Fluoroscopic investigations of the large bowel

CHAPTER 13 Fluoroscopic investigations of the large bowel





Introduction


Halligan et al. (2003) and Halligan (2004) have suggested that ‘a barium enema list is not the attractive proposition it once was’ and that ‘radiologists, both trainees and consultants, are less inclined to take an interest’ in barium enema; in addition, the lack of interest is compounded by the perception that the examination is ‘old fashioned and behind the cutting edge of imaging’. The belief that the sensitivity of the double contrast barium enema (DCBE) for colorectal cancer (CRC) is poor at only about 85% adds to the lukewarm view of the examination. Indeed, Shorvon (2003) implied that there is no room for improving the DCBE and that it is ‘on a developmental plateau’.


It has been suggested by Glick (1997) that there has been a bias against the DCBE associated with a number of studies in which 75–95% of missed cancers were perceptive errors rather than technical error. This finding would suggest that many of the possible shortcomings of the DCBE examination could be overcome by double reading.


However, it is possible to achieve a very high sensitivity if appropriate attention is given to technique. It may be the case that the image sequence of the DCBE has been optimized, but fluoroscopy equipment continues to improve and is now producing higher quality images at a fraction of the radiation dose required just a few years ago.


In the USA, the DCBE was considered to detect the majority of clinically important lesions and was therefore deemed to be an appropriate method for colorectal cancer screening (Winawer et al., 1997). These considerations were supported by the American College of Gastroenterology, The American Association of Colon and Rectal Surgeons and the American Society of Gastrointestinal Endoscopy. A survey of US radiologists, published in 2002, indicated that 75% believe the DCBE to be a ‘very effective’ colorectal cancer screening procedure and, at that time, Medicare approved DCBE as a CRC screening modality in the USA (Klabunde et al., 2002). Ciatto and Castiglione (2002), in reviewing the use of the DCBE within a screening program, also concluded that DCBE was a useful adjunct to screening colonoscopy.



Complications


Vora and Chapman (2004) reviewed 348 000 barium enemas performed by 59 radiographers; 89 complications were reported (1:3900) including five deaths (a mortality rate of 1:70 000). Culpan and Chapman (2002) reported on 54 complications in a review of 134 700 barium enema examinations performed over a 3-year period by 250 radiographers who had attended the Leeds barium enema training course. The complication rate was 1:2500; three deaths indicated a mortality rate of 1:44 900.


The complication and mortality rates for radiographers are not dissimilar to those reported by Blakeborough et al. (1997a) in reviewing the responses of 756 UK consultant radiologists who had performed 738 216 barium enemas in a 3-year period. A total of 82 complications were reported by 77 radiologists (1:9000) including three deaths (a mortality rate of 1:56 786).


Complications associated with the barium enema include perforations, cardiac events and cerebrovascular accidents. In reviewing rectal perforation after a barium enema, de Freiter et al. (2006) report that the most catastrophic course with a high mortality rate develops from sepsis and peritonitis resulting from intraperitoneal perforation. Also reported as prognostically unfavorable is the venous intravasation of barium.


Comment was also made in this paper regarding the introduction of excessive intracolonic pressures, excessive colonic distension and also concern regarding the use of rectal balloon catheters. These results compare favorably with colonoscopy (de Freiter et al., 2006). Updating the British Society of Gastroenterology guidelines, Teague (2003) refered to previous audits including one by Quine et al. (1995) (in which the 30 day mortality was found to be 1:2000) and he indicated there was no evidence to suggest that mortality rates had improved significantly since the 1990s.




Using smooth muscle relaxants


Hypotonia of the colon and rectum has a number of beneficial effects:






The rectal infusion of agents such as 30 ml of peppermint oil solution has been demonstrated to have an antispasmodic effect (Asao et al., 2003). The most commonly used hypotonic agents are 20 mg in 1 ml hyoscine butylbromide (Buscopan) or 1 mg in 1 ml glucagon (Fink and Aylward, 1995; Goei et al., 1996). The IV injection of Buscopan is likely to have no effect on the diagnostic quality of the examination whether it is given before or after the infusion of barium (Elson et al., 2000).


It is not uncommon practice to avoid giving Buscopan in patients who have glaucoma, however, it has been reported by Fink and Aylward (1995) that the risk only relates to patients with undiagnosed (therefore untreated) angle closure glaucoma. The recommendation is to abandon the question about the presence of glaucoma and advise instead that patients should seek urgent medical advice should eye pain and visual loss develop. However, the authors did recommend caution in the presence of heart disease as this was considered of significant importance (Fink and Aylward, 1995).


