The IIV may readily display incompetence without maneuvers in some cases. To determine incompetence in the IIV, augment the upper thigh or apply hand pressure and release maneuver on the lower abdomen. Measure the diameter and record the velocity. Duplex ultrasound image showing intraluminal irregularities.Ĭontinue to the internal iliac vein (IIV) and assess for patency and flow direction. Venogram showing compression of left CIV and corresponding duplex ultrasound with measurements.įigure 4. Multiple scanning planes and acoustic windows should be utilized.įigure 3. Examine the walls of the CIV for evidence of wall thickening, flow defects, or any subtle wall abnormalities, particularly at the level where the CIA crosses anterior to the vein and immediately inferior to this region ( Figure 4). Ensure that color settings allow for accurate depiction of the patent lumen to avoid color saturation. Color Doppler can be used as a guide for measuring the diameter when the walls are not easily seen. Utilizing spectral Doppler, record velocities in each segment. Using B-mode, measure the diameter of the left CIV at the level of the overlying right common iliac artery (CIA) ( Figure 3) in the mid segment and the lower segment. Rotate the transducer to image the left CIV in a longitudinal view. Record velocities in the left renal vein at both sites to determine if there is compression of the left renal vein.įollow the IVC in the transverse plane to visualize the confluence of the CIVs. Using B-mode and color Doppler, measure the diameter of the vein in the aortomesenteric region and compare it to the diameter near the renal hilum. Locate the left renal vein as it passes between the aorta and superior mesenteric artery or spine (be aware of a retroaortic left renal vein). If evidence of narrowing is detected, place the patient in the left lateral decubitus position and reassess diameters ( Figure 2). Beginning at the level of the xiphoid process, locate the suprarenal IVC and scan the length to the common iliac vein (CIV) confluence, documenting patency, waveform patterns, and diameters. It is important to ensure that the probe pressure does not affect the diameter of the veins being assessed, as this can create a false-positive finding. Example of measurements of stenotic area with disturbed flow (A) and diagram of duplex report (B). The spectral Doppler sample volume is set to the size of the vein lumen, and Doppler angles for velocity measurements must be ≤ 60°.įigure 2. The pulse repetition frequency should be on the low setting, with the gain adjusted accordingly. A lateral decubitus position can also be utilized in difficult cases.Īn abdominal venous preset is used to maximize the frame rate and to optimize focus. The optimal position for scanning patients is supine in a reverse Trendelenburg position (45°) with arms at their side or comfortably on their chest ( Figure 1). The time frame for the scan is 45 to 60 minutes, depending on operator experience and patient characteristics. A low-frequency, curved array transducer is usually required however, higher frequencies might be needed in patients with a low body mass index. This must include adjustable range-gated Doppler to assess veins of varying sizes and real-time B-mode to allow monitoring of the phasic changes in vein diameters. The optimal position for scanning the patient.Ī high-resolution color Doppler ultrasound system allows for real-time assessment of the abdominal veins with both B-mode and spectral Doppler analysis.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |