Virtual colonoscopy finds significant pathology in patients referred after failed colonoscopy, according to a study presented at the Digestive Disease Week (DDW) meeting in New Orleans. The results show the need for a complete colon exam and highlight VC's strengths in detecting extracolonic abnormalities.
A significant percentage of conventional colonoscopy exams -- generally, about 20%, but as many as half in some studies -- fail because the colonoscope does not reach the cecum for several reasons.
In an effort to determine the value of virtual colonoscopy (also known as CT colonography or CTC), researchers from Utrecht University in the Netherlands reviewed 96 consecutive cases of VC performed after failed colonoscopy to determine the virtual study's diagnostic yield.
The most frequent indications for colonoscopy were iron deficiency anemia (24%), a change in bowel habits (19%), rectal bleeding (18%), colorectal cancer (CRC) screening or surveillance (12%), diarrhea (7%), constipation (8%), abdominal pain (5%), and suspicion of CRC on abdominal ultrasound (2%), Dr. Paul Pullens and colleagues explained in an abstract accompanying their poster presentation.
When colonoscopies in these patients failed to reach the cecum, virtual colonoscopies were ordered. After VC, the researchers reviewed all intra- and extracolonic findings and evaluated them for further diagnostic or therapeutic workup. All of the patients were symptomatic and therefore considered to be at above-average risk of colonic polyps or cancer, they wrote.
The reasons for incomplete colonoscopy were a fixated sigmoid colon (33%), strong angulation of the sigmoid colon (18%), intractable pain during colonoscopy (7%), spastic or atonic colon (7%), obstructive CRC (4%), dolichocolon (3%), abdominal wall herniation (3%), insufficient bowel preparation (3%), undetermined colonic stricture (2%), other (9%), or unreported reasons (9%), the authors reported.
The colonoscope was limited to the left side of the colon in 51% of the cases, the authors noted. By itself, colonoscopy detected six patients (6%) with colorectal cancer and 19 (20%) with polyps.
Subsequent virtual colonoscopy found additional polyps in five patients (5%) and an additional colorectal cancer in two cases (2%), Pullens and his colleagues reported.
Virtual colonoscopy found an additional 12 lesions considered clinically significant in 11 of 96 patients (11%) whose colonoscopy exams had been incomplete. If patients with known CRC are added to the analysis, virtual colonoscopy yielded additional information in seven patients.
"Of the five patients with polyps, a polyp in one patient was found to harbor CRC at second colonoscopy. This polyp was located in a colon part that had been inspected at prior colonoscopy (missed colorectal cancer)," Pullens and colleagues wrote in their abstract.
Significant extracolonic abnormalities were found at CTC in five patients (5%), including fistulizing diverticulitis (n = 2), gastric lymphoma (n = 1), liver abscess (n = 1), and infected embolisms in the renal arteries (n = 1).
"CTC revealed 12 relevant additional lesions (both intra- and extracolonic) in 11 of 96 (11%) patients with incomplete colonoscopy," they concluded.
If staging patients with known colorectal cancer are also considered, virtual colonoscopy yielded additional information in seven patients (six colorectal cancers found with colonoscopy plus one missed cancer), for a total of eight patients (19%) who had clinically relevant additional findings as a result of CTC.
By Eric Barnes
AuntMinine.com staff writer
May 6, 2010
Related Reading
Massive VC study yields trove of extracolonic cancers, March 23, 2010
VC obviates need for colonoscopy even in symptomatic patients, February 24, 2010
VC screening offers a fresh look at urolithiasis, February 16, 2010
Risks from colonoscopy in elderly increase with age, comorbidities, July 13, 2009
Extracolonic findings can't be ignored, VC expert says, June 1, 2009
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![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
