From the Guidelines

Chronic venous insufficiency of the colon is not a recognized medical condition.

The provided evidence does not mention chronic venous insufficiency of the colon, instead, it focuses on nonthrombotic iliac vein lesions (NIVL) and their diagnosis and treatment 1.
The consensus statement from the VIVA Foundation, the American Venous Forum, and the American Vein and Lymphatic Society recommends the use of invasive diagnosis with venography and IVUS for NIVL treatment 1.
The evidence suggests that IVUS is more sensitive than venography for detecting venous pathology, particularly compression, and is recommended for dynamic evaluation of NIVL 1.

The study highlights the importance of clinical evaluation and venography/IVUS for the diagnosis and treatment of NIVL, rather than relying on axial imaging with CT or magnetic resonance imaging alone 1.
The use of IVUS for NIVL intervention has become commonplace due to its greater sensitivity for venous pathology, and its ability to detect vessel wall features such as mural thickening and nonfunctional valves 1.
The definitive threshold for treatment to improve symptoms among patients with NIVL remains an area of ongoing debate and investigation, with some studies suggesting an area reduction of >50% or a diameter reduction of >61% as a metric for patient selection 1.

From the Research

Chronic venous insufficiency (CVI) is a common disorder characterized by the retrograde flow of blood in the lower extremity 2.
It is a progressive degenerative disease of the venous walls in the superficial venous system of the legs, which can impair the quality of life of those affected 3.
CVI can be asymptomatic, cause subjective symptoms, or lead to objective alterations, such as edema, cutaneous alterations, and venous leg ulcers 3.

The pathophysiology of CVI is only partly elucidated, and even the development of varicose veins remains unexplained 4.
Vein valve dysfunction appears to be the common final pathway in the development of CVI, resulting in increases in retrograde flow and distal venous pressure 2.
Microcirculation is greatly affected by CVI, which occasionally induces skin changes and ulcers 4.

The diagnosis of CVI is established by history, physical examination, and functional venous testing with duplex imaging or phlebography 2.
Classification systems, such as the CEAP classification, have been developed to stratify CVI according to its severity and guide therapeutic endeavors 3.
Instruments, such as the venous clinical severity score, are used for assessment of the severity of CVI 3.

Treatment of CVI targets the improvement of subjective complaints and objectifiable alterations, as well as the prevention of complications such as phlebitis and formation of ulcers 3.
Invasive procedures, compression treatment, and pharmaceutical treatment are complementary, and a combination of these procedures can be meaningful 3.
Compression therapy with medical compression stockings is the gold standard in the noninvasive treatment of symptomatic venous diseases 3.

There is no evidence to suggest that chronic venous insufficiency is directly related to the colon 4, 2, 3, 5, 6.
The provided studies focus on chronic venous insufficiency in the context of the lower extremities, and there is no mention of the colon.