48

QUALITY OF BARIUM ENEMAS

SIR,-For many years the barium enema has been the first-linediagnostic investigation of colonic disease. Comparison with thenewer technique of fibroptic colonoscopy has emphasised theshortcomings of the single contrast enema in contrast to the relativeaccuracy of the double contrast barium enema technique (DCBE).Although DCBE is less accurate than colonoscopy it is quicker,safer, and cheaper. DCBE hoeever, is accurate only if technicallywell executed and after good bowel preparation. Simply introducingair into a poorly cleansed colon already filled with barium mayworsen the problems of radiological interpretation but give theclinician the mistaken impression that his patient has been

accurately investigated.We have reviewed the barium enema films of 1000 patients

referred for colonoscopy after barium enema done at this hospitalspecialising in colorectal disease or at general hospitals in Londonand elsewhere in southern England. The barium enemas werereviewed before colonoscopy and divided into double contrast orsingle contrast examinations according to whether or not air hadbeen used and then classified as technically "good", "average", or"poor" quality procedures.A "good quality" enema was one with a perfectly clean, well

distended, and barium-coated colon with all areas well seen on atleast one film. "Average quality" meant some faecal residue or somedifficulty in seeing all areas in fully air contrast even thoughsufficient numbers of films had been taken. A "poor quality"examination was one with larger amounts of faecal residue, withinadequate distension or failure to coat the bowel with barium. Agood quality barium enema should exclude a carcinoma or largepolyp with near certainty; an average quality examination should doso with high probability but a poor quality examination carries nosuch guarantee. Of the 400 examinations done at this hospital 94%were double contrast examinations, single contrast technique beingused only for incontinent patients unable to hold air. Of the 600examinations from other hospitals 70% were DCBE and 30% weresingle contrast studies. Of the DCBEs by specialist radiologists 68%were good quality, 30% average, and 2% poor quality. The DCBEsfrom other hospitals rated as 30% good quality, 47% averagequality, and 23% poor quality.Although the patients referred to us form a heterogeneous group

with a possible bias towards selection of those with unsatisfactoryexaminations we feel that some basic points are illustrated by ourfindings.Even a specialist radiological unit cannot produce high-quality

barium enema films in all patients. Many general hospitals appearto carry out a significant percentage of almost worthlessexaminations. The danger is that, whatever the quality of the films,the radiologist issues a report and attempts a dogmatic conclusionsuch as "no abnormality seen on this examination". It seems to usthat the radiologist’s report should specifically mention both thetechnique used and the level of confidence of the report on technicalgrounds. The films of a barium enema should always be reviewed bythe clinician (ideally with a radiologist) before accepting the reportas accurate since clearly some reports can be accepted with moreconfidence than others and some examinations may need repeating.The high percentage of double contrast enemas from general

hospitals is gratifying in showing an attempt to raise the standard ofcolon radiology but the fact that only 30% of these examinationswere technically of good quality emphasises the need to encourage(or demand) further improvement in barium enema technique. Ifthe films upon which our quality audit is based are representative ofthe barium enema service generally available in the UK it should benoted that over a half are performed with a bad technique (singlecontrast) or with a good technique (double contrast) badly executed.

St Mark’s Hospital,London EC1V 2PS

CHRISTOPHER B. WILLIAMSTAKASHI NISHIGAMI

1 Gelfand DW, Ott DJ. Single-versus double-contrast gastrointestinal studies. Criticalanalysis of reported studies. Am J Radiol 1981; 137: 523-28.

2 Williams CB, Macrae FA, Bartram CI. A prospective study of diagnostic methods inadenoma follow-up. Endoscopy 1982, 14: 74-78

3. Fork FT Reliability of routine double-contrast examination of the large bowel. Aprospective study of 2590 patients. Gut (in press).

X-RAY FOLLOW-UP FOR TUBERCULOSIS

SIR,-Dr Goldman (March 12, p 592) suggests regularradiological follow-up as an alternative to chemoprophylaxis formost patients with fibrotic lesions and significant tuberculin tests.We submit that there are no data to support this opinion. It has beenthe experience of several observers that routine, periodic X-rayfollow-up is totally unproductive and is costly both financially andin terms of radiation. 1,2 Furthermore patients with symptoms havebeen known to put off seeking medical care because "they had anX-ray not too long ago" or "my regular annual visit is in 3 months, Ithink I’ll wait it out". If one wants to do periodic X-rays looking forsymptomless lesions, there is, to carry such a recommendation tothe absurd, no reason why weekly X-rays rather than annual checkswould not be more productive as well as practical.A US Public Health Service monograph on The Selection of

Patients for X-ray Examination (in press) makes the recommen-dation to which we subscribe: "After an initial evaluation whichincludes a chest X-ray examination, repeating chest X-rayexaminations of individuals with significant tuberculin reaction(without current disease) whether or not they have been treated withIsoniazid, have not been shown to be of sufficient clinical value tojustify their continued use". Until tuberculosis is totally undercontrol in Britain as well as the United States, resources should beallocated where the benefits clearly outweigh the costs.

Pulmonary Division,Department of Medicine,University of Medicine & Dentistry of New Jersey,New Jersey Medical School,University Hospital,Newark, New Jersey 07103, USA

LEE B. REICHMANBONITA T. MANGURA

SHEFFIELD COT DEATHS PROJECTSIR,-Dr Carpenter and his colleagues (April 2, p 723) have once

again produced some very substantial claims for the success of theSheffield cot deaths project. However, their article is based on a verysmall number of events. The table of "possibly preventable deaths"(table VIII) shows a total of only 29 deaths over a 6t year period; tosubdivide these deaths into three periods and to calculate

percentage differences from expected mortality (to produce, forexample, a 2507o reduction based on just 5 deaths) seems a little rash.

I suggested to Dr Carpenter, during the discussion of his earlierpaper presented to the Royal Statistical Society,3 that much of the"improvement" in Sheffield can, in fact be traced to low mortalitythroughout the Trent area. Table i shows post-perinatal mortalitynumbers and rates for 1975-80 for England and Wales, for theTrent region, and for the then Sheffield area, for all deaths fromrespiratory diseases, cot deaths (so stated), and accidents and otherexternal causes (roughly speaking, Carpenter’s "possiblypreventable" deaths). The numbers of such deaths in Sheffield are

1. Reichman LB. Routine followup of an active tuberculosis: a practice that has beenabandoned. Am Rev Resp Dis 1973; 108: 1442-43.

2. Reichman LB. Tuberculosis screening and chest x-ray films. Chest 1975; 68 (suppl):448-51.

3. Carpenter RG. Scoring to provide risk-related primary health care: Evaluation andupdating during use. J Roy Statist Soc A 1981; 146: 1-32.

TABLE I-"POSSIBLY PREVENTABLE" POST-PERINATAL DEATHS:

NUMBERS AND RATES PER 1000 LIVE BIRTHS FOR ENGLAND AND

WALES, TRENT REGION, AND SHEFFIELD AREA 1975-80’

Trent=Trent Regional Health Authority. Sheffield=former Sheffield Area Health

Authority.