A prospective observational study on the effectiveness and safety of bemiparin,first dose administered 6 h after knee or hip replacement surgery

Introduction Bemiparin has shown to be effective and safe in clinical trials in total knee or hip replacement. Materials and methods We conducted a prospective, open, multicentre, uncontrolled study to audit the utilisation patterns of bemiparin 3,500 IU/day, first dose administered 6 h after surgery, in 1,009 patients undergoing total hip or knee replacement surgery in standard clinical practice. We analysed rates of documented symptomatic venous thromboembolism (VTE) [deep-vein thrombosis (DVT) and pulmonary embolism (PE)] confirmed by objective methods, major bleeding, death, thrombocytopaenia and other adverse events up to 6 weeks. Results Rate of documented symptomatic DVT was 0.3% (95% CI, 0.1–0.9%). No cases of documented PE were reported. There were 14 (1.4%) major bleedings (95% CI, 0.8–2.3%). Neuraxial anaesthesia was used in 937 (92.9%) patients. There were no cases of spinal haematoma, fatal bleeding or bleeding in critical organs. There were 6 (0.6%) cases of mild thrombocytopaenia, which did not require treatment discontinuation. No cases of severe type II heparin-induced thrombocytopaenia were observed. There were no deaths during bemiparin prophylaxis. The median length of hospitalisation was 9 days and 92.5% of patients continued prophylaxis post-hospitalisation for a total median time of 38 days. There were no thromboembolic or bleeding complications during post-hospitalisation prophylaxis. Postoperative start of prophylaxis with bemiparin permitted that 29.3% of patients could be admitted to hospital the same day of the intervention. Conclusion Bemiparin prophylaxis, started 6 h after surgery and given for 5–6 weeks after total hip or knee replacement, was associated with low rates of VTE, major bleeding and other adverse events in normal clinical practice. Bemiparin thromboprophylaxis started 6 h after surgery makes neuraxial anaesthesia/analgesia procedures easier, without compromising efficacy.     

Thromboembolic complications after total hip replacement

We conducted a retrospective analysis of 1,640 consecutive patients undergoing total hip replacement between 1990 and 1997 under general anesthesia and receiving three different prophylactic regimens. The thromboembolic prophylaxis consisted of low-dose unfractioned heparin (UFH), low-molecular-weight heparin (LMWH), or indobufen (INDO). Postoperatively, occurrence of symptomatic deep vein thrombosis (DVT) or pulmonary embolism (PE) was recorded during the first 30 days after surgery and at a routine follow-up visit. Symptomatic DVT was diagnosed in 16 patients (0.9%), while PE occurred in eight patients (0.5%). Patients receiving UFH showed a higher incidence of symptomatic DVT (3.6%) than those patients receiving either LMWH (1.3%) or INDO (0.3%), with an odds ratio for developing symptomatic DVT when receiving UFH versus other treatments of 6.05 (95% confidence intervals [CI95%]: 3.63-10.07) (P=0.001). On the other hand, the diagnosis of PE was more frequently seen in patients receiving cemented hip arthroplasty (2.4%) than in patients receiving uncemented hip arthroplasty (0.34%), with an odds ratio of 3.185 (CI95%: 2.01-5.02)(P=0.05).     

Surgery, venous thrombosis and anti-Xa.

Deep venous thrombosis is a common and unpredictable complication of surgery. In this study it is proposed that patients who develop this complication may be predicted by a low preoperative level of a naturally occurring inhibitor of coagulation, anti-Xa. Two groups of patients were investigated. Women taking the oral contraceptive pill had lower preoperative anti-Xa levels than their non-pill controls (P less than 0.01) and in addition had a significantly higher incidence of deep venous thrombosis (DVT) following emergency surgery (P less than 0.05). In 90 patients undergoing total hip replacement, the mean preoperative anti-Xa level of those patients who developed DVT was significantly lower than those who did not (P less than 0.001). Ninety-four per cent of patients with a preoperative anti-Xa level of less than 80 per cent developed DVT. The effect of low dose heparin on anti-Xa was studied. The results suggest a mechanism for the cause of postoperative thrombosis which also permits selection of individual patients who will develop this complication.     

