What is a Colonoscopy?

What is a Colonoscopy?

The assessment of credibility of clinical criteria for setting up indications for performance of virtual colonoscopy – multispiral computed tomography

Abstract

Despite to increased opportunities in diagnostics of neoplasms, colorectal cancer in 70-93% of cases is diagnosed in advanced stages and colorectal polyps, as a general rule, are found occasionally, when patients are checked up due to some other diseases [1,3,6,7]. According to H.D. Bond et al. [9], 95% of malignant tumors develop from benign adenomatous polyps. Negative perception  of colonoscopy (painful and long lasting procedure) by patients, low probability of full examination of colon are the factors, that pushed for expanding exploratory possibilities in cases of colonic polyps and polyposis. [6,8,15,18]. Virtual colonoscopy multispiral computed tomography (VC MSCT) became popular in abdominal surgery as a method of targeted identification of pathological focus and noninvasive assessment of its histological structure. [2,5,11,12,16]. The indications for VC are as follows: appearance and manifestation of clinical signs, directly or indirectly indicating on colonic lesion, as well as availability of well known risk factors for development of malignant tumors, including the patient’s age over 50. [2,5,17,19,20].

At the same time, the indications for VC MSCT in patients with colonic polyposis are not perfectly defined. In

market economy and insurance medicine environment early detection of diseases is both important for health of patients and allows to avoid possible claims to doctor for caused health impairment and unnecessary financial expenditures.

VC MSCT is one of the most expensive examination methods [4]. That is why optimization of diagnostic tests, identification and refinement of indications for VC MSCT is one of urgent issues of modern diagnostic medicine.

Material and methods. The survey is based on retrospective analysis of case reports of 229 patients undergone VC MSCT of colon. 138 of these patients were operated on to remove colonic polyps. The patients age varied between 15 and 42 years (39.0±0.5), 92  (66.7%) were males and 46 (33.3%) – females. VCT of colon had been performed on the device manufactured by Philips (Netherland).

Criteria for exclusion from the survey: signs of obstruction or ischemia of colon; biopsy or colonic polyp removal less than 14 days before the examination; retention of barium after X-ray examination of abdominal cavity; existence of colostomy; cases with allergy to medicaments; cases of confirmed glucagon-producing tumor, unsulinoma, pheochromoblastoma, pregnancy, absolute claustrophobia [10,13.14]

The data acquired was statistically treated using the Statistica V.6.0 software. The difference was considered significant at Р≤0,05.

Results and discussions. The diagnosis of colonic polyps and polyposis is made on the basis of instrumental (X-ray and endoscopy) examination. Nevertheless, clinical investigation methods are also of high importance:

• Patient claims allow to reveal symptoms related to digestion and absorbtion problems, intestinal discomfort, pathologic discharges;

•  Anamnesis — here one can collect information about availability of family polyposis, experienced inflammatory diseases of colon, colitis or other preceding diseases;

• Data of objective investigation: examination, palpation and percussion of abdomen.

• Digital investigation of rectum.

In 106 (46,3%) out of 229 examined cases there have been notified hemorrhages during or after defecation, in 58 (25,3%) – pain in upper and lower parts of intestine, in 41 (17,9%) stool was formed or semiformed with fluid mucus or without mucus, in 24 (10,5%) patients there was revealed significant weight loss in the last 6-12 months, meteorism (table 1).

Table 1. Clinical signs used for making provisional diagnosis of colonic polyposis, abs. (%)

Symptom

Total out of 229 patients

VCT diagnosis

True-positive result

True-negative result

False positive result

False-negative result

Bleeding during or after defecation

86 (37,6)

66 (28,8)

3 (1,31)

2 (0,87)

15 (6,6)

Pains in upper or lower part of abdomen, general weakness, frequent stool

58 (25,3)

11 (4,8)

17 (7,4)

19 (8,3)

11 (4,8)

Formed or semiformed stool with fluid mucus or without mucus

41 (17,9)

23 (10,0)

-

-

18 (7,9)

Significant body weight loss in the last 6 or 12 months, meteorism.

44 (19,2)

8 (3,5)

22 (9,6)

9 (3,9)

5 (2,2)

Total

229 (100)

108 (47,2)

42 (18,3)

30 (13,1)

49 (21,4)

Until quite recently the preparation of colon to examination traditionally used to boil down to intake of laxatives (as a rule – the castor oil) and cleansing enemas. However taking into account the world experience the need of using alternative methods of defecation of the colon became obvious, and the lavage method is one of them  [4,6].

Since 2006 we started to use the drug “Fortrans”, which is iso-osmotic solution of polyethylene glycol  (Macrogol 4000) and electrolytes, for preparation of colon to colonoscopy. Thanks to macrogol, which is not metabolized and not absorbed in intestine, there is achieved effective gut lavage at oral intake without any significant side effects. There were not registered any metabolic disorders and aggravation of patient’s condition.

