I. Rectal and anal finger retrieval
Rectal finger examination is simple and easy to perform. Rectal finger examination is still the most basic and important examination method among a series of pre-surgery examinations for rectal cancer.
Laboratory examination
(1) Stool occult blood test: this method is simple and easy to use, and it is the initial screening method for colon cancer screening and routine examination of colon diseases. Immunological methods can also be applied to improve the correct rate if necessary.
(2) Hemoglobin test: Barium enema or fiber colonoscopy should be recommended for those with unexplained anemia and hemoglobin below 100g/L.
(3) Serum carcinoembryonic antigen (CEA) test: CEA test does not have specific diagnostic value, so it is not suitable for screening or early diagnosis, but it is helpful for estimating prognosis, monitoring the efficacy and recurrence.
Endoscopy (fiberoptic colonoscopy)
Sigmoidoscopy or fiberoptic colonoscopy should be routinely performed for anyone who has blood in the stool or changes in stool habits and no abnormal findings on rectal finger examination. Endoscopy can observe the lesion under direct vision and take biopsy for pathological diagnosis.
Fibrous colonoscopy is the most effective, safe and reliable examination method for the diagnosis of lesions in the large intestine, and most of the early colorectal cancers can be detected by endoscopy.
Double contrast imaging
Traditional barium enema X-ray examination often has difficulty in showing early stage cancer and colorectal adenoma, while double contrast imaging technology has greatly improved the detection rate and diagnostic accuracy of early colorectal cancer and small adenoma, and has become a routine examination in radiology department.
V. CT diagnosis
CT can not be used as a method of early diagnosis, but it is of great significance to the staging of colon cancer, especially for patients who are estimated to be unable to be operated directly, but may be surgically removed after applying external radiation or local intracavitary radiotherapy. The tumor can be directly observed invading the pelvic muscles (levator ani, internal olecranon, coccygeus, pear), bladder and prostate.
A CT scan of the pelvis can be performed at 3 months after surgery as a base film to facilitate follow-up. In addition, CT can provide correct localization and determine the appropriate target volume for the application of radiotherapy for recurrent rectal cancer.
Ultrasonography
Endorectal ultrasonography is a new diagnostic method for detecting the invasion of rectal cancer and the degree of tumor infiltration into the rectal wall, which has been used in clinical practice since 1983. Endorectal ultrasonography can correctly diagnose the location and size of tumor invasion.
Magnetic resonance examination
Some researchers claim that magnetic resonance imaging (MRI) is more meaningful than CT for external invasion of rectal cancer. However, there are still many technical problems in MRI that need to be improved, and the understanding of the image provided by MRI also needs to be further deepened.
VIII. PET-CT examination
PET-CT examination consists of a combination of PET and CT equipment, and is performed simultaneously. The combination of PET to check the metabolic activity of local tumor and CT to show the local anatomical structure can identify benign and malignant and stage the tumor to guide the surgical treatment plan. Therefore, it has become the most advanced non-invasive examination tool today.