Chapter 100: Maternal Emergencies After 20 Weeks of Pregnancy and in the Postpartum Period

INTRODUCTION

This chapter examines the diagnosis and treatment of the most important maternal emergencies occurring after 20 weeks of pregnancy and during the postpartum period. The second half of pregnancy is often characterized as ≥20 weeks of gestation for simplicity, but until 24 weeks, the chances of fetal survival are less than 50%. The postpartum period is generally accepted as the 6 weeks after delivery. Vast physiologic shifts in maternal cardiovascular tone occur as pregnancy progresses, highlighting the need for maternal blood pressure recordings and fetal heart tones during any ED visit. Conditions discussed are thromboembolic disease; chest pain; disorders associated with elevated blood pressure (hypertension, preeclampsia and HELLP syndrome [hemolysis, elevated liver enzymes, and low platelet count], and eclampsia); vaginal bleeding in the second half of pregnancy; premature rupture of membranes; postpartum hemorrhage; amniotic fluid embolus; peripartum cardiomyopathy; and endometritis.

THROMBOEMBOLIC DISEASE OF PREGNANCY

Venous thromboembolism includes deep venous thrombosis (DVT) and pulmonary embolism (PE) and is the leading cause of maternal morbidity and mortality in industrialized nations. Compared with nonpregnant women, the risk of venous thromboembolism increases fivefold during pregnancy and is increased by 60-fold in the first 3 months after delivery.^1,2

PATHOPHYSIOLOGY

Pregnancy-related hypercoagulability is due to increased levels of clotting factors, increased platelet and fibrin activation, and decreased fibrinolytic activity, all of which are adaptations to prevent maternal hemorrhage. Physiologic changes include venous stasis, decreased venous outflow, and uterine compression of the inferior vena cava and iliac veins (particularly the left common iliac and left leg veins). Clots tend to develop in the deep venous system of the legs and pelvis, which includes the internal iliac, femoral, greater saphenous, and popliteal veins. Up to 24% of DVTs are complicated by PE, so early DVT diagnosis is important.^1-6

RISK FACTORS AND CLINICAL FEATURES

Physiologic signs and symptoms of thromboembolic disease, such as tachycardia, tachypnea, lower extremity edema, and dyspnea are nonspecific and also occur during normal pregnancy. Predictive scoring criteria, such as Wells criteria, have not been validated in pregnant women, but left leg symptoms, calf circumference difference ≥2 cm, and leg symptoms in the first trimester are associated with DVT. Iliac vein thrombosis often presents with unilateral swelling of the entire leg and groin or back pain.

A personal or family history of thrombosis is an important risk factor. Other major risk factors include thrombophilias (not identifiable at the first presentation), obesity, maternal age >35, smoking, sickle cell disease, diabetes, hypertension, immobility, in vitro fertilization (greater risk for twins ...