In 1954, Homans reported that venous thromboembolism (VTE) may occur after prolonged sitting in a number of situations including at the theatre, and during aeroplane flights and car travel.1 Since this report, attention has focused primarily on the risk of VTE associated with prolonged air travel, with ‘traveller’s thrombosis’ now recognised as an important complication of long-distance air travel, particularly in persons with additional risk factors.2,3 More recently, we reported a case in which immobility associated with sitting for prolonged periods at a computer represented the major risk factor for a life-threatening VTE.4 The term ‘eThrombosis’ was used to describe this condition. It was suggested that, with the widespread use of computers in relation to work, recreation and personal communication, the potential burden of eThrombosis may be considerable. In this regard, it has been surprising that there has been only one published case report of eThrombosis,4 or indeed one published case of VTE due to cramped seating at the theatre.1 In this report we present a case in which both being seated in cramped conditions at a picture theatre and repeated, prolonged sitting at a computer were recognised as two risk factors for the development of a proximal, lower-limb deep vein thrombosis (DVT).

A 53-year-old woman reported developing sudden onset severe pain in her right leg within 30 minutes of leaving the theatre. She had sat in cramped conditions in a provincial picture theatre for three hours watching the film ‘The Lord of the Rings: The Two Towers’. The following morning the pain had persisted and was associated with swelling of her right leg, and as a result she sought urgent medical review. A right, superficial femoral vein and popliteal vein thrombosis was diagnosed by Doppler ultrasound. No investigations of associated pulmonary embolism were undertaken due to the lack of respiratory symptoms. She received low-molecular-weight heparin and concomitant oral warfarin therapy, which was continued for a six-month period. In terms of relevant past medical history, she experienced a right, proximal, lower-limb DVT when aged 26, associated with oral contraceptive use. This DVT fully resolved with anticoagulant therapy, confirmed by a follow-up ultrasound. Further enquiry revealed that she often undertook prolonged computer use in which she would sit for two to three hours at a time without getting up.

This case represents the second report in the medical literature of a DVT associated with sitting in cramped conditions at a theatre. The risk was probably also increased through the frequent, prolonged computer use in which the patient would sit for two to three hours at a time. Regardless of the relative contribution of the different situations in which the seated immobility occurred, this case does illustrate the potential risks associated with prolonged sitting in cramped conditions. This situation is similar to that associated with long-distance air travel, of which ‘traveller’s thrombosis’ is now a well-recognised outcome.2,3

To encompass the wide range of situations in which prolonged sitting may lead to a VTE, we have coined the phrase ‘seated immobility thromboembolism (SIT) syndrome’. The SIT syndrome would include immobility associated with long-distance travel (air, train and road), prolonged computer use at work or in recreation, other forms of employment or recreation that involve sitting for prolonged periods, and other situations such as being seated in cramped conditions at the theatre.1–5 One name to rule them all, one name to find them (modified from Tolkien JRR, The Lord of the Rings, Allen & Unwin (London), 1954). Hopefully, the use of SIT as the acronym for this condition will encourage recognition of seated immobility as a risk factor for VTE and the implementation of measures to reduce its occurrence. Pending further research it would seem prudent to advise all persons who sit for prolonged periods, regardless of the situation, to undertake frequent foot exercises while seated, not to cross their legs when seated and to stand up and walk around regularly if possible.

Author information: Richard Beasley, Director; Patricia Heuser, Research Nurse; Matt Masoli, Senior Research Fellow, Medical Research Institute of New Zealand, Wellington

Correspondence: Professor Richard Beasley, Medical Research Institute of New Zealand, P O Box 10055, Wellington. Fax: (04) 472 9224; email: richard.beasley@mrinz.ac.nz