and therapists? How many of the patients with fitted limbs were also given wheelchairs? Unfortunately, it is true to say that patients who are given wheelchairs have a relative disincentive to use the prosthesis. The authors’ results are at variance with other studies which have shown that below-knee amputees have fewer psychological problems and survive longer with a better functional outcome than above-knee amputees.