A 32-year-old woman is brought to the emergency department after she was found wandering aimlessly in the street. She lives in a homeless shelter and has not received medical care in several years. The patient has no chronic medical problems or previous surgeries. She has a history of intravenous drug use and 16-pack-year cigarette use. Temperature is 37.2 C (99 F), blood pressure is 120/60 mm Hg, and pulse is 94/min. BMI is 19 kg/m². On examination, the patient is mildly agitated, but oriented to person and place. Her sclerae are icteric. The mucous membranes are moist, but there is evidence of poor oral hygiene and multiple dental caries. There are scattered bilateral petechial lesions on the extremities and trunk. Cardiac, abdominal, and neurologic examinations are unremarkable. Bimanual pelvic examination reveals a uterus consistent with 14 weeks gestation. Laboratory results are as follows: Urine pregnancy test is positive. Which of the following is the most likely diagnosis?

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Explanation: 11ec2b69_bf81_d531_8f63_fd38f73eae69_MD0005_00 This patient has altered mental status, a petechial rash, renal failure, thrombocytopenia, and a microangiopathic hemolytic anemia (eg, hyperbilirubinemia, scleral icterus), a presentation consistent with thrombotic thrombocytopenic purpura (TTP). Other features of TTP include fever, seizure, coma, and gastrointestinal symptoms (eg, nausea, abdominal pain). TTP occurs as a result of an either inherited or acquired deficiency in the activity of ADAMTS13, a von Willebrand factor-cleaving protease. Pregnancy is associated with an ADAMTS13 deficiency that becomes more pronounced with increasing gestational age and persists into the postpartum period and can precipitate TTP. TTP is a life-threatening condition that requires emergency treatment with plasma exchange. (Choices A and B) Acute fatty liver of pregnancy typically presents in the third trimester with nausea, vomiting, epigastric pain, malaise, and elevated transaminases. HELLP syndrome typically presents in the third trimester with hemolytic anemia, thrombocytopenia, and elevated transaminases. These diagnoses are unlikely in this patient due to the early gestational age and normal transaminases. (Choice C) Serum sickness typically presents with a rash and renal failure 1-2 weeks after antigenic exposure. However, patients also typically have an associated polyarthralgia, which is not seen in this patient. (Choice D) Wernicke encephalopathy (eg, thiamine deficiency) typically presents with an altered mental status. However, Wernicke encephalopathy also presents with oculomotor dysfunction (eg, nystagmus) and gait ataxia, which are not seen in this patient. Educational objective: Thrombotic thrombocytopenic purpura (TTP) presents with a petechial rash, neurologic abnormalities, thrombocytopenia, and microangiopathic hemolytic anemia. TTP can occur during pregnancy or in the postpartum period. Treatment is with plasma exchange. References: Thrombotic thrombocytopenic purpura: from diagnosis to therapy. (http://www.ncbi.nlm.nih.gov/pubmed/26418759) Pregnancy associated thrombotic thrombocytopenic purpura: practical issues for patient management. (http://www.ncbi.nlm.nih.gov/pubmed/26626962)

A 32-Year-Old Woman Is Brought to the Emergency Department After