***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: Study Design . Thromboembolic disease ( TED ) after anterior/posterior spinal reconstructions  was prospect ively evaluated in 66 consecutive patients . Objective . Determine the incidence of TED after  anterior/posterior spinal reconstruction .  Summary of Background Data . Few studies have examined the rate of TED after potentially high-risk combined anterior/posterior reconstructions . Magnetic resonance venography ( MRV ) is more effective at detecting pelvic deep venous thrombosis ( DVT ) than conventional screening , but has not been used in these patients . Methods . We undertook a prospect i ve cohort study of 66 consecutive adult patients ( mean , 52.7 ± 9.6 years ) undergoing combined anterior/posterior spinal reconstructions for spinal deformity . All patients received only mechanical DVT prophylaxis .  After surgery , MRV and bilateral lower extremity Doppler ultrasounds were obtained to screen for DVT , and contrast-enhanced spiral computed tomography scans were obtained for clinical suspicion of pulmonary embolism ( PE ) . Results . The total incidence of postoperative TED was 13.6 % ( 9 patients ) . The overall rate of DVT was 9.1 % ( 6 patients ) , one-third occurring in the pelvis . PE developed in 7.6 % ( 5 patients ) . In 2 patients , PE developed less than 48 hours after positive dopplers . In 3 patients , PE developed despite negative screening studies . Right-sided thoracoabdominal approaches were associated with an increased risk of developing DVT ( P = 0.03 , Odds Ratio 9.8 ) , PE ( P = 0.01 , Odds Ratio 20 ) , and TED ( P = 0.004 , Odds Ratio 12 ) . Conclusion . We report a high rate of TED after extensive anterior/posterior spinal reconstructions , for which a right-sided thoracoabdominal approach is an independent risk factor and screening ineffective at preventing PE . These patients should be considered at high risk for postoperative TED In a prospect i ve , r and omized , double-blind investigation of anticoagulant agents for prevention of deep vein thrombosis in patients undergoing operations at the lumbar-vertebral disc , 179 patients were r and omly allocated to two groups . 87 patients received a fixed combination of low-molecular weight heparin 1,500 U-aPTT plus dihydroergotamine 0.5 mg ( LMWH/DHE ) once a day and additionally one injection of placebo per day , 92 patients received a fixed combination of sodium heparin 5,000 U plus dihydroergotamine 0.5 mg ( HDHE ) twice a day . Treatment was initiated two hours preoperatively in both groups and continued for at least seven days . Deep vein thrombosis ( DVT ) , detected by the 125Iodine-labelled fibrinogen uptake-test , occurred in four patients treated with LMWH/DHE and in three patients with HDHE . In all seven patients phlebography was performed , confirming the diagnosis of DVT in one patient of the LMWH/DHE group and in two patients of the HDHE group , only . No increased bleeding was found in either group . Especially no neurological complications caused by epidural bleeding were observed . We therefore recommended to treat routineously all patients undergoing operations at the vertebral disc with antithrombotic agents .  The advantages of the once daily regimen with low-molecular weight heparin include better patients ' acceptance and less nursing time We performed a prospect i ve study of 317 patients in order to determine the prevalence of deep venous thrombosis after reconstructive operations on the spine ; 126 of the patients were examined with  duplex ultrasound assessment s of the lower extremities to ensure that no asymptomatic thrombi were being missed . Thigh-high stockings and sequential pneumatic compression of the lower extremities were used , in all patients , for prophylaxis against venous thrombosis . No antiplatelet agents or anticoagulant medications were administered . There was no evidence of thrombosis on any of the duplex ultrasound studies . Subsequently , venous thrombosis developed and was treated successfully in one of the 126 tested patients and in one of the 191 untested patients , and a fatal pulmonary embolus developed in one of the untested patients . The over-all clinical prevalence of thrombotic complications was 0.9 per cent ( three complications in 317 patients ) . All three of the patients who had clinical evidence of thrombosis had had an anterior lumbar procedure because of a degenerative disorder or trauma ; however , we could not prove that this approach or these diagnoses were significant risk factors for