Venous Thromboembolism in Pregnancy: A Review Article of Current Best Practice

Review Article

Austin J Obstet Gynecol. 2024; 11(1): 1226.

Venous Thromboembolism in Pregnancy: A Review Article of Current Best Practice

Raman Dabas; Ayman Aboda*; Brian Mccully

Department of Obstetrics & Gynaecology, Mildura Base Public Hospital, Australia

*Corresponding author: Ayman Aboda Department of Obstetrics & Gynaecology, Mildura Base Public Hospital, Mildura 3500, Victoria, Australia. Email: aymanaboda@hotmail.com

Received: January 03, 2024 Accepted: February 08, 2024 Published: February 15, 2024

Abstract

Venous Thrombo-Embolic Disease (VTE) during pregnancy, including both Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE), is a leading cause of maternal mortality. It contributes to 20% of such deaths in developed countries. The incidence of VTE is estimated at 0.5–2 cases per 1000 pregnancies, with incidents spread across all trimesters, often involving the iliofemoral vessels. The review aims to present the current understanding and recent advancements in managing, diagnosing, and preventing PE and VTE, acknowledging the unique challenges and risks during pregnancy.

Physiological changes in pregnancy, such as hypercoagulability, venous stasis, and vascular injury, increase the risk of VTE, including PE. Diagnosing PE in pregnant women is particularly challenging due to symptom overlap with normal pregnancy changes and risks associated with diagnostic imaging. Treatment most often requires anticoagulant therapy, usually with LMWH and UFH, which are chosen for their efficacy and safety. Management is multidisciplinary and acknowledges individualized care plans, especially post-partum. Ultimately, the goal is to ensure maternal and fetal safety through a nuanced approach to diagnosing and treating PE and VTE during pregnancy.

Introduction

Venous Thrombo-Embolic Disease (VTE), encompassing Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE), is a leading cause of maternal mortality [1]. While it remains a relatively rare occurrence, its impact is profound, contributing to 20% of maternal deaths in developed countries [2-4]. Understanding the prevalence and implications of PE is crucial for clinicians, as it informs both preventive strategies and the management of at-risk pregnancies where the unique physiological changes in pregnancy, such as increased blood coagulability, reduced blood flow from the legs, and potential injury to blood vessels, significantly elevate the risk of thrombotic events [5]. This review aims to provide a comprehensive understanding of the pathophysiology, risk factors, diagnosis, management, and prevention of VTE and PE in the context of pregnancy, highlighting the unique challenges and considerations in this patient population. The increased incidence of VTE during pregnancy is attributed to physiological changes that enhance thrombosis. Elevated levels of prothrombotic factors, such as factors II, VII, VIII, IX, X, fibrinogen, and von Willebrand factor, along with decreased anticoagulant activity and diminished fibrinolysis, create a hypercoagulable state [6]. Progesterone, a pre-eminent pregnancy hormone, relaxes smooth muscle, leading to vasodilation of blood vessels, particularly veins. In the lower extremities, this can lead to stasis or venous pooling, another reason thrombosis may be more likely to occur. In some cases, blood flow is further inhibited by the weight of other organs, most significantly, the gravid uterus or, more rarely, other vessels, as may occur with the May-Thurner syndrome [7,8]. The risk for PE and VTE in pregnancy is heightened by a history of thrombophilia, such as with Factor V Leiden mutation, a genetic disorder inherited from one or both parents that results in an abnormal variant of Factor V, known as Factor V Leiden, which is more resistant to inactivation by protein C, a natural anticoagulant in the blood, leading to an increased tendency to develop blood clots, particularly in the deep veins of the legs and in the lungs [9,10]. Other factors, such as surgery, prolonged immobility, pregnancy, oral contraceptive use, and smoking, can further increase the risk, as can pregnancy-specific conditions such as preeclampsia and caesarean delivery. Factors also include obesity, advanced maternal age, high-order parity, multiple pregnancies, and pre-existing conditions like diabetes and vascular disease [11,12]. Physiological changes in the postnatal factors are particularly critical and can be exacerbated by complications, including operative delivery and bed rest, haemorrhage and sepsis [13]. Diagnosing PE during pregnancy remains challenging due to an overlap of diagnostic symptoms with common pregnancy-related changes, such as shortness of breath and tachycardia [13,14]. Up to 70% of PE patients do not present with DVT at diagnosis, complicating the clinical picture [15,16]. Traditional diagnostic tools, such as the Wells Scale and Geneva score, are not commonly used in pregnancy and other approaches, including the 'LEFT' rule, remain non-specific [17]. Radiological diagnosis is critical; however, utilization must balance the need for diagnosis with the potential exposure risk to the mother and fetus. Venous dopplers, chest X-rays, Ventilation Perfusion (V/Q) scans, and computed tomography pulmonary angiograms CTPA are all employed, with caution, to minimize fetal exposure [18].

