Pulmonary embolism is the most common cause of maternal death during pregnancy. CASE REPORT. We report a 28-year-old obstetric patient (35th gestational week) who was admitted to the hospital because of intermittent vaginal bleeding caused by placenta totalis et accreta. Eleven days after admission she suffered a cardiac arrest. After cardiopulmonary resuscitation, an emergency caesarian section was performed and a healthy child was delivered. Abdominal sonography (B-mode) showed a floating thrombus in the inferior vena cava. Perfusion scintigraphy and cavography were normal; a computed tomography i.v. contrast medium study confirmed the presence of the thrombus. An open thrombectomy was performed to protect the patient from further pulmonary emboli. After 8 days she left the intensive care unit without residual complications. CONCLUSION. This case emphasises the importance of bedside sonography as a diagnostic method of identifying the source of a thrombus in patients with suspected pulmonary embolism.