***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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    Input: In a prospect i ve , r and omized multicentre trial the efficacy and safety of the low molecular weight heparin ( LMWH ) fraction Fraxiparin ® and unfractionated calcium heparin ( Calciparin ® ) were compared for the prevention of postoperative deep vein thrombosis . Of 1909 patients included in the trial 1896 underwent abdominal surgery  and received either one daily subcutaneous injection of 7500 anti‐X a units Fraxiparin or 5000 units calcium heparin three times a day subcutaneously . Elastic compression stockings were worn by both groups of patients in the postoperative period . Before r and omization the patients were stratified in two subgroups with or without malignant disease . To assess the rate of deep vein thrombosis ( DVT ) , 125I‐labelled fibrinogen leg scanning was performed daily for 7 postoperative days . Positive results were confirmed by phlebography whenever possible . Venous thrombosis occurred in 27 of 960 patients ( 2.8 per cent ) given Fraxiparin and in 42 of 936 patients ( 4.5 per cent ) given calcium heparin ( P = 0.034 ) . The rates of proximal vein thrombosis were 0.4 per cent ( 4 patients ) and 1.4 per cent ( 13 patients ) respectively ( P<0.05 ) . Pulmonary embolism occurred in 2 of 960 patients ( 0.2 per cent ) treated with Fraxiparin and in 5 of 936 patients ( 0.5 per cent ) treated with calcium heparin . The two treatments were equally well tolerated . Intra‐ and postoperative blood loss , the number of wound haematomas as well as frequency and volume of transfusions were similar in both groups . The present trial demonstrates that a single daily subcutaneous injection of Fraxiparin is more effective than the established low dose subcutaneous heparin prophylaxis with 5000 units three times per day in preventing postoperative DVT after abdominal surgery in patients wearing compression stockings The effect of low-dose heparin prophylaxis on  venous thrombosis and bleeding after major elective surgery was studied in a prospect i ve controlled study of 820 patients . The total incidence of venous thrombosis detected with leg-scanning using fibrinogen labeled with radioactive iodine ( 125I ) was reduced from 16.0 % in the control group to 4.2 % in treated patients . More important , the incidence of popliteal or femoral vein thrombosis was reduced from 2.9 % to 1.0 % . Prophylaxis result ed in a slight increase in bleeding-minor wound hematoma , mean volume of blood transfused , and a post-operative hematocrit fall in treated patients . However , increased bleeding was clinical ly minor , and prophylaxis was well tolerated In a prospect i ve r and omized controlled study on postoperative thromboembolism , 259 patients undergoing elective general surgery , emergency general surgery , total hip replacement or hip fracture surgery were given thromboembolic prophylaxis with either a combination of dextran 70 and dihydroergotamine ( DHE ) or with dextran 70 alone . 500 ml dextran 70 was infused twice on the day of operation , once on postoperative days 1 and 3 , and also on day 5 if the patient was still confined to bed . 0.5 mg DHE was given s.c . twice daily starting before operation and continued for 3 or 5 postoperative days . In hip fracture patients prophylaxis was started as soon as the diagnosis was made . 500 ml dextran 70 was given every other day before operation . DHE was given twice daily if so indicated from r and omization . The patients were screened for deep‐vein thrombosis ( DVT ) with the 125I‐labelled fibrinogen test for 8 days and followed for one month postoperatively . In hip fracture surgery the incidence of DVT was significantly reduced by the combination of dextran 70 and DHE compared to dextran 70 alone ( 1/32 vs. 11/36 , P = 0.003 ) . However , this synergistic effect  of DHE could not be detected in the other patient groups . Fatal pulmonary embolism did not occur . No severe side effects attributable to prophylaxis were noted in either group The potential antithrombotic effect of a new low molecular weight heparinoid , Org 10172 , was examined in a r and omized , double-blind , placebo-controlled , dose-ranging pilot study of the prevention of deep venous thrombosis ( DVT ) in 45 high-risk patients having major thoracic or abdominal surgery for cancer .  