Why is she still at risk of a pulmonary embolus?
Our patient had a duplication of the IVC and the L IVC did not have a filter so she was still at risk of a PE. The IVC forms between six and ten weeks gestation. The infrarenal portion of the IVC is formed from the R supracardinal vein while the L supracardinal vein regresses. If the L supracardinal vein fails to regress, two IVCs are formed. This occurs in 0.2-3% of the population.
The significance of this anomaly is demonstrated in this case where a single IVC filter was not protective against PE. The anomaly is also associated with horseshoe kidney and malrotation of the gut.
Duplication occurs in other vascular structures as well The aortic arch can be duplicated causing a complete vascular ring that can compress the trachea or esophagus. The treatment is surgical if patients are symptomatic. Partial duplication can mimic dissection on ultrasound.
Our patient had bilateral DVTs but radiology was unable to place a second filter . Her course was complicated by a GI bleed where her pancreatic tumor was eroding into the duodenum. The bleeding stopped spontaneously and she was discharged on lovenox.
Royal SA, Callen PW. CT evaluation of anomalies of the inferior vena cava and L renal vein. AJR AmJ Roentgenol. 1979;132(5):759-63
Smith TR, Frost A. Anomalous inferior vena cava associated with horseshoe kidneys.Clin Imaging 20(4):276-8.
Shaha P, Garg A, et al. Duplication of inferior vena cava with associated anomalies: a rare case report. J Clin Diagn Res 2016Mar;10(3) doi:10.7860/JCDR/2016/18240.7406.