The benefits and contraindications of Buscopan (from the Boehringer Ingelheim professional leaflet on 20 mg/1 ml solution ‘Buscopan’) and glucagon (from Novo Nordisk professional leaflet on glucagen 1 mg hypokit) are given in Table 13.1.


Table 13.1 Hyascine butylbromide (Buscopan) versus glucagon (Glucagen)
























































Hypotonic agent Buscopan Glucagen
Benefits Good hypotonia achieved Can be used in the presence of narrow angled glaucoma
Good colonic distension
Good active duration lasting for most of the examination
Significantly cheaper
Side effects Temporary tachycardia Can cause nausea
Blurred vision Shorter acting
Dizziness Poorer colonic distension
Drying of the mouth  
Contraindications Myasthenia gravis Insulin dependent diabetes (glucagon has the opposite effect to insulin)
Megacolon
Narrow angle glaucoma
Tachycardia
Prostatic enlargement with urinary retention
GI stenosis or paralytic ileus
Poorly controlled angina
Relative contraindications   Elderly patient with a heart condition
Pheochromocytoma
Insulinoma
Glucagonoma


The double contrast barium enema


Good bowel preparation is an important precursor to a successful DCBE (see Chapter 3). Poor coating or residue can mask or mimic pathology and should be reported as such and an alternative strategy should be suggested (e.g. a limited repeat examination following further bowel preparation, to review those areas not well demonstrated).


Prior to commencement of the examination, talking to the patient can determine the success of the bowel preparation as well as contraindications to the use of hypotonic agents. The practitioner can also identify any limitations of mobility and the nature and degree of any comorbidities, as this might have a bearing on the approach to the examination.


The predominant difference in rectal tube types is related to whether or not they have a balloon cuff. There is limited advantage to having a cuff, as it can assist with contrast retention in a patient with poor sphincter control. However, significant complications can occur, such as perforation, following inadvertent cuff insufflation and barium infusion within the vagina due to incorrect tube placement. Colonic perforation following cuff insufflation in the rectum is associated with high, artificially induced, intraluminal pressure. It has been advised that balloon cuffs should be avoided (Blakeborough et al., 1997b; Chapman and Blakeborough, 1998; Culpan and Chapman, 2002).


The objective standard of all DCBE techniques should be the same:


To provide a collective series of images that demonstrate the whole of the distended colon and rectum in double contrast (with a record of the appendix, terminal ileum or ileocecal valve to confirm arrival at the cecal pole).


If the standard has not been met, the examination, although it may be considered diagnostic is, by definition, technically suboptimal.


The technique described below using ‘C’ arm fluoroscopy is only one of a number of approaches to the DCBE. As long as the objective standards are met and there is consistency of approach, local variances need not be of any consequence.



Air or CO2 double contrast


Air or carbon dioxide (CO2) can be given to insufflate the bowel. Although practitioners need to be aware of the risks associated with over distension of the colon, if the bowel is collapsed in any view, consideration should be given to increasing gas input.


There are numerous papers discussing the benefits of air and CO2. CO2 dissolves faster and, although the mucosal coating is the same, the discomfort of CO2 is reported as less. However, air is considered to provide better distension and this might outweigh the advantages in patient acceptability that CO2 provides. Should colic result from air distension or should the effect of the chosen hypotonic agent wear off, maintaining rectal intubation will allow colonic decompression at any time but, particularly, as a routine at the end of the examination (Scullion et al., 1995, Holemans et al., 1998). One example of a DCBE protocol follows:















As imaging of the sigmoid colon has been completed, we are not worried at this point that the direction of the patient rotation has been aiding the passage of barium into and over the hepatic flexure. Turning the patient towards the left anterior oblique (LAO), the colon is screened both to make sure there is enough barium to demonstrate the right colon and to identify where barium is pooling in the region of the splenic flexure and descending colon. To remove the pooled barium in the left colon, the table is tilted head up (it is not normally necessary to stand the table erect both from the view point of patient comfort and to reduce the risk of them becoming hypotensive and possibly fainting (Roach et al., 2001)).


Dec 26, 2015 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Fluoroscopic investigations of the large bowel
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