Org 10172 was given in doses of 500 , 750 or 1000 U bd subcutaneously . DVT occurred in 9 of 14 patients given placebo and in 4 of 11 patients given 500 U bd but in none of the 20 patients given 750 or 1000 U bd . Operative blood loss and post-operative bleeding were not significantly different between the groups but one patient given 1000 U bd had major post-operative bleeding . Average mid-interval and trough plasma anti-Xa levels reached 0.26 and 0.20 U/ml respectively following the highest dose . It is concluded that Org 10172 is a potentially useful antithrombotic agent and that the effective and safe dose appears to be between 500 and 1000 U bd for prevention of DVT in high-risk patients Objective To compare the effectiveness and safety of low-dose unfractionated heparin and a low-molecular-weight heparin as prophylaxis against venous thromboembolism after colorectal surgery . Methods In a multicenter , double-blind trial , patients undergoing resection of part or all of the colon or rectum were r and omized to receive , by subcutaneous injection , either calcium heparin 5,000 units every 8 hours or enoxaparin 40 mg once daily ( plus two additional saline injections ) . Deep vein thrombosis was assessed by routine bilateral contrast venography performed between postoperative day 5 and 9 , or earlier if clinical ly suspected . Results Nine hundred thirty-six r and omized patients completed the protocol and had an adequate outcome assessment . The venous thromboembolism rates were the same in both groups . There were no deaths from pulmonary embolism or bleeding complications . Although the proportion of all bleeding events in the enoxaparin group was significantly greater than in the low-dose heparin group , the rates of major bleeding and reoperation for bleeding were not significantly different . Conclusions Both heparin 5,000 units subcutaneously every 8 hours and enoxaparin 40 mg subcutaneously once daily provide highly effective and safe prophylaxis for patients undergoing colorectal surgery . However , given the current differences in cost , prophylaxis with low-dose heparin remains the preferred method at present Deep vein thrombosis and its sequel , pulmonary embolus , are possibly the greatest threats to recovery after surgical operation . In a r and omized , controlled clinical trial in which the 125I-fibrinogen uptake test , Doppler ultrasound , and phlebography were used for diagnosis , it was found that low doses of calcium heparinate administered subcutaneously and sodium pentosan polysulfate intramuscularly were effective in preventing deep vein thrombosis ( DVT ) , postoperatively . The incidence of DVT was as follows : 9 % in the group treated with heparinate ; 15 % in the group treated with sodium pentosan polysulfate ; nad 51 % in the untreated control group BACKGROUND Various studies have been performed in general surgery patients comparing low molecular weight heparin ( LMWH ) with st and ard heparin ( SH )  for the prevention of  postoperative deep vein thrombosis ( DVT )  , revealing contradicting results . Therefore , we have compared the efficacy and safety of a LMWH for the prevention of  DVT after major general surgery . PATIENTS AND METHODS Patients received either 20 mg LMWH ( enoxaparin ) once daily , or 5,000 IU SH TID , starting preoperatively in a prospect i ve , r and omized , double-blind international multicenter trial . DVT was diagnosed using fibrinogen I 125 leg scanning . Major and minor bleeding were assessed clinical ly . RESULTS A total of 718 patients were r and omized to LMWH , and 709 patients to SH .  DVT was detected in 58 LMWH-treated patients ( 8.1 % , 95 % confidence interval [ CI ] 6.2 % to 10.3 % ) and in 45 patients allocated to SH ( 6.3 % , 95 % CI 4.7 % to 8.4 % , P > 0.05 ) . Major bleeding complications occurred in 11 LMWH-treated patients ( 1.5 % , 95 % CI 0.8 % to 2.7 % ) and in 18 patients to whom st and ard heparin was administered ( 2.5 % , 95 % CI 1.5 % to 3.9 % , P > 0.05 ) . Four LMWH-treated patients ( 0.6 % ) required reoperation for bleeding as compared to 13 patients in the SH group ( 1.8 % , P = 0.03 ) . CONCLUSION This LMWH appeared as effective and safe as SH . In view of its more convenient way of administration , this LMWH might be preferred for