利伐沙班预防全髋关节置换术后深静脉血栓的临床效果

目的 评价利伐沙班预防全髋关节置换术后深静脉血栓（DVT）的临床效果.方法 将312例行全髋关节置换术的患者随机分为对照组（皮下注射低分子肝素钙,n=156）和实验组（口服利伐沙班,n=156）.检测术前及术后14 d的凝血指标,B超检查评价DVT的发生情况.观察术后肺栓塞、严重器官出血及切口大血肿等并发症,记录术后24 h内切口引流量.结果两组术后14 d的凝血指标与术前比较差异无统计学意义（P〉0.05）,术后14 d两组间比较差异亦无统计学意义（P〉0.05）.实验组的DVT发生率低于对照组（P〈0.05）.两组均未出现肺栓塞、严重器官出血及切口大血肿;术后24 h两组引流量比较差异无统计学意义（P〉0.05）.结论利伐沙班可以有效预防全髋关节置换术后DVT的发生,抗凝效果显著优于低分子肝素钙,且不增加潜在的出血风险.     

Efficacy and safety of weight-adapted nadroparin calcium vs. heparin sodium in prevention of clinically evident thromboembolic complications in 1,190 general surgical patients

AIMS: In a prospective, randomized, single, general surgery center trial, comparison of the safety and efficacy of two low molecular weight heparin (LMWH; anti-Xa heparin sodium and weight-adapted nadroparin calcium) regimens was made. PATIENTS AND METHODS: Eleven hundred and ninety patients undergoing various elective and emergency operations were randomized to receive daily either a fixed dose of 3,000 IU anti-Xa heparin sodium or a variable body weight-dependent dose of nadroparin calcium (weight <50 kg, 2,050 IU anti-Xa (WHO); 51-80 kg, 3,075 UI; 81-100 kg, 4,100 UI, and >100 kg, 6,150 UI) once until discharge. The first injection was administered 2.5-6 h before elective and emergency operations, respectively. Patients with clinical suspicion of deep venous thrombosis (DVT) underwent phlebography. Patients with signs of pulmonary embolism (PE) were further investigated by a ventilation-perfusion scan. RESULTS: Statistically, there were no significant differences in the incidence of clinically evident DVT, PE or LMWH-related complications between both prophylactic regimens. Only 4 of the total of 15 hemorrhagic complications (4 wound hematomas in the nadroparin calcium group) were not classified as clearly surgically related, Two DVTs were confirmed by phlebography (both in the nadroparin calcium group). PE was confirmed by ventilation-perfusion scans (1 fatal, 1 on autopsy) in 1 patient with heparin sodium and in 6 patients with nadroparin calcium. CONCLUSIONS: Both regimens were equally safe and the risk of clinically evident DVT and PE was similar.     

低分子肝素预防髋膝关节术后下肢深静脉血栓形成

目的 评价低分子肝素预防髋、膝关节术后深静脉血栓形成（DVT）的疗效和安全性。方法 1997年4月－1998年10月选择接受髋、膝周围手术的患者46例均为40岁以上,3个月内无血栓栓塞性疾病史、无凝血功能障碍,术前经彩色多普勒超声法筛查,双下肢无DVT,随机分成两组。预防组应用低分子肝素（速避凝）预防DVT,对照组不采用任何预防措施。术后第4－7天行患侧静脉造影,了解深静脉血栓的发生情况。结果 对照组中8例发生DVT,占34．8％;预防组中1例发生DVT,占4．3％。经统计学处理有显著性差异（P＜0．05）。两组均未发生明显的出血并发症。结论 低分子肝素能安全、有效地预防髋膝关节术后深静脉血栓形成。     

Prophylaxis of venous thrombosis after major thoracic surgery

The high incidence (50-60%) of deep venous thrombosis of the legs (DVT) after major thoracic surgery is reduced only by about half with routine low-dose heparin prophylaxis. The present study compared the efficacy of a higher dose of heparin (7500 U twice daily) with the commonly used dose of 5000 U twice daily in preventing scan-detected DVT in 100 consecutive patients having thoracotomy for carcinoma of the lung or oesophagus. After the higher dose of heparin, postoperative DVT was not significantly less frequent (22% compared with 33% for total DVT) but was significantly less extensive (8% and 14%, respectively, for bilateral calf DVT, and 0% and 4% for popliteal DVT). Despite prophylaxis, DVT was especially common after oesophagogastrectomy (41% total DVT, 30% extensive DVT). No excessive postoperative bleeding was noted in either group. It is concluded that an increased dose of heparin safely offers increased prophylaxis against DVT in patients undergoing major thoracic surgery for cancer.     

