ix for colorectal carcinoma

Investigations for colorectal carcinoma

Blood count and routine biochemistry
Serum carcinoembryonic antigen level (related to outcome)
Colonoscopy is gold standard for investigation and allows for biopsies and polypectomies to obtain specimens for histological examination
Sigmoidoscopy
Endoanal ultrasound and pelvic MRI are used for staging rectal cancer
CT and PET scanning help to evaluate tumour size, local and secondary spread and hepatic metastases

ENDOSCOPY

Video endoscope have three chips mounted on the tip of the instrument to relay colour images via an image processor to a television monitor.

The tip of the endoscope can be angulated in all directions, channels are present in the endoscope for air insufflation, water injection, suction and for the passage of biopsy forceps or brushes for obtaining tissue.

Sigmoidoscopy: views the rectum. There are rigid and flexible sigmoidoscopy. Rigid ones can reach lower 20-25 cm of lower bowel. Flexible sigmoidoscopy gain better access than rigid ones but about 25% of colon cancers are still out of reach.

Pre-procedure: give 2 phosphate enemas; get written consent.

Colonoscopy: allows good visualisation of the whole colon and terminal ileum. Biopsies can be obtained and polyps removed. 90% success rate of reaching the terminal ileum.

Prep: prescribe sodium picosulfate 1 satchet morning and afternoon, the day before the procedure. Obtain written consent.

Procedure: sedation and analgesia are given before a flexible colonoscope is passed per rectum around the colon

Complications: abdominal discomfort; incomplete examination, perforation(0.2%) haemorrhage after biopsy.