A 32-year-old patient was admitted to the emergency department due to G1P0 threatened labor at 39 weeks with severe preeclampsia. Her medical and family history was unremarkable, no hypertension or ICH history. Physical examination on admission: T( body temperature) 36.7 ℃, P(pulse rate) 102 times min−1, R(respiratory rate) 20 times min−1, BP(blood pressure) 188/109 mmHg. The patient was treated with 20% mannitol 250 ml, 5% magnesium sulfate 100 ml, and urapidil 50 mg to prevent eclampsia. Her blood pressure was controlled between 140–160/100–110 mmHg and the headache relieved. Relevant examinations were completed immediately, blood routine showed mild thrombocytopenia(PLT 132 × 109 L−1), routine biochem examination indicated suspicious hemolysis[ lactate dehydrogenase (LDH) 2136U L−1, broken erythrocytes were not found] and elevated liver enzymes [alanine aminotransferase (ALT)186U L−1, aspartate aminotransferase (AST) 372U L−1]. Urinalysis indicated hematuria and proteinuria. Severe preeclampsia and class3 HELLP syndrome (the mildest type) were diagnosed. Considering that the fetus was full-term but unable to deliver vaginally within a short time, the patient was intended to terminate the pregnancy by cesarean section under epidural anesthesia. However, the patient had poor response to language when entered the operating room 5 h after admission, the GCS score is 13 points, her verbal response and eye-opening response each lose 1 point, and the catheter drainage fluid was hematuria. The anesthesiologist decided to perform general anesthesia after comprehensive evaluation. Before anesthesia induction, arterial blood was collected for thromboelastography (TEG) detection. The patient underwent a cesarean section and a girl was delivered. During the operation, the surgeon reported severe bleeding from the surgical incision. The TEG result received after surgery showed low PLT or function, low fibrinogen level or function and coagulation disorder (R 8.4 min, K 5.3 min, Angel 39.2°, MA 43.6 mm, CI-0.7, G3.9 k D/SC). Combined TEG result with significant increased liver enzymes before surgery, we suspected serious HELLP syndrome was the reason of bleeding tendency []. The patient was transported to the central ICU with tracheal tube after surgery. The laboratory test results in ICU indicated hemolysis (H), elevated liver enzymes (EL), low PLT (LP) (PLT 30 × 109 L−1) and coagulation disorder, the class1 HELLP syndrome (the most severe form) was verified. Blood transfusion (5U suspended red blood cells and 1U platelets) was adopted. The patient's PLT increased, liver enzymes decreased, coagulation function returned to normal except D-dimers and fibrinogen degradation Products (FDP) (PLT 70 × 109 L−1, ALT 90U L−1, AST 139U L−1, LDH 1753U L−1, FDP 15.5ug ml−1, D-dimers 4.65 mg L−1), endotracheal tube was removed 1 day later. The laboratory test results improved (PLT 74 × 109 L−1, FDP15.0ug ml−1, D-dimers4.82 mg L−1, others are normal) 2 days after surgery. The blood pressure was well controlled with continuous urapidil pumping. However, the patient had repeated attacks of headache and convulsions, each time lasting for tens of seconds, and the Babinski's sign, Buchner's sign, and Kirschner's sign were positive. Considering the possibility of eclampsia, magnesium sulfate, urapidil and other symptomatic treatments were given. Then skull CT suggests ICH in the right temporal lobe and basal ganglia. The CTA and CTV showed no obvious cerebral vascular malformation. Then she was admitted to the operation room for clearance of intracerebral hematoma in emergency. The patient did not complain obvious headache after surgery and vital signs were stable after surgery. She was transferred out of ICU 6 days later. About 14 days after admission, the patient developed a progressive decline in blood cells and PLT, and developed suspected septic shock(somnolence, T 39.7℃, BP 81–99/35-68 mmHg, HR 172–180 times min−1, R 46 times min−1, procalcitonin: 34.13 ng ml −1) and coagulation disorder [Prothrombin time (PT) 20.4 s, International Normalized Ratio (INR) 1.76, activated partial thromboplastin time (APTT) 67.3 s, FDP 237.8 μg ml−1, D-dimers: 93.62 mg L−1]. The aggressive platelet transfusion and the use of colony stimulating factor had been adopted, ceftazidime, meropenem, and vancomycin were used to treat the infection of the patients. At that time, we considered it was caused by HELLP syndrome or infection-related hemophagocytic syndrome. But the auxiliary examination did not meet the diagnostic criteria of hemophagocytic syndrome (abdominal CT and bone marrow biopsy were normal, repeatedly searches for viral and bacterial infectivity indicators were failed). Prophylactically, steroid pulse therapy and intravenous immunoglobulins therapy were administered. We complete ferritin, interleukin 2 receptor (IL-2R), NK cell activity and genetic mutation associated with hemophagocytic syndrome. After 49 days in hospital, hemophagocytic syndrome was diagnosed [persistent fever (> 38·5 °C); severe pancytopenia; hypertriglyceridemia; low and absent NK cell; ferritin concentrations on the 34th day:16,279.0 ng mL−1, IL-2R concentrations on the 34th day: 6757.0 IU ml−1; abdominal CT on the 41th day showed splenomegaly; bone marrow biopsy on the 42th day showed hemophagocytosis ] [, ]. However, there were no abnormal genes related to hemophagocytic syndrome, no tumor markers in the blood system been found. The EBV (Epstein barr virus)-DNA, CMV (cytomegalo virus)-DNA and other viruses and bacterial infection indicators were negative. The ANCA (Anti Neutrophellol Cytoplasmic Antibody), antinuclear antibody spectrum and humoral immunity were normal. So, the cause of hemophagocytic syndrome is still unknown. The patient was discharged in 2 months after admission finally.