A Scottish Hebridean antithrombin III deficient family--twelve years on

The members of this family with ATIII deficiency have been followed for at least 12 years (1976-1989). All those with previous venous thrombo-embolism have been free from recurrence when on warfarin. During the half century 1931-1981, all 11 full term pregnancies in four affected patients were associated with venous thromboembolism; one patient was enigmatic having one full term pregnancy, without thrombotic event; between 1982 and 1989 three pregnancies have been actively managed with no clinical thrombosis. Management involved use of monitored, self administered, subcutaneous heparin before or very soon after conception and throughout pregnancy (warfarin having been stopped), planned delivery under cover of intravenous antithrombin III, reduction of heparin dosage at delivery and reintroduction of warfarin in the puerperium. The recognised hazards of heparin therapy in pregnancy did not occur. The involvement of the arterial system is reviewed. Clinical evidence provides tentative suggestions on (a) possible additional risk of cigarette smoking (b) avoidance of venography (c) avoidance of varicose vein surgery. A probe is now available for the defective antithrombin III gene in this family, but there has been no occasion yet to apply this in antenatal diagnosis.