Insufficient Evidence for Routine Use of Thromboprophylaxis in Ambulatory Patients with an Isolated Lower Leg Injury Requiring Immobilization: Results of a Meta-Analysis

Abstract Background:   There are no generally accepted guidelines for the prevention of venous thromboembolism (VTE) in ambulatory patients requiring immobilization after an isolated lower leg injury. Our objective was to evaluate the effectiveness and safety of pharmacological interventions for preventing VTE in these patients. Study Design:   Meta-analysis of randomized controlled trials. Materials and Methods:   We searched PubMed/Medline, EMBASE and the Cochrane Central Register of Controlled Trials for trials with random allocation of thromboprophylaxis, notably low molecular weight heparin (LMWH) versus no prophylaxis or placebo, in ambulatory patients with below-knee or lower leg (including the knee joint) immobilization. Outcome was analyzed using MIX to calculate the pooled risk ratio/relative risk (RR) for each outcome, along with its 95% confidence interval (CI). Results:   The RR of asymptomatic deep vein thrombosis (DVT) was 0.66 (95% CI 0.44; 1.02) for below-knee immobilization and 0.51 (95% CI 0.37; 0.70) for lower leg immobilization. Low molecular weight heparin versus no prophylaxis or placebo was evaluated. The incidence of symptomatic DVT and PE was too low to show any statistically significant difference between thromboprophylaxis and controls in both groups. Although only one adverse bleeding event was considered to bemajor, the RR for any adverse bleeding event was 1.94 (95% CI 1.03; 3.67). Conclusion:   There is insufficient evidence to warrant routine use of thromboprophylaxis in ambulatory patients with below-knee or lower leg immobilization after an isolated lower leg injury. The incidence of symptomatic VTE is too low to show a relevant clinical benefit from thromboprophylaxis.     

Intraoperative heparin thromboembolic prophylaxis in primary total hip arthroplasty. A prospective, randomized, controlled, clinical trial.

Venous thromboembolic disease remains the most common and potentially fatal complication after total hip arthroplasty (THA). Proximal femoral deep vein thrombosis (DVT) is especially prone to propagate and embolize. The authors' hypothesis was that intraoperative intravenous heparin administration could reduce proximal DVT in THA. There were 286 patients who entered into a prospective, double-blind, randomized clinical trial at the authors' institution between June 1988 and May 1990. All patients had unilateral primary THA under hypotensive epidural anesthesia. The epidural catheter was placed at least 60 minutes before heparin administration. Intravenous heparin was given during surgery only. All patients received aspirin twice daily (650 mg/day) after surgery. Detection of DVT was by contrast venography on Postoperative Day 6 or 7. The study was divided into three phases. There was four groups: control (intraoperative saline), 30 minutes (1000 U heparin at beginning of surgery followed by 500 U every 30 minutes), continuous adjusted (1000 U or 1500 U initial bolus followed by continuous heparin infusion maintaining anticoagulation at 30%-50% elevation from baseline), and fixed dose (1000 U bolus before hip dislocation, and 500 U bolus before femoral canal preparation). Proximal femoral DVT was effectively reduced from 9.1% in the control group to 1.7% in the heparin groups (1.7% in 30 minute, 1.6% in continuous adjusted, 1.7% in fixed dose) (p less than 0.02). The overall DVT rate was also significantly reduced from 24.3% to 10% (p less than 0.01). No adverse effects from heparin administration were noted. Postoperative drainage, hematocrit levels on Postoperative Day 2 and at discharge, and transfusion requirements were not significantly different among the groups. The current recommended protocol is 1000 U bolus five minutes before hip dislocation, followed by 500 U bolus five minutes before femoral preparation. This, in conjunction with hypotensive epidural anesthesia and postoperative aspirin, is effective in reducing proximal DVT to less than 2% in primary THA.     

