Peripheral blood smears of two pregnant women with sickle cell disease who had clinical evidence of pulmonary embolism revealed significant numbers of erythrocytes having the appearance of "blister cells." These cells resemble a round or conical basket with a handle, giving the appearance of a cell with a large vacuole at one pole but with intact cell membrane. One patient had homozygous hemoglobin SS disease and died three days after hospitalization. The second patient had hemoglobin SC disease and recovered. A normal infant was born to this patient ten weeks later. "Blister cells" were not observed in 15 patients (one pregnant) with hemoglobin SS disease, and four patients (one pregnant) with hemoglobin SC disease without pulmonary infarction.
Karayalcin G, Imran M, Rosner F. "Blister Cells"Association With Pregnancy, Sickle Cell Disease, and Pulmonary Infarction. JAMA. 1972;219(13):1727–1729. doi:10.1001/jama.1972.03190390013004