After MSCT examination colonic polyposis has been found at 138 (60,3%) patients, and in 108 (47,2%) out of them all clinical signs fully concurred with VC MSCT data, in 30 (13,1%) not full recurrence has been registered, i.e. the result was false positive. In 42 (18,3%) patients there were some signs, specific for colonic polyposis, however the diagnosis was not confirmed at VC MSCT – true negative result. In 49 (21,4%) patients VC MSCT could not reveal colonic polyposis, regardless to availability of all clinical signs of the disease – false negative result.

The thorough examination of those patients with true-negative and false-negative results allowed to identify that the cause of hemorrhage during defecation in 2 (0,77%) patients was hemorroids, in 1 (0,44%) – proctosigmoiditis, in 2 (0,87%) patients – fissures of anal canal, in 1 (0,44%) – pararectal fistulas, in 5 (2,2%) patients – nonspecific ulcerative colitis, in 7 (3,1%) patients – gastric and duodenal ulcers. Pains in upper and lower parts of abdomen with general weakness and frequent stools were specific for the patients with chronic ulcerative colitis and enterocolitis. In males the pains in the lower part of abdomen, weakness and loose stools have been found in cases of chronic prostatitis, cystitis, urethritis, pyelonephritis, in females – the symptoms basically were found in concurrence with endometritis and ovarial endometriosis, chronic cystitis, chronic vulvovaginitis.

In females the diseases of small pelvis often were concurrent with lung diseases. Thus, chronic pneumonia has been found in 3 (1,3%) patients, chronic obstructive bronchitis – in 2 (0,87%). General weakness, pains right hypochondrium with frequent stools, often containing mucus have been observed in patients with chronic hepatitis – 46 (2,6%).

The polyps revealed have been localized (table 2) in the right colon and hepatic flexure (27,5%), cecum (18,8%), left colon and splenic flexure (15,2%), rectum (14,5%), sigmoid colon (13,0%), rarely in transverse colon (10,9%). More frequently there were found solitary polyps (34,1%), duffuse polyposis of colon (33,3%) and Peuta-Jeghers syndrome (10,9%). Quite often there were found multiple polyps (18,8%); the Gardner’s symptom was found rarely (2,9%).

Table 2. Characteristics of the polyps revealed at VC MSTC

Diagnosis

Number of patients, n=138

Abs.

%

Localization:

- rectum

20

14,5

- sigmoid colon

15

10,9

- colon transversum and left colon

Colon and splenic flexure

15

10,9

- right colon and hepatic flexure

38

27,5

- cecum

26

18,8

Solitary Polyp

47

34,1

Multiple polyps

26

18,8

Diffuse polyposis

46

33,3

Gardner’s Syndrome

4

2,9

Peuta-Jeghers Syndrome

15

10,9

Histological types of the polyps:

- glandular

52

37,7

- adenomatous

58

42,0

- villous

18

13,0

Non-polypous formations

10

7,3

Size of polyp, mm:

- up to 0,1

66

47,8

- from 1 to 7

53

38,4

- from 8 to 10

11

8,0

- over 10

8

5,8

At histological examination there were found more frequently adenomatous (42,0%), glandular (37,7%), villous (13,0%) polyps, non-polypous formations were found rarely (7,3%). The formation was considered as non-polypous if its height was less than half of its diameter. The morphological classification of the formation has been performed in accordance with Paris classification of epithelial tumors, which identifies pedunculated polypous formations (0-1р), which were found in 2 (1,4%) patients, with wide base (0-1S) – in 1 (0,7%) patient; non-polypous formations – flat elevated (0-IIа) – in 2 (1,4%), flat (0-IIв) – in 3 (2,2%) и and flat recessed (0-IIс) – у 1 (0,7%), as well as ulcerated neoplasm (0-III) – in 1 (0,7%) patient. Flat elevated formations which were more than 20 mm have been considered as lateraly spreading tumors – LST. The sizes of the polyps were in the focus of our interest, because it was of high importance for comparative evaluation of diagnostic effectiveness of the examination methods in use.

At VC MSCT the most frequently diagnosed polyps were less than 0,1 mm – 47,8% of cases, as well as from 1 to 7 mm – 38,4%, and not so often – from  8 to 10 mm – 8,0% и more than 10 мм – 5,8%.

Thus, after analysis of the diagnostic tests the diagnosis of colonic polyposis was not confirmed in 39,7% of patients. The sensitivity of prognostic factors made 97,8% (Р<0,001), specificity – 58,3% (Р>0,05), diagnostic accuracy – 65,5% (Р>0,05). Low specificity and diagnostic accuracy argues for the need to search the ways for further optimization of diagnostic programs, specifying indications to perform VC MSCT in patients suspected to have colonic polyposis. This would allow to start the treatment course earlier, reduce the unnecessary expenses of patients related to VC MSCT. It would be suitable to note, that VC MSCT in Uzbekistan costs to patient 120’000 Uzbek Soums (it is about 80 USD). Making more precise diagnosis would save funds of 91 patients with preliminary diagnosis of colonic polyposis. Besides, the data acquired proves the appropriateness of thorough selection of patients using additional screening  for refining the diagnosis.