低分子肝素预防髋、膝关节手术后下肢深静脉血栓形成的多中心研究

目的 探讨国人髋、膝关节手术后下肢深静脉血栓（deepvenous thrombosis,DVT）的发生率及应用低分子肝素预防DVT的有效性和安全性。方法 根据入选标准选择120例髋、膝关节手术患者,分别在北京、上海、广州三个中心参加该项研究,观察组和对照组分别为68例和52例。观察组中男30例,其中全髋关节置换术19例,全膝关节置换术2例,动力髋螺钉（DHS）9例;女38例,其中全髋关节置换术17例,全膝关节置换术17例,DHS4例。对照组中男21例,其中全髋关节置换术19例,全膝关节置换术1例,DHS1例;女31例,其中全髋关节置换术15例,全膝关节置换术15例,DHS1例。结果 除观察组与对照组女性全髋关节置换术患者术中、术后失血量差异有统计学意义（P〈0．05）外,其余出血量差异均无统计学意义（P〉0．05）。手术前后血红蛋白、血小板、凝血酶原时间及活动度与活化部分凝血活酶时间变化差异均无统计学意义（P〉0．05）。两组患者术后下肢DVT发生率差异有统计学意义（P〈0．05）。观察组总的不良反应发生率为8．8％（6.68）。结论 低分子肝素可以有效预防髋、膝关节置换术后DVT的发生,同时对于已发生的DVT有良好的治疗效果,不良反应发生率低。     

利伐沙班与低分子肝素在预防人工全膝关节置换术后深静脉血栓形成的分析

[目的]观察利伐沙班与低分子肝素在预防人工全膝关节置换深静脉血栓的疗效性和安全性.[方法]回顾性分析2009年5月～2011年2月行人工全膝关节置换术的患者200例,将其分为两组,利伐沙班组100例,给予利伐沙班10mg/d口服,连续14d;低分子肝素组的100例,术后给予低分子肝素5000IU/d皮下注射,连续14d.术后14d行双下肢静脉彩超检查有无深静脉血栓形成,并观察两组用药期间有无肺动脉栓塞和严重出血事件的发生.[结果]利伐沙班组深静脉血栓形成的发生率5％,显著低于低分子肝素组的9％,两组均末发生肺动脉栓塞和严重出血事件.[结论]应用利伐沙班较低分子肝素更有效预防膝关节置换术后下肢深静脉血栓的形成,出现严重出血事件很少,二者均较安全.     

The thromboprophylactic effect of a low-molecular-weight heparin (Fragmin) in hip fracture surgery. A placebo-controlled study.

A prospective, randomized, double-blind trial concerning thromboprophylaxis in 82 patients in whom hip fracture surgery was performed was conducted to compare a new low-molecular-weight heparin (Fragmin) with placebo. Deep venous thrombosis (DVT) was detected by 125-I-fibrinogen uptake test followed by ascending phlebography when positive. Sixty-eight patients completed the study, and a 50% reduction in the incidence of DVT was demonstrated: nine of 30 patients in the treatment group (30%) and 22 of 38 patients in the placebo group (58%) developed DVT. This significant difference was achieved by one daily dose of 5000 IU Fragmin subcutaneously, commenced preoperatively and continued for six days. There were no differences in bleeding or other complications in the two groups. Fragmin given once daily offers an effective and safe thromboprophylaxis in hip fracture surgery.     

Deep vein thrombosis prophylaxis: a survey of current practice in Australia and New Zealand.

A survey of current practice for deep vein thrombosis (DVT) prophylaxis was undertaken in Australia and New Zealand. The most common indications for prophylaxis were a history of thrombo-embolism, the type and length of surgery and obesity. Prophylaxis was used in 65% of patients having hip surgery and in 39% undergoing knee surgery. In general surgery the corresponding rate was around 67% for colorectal surgery, hepatobiliary, upper gastrointestinal and major abdominal vascular surgery. Apart from open-heart cardiothoracic surgery (66%), use in other specialties was less than 50%. Physical methods (anti-embolism stockings, calf stimulation and calf compression devices) were most commonly used for prophylaxis (46%) with heparin being used by 40%. The main side effect reported with heparin was bleeding (18%). The estimated incidence of DVT and pulmonary embolus (PE) was 2.8 and 0.4% for general surgery, 2.7 and 0.7% for orthopaedic surgery and 6.6 and 1.3% for hip surgery. Intravenous heparin followed by oral anticoagulants was the most commonly used treatment for established DVT and nearly all respondents used intravenous heparin and oral anticoagulants for treatment of PE. Venography was the favoured objective test for diagnosing DVT. The principal reason for considering a change in prophylactic policy was the potential availability of an agent with increased efficacy and a reduced incidence of haemorrhagic complications.     

