A 37-year-old woman, gravida 1 para 0, at 25 weeks gestation is evaluated in the antepartum unit due to increasing chest pain. The patient describes a sharp, substernal chest pain that is worse with inspiration and radiates to the right upper quadrant. She has no fever, cough, or rashes. The patient has had no vaginal bleeding or leakage of fluid. She has a twin pregnancy and was admitted for inpatient monitoring for preterm labor 6 days ago. The patient has reduced her activity level because walking increases the contractions, and she has been receiving heparin for venous thromboembolism prophylaxis. Her pregnancy has been otherwise uncomplicated. Temperature is 37.2 C (99 F), blood pressure is 130/86 mm Hg, pulse is 116/min, and respirations are 24/min. Heart rates for both fetuses are 155/min. Lung auscultation shows decreased breath sounds over the right lung base. The uterus is nontender. The lower extremities have bilateral 1+ pitting edema to the knees. Laboratory evaluation is as follows: Which of the following is the most likely diagnosis in this patient?

Question

A 37-year-old woman, gravida 1 para 0, at 25 weeks gestation is evaluated in the antepartum unit due to increasing chest pain.  The patient describes a sharp, substernal chest pain that is worse with inspiration and radiates to the right upper quadrant.  She has no fever, cough, or rashes.  The patient has had no vaginal bleeding or leakage of fluid.  She has a twin pregnancy and was admitted for inpatient monitoring for preterm labor 6 days ago.  The patient has reduced her activity level because walking increases the contractions, and she has been receiving heparin for venous thromboembolism prophylaxis.  Her pregnancy has been otherwise uncomplicated.  Temperature is 37.2 C (99 F), blood pressure is 130/86 mm Hg, pulse is 116/min, and respirations are 24/min.  Heart rates for both fetuses are 155/min.  Lung auscultation shows decreased breath sounds over the right lung base.  The uterus is nontender.  The lower extremities have bilateral 1+ pitting edema to the knees.  Laboratory evaluation is as follows:  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_da3c_d741_bc81_f9eb75467392_MD0003_00 This patient most likely has heparin-induced thrombocytopenia (HIT), a life-threatening condition that causes low platelet levels and a paradoxical prothrombotic state. HIT typically occurs 5-10 days after heparin exposure and affects up to 5% of patients. In these patients, heparin forms a complex with a platelet surface protein (platelet factor 4), inducing the immune system to produce HIT antibodies. These antibodies bind to platelet surfaces, leading to: HIT antibodies platelet consumption by the reticuloendothelial system, causing thrombocytopenia (ie, platelets <150,000/mm³ in nonpregnant patients or <100,000/mm³ in pregnant patients or a >50% decrease in platelet count in any patient). platelet activation with the release of procoagulant factors, causing venous or arterial thrombosis. This patient has symptoms of an acute pulmonary embolus, including sharp chest pain that worsens with inspiration (ie, pleuritic chest pain), tachypnea, and decreased breath sounds over the right lung base. An embolus in the right lower lobe can also cause radiating pain to the epigastrium and right upper quadrant. Management of patients with suspected HIT includes immediate discontinuation of heparin and initiation of therapeutic anticoagulation with a nonheparin anticoagulant (eg, fondaparinux in pregnant patients). (Choice A) Acute fatty liver of pregnancy can present with right upper quadrant pain and thrombocytopenia; however, patients with this condition also have elevated aminotransferases due to fulminant liver failure, which are not seen in this patient. (Choice B) HELLP (Hemolysis, Elevated Liver enzymes, and Low Platelet count) syndrome can present with thrombocytopenia; however, affected patients typically have additional laboratory abnormalities (eg, hemolytic anemia, elevated liver enzymes). This patient's hemoglobin and liver transaminases are normal for pregnancy, making this diagnosis less likely. (Choice D) Preeclampsia with severe features can cause right upper quadrant pain and thrombocytopenia. However, patients with preeclampsia with severe features typically have hypertension (systolic pressure ≥140 mm Hg or diastolic pressure ≥90 mm Hg) and elevated creatinine (reflecting end-organ damage due to hypertension). (Choice E) Thrombotic thrombocytopenia purpura can present with thrombocytopenia and abdominal discomfort; however, patients typically have fever, purpura, elevated creatinine, and neurologic findings (eg, weakness, confusion). Educational objective: Heparin-induced thrombocytopenia typically presents with thrombocytopenia and paradoxical thrombosis (eg, pulmonary embolus) within 5-10 days of heparin exposure. References: Current management of heparin-induced thrombocytopenia. (http://www.ncbi.nlm.nih.gov/pubmed/26368591) Evidence-based management of anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/22315259)

A 37-Year-Old Woman, Gravida 1 Para 0, at 25 Weeks