The instant enema in inflammatory disease of the colon

Olin.gadiol. (1979) 30, 165-173

The Instant Enema in Inflammatory Disease of the Colon 13.M. THOMAS

St Mark's Hospital, City Road, London, and University College Hospital, Gower Street, London The instant, or unprepared, double contrast barium enema has been used routinely at St Mark's Hospital in the investigation of active inflammatory disease of the colon since 1963. The use of air contrast is preferred to show the fine detail of the mucosal changes and to detect early involvement. With the instant enema technique the diagnostic results are satisfactory and patients are minimally disturbed by the procedure. The majority of examinations consist of a total of four films, which includes a plain film of the abdomen prior to the administration of contrast. For short-term follow-up a repeat enema with a single film is usually adequate.

INTRODUCTION The prerequisite of a diagnostic barium enema is, as a rule, a clean and empty colon; the wide variety in the methods employed to this end testifies to the difficulty experienced in achieving this necessary but unphysiological emptying of the large bowel. In the presence of active inflammatory disease of the colon, however, we believe that preliminary bowel preparation is unnecessary. The reason for this is that inflamed areas of the colon are, as a rule, relatively free of faecal content and that conversely the presence of significant formed faecal content is usually an indication of a normal, uninflamed mucosa. The instant enema was devised by Young (1963) at St Mark's Hospital in order to give the clinician immediate information as to the extent of the mucosal lesion seen sigmoidoscopically in patients with procto-colitis. The diagnostic results were found to be satisfactory, showing the proximal limit of disease in 29 of the 30 abnormal cases in the initial study. Subsequently a review of 100 cases of proctocolitis showed a close correlation between the absence of normal haustra and faeces on the plain film, and a mucosal lesion in the contrast films (Halls and Young, 1964). Further experience has confirmed the diagnostic accuracy of this technique, and a recent review of 50 consecutive patients referred for examination at St Mark's Hospital showed agreement between sigmoidoscopic and radiographic appearances in 48. In many of these patients, the proximal limit of disease was shown only by radiological examination. Patients are less disturbed by this procedure than by a conventional single contrast barium enema, in which barium is introduced to distend the whole Colon to the caecum.

Because of this ability to show the nature and extent of the mucosal lesion by a double contrast study without preparation, we believe that it is both unnecessary and unjustifiable to submit a patient with active inflammatory disease of the colon to an onslaught with aperients, suppositories or washouts. The double contrast technique is preferred to show finer detail of the mucosa and allows more accurate detection of early involvement than the single contrast enema (Welin and Brahme, 1961;Fraser and Findlay, 1976).

TECHNIQUE

A plain abdominal film is obtained prior to the commencement of the enema. This film shows the amount and distribution of faecal content which allows prediction of expected mucosal change on the contrast films (Young, 1963). There may be positive evidence of inflammatory disease such as tubular, hazy or irregular colonic gas shadows; in patients with active total colitis the shortened, tubular colon, or parts of it, may be air-filled and readily visible (Halls and Young, 1964; Bartram, 1976). Careful inspection of the preliminary film is of particular importance in all acutely ill patients so that the possible complication of toxic dilatation can be recognised. The diagnosis of this sinister complication is of great importance, both in terms of clinical management and because its development is an absolute contra-indication to any form of contrast examination. In doubtful cases, serial plain films at daily intervals will show whether progressive dilatation is occurring and during this period contrast examination is withheld. Measurement of the width of the colon in toxic dilatation has been made, and

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the upper limit of normal for the diameter of the transverse colon on a plain film is said to be 5.5 cm (Hywel-Jones and Chapman, 1969). Such measurements, however, are only of value in the clinical context and in association with other radiological signs of the condition, such as disturbance of the normal haustral pattern and - of particular importance - the presence o f mucosal islands which usually show quite well as soft tissue shadows at the margins of the air-filled dilated bowel. In an acutely ill patient, these mucosal islands indicate acute destruction of the surrounding mucosa (Brooke and Sampson, 1964). After inspection o f the plain film, barium is run into the colon until the level of the splenic flexure or mid transverse colon is reached, or until the patient complains of pain. In procto-colitis it usually suffices to stop the administration of barium as soon as formed faeces are encountered. Although contrary to general principles, the lack of demonstration by the instant enema technique of the right colon, should this not fill, does not appear to lead to significant omissions in the diagnosis of pathology in patients with distal procto-colitis. The rectum is then drained o f barium prior to air insuffiation and in this context the tube used to administer the barium needs

Fig. 1 - Lateral view of rectum. The end of the tube of the large balloon catheter is shown firmly wedged against the bowel wall.