DEEP VEIN THROMBOSIS PROPHYLAXIS: A SURVEY OF CURRENT PRACTICE IN AUSTRALIA AND NEW ZEALAND

A survey of current practice for deep vein thrombosis (DVT) prophylaxis was undertaken in Australia and New Zealand. The most common indications for prophylaxis were a history of thrombo-embolism, the type and length of surgery and obesity. Prophylaxis was used in 65% of patients having hip surgery and in 39% undergoing knee surgery. In general surgery the corresponding rate was around 67% for colorectal surgery, hepatobiliary, upper gastrointestinal and major abdominal vascular surgery. Apart from open-heart cardio-thoracic surgery (66%), use in other specialties was less than 50%. Physical methods (anti-embolism stockings, calf stimulation and calf compression devices) were most commonly used for prophylaxis (46%) with heparin being used by 40%. The main side effect reported with heparin was bleeding (18%). The estimated incidence of DVT and pulmonary embolus (PE) was 2.8 and 0.4% for general surgery, 2.7 and 0.7% for orthopaedic surgery and 6.6 and 1.3% for hip surgery. Intravenous heparin followed by oral anticoagulants was the most commonly used treatment for established DVT and nearly all respondents used intravenous heparin and oral anticoagulants for treatment of PE. Venography was the favoured objective test for diagnosing DVT. The principal reason for considering a change in prophylactic policy was the potential availability of an agent with increased efficacy and a reduced incidence of haemorrhagic complications.     

Systematic review of thromboprophylaxis in colorectal surgery – an update

OBJECTIVE: The incidence of thromboembolism after colorectal surgery is higher than after general surgery. The aim of this paper is to update a systematic review addressing thrombosis prophylaxis in connection with colorectal surgery. METHODS: MEDLINE, EMBASE, LILACS, abstract books and reference lists from reviews were searched without language restrictions for randomized controlled trials or clinical controlled trials comparing prophylactic interventions and/or placebo up til August 2003. Five hundred and fifty-eight studies were identified of which 19 fulfilled the inclusion criteria. Data extraction was done by at least two of the authors. Outcome was deep venous thrombosis and/or pulmonary embolism diagnosed by various methods. RESULTS: Any kind of heparin is better than no treatment or placebo (11 studies) with a Peto Odds ratio (POR) at 0.32 (95% CI 0.20-0.53). Unfractionated heparin and low molecular weight heparin (4 studies) were equally effective POR 1.01 (95% CI 0.67-1.52). The combination of graduated compression stockings and LMWH is better than LMWH alone (2 studies) with a POR at 4.17 (95% CI 1.37-12.70). CONCLUSION: The optimal thromboprophylaxis in colorectal surgery is the combination of graduated compression stockings and low-dose unfractionated heparin or low molecular weight heparin.     

The role of low molecular weight heparin in total knee arthroplasty

Low-molecular-weight heparin prophylaxis is an acceptable, if not superior, alternative to heparin and warfarin prophylaxis in TKA. Considering the current popularity of pharmacologic prophylaxis after total hip and total knee arthroplasty and the advantages of low-molecular-weight heparins over traditional pharmacologic agents, these agents have the potential to become the prophylactic agent of choice against DVT in TKA. There are several practical differences between low molecular weight heparins and warfarin. Low molecular weight heparins are administered by subcutaneous injection and do not require drug-level or blood monitoring. Warfarin, although administered orally, must be maintained within an appropriate international normalized ratio (INR=2-3) with daily dose adjustments and takes 36 hours to produce a measurable effect, which may leave patients relatively unprotected during the early postoperative period. Comparative trials have demonstrated that low molecular weight heparins are more efficacious than warfarin in producing a greater overall reduction in the incidence and risk of DVT, but show similar rates of PE. Some studies suggest that bleeding may be a greater problem with low molecular weight heparin. Despite the superior efficacy of low molecular weight heparin, the prevalence of venous thromboembolism after TKA continues to be substantial compared with total hip arthroplasty, with at least a quarter of patients still affected. Additional prophylaxis strategies for this indication are needed and could include combining mechanical prophylaxis (eg, external pneumatic compression) with low molecular weight heparin. An appropriate management strategy should be established for all patients undergoing TKA. This should include identification of high-risk patients, cautious transfusion of blood products, pharmacologic prophylaxis with an acceptable agent for TKA, early mobilization, postoperative screening in high-risk patients, and continuing pharmacologic prophylaxis for an appropriate period postoperatively.     

Late occurring clinical deep vein thrombosis in joint-operated patients

In a prospective study of 4,840 patients, we determined the annual incidence of clinical deep vein thrombosis (DVT) in mobilