PMC10155737_01
Ascites pocket with stranding - initial mimic for IVC raising concern for IVC thrombus. Color Doppler ruled out presence of vascular structure. (POCUS subcostal view in longitudinal axis. Probe is in subcostal position with marker pointing cranially).
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POCUS IVC in the longitudinal axis showed anechoic linear tubular structure with mobile hyperechoic density (Figure 1, Video S1) initially raising suspicion for IVC thrombus.
L sided IVC (blue arrow) with bilateral renal vein insertion. Aorta on the R side (red arrow). (CT abdomen/pelvis w/contrast - coronal view).
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Anomalous IVC was suspected and explored further with CT abdomen/pelvis that showed L sided IVC with azygous continuation superior to the level of renal veins (Figure 2-5, Video S2).
L sided IVC crossing to the right anterior to the aorta. (CT abdomen/pelvis w/contrast - coronal view).
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Anomalous IVC was suspected and explored further with CT abdomen/pelvis that showed L sided IVC with azygous continuation superior to the level of renal veins (Figure 2-5, Video S2).
Azygos continuation of L sided IVC (blue arrow). (CT scan abdomen/pelvis w/contrast - axial plane).
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Anomalous IVC was suspected and explored further with CT abdomen/pelvis that showed L sided IVC with azygous continuation superior to the level of renal veins (Figure 2-5, Video S2).
POCUS view of IVC continuing as azygos (blue arrow). (Subcostal view - image obtained by following IVC in long axis (near the sagittal plane), and then rotating the probe in a counter-clockwise fashion along the long axis of the individual diverging vessels, settling on the azygos vein along its specific long axis. Thus, the image is oriented with the dot aligning along a plane between the transverse plane and the sagittal plane).
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Anomalous IVC was suspected and explored further with CT abdomen/pelvis that showed L sided IVC with azygous continuation superior to the level of renal veins (Figure 2-5, Video S2).
IVC embryogenesis. a) Primitive veins contributing to the development of IVC. b) Adult IVC with its originating venous systems.Suprahepatic segment originates from the vitelline veins. Suprarenal/infrarenal segment originates from the subcardinal veins. Infrarenal segment from the supracardinal veins. Iliac veins from the posterior cardinal veins.
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Figure 6 illustrates the primitive venous system and their contribution in the formation of mature IVC segments. The primitive three pairs of cardinal veins are symmetric but following successive anastomosis, crossings and fusions turn into a single large trunk on the right side whereas the left sided vessels slowly atrophy to the point of obliteration (Figure 6a).