whenever possible to have a sufficiently wide lumen to allow free drainage. Occasionally a soft rubber catheter, of necessarily small bore, may be required for patients with painful ano-rectal disease or strie. ture formation;the use of catheters with an inflatable balloon is in any event controversial and is certainly contra-indicated in the presence of active inflarn. matory disease o f the rectum. Where this balloon catheter has been used it is not uncommon to see the tube end wedged firmly against the bowel wall (Fig. 1), which in the presence of a friable and inflamed mucosa is clearly undesirable. Drainage of the rectal barium at this stage relieves much o f the dis. comfort of the examination. Air is then injected gently through a Higginson's syringe which may be connected to the tube or inserted directly into the rectum. If only the distal colon has filled with barium, injection of the air with the patient in the prone (or supine) position usually suffices to produce satisfactory air distension. Otherwise air insufflati0n may be continued with the patient rotating in turn through 360 ° , as in the full double contrast enema (Young, 1969). Fluoroscopy is kept to a minimum

Fig. 2 - Ulcerative colitis, prone film. Disease extends to about the level of the hepatic flexure.

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Fig. 4 - Ulcerative colitis, erect film (same patient as Fig. 3). T h e proximal limit o f disease is dearly shown at the splenic flexure.

Fig. 3 - Ulcerative colitis, lateral film (same patient as Fig. 4), showing widening of t h e presacral space.

during the examination, being used essentially to observe the flow of barium and to check the degree of air distension. Insufflation with air may be monitored by fluoroscopy or by palpation o f the abdomen. The occurrence of pain, or an inability to see or feel this normal intraluminal passage of air, requires immediate reassessment. When performed in this way the injection of air even in the presence of acute inflammation with an ulcerated, friable and haemorrhagic mucosa seems in no way to represent a particular hazard. Very occasionally the occurrence of abdominal pain, local tenderness and increased fever shortly after the examination in patients with severe disease has suggested the possibility of a local Perforation, but such cases are extremely uncommon and have never been associated with demonstrable free gas or required active intervention.

Three standard films are then obtained, a prone and left lateral with the overcouch tube (Figs 2 and 3 respectively) and an erect film (Fig. 4) which may be overcouch or taken on a 35 x 35 cassette with the undercouch tube.

RESULTS It is not the purpose of this paper to discuss in any detail the radiological signs which may be found in colonic inflammatory disease on the double contrast enema but it may be helpful to consider briefly some o f the main radiological abnormalities as an illustration o f the technique. The principal aim of the technique is to demonstrate and document the degree and extent of the mucosal lesion. It is accepted that the radiological appearances may be normal despite minor sigmoidoscopic abnormality; a loss of vascular pattern for instance is not reflected in detectable radiological change. The barium enema findings otherwise correlate

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Fig. 5 - Prone film in ulcerative colitis. Fine granularity distally; faecal content and normal mucosal line in the descending colon.

Fig. 6 - Coarse granularity in ulcerative colitis.

well with sigmoidoscopic appearances (Simpkins and Stevenson, 1972), although the results of colonoscopy show that radiology may underestimate the extent of disease in a proportion of patients (Williams, 1975), The double contrast enema coats the mucosal surface of the colon with a thin, even layer of barium,, this barium-coated mucosal surface seen tangentially against the air distended lumen is referred to as the mucosal line, which is normally thin, sharp and un. broken. In the presence of early inflammation this line becomes blurred and slightly thickened and such early change is accompanied, in procto-colitis, by a faint mucosal granularity of fine punctate type visible en .face. It is in the demonstration of the detail of the mucosal surface that the double contrast study is superior to a single contrast study in the detection

Fig. 7 - Prone film showing sub-total ulcerative colitis with unusually deep collar-stud ulceration.

Fig. 8 - Marginal spiculation seen in the transverse colon on a single, contrast enema due to filling of the innominate grooves.

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Fig. 9 - P o s t - i n f l a m m a t o r y polyp f o r m a t i o n in ulcerative colitis.

of the early changes of inflammatory disease. In the single contrast enema the mucosal surface is shown only at the margin of the barium-filled bowel, or on an after evacuation film. The comparison

Fig. 10 - Erect film showing a clinically unsuspected active total ulcerative colitis.

Fig. 11 - Mucosal granularity in ulcerative colitis extending Proximally into the descending colon.

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between the normal mucosal line in the descending colon and fine granularity in the rectum and sigm0id is shown in Fig. 5. More severe disease is reflected by coarser punctate opacification (coarse granularity) and the mucosal line here usually appears beaded (Fig. 6). Frank ulceration is clearly shown as circular pools of barium en face and marginal projections of barium outwards in profile; deeper ulcers may be of collar-stud type (Fig. 7). In the recognition of early disease the presence of signs of mucosal inflammation must be distinguished from the artefacts produced by filling of the socalled innominate grooves of the colon (Williams, 1965) (Fig. 8). The marginal projections here are thin and spiky, may be visible on some films but not on others and are particularly seen in single contrast studies, often on the after evacuation film. Quite frequently the marginal projections can be seen to form a palisade of varying regularity and to continue into fine parallel linear streaks along the circumference of the bowel. One presumes that this effect is related to barium particle size and consistency, since it is virtually never seen with Unibaryt-C (4kg in 2½ litres of water). There may be vaiying degrees of inflammatory polyp formation (Fig. 9) and where ulceration and polypoid change coexist, the term 'mamillation' has been used in the descriptive sense (Young, 1969). Haustral abnormalities may of course also be evident, tending towards a uniform

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Fig. 12 - Single prone film obtained at short-term follow-up showing marked exacerbation o f disease (same patient as Fig. 11).

Fig. 13 - Crohn's disease of the right colon with ulceration, narrowing and deep fissuring. The colon elsewhere is normal,

diminution or loss in ulcerative colitis and characteristically patchy and eccentric loss in Crohn's disease. In this context it must be remembered that lack of haustration in the left colon may be a normal variant. Not infrequently the instant enema shows an active total colitis in patients where disease was thought clinically to be merely distal (Fig. 10). When used for short-term follow-up, as for instance to assess response to medical treatment where the clinical result is equivocal, a repeat examination with a single prone film is usually quite sufficient to show whether the disease is improving or worsening (Figs. 11, 12). In Crohn's colitis the degree and extent of mucosal involvement is shown in the same way. In this condition, the presence of strictures, mucosal oedema, cobblestoning, ulceration and fissuring are readily shown. Figs 13-15 show examples of the instant enema in patients with Crohn's disease; the first two show colonic involvement and in the third recurrence of Crohn's disease is demonstrated in the small bowel, following previous surgery.

DISCUSSION In our experience the prone, lateral and erect views suffice to give the necessary information as to the extent and degree of involvement in patients with inflammatory disease of the colon. The prone film shows the overall extent of disease and the colonic haustral pattern; it usually affords a satisfactory air contrast view of the distal colon. If on this film the mucosal detail in the distal colon is obscured by a pool of barium, a supine film ensures a redistribution of barium and air to give an air contrast view of the previously barium filled segment. Substitution of a supine film for the prone film may be made prior to radiography if such a pool of barium is observed on fluoroscopy. Alternatively, a right lateral decubitus film may be obtained. These alternative or additional views are seldom necessary unless too much barium is administered. The lateral film shows the recto-sigmoid junction and the width of the presacral space. The presacral space is frequently, but by no means invariably, increased in proctitis (Chrispin and Kelsey

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Fig. 14 - Crohn's disease of the ano-rectal region spreading in continuity t h r o u g h the left colon,

Fig. 15 - Recurrent Crohn's disease in the distal small bowel following a previous ileo-transverse colostomy.

Fry, 1963; Edling and Eklof, 1963) and increase and decrease in width may parallel exacerbation and remission of disease. In some patients this space may remain permanently increased in size (above 1 cm) in association with a narrowed and tubular rectum (Farthing and Lennard-Jones, in the press). It is generally considered that patients in this group may not only have distressing urgency and possible incontinence but are also unsuitable for consideration of surgical treatment by colectomy and ileo-rectal anastomosis. On the other hand, an increased width of the presacral space in the absence of any other sign of mucosal disease and in the presence of a normally distended rectum can usually be ignored and is often related to fat deposition in the obese. Other causes of enlargement of the presacral space should not as a rule cause confusion (Teplick et al., 1978). The erect film (Fig. 4) shows the transverse colon and flexures in particular and also the ascending colon and caecum 4f4hese have filled. In procto-colitis the criterion we have used in deciding whether an instant enema or an enema after full preparation is to be performed is, essentially, the presence or absence of sigmoidoscopically visible inflammation. Such a simple differentiation of the method of examination is readily made since

sigmoidoscopy should always precede radiological examination. The instant enema is inadequate for the examination of patients in whom the diagnosis of procto-colltis is by supposition alone. If endoscopy shows only a mild proctitis with a defined upper limit of disease, an enema after full preparation is usually indicated. We have also found the instant enema to be satisfactory for the investigation of patients with Crohn's disease of the colon in an acute phase. In patients with suspected early Crohn's colitis, or those with an established diagnosis but quiescent disease, it is our present policy to give full preparation. In the former group a clean colon is often required to identify the discrete, shallow ulceration which may occur within an otherwise normal mucosa, and in the latter group the colon frequently contains a considerable faecal residue. When for any reason there is doubt about the appropriate mode of examination, a decision may be made by inspection of a preliminary plain film of the abdomen. The presence on this film of formed faecal content throughout the colon argues very strongly against the presence of active mucosal disease. In these circumstances, therefore, full preparation is required.

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In view of the lack of need for preparation, patients when required may be referred directly from the out-patient department for examination (hence the title 'instant'), so that investigation may be completed at a single session, providing the departmental work-load allows this. We do not usually regard sigmoidoscopy as a contra4ndication to X-ray examination at the same session. In patients who are acutely ill it may, however, be wise to allow a lapse of 24 hours between the two examinations. It is also true to say that an excessive amount of air remaining after endoscopy, and particularly colonoscopy, may impede the flow of barium and impair mucosal coating. In the past we have not regarded small mucosal biopsies as a contra-indication to barium enema examination if necessary on the same day, but when a biopsy has been taken it is probably wise as a general rule to allow a lapse of 10 days before proceeding with a barium enema. Young (1969) and Simpkins and Young (1971) have pointed out that patients with total colitis of long standing are not suitable for examination by the instant enema technique, owing to the possibility of overlooking a complicating carcinoma. The need for preparation in this group hinges on the activity of the disease: if the disease is active in a patient with total colitis, the whole colon is usually readily outlined by this technique and in these circumstances the risk of missing a radiologically demonstrable carcinoma is negligible. On the other hand, patients with a total colitis in remission should certainly be examined after full preparation. The whole problem of the detection of neoplasm in these patients is fraught with difficulty. This is partly because the growth if it occurs tends to be plaque-like, which may be difficult to detect, or in the form of a stricture, which may be indistinguishable from a benign lesion. Many of the strictures which lead to suspicion of neoplasm in patients with long-standing colitis have been shown on colonoscopic biopsy to be benign, as in a recent series of 28 patients with radiologically demonstrated strictures referred for colonoscopy at St Mark's Hospital, in which only three were found to be malignant (Hunt etaL, 1975). These benign strictures are attributed to hypertrophy, of the muscularis mucosae, which may occur in both ulcerative colitis and Crohn's disease. The subject of carcinoma in long-standing ulcerative colitis has been reviewed by Counsell and Dukes (1952), Fennessey et al. (1968) and Simpkins and Young (1971). In practice it seems that malignant change, although an ever-present threat in the high-risk group of patients, is in fact, relatively uncommon (Edwards and Truelove, 1964; Ritchie, 1971; Lennard-Jones et aL, 1974; Ritchie, 1974; Lennard-Jones et aL, 1977). The evaluation of

pre-malignant change in rectal biopsies (Morson and Pang, 1967; Riddell and Morson, 1974) and the increasing use of colonoscopy with multiple endo. scopic biopsies (Hunt et al., 1975) may in tirae relieve the radiologist of some of his responsibility in these patients. CONCLUSIONS The instant or unprepared double contrast enema is a recommended technique of investigation for patients with known inflammatory disease of the colon in an active phase, affording accurate radio. logical information with the least disturbance to the patient. The presence of faecal content does not in the great majority of cases lead to significant diagnostic difficulty since even where present the insufflation of air allows demonstration of the mucosal line. A prepared enema is indicated where the diagnosis of inflammation is in doubt, either on clinical grounds or because of previously equivocal contrast studies. Similarly, a repeat examination after prepara. tion may occasionally b e required if the result of the instant enema itself is equivocal due for instance to the presence of faecal material adherent to the mucosa. In practice we find that this is very seldom necessary. The avoidance of pain and distress is particularly important in these patients as they are often ill and are likely to require multiple examinations during the course of their illness (Young, 1969). The following reasons are suggested to account for the better tolerance of the instant double contrast enema by the patient with inflammatory disease of the colon, as opposed to other forms of contrast study. (i) Possibly distressing bowel preparation is omitted. (ii)No attempt is made to fill the whole colon with barium and hence the patient is spared the increasing urge to evacuate as the colon, and particularly the rectum, distends. (iii) The rectum is drained of barium as soon as possible, again tending to reduce the desire to evacuate. (iv) Air, on the whole, seems to be better tolerated than barium. (v) The technique reduces the radiation dose to a minimum compatible with diagnostic accuracy which is important in patients who may require repeated studies.

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