Current issues of ACP Journal Club are published in Annals of Internal Medicine


Diagnosis

Hydrocolonic sonography was better than conventional abdominal sonography and approached the accuracy of colonoscopy for detecting colonic tumors

ACP J Club. 1992 Nov-Dec;117:86. doi:10.7326/ACPJC-1992-117-3-086


Source Citation

Limberg B. Diagnosis and staging of colonic tumors by conventional abdominal sonography as compared with hydrocolonic sonography. N Engl J Med. 1992 Jul 9;327:65-9.


Abstract

Objective

To compare hydrocolonic sonography with conventional transabdominal sonography in the diagnosis and staging of colonic tumors using colonoscopy as the diagnostic standard.

Design

Blinded, independent comparison of the diagnostic performance of colonoscopy and both sonograms.

Setting

University-affiliated hospital in Darmstadt, Germany.

Patients

300 consecutive patients (mean age 56 y) referred for colonoscopy to evaluate abdominal pain, diarrhea, weight loss, or fecal occult blood.

Description of test and diagnostic standard

During hydrocolonic sonography, a total of up to 1500 mL of water was instilled into the colon after an intravenous injection of 20 mg of scopolamine N-butyl bromide for bowel relaxation. Continuous transabdominal sonographic examination of the large intestine was carried out beginning at the time of water instillation using a real-time scanning device. Diagnosis of colonic tumors was based on evidence of intraluminal masses fixed to the wall, the appearance of lesions within the intestinal-wall structure and the surrounding connective tissue, or both. Conventional transabdominal sonography was done with 3.5-, 5.0-, and 7.5-MHz transducers. A colonic tumor was diagnosed when there was evidence of a pathologic bowel loop. Colonoscopy, the diagnostic standard, always followed hydrocolonic sonography. Polypectomy and histologic examination were done on all polyps detected.

Main results

A colonic carcinoma was diagnosed by colonoscopy in 29 patients, 28 of whom were correctly diagnosed using hydrocolonic sonography (sensitivity 97% [95% CI 82% to 100%], specificity 100% [CI 99% to 100%]). {The likelihood ratio of a positive test result (+LR) approached infinity and the likelihood ratio of a negative test result [-LR] was 0.03.}* Only 9 of the 29 carcinomas were diagnosed by conventional transabdominal sonography (sensitivity 31% [CI 15% to 51%], specificity 99% [CI 97% to 100%]). {The +LR was 31 and the -LR was 0.70.}* 75% of T2 tumors, 85% of T3 tumors, and 75% of T4 tumors were correctly classified by hydrocolonic sonography (no T1 carcinomas were found). No polyps could be detected by conventional transabdominal sonography, whereas hydrocolonic sonography correctly identified 38 of 42 polyps ≥ 7 mm (sensitivity 91% [CI 77% to 97%], specificity 100% [CI 99% to 100%] {+LR approached infinity and the -LR was 0.09}*) and 3 of 12 polyps < 7 mm (sensitivity 25% [CI 5% to 57%], specificity 97% [CI 94% to 99%] {+LR was 8.3 and the -LR was 0.77}*).

Conclusions

Hydrocolonic sonography was more sensitive than conventional transabdominal sonography in detecting colonic carcinoma and polyps and almost as accurate as colonoscopy for carcinomas and large polyps. More precise staging of colonic tumors was also achieved with hydrocolonic sonography.

Source of funding: Deutsche Krebshilfe.

For article reprint: Dr. B. Limberg, 2nd Department of Internal Medicine, Clinic Wolfenbättel, Academic Hospital of the University of Göttingen, Alter Weg 80, 3340 Wolfenbättel-Braunschweig, Germany.

*Numbers calculated from data in article.


Commentary

What is the best diagnostic test to use in the workup of rectal bleeding and other gastrointestinal symptoms? To the old debate between barium enemas and colonoscopy (1) can now be added a new modality, hydrocolonic sonography. Although conventional transabdominal ultrasonography has not proved useful in the evaluation of large bowel neoplasia, the instillation of water in the colon is a clever innovation. Limberg has previously shown its efficacy in the diagnosis of inflammatory bowel disease (2).

The article by Limberg is an update of an earlier study by this investigator (3), confirming its efficacy in diagnosing colorectal neoplasia in a series of apparently typical patients referred for colonoscopy. It almost equals the sensitivity of colonoscopy in identifying carcinomas and large polyps. Its real competition, however, is with barium enemas, with which it has comparable efficacy, but hydrocolonic sonography avoids radiographic exposure and adds the ability to evaluate the bowel wall and stage the tumors.

Before running out to buy a hydrocolonic ultrasonography kit, however, some questions need to be addressed. Other groups need to replicate Limberg's findings. What is the duration of the procedure? How important are small polyps (< 7 mm), for which this procedure is relatively useless?

Alfred I. Neugut, MD, PhD
Columbia UniversityNew York, New York, USA

Alfred I. Neugut, MD, PhD
Columbia University
New York, New York, USA


References

1. McCarty RL. Colorectal cancer: the case for barium enema. Mayo Clin Proc. 1992;67:253-7.

2. Limberg B. Diagnosis of acute ulcerative colitis and colonic Crohn's disease by colonic sonography. JCU J Clin Ultrasound. 1989;17:25-31.

3. Limberg B. Diagnosis of large bowel tumours by colonic sonography. Lancet. 1990;335:144-6.