Summary:

1. In 39.7% cases the VC MSCT does not confirm the diagnosis of colonic polyposis.

2. The important cause of the high frequency of diagnostic errors  is low diagnostic specificity and diagnostic preciseness of the clinical symptoms used for making preliminary diagnosis of colonic polyposis.

References:

1. Belous Т.А.. Pathomorphology of precancerous conditions of colon.//Russian J. Of Gastroenterology, Hepathology and Coloproctology. – 2002. – № 4.0. –P.50-56.
2. Virtual colonoscopy: procedure./ Khomoutova E.U., Ignatieva Y.T., Skripkin D.A., Phillipova Y.G.//Radiology – Practice. – 2009. – №2. – P.21-27.
3. Greenhalh T. Basics of Evidence Based Medicine./Transl. from Engl.- M.Geotar-Med. – 2004. –P. 240.
4. Nikiforov, P.A. Bazarova, M.A. Nikitina S.A., Golubeva S.V.. The first experience of use of “Fortrans” in preparing to colonoscopy.//Materials of the 3rd Russian Gastroenterological week. Russian J. Of Gastroenterology, Hepatology and Coloproctology. – 1997. – № 5.–P.93
5. Khomoutova E.Y., Ignatiev Y.T. Multispiral computed virtual colonoscopy in diagnostics of colonic pathology (Review)//Med. Visulisation. – 2008. – №5. – p.73.
6. Cherkasov M.F. Opportunities of screening method in colorectal cancer case finding. // Actual issues of Coloproctology., Moscow, Medicine, 2006
7. Adler G., Fiocchi C., Vorobiev G.J., Lasebnik L.B. Inflammatory Bowel Disease-Diagnostic and Therapevtic Stratigies// Falk Symposium 154. – 2007. – P.237.
8. Akemi Ito. Indications and limitations of endoscopic surgery on colorectal tumors Digestive Endoscopy,V12, 2000, s16
9. Bond J.H. Polyp Guideline: diagnosis, treatment, and surveillance for patients with colorectal polyps //Amer. J. Gastroenterol. –2000. – Vol.95, №11. – P.46–54.
10. Bories E, Pesenti C, Monges G, Lelong B, Moutardier V, Delpero JR, Giovannini M. Endoscopic mucosal resection for advanced sessile adenoma and early-stage colorectal carcinoma. Endoscopy 2006; 38: 231-235
11. CT colonography predictably overestimates colonic length and distance to polyps compared with optical colonoscopy / Duncan JE, McNally MP, Sweeney WB, et al // AJR Am J. Roentgenol. – 2009. – Vol.193, N5. – P.1291-5.
12. CT colonography: accuracy of initial interpretation by radiographers in routine clinical practice / Burling D, Wylie P, Gupta A, et al  // Clin Radiol. – 2010. – Vol.65, 2. – P.126-32.
13. Endoscopic mucosal resection for colonic non-polypoid neoplasms /Ning-Yao Su, Chen-Ming Hsu, Yu-Pin Ho et al. //Amer J. Gastroenterol. – 2005. – Vol.100. – P.2174-2179.
14. Ming-Yao Su, Chen-Ming Hsu, Yu-Pin Ho et al. Endoscopic mucosal resection for colonie non-polypoid neoplasma// Ann. J. Gastroenterol.-2005. –Vol. 100. –P.2174-2179.  Endoscopic mucosal resection for colonic non-polypoid neoplasms /Ning-Yao Su, Chen-Ming Hsu, Yu-Pin Ho et al. //Amer J. Gastroenterol. – 2005. – Vol.100. – P.2174-2179.
15. Nakajima T. Problem of total colonoscopy for mass screening of colorectal cancer //Dis. Colon. Rectum. – 2004. – Vol.47. – P.1052.
16. Pickhard P.J. Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults //New Engl. J. Med. – 2003. – Vol.349. – P.2191-2200.
17. Rivera M. Virtual colonoscopy //Gastroenterology. – 2003. – Vol.3. – P.284-287.
18. Rubito C.A. Classification of Colorectal Polyps: Guidelines for the Endoscopist //Endoscopy. – 2002. – Vol. 112. – P.226 – 236.
19. Suuzuk K, Rockey DC, Dachman AH.CT colonography: advanced computer-aided detection scheme utilizing MTANNs for detection of “missed” polyps in a multicenter clinical trial // Med Phys. – 2010. – Vol.37, N 1. – P.12-21.
20. Thornton E, Morrin MM, Yee J. Current status of MR colonography // Radiographics. – 2010. – Vol.30, N 1. – P.201-18.

About the Author

Navrusov S.N., Sapaev D.A., Sapaeva Sh. A.

Republican Research Center of Coloproctology, Tashkent Medical Academy

What is a Colonoscopy?

Incoming search terms:

• fortrans colonoscopy
• how bad is it that I have not had a colonoscopy at 46 with family polyposis