Which of the following is the investigation of choice for diagnosing carcinoma colon: September 2005
Ans. C: Colonoscopy Laboratory studies are done with a goal of assessing patients organ function (liver, kidneys) in anticipation of diagnostic and therapeutic procedures (imaging, biopsy, surgery, chemotherapy) and also to estimate tumor burden (CEA level). - Complete blood cell count - Chemistries and liver function tests - Serum carcinoembryonic antigen (CEA) should be obtained preoperatively as it carries prognostic value and when highly elevated may indicate more advanced, disseminated disease Adequate imaging of the chest and abdomen should be obtained for staging purposes, ideally preoperatively. - Chest radiograph or chest CT scan - Abdominal barium study to better delineate primary lesion preoperatively - Abdominal/ pelvic computerized tomography (CT scan), contrast ultrasound of the abdomen/liver, and abdominal/pelvic MRI are appropriate for imaging abdomen and liver, for the purpose of staging. - Positron emission tomography (PET) scans are emerging as a very useful modality for staging and assessment of colorectal cancers. The newest addition, a fusion PET-CT scan, allows for detection of metastatic deposits and has added tissue-based resolution of CT scan. A suspicion of colorectal cancer diagnosis warrants rectal examination and colonoscopy with a biopsy of suspicious lesion. Colonoscopy is the investigation of choice if colorectal cancer is suspected provided the patient is fit enough to undergo bowel preparation. - Sigmoidoscopy - Double contrast barium enema is indicated when colonoscopy is contraindicated.
X-ray abdomen
CT scan
Colonoscopy
Barium enema