Colonoscopy () or coloscopy () is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It can provide a visual diagnosis (e.g., ulceration, polyps) and grants the opportunity for biopsy or removal of suspected colorectal cancer lesions. Colonoscopy can remove polyps smaller than one millimeter. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are precancerous or not. It can take up to 15 years for a polyp to turn cancerous.Colonoscopy is similar to sigmoidoscopy—the difference being related to which parts of the colon each can examine. A colonoscopy allows an examination of the entire colon (1,200–1,500 mm in length). A sigmoidoscopy allows an examination of the distal portion (about 600 mm) of the colon, which may be sufficient because benefits to cancer survival of colonoscopy have been limited to the detection of lesions in the distal portion of the colon.A sigmoidoscopy is often used as a screening procedure for a full colonoscopy, often done in conjunction with a fecal occult blood test (FOBT). About 5% of these screened patients are referred to colonoscopy.Virtual colonoscopy, which uses 2D and 3D imagery reconstructed from computed tomography (CT) scans or from nuclear magnetic resonance (MR) scans, is also possible, as a totally non-invasive medical test.
It is seen protruding into the amniotic cavity near the insertion of the cord. Doppler examination shows anechoic cystic areas, with pulsatile flow in spectral analysis. Some chorioangiomas may be solid masses, and may not be identifiable in gray-scale imaging. Therefore, the investigation of choice is Colour Doppler, which also distinguishes it from placental hematoma.They can also be detected with MRI.Histologically, chorioangiomas consist of abundant vascular channels and may be cellular. Management
Expectant management is recommended for chorioangioma as majority of them are asymptomatic. Large tumors are monitored with ultrasonogram every 1–2 weeks. In case of maternal or foetal complications, possible interventions are serial foetal transfusions, fetoscopic laser coagulation of vessels supplying the tumor, endoscopic surgical devascularization and chemosclerosis using absolute alcohol. Prognosis
Large chorioangiomas with decreased echogenicity, decreased tumor volume and decreased blood flow in colour doppler images are may undergo spontaneous infarction. When chorioangiomas have deceased blood flow, fetal hemodynamics and clinical outcome are found to be improved. Epidemiology
It is the most common tumor of the placenta. Chorioangiomas over the size of 5 cm in diameter are rare, and occur at a rate of 1:3500 to 1:16,000 births. Smaller chorioangiomas are more frequent, with an incidence of 14‑139:10,000 births. However, many small chorioangiomas may not be sonologically visible and hence go unreported. In a clinical study, more than half of all tumors were discovered only by histological techniques. History
Chorioangioma was first described by Clarke in 1798. See also
Hemangioma
Chorangiosis

References
External links
Chorangioma (pathweb.uchc.edu)
Chorangioma (humpath.com)