thromboprophylaxis BACKGROUND The American College of Chest Physicians addressed the dilemma of identifying optimal therapy for venous thromboembolism ( VTE ) prophylaxis and published their Fourth Consensus Conference on Antithrombotic Therapy in 1995 , with recommendations for prophylactic therapy . Despite these recommendations , appropriate VTE prophylactic therapy is underused . OBJECTIVES To examine routine practice s in the prevention of VTE in high-risk surgical patients and to determine the extent of adoption of grade A prophylactic therapies as recommended by the American College of Chest Physicians . METHODS Retrospective medical record review in 10 teaching or community-based hospitals located in the United States . Medical charts of 1907 patients were r and omly selected for review from the population of patients who underwent high-risk major abdominal surgery , total hip replacement , hip fracture repair , or total knee replacement between January 1 , 1996 , and February 28 , 1997 . RESULTS Of 1907 patients ,  VTE prophylaxis  was used in 89.3 % ; use was 93.7 % in each of the 3 orthopedic surgery groups and 75.2 % in the high-risk major abdominal surgery group . The percentage of patients receiving grade A therapy  was highest in the hip replacement group ( 84.3 % ) vs. the other groups ( knee replacement , 75.9 % ; hip fracture repair , 45.2 % ; abdominal surgery , 50.3 % ) . CONCLUSIONS The use of  grade A prophylaxis  was related to the type of surgery , with the highest use seen in total hip replacement and the lowest in hip fracture repair . One in 4 patients who underwent high-risk major abdominal surgeries failed to receive any form of VTE prophylaxis . Publication of consensus statements alone may be insufficient to ensure the incorporation of important new clinical information into routine practice The frequency of deep venous thrombosis ( DVT )  was studied in 98 patients undergoing major abdominal surgery . All the patients received low dose heparin prophylaxis 5000 i.u . every 12 h for 5–7 days . In each patient , a graduated compression stocking was also worn and r and omly allocated to one of the legs and the other leg served as a control . DVT was diagnosed by the 125I‐fibrinogen method . Four patients developed bilateral DVT and 8 patients unilateral DVT , all of whom developed it in the control leg . The difference in unilateral DVT between stockinged and control legs was significant ( P < 0·004 ) . It is concluded that a combination of low dose heparin and graduated compression stockings is more effective than low dose heparin alone in reducing the frequency of postoperative DVT . It is suggested that this combination of prophylaxis might be of value in high risk patients The optimal administration regimens of low molecular weight heparins ( LMWHs ) have not yet been established . The aim of this study was to compare the efficacy and safety of 2500 and 5000 XaI units of the LMWH dalteparin in patients undergoing elective general surgery for malignant and benign abdominal disease . Prophylaxis was started in the evening before surgery and given once-daily every evening thereafter . The study was design ed as a prospect i ve , r and omized , double-blind , multicentre trial . Some 66.4 per cent of patients were operated on for a malignant disorder . The primary endpoint was deep vein thrombosis ( DVT ) detected with the fibrinogen uptake test . Bleeding complications were recorded and classified . Analysis was made both on an intention to treat basis and in patients given correct prophylaxis ( 86.3 per cent ) . A total of 2097 patients were r and omized and 27 excluded after r and omization . A technically correct fibr 
    Output:
    
Heparin decreased the rate of proximal DVTs .
There was no difference between LMWH and unfractionated heparin in efficacy , DVT location , or bleeding complications .
Conclusion Using RCT data , this study demonstrates a greatly reduced DVT rate with pharmacologic prophylaxis in cancer patients , and higher doses appear more effective .
Complication rates are low and should not prevent the use of prophylaxis in most patients .
Finally , we found no difference between LMWH and unfractionated heparin in these RCTs .
These results highlight the importance of routine pharmacologic prophylaxis in surgical patients with malignancy