In managing PE and VTE during pregnancy, a balance must be struck between the effective treatment of the mother and the safety of the fetus. Anticoagulant therapy, the cornerstone of treatment, must be carefully tailored to mitigate risks while providing effective thromboprophylaxis. This balance requires a nuanced understanding of the available therapeutic options, including the mainstays of treatment: low-molecular-weight heparin (LMWH) and Unfractionated Heparin (UFH). LMWH is preferred due to its efficacy and lower risk profile, while warfarin and newer anticoagulants like dabigatran and rivaroxaban are generally avoided during pregnancy due to their potential risks [19,20].

Current guidelines emphasize the need for individualized treatment plans, effective anticoagulation and a multidisciplinary approach to care for the best possible outcome. The importance of preventive measures and post-partum care, particularly in women with identifiable risk factors, is also highlighted [14,21,22]. In cases of severe symptoms or high-risk PE, treatment options extend to thrombolytic therapy, surgical embolectomy, and catheter-based interventions [14]. The use of Inferior Vena Cava Filters is limited and cautiously approached in pregnant patients. Systemic thrombolysis, though a relative contraindication in pregnancy, is considered in life-threatening situations. The complexity of VTE management is further underscored during labour and delivery, especially when neuraxial anaesthesia is planned. Post-partum, the resumption of anticoagulation is carefully timed to balance thrombotic and haemorrhagic risks [23].

Case Presentation

A 29-year-old primigravidae woman at 38+4 gestation reported spontaneous pre-labour rupture of membranes. On presentation to the birthing suite, she was found to have an incidental tachycardia of 120-150 bpm. She was asymptomatic, with no shortness of breath or chest pain. There was no history of calf pain or URTI, and there was no history of recent travel or surgery. She was on no medications and had no past or family history of VTE disease. Earlier in the first trimester of her pregnancy, her General practitioner had noted tachycardia on a routine antenatal visit. A Holter recording had been normal. Her Antenatal history, including routine investigations, was otherwise normal.

On inspection, the patient was anxious. She could speak in complete sentences. There were no palpitations. A cardiovascular examination found a blood pressure of 116/68 and a regular heart rhythm with a rate varying between 120- 151 beats/min. There were no heart murmurs. There was no peripheral oedema or calf tenderness. Her oxygen saturation was 98% on room air. Respiratory examination was normal, with bilateral air entry and normal breath sounds. Abdominal examination findings were consistent with term pregnancy. A cardiotocogram CTG was normal, and there was no palpable uterine activity. An Amnisure test confirmed rupture of membranes during speculum examination. An ultrasound scan of the pregnancy confirmed appropriate fetal growth with normal cord dopplers and amniotic fluid volume.

An electrocardiogram was performed, which confirmed sinus tachycardia. Chest x-ray was normal. Both lung fields were fully inflated with no evidence of pleural effusion or pneumothorax. Bloods were taken for Full blood count, Urea and electrolytes, Liver function and urate. A CRP and Thyroid function were also requested, as well as a coagulation profile including fibrinogen. These were all normal. A serum Troponin was also normal. She tested negative for COVID, Influenza A, and Respiratory Syncytial Virus RSV.

She had a thoracic computed tomography with intravenous contrast of pulmonary arteries CTPA. She wore lead shielding to minimize radiation exposure to the fetus. The findings demonstrated occlusive filling defects in the anterior right pulmonary artery branches and nonocclusive filling defects in the anterior segmental branches of the left upper lobe pulmonary artery (Figure 1 & 2). There were also several non-occlusive filling defects in the left lower lobe pulmonary artery. Ventilation scans were normal. A diagnosis of bilateral segmental and subsegmental branch pulmonary emboli was made.

Citation: Dabas R, Aboda A, Mccully B. Venous Thromboembolism in Pregnancy: A Review Article of Current Best Practice. Austin J Obstet Gynecol. 2024; 11(1): 1226.