thrombosis ( p < 0.05 ) . While it is possible that some thrombi may have escaped both clinical and ultrasonic detection , such thrombi apparently were not enough of a danger to warrant the use of intensive prophylactic procedures that are associated with more risk . On the basis of this prospect i ve study , therefore , we think that routine screening for the detection of asymptomatic thrombosis in patients who have had a procedure on the spine is unwarranted We prospect ively studied the incidence of deep vein thrombosis ( DVT ) of the thigh in 117 patients having posterior lumbar spinal fusion with instrumentation and bone grafting for degenerative disk disease or spondylolisthesis . Patients with neoplasm , infection , trauma , or history of DVT were excluded . Patients were r and omized into two groups . In the operating room , group 1 patients were placed in thigh-high antiembolic compression stockings ( TED hose ) , and group 2 patients were placed in antiembolic stockings and pneumatic compression stockings . In both groups , the stockings were used until discharge . Postoperatively , patients in both groups received 600 mg buffered aspirin twice daily . Comparative analysis of the two groups showed no difference in operative time , blood loss , number of levels of lumbar vertebrae fused , time to mobilization , weight , age , or sex . All patients had duplex scanning of the thigh postoperatively . No patient in the series was observed to have acute DVT by clinical examination or by ultrasonography Summary We have evaluated the incidence of bleeding complications using miniheparin(2 × 2500IU daily)-dihydroergotamine starting preoperatively in a r and omized , controlled , prospect i ve , double-blind study in 50 patients undergoing herniated lumbar disc operations . There was no difference in the incidence of intraoperative bleeding problems between the two groups . Preoperatively , 13 patients have been treated in another hospital with conventional low-dose heparin , and of these 13 patients , 7 developed bleeding complications . There were two deep wound hematomas in the placebo group . Early removal of stitches or operative revision of the wound was not necessary in either group . We conclude that the use of minidose heparin-dihydroergotamine is feasible for the prevention of thromboembolic complications in patients undergoing herniated lumbar disc operations , since an increased incidence of bleeding complications was not observed . This preventive method should therefore be further clinical ly evaluated Study Design . Intermittent pneumatic compression stockings ( IPC ) alone were prospect ively used to avoid deep venous thrombosis ( DVT ) and pulmonary embolism ( PE ) in 100 consecutive patients undergoing single-level anterior corpectomy/fusion ( ACF ) and in 100 patients having multilevel ACF/posterior fusion . Objectives . To determine the optimal prophylaxis against DVT and PE for patients undergoing anterior cervical spinal surgery . Background Data . Mini-heparin and low-dose heparin prophylaxis in neurosurgery poses a 2 % to 4 % risk of major postoperative hemorrhage with result ant neurologic sequelae . Methods . Prophylaxis consisted of IPC alone . Doppler studies of the lower extremities were routinely obtained 2 days after surgery . Single-level ACF ( 100 patients ) addressed two-level disc disease , spondylostenosis , and ossification of the posterior longitudinal ligament ( OPLL ) . One hundred patients undergoing multilevel ACF ( 3 + levels ) with posterior fusion ( C2–T1 ) exhibited OPLL/spondylostenosis . Results . One patient undergoing single-level ACF developed DVT/PE 6 days after surgery ; she exhibited Factor V Leiden mutation ( hypercoagulability syndrome ) . Although 7 patients undergoing circumferential surgery developed DVT 2 to 14 days following surgery ( mean , 7.15 days ) , only two clots localized in the iliac veins result ed in PEs ( days 10 and 14 after surgery ) . Conclusions . IPCs were as effective for prophylaxis against DVT/PE for 100 patients undergoing single-level ACF and for 100 having circumferential procedures as existing therapies ( mini-heparin and low-dose heparin ) , without the risk of hemorrhage . However , the 1 % and 2 % respective rates of PE were comparable to frequencies of PE encountered in other cranial/spinal series using mini-heparin and /or low-dose heparin regimens but avoided the 2 % to 4 % risk of major postoperative hemorrhage There is a need to improve postoperative analgesia to support the trend to shorter hospitalization after minimally invasive spine surgeries . Ketorolac Tromethamine has proven efficacy in decreasing postoperative pain but there is concern with postoperative epidural bleeding after spine procedures . We prospect ively assessed the incidence of bleeding complications after microdiscectomy in patients treated with a single 30 mg intraoperative dose of Ketorolac subsequent to wound closure . Group 1 consisted of 44 patients , 24 women and 20 men with mean age of 35.7 years ( 20 to 68 y ) treated with Ketorolac . Group 2 consisted of 45 patients , 28 men and 17 women with mean age 46.8 years ( 32 to 74 y ) , who underwent discectomy without Ketorolac .  