Reporting Standards for Inferior Vena Caval Filter Placement and Patient Follow-up: Supplement for Temporary and Retrievable/Optional Filters

Patient Assessment 

Data regarding general patient information, the method of diagnosis of DVT or PE, risk factors for thrombosis, and the indications for filter placement, should all be described according to the previous Standards (1). Any additional indications should be specifically addressed, as should any contraindications (5). In addition the protocol must state if the filter was placed with the intention that it would be retrieved, or if it was intended as a permanent filter, or if this was not determined. If filter retrieval was planned the rationale for this should be described: in particular the reasons why the patient may no longer require a filter, and could benefit from filter retrieval should be included.

Device Assessment 

The manufacturer and type of filter should be recorded, along with a description of the delivery system and the technique of placement. The size of the introducer system should be specified. The device should be categorized as either a Temporary Filter or a Retrievable/Optional Filter if possible (6). A Temporary Filter is attached to a wire or catheter that either protrudes from the skin entry site, or may be buried in the adjacent subcutaneous tissues (6, 7). Consequently, this type of filter must generally be removed. A Retrievable/Optional Filter is similar to a conventional filter, but it has additional features allowing removal from the body [such as a retrieval hook (6, 8, 9), a specifically designed removal device (10), or struts/fixation hooks that can be removed from the vena cava wall after endothelialization has occurred (7, 10)]. These features should be described. Any drug coating, or other technique used to influence incorporation of the device into the vena cava must be described in detail (11).

The reason for device selection should be noted as described in the previous Standards (1). In addition the following points should also be addressed: (i) was the device selected because retrieval/removal was planned? (ii) was a device that was designed to be a permanent filter modified for non-permanent use (12, 13)? In a large series where several different devices were used, all data must be collected and reported for each type of filter.

Procedural Assessment 

This should be described according to the Standards (1).

Placement Problems 

In addition to the requirements of the previous Standards (1), it should be noted if filter placement was adequate to permit filter retrieval. Any complication should be described as Minor or Major according to the SIR Standards of Practice Committee Classification (5).

Filter Retrieval/Removal 

The results of retrieval must be expressed according to the protocol described in “Patient Assessment,” and any changes in the medical condition of the patient, or other factors, that led to a change in the protocol must be described. The removal device should be described. The manufacturer, the size of the system, the type of removal device, and a brief description of the device and the method of use should be included. The requirements under “Procedural Assessment” in the Standards document (1) should be followed, but additional points that must be addressed are listed in the Table. All complications should be described and classified as Minor or Major.

Reporting Criteria for Filter Retrieval

	1. Anticoagulant medications: Specify type and duration of use
	2. Implantation period
	3. Filters not retrieved: Specify reasons
	4. Site of venous access for retrieval
	5. Imaging of vena cava prior to retrieval: Include imaging technique, position of filter and trapped emboli
	6. Complication or technical difficulty during retrieval: Describe any additional equipment or techniques used
	7. Imaging of vena cava following retrieval: Include imaging technique and evidence of vena caval injury

With regard to the implantation period, the maximum implantation period of the device according to the manufacturer should be stated. If filters were retrieved after a longer implantation period than is recommended by the manufacturer, this must be stated. Relevant human and/or animal data regarding implantation times should be briefly described. If filter repositioning was undertaken in an attempt to prolong the implantation period (14), the technique and rationale should be described.

In addition to those listed in the Table, the following details should be addressed: (i) were imaging tests used to evaluate the venous system for DVT prior to filter removal? (ii) the position of the filter at the time of retrieval, or on follow-up imaging, should be compared to the position immediately following placement, (iii) if trapped emboli were identified within the filter, or removed with it, this should be documented along with an estimate of the size of the emboli, (iv) any pharmacological or mechanical thrombolytic techniques used to remove trapped emboli should be described, (v) if trapped emboli were removed what measures were taken to prevent and diagnose recurrent PE? (vi) an indication of the amount of force required to retrieve the filter may be included (14), (vii) radiation dose (fluoroscopy time if radiation dose is not available) and the type and dose of contrast agent used should also be recorded (15, 16), (viii) if retrieved filters were submitted for histologic or bacteriologic evaluation the results should be reported (17).

Follow-up Assessment 

The previous Standards document should be followed, both for patients from who filters were retrieved and for those where filters were left in permanently (1). The methods used (both pre- and postfilter retrieval) to diagnose and exclude DVT, PE and chronic venous insufficiency, and the results of these investigations, should be included. If the venous access site used for filter retrieval was evaluated for thrombosis, it is recommended that the results of this imaging be reported. In addition, if placement of a second filter was required the type of filter and the reason for choosing it should be described. Complications should be classified as Minor or Major.