Authors: (including presenting author): :
Lee LTL (1), Li KTJ (1), Chan LW (1)
Affiliation: :
(1) Department of Obstetrics and Gynaecology, Pamela Youde Nethersole Eastern Hospital
Keyword 1: :
Venous Thromboembolism
Keyword 2: :
Pregnancy Complications
Introduction: :
International data report a prevalence of venous thromboembolism (VTE) in pregnancy of 1.4 per 1000, with a meta-analysis in China showing a similar rate of 1.3 per 1000.
Objectives: :
Our study aims to study the prevalence in the regional setting with a large sample size, with the use of standardized computerized techniques and CDARS, as well as to describe natural history and potential risk factors.
Methodology: :
We conducted a 20-year retrospective study of ethnic Chinese delivering in our unit between 2004 and 2023. Non-local residents without identity cards were excluded. VTE cases were identified through electronic delivery, drug, and imaging records. We further conducted a case-control study to compare these cases with age-matched controls (1:5 ratio), to identify potential risk factors in our population. Primary outcome was prevalence of VTE in pregnancy; secondary outcomes included risk factors, pregnancy outcomes, and medical comorbidities.
Result & Outcome: :
During the study period, our unit did not adopt routine pharmaco-prophylaxis. Among 43,626 deliveries, 22 VTE cases were identified – 0.50 per 1000 deliveries. Most occurred antepartum (68.2%), with deep vein thrombosis (72.7%) being the predominant diagnosis. The majority (95.5%) had no known medical comorbidities. Substance abuse was significantly more common in VTE cases (13.6% vs 0.9%, p=0.001*), while smoking was more common but did not reach statistical significance. Adverse pregnancy outcomes were more frequent, including Caesarean section (63.6% vs 36.4%, p=0.018*), preterm delivery (27.3% vs 7.3%, p=0.005*), and blood transfusion (22.7% vs 2.7%, p< 0.001*). Our study was conducted in a methodical manner, with exhaustive search in multiple databases with CDARS to identify potential cases, and demonstrates its utility in conducting large-scale population-based studies. Within our locality, a retrospective study by a tertiary unit in the New Territories in 2001 gave a prevalence of 1.88 per 1000, while one published later in 2019 by another tertiary unit on Hong Kong Island gave a figure of 0.4 per 1000. Our VTE prevalence at 0.50 per 1000 was consistent with the latter and lower than reported in literature, and could be related to regional or socio-economic differences. There was also an apparent decline in postpartum VTE, which may reflect improvement in care over time. As VTE remains relatively uncommon in our population and setting, the risks and benefits of pharmaco-prophylaxis must be carefully weighed. Most VTE cases had no prior risk factors or comorbidities, clinicians should therefore maintain a high index of suspicion when pregnant patients present with suggestive symptoms.