Postoperative bleeding complications were monitored along with pain levels and time to discharge . We detected no significant postoperative changes in coagulation parameters or bleeding from the surgical site in either group . Both group 1 and 2 had averaged preoperative visual analog scale scores for leg pain of 8 . Group 1 had an average postoperative visual analog scale score of 2.6 compared with 4 for group 2 two hours after surgery . Single dose intravenous Ketorolac provided beneficial analgesia without significant increase in risk of bleeding after microdiscectomy , enabling us to consistently perform microdiscectomy as an ambulatory procedure . Meticulous hemostasis should be accomplished before closure . Prolonged postoperative use is a promising alternative to narcotics STUDY DESIGN Adult spinal surgery patients were studied prospect ively to determine the incidence of sub clinical deep venous thrombosis . An overlapping group of patients was review ed retrospectively for symptomatic thromboembolism . OBJECTIVES To determine the incidence of symptomatic and asymptomatic thromboembolism in spinal surgery patients . SUMMARY OF BACKGROUND DATA Although thromboembolic complications are known to occur after spinal operations , there are limited published data on the incidence of pulmonary embolus or deep venous thrombosis after major spinal surgery . METHODS One hundred sixteen adult spinal surgery patients were examined with duplex ultrasound  to determine the incidence of deep venous thrombosis . Seventy-three of these patients also underwent lung perfusion scans to look for sub clinical pulmonary embolism . A retrospective review was conducted of symptomatic thromboembolic complications occurring in a 2-year period at the authors ' center . Three hundred and eighteen major spinal reconstructive procedures were performed during the period review ed , which included the period of the prospect i ve study and therefore the patients of the prospect i ve group . Thigh-length compression stockings and pneumatic compression leggings were used for prophylaxis in all patients . RESULTS One patient had an asymptomatic iliac vein thrombosis , and seven patients had symptomatic pulmonary embolism ( 2.2 % ) . Six of the symptomatic pulmonary emboli occurred after combined anterior/posterior spinal fusions ( 6 % ) , whereas only one occurred after posterior decompression and fusion ( 0.5 % ) . CONCLUSIONS Duplex ultrasound appeared insensitive for diagnosing clots before embolization in this patient group . Simple mechanical prophylaxis for thromboembolism , which may be adequate for patients undergoing posterior procedures , may not be as protective for patients undergoing combined anterior/posterior spine surgery Study Design . A prospect i ve clinical study using venography to evaluate deep venous thrombosis after posterior spinal surgery . Objectives . To demonstrate the prevalence of deep venous thrombosis after posterior spinal surgery with no prophylaxis . Summary of Background Data . There have been few studies about the occurrence of deep venous thrombosis after spinal surgery in which venography was used for screening . Methods . Of the enrolled 134 patients undergoing posterior spinal surgery , 110 ( 82.1 % ) were examined with complete surveillance for deep venous thrombosis by venography .  There were 64 males and 46 females . The average age at operation was 59.0 years ( range , 14–86 years ) . The levels of the operation were cervical in 54 , thoracic in 7 , and lumbar in 49 . All procedures were performed with patients under general anesthesia . Neither mechanical methods nor anticoagulation medications were used 
    Output:
    
Fatal pulmonary embolism was rare .
CONCLUSION Venous thromboembolism is uncommon after elective spine surgery .
Trauma patients are at increased risk , and chemical prophylaxis should be considered .