We read the case-report of Neill et al. (Vol 104, December 1997)1 with interest, having recently been involved in a similar case, where an inferior vena cava filter was used in a 20 year old woman at 25 weeks gestation in her first pregnancy.
Our patient presented with pain and discolouration of her left leg. Doppler ultrasound confirmed a left ilio-femoral thrombosis, with extensive fresh unstable clot in the distal iliac vein, while the inferior vena cava (IVC) was patent. In view of her high risk of pulmonary embolism, a Gunther tulip vena cava filter (William Cook Europe, Bjaeversikov, Denmark) was inserted, using a standard technique via the right internal jugular vein under low-dose pulsed fluoroscopic imaging. The filter was placed with its upper end below the right renal vein, rather than in the suprarenal position recommended by Neill et al.1 because of the potential risk of renal vein thrombosis. The Gunther tulip filter was selected in our patient because of the possibility of retrieval for up to 10 days after insertion.
Unfortunately, extensive thrombus was still present in the left ilio-femoral vein after nine days, despite full heparin anticoagulation. In view of this, a decision was taken to leave the filter in situ. The patient continued her pregnancy with heparin anticoagulation until 37 weeks gestation, when labour was induced and she had a normal delivery of a live infant. She was anticoagulated with warfarin for three months after delivery. Subsequent thrombophilia investigations demonstrated the presence of a Leiden V mutation.
We are concerned about the likely long term effects of a permanent IVC filter in such a young woman. We carried out a review of the literature, and came across several disturbing reports of complications resulting from migration of all or part of the filter, including intra-cardiac migration2.
We feel that the use of the term ‘retrievable’ is somewhat misleading when applied to these devices In pregnancy, unless the thromboembolic event occurs in a patient after fetal lung maturity has been achieved, it is likely that the filter will need to remain in situ for longer than 10 days, in order to reduce the risk of embolism in the remainder of the pregnancy and the postnatal period. It is unclear from the literature whether the presence of the filter itself is an indication for long-term anticoagulant treatment, although one report suggested that there was no benefit from anti-coagulation after placement of the filter3. We agree with Neill et al. that follow up of young patients with IVC filters is necessary to identify the long-term risks of these devices Inferior vena cava filters will continue to have a role in patients at high risk of pulmonary embolism and those who have heparin hypersensitivity; however, we would caution against their widespread use in young women until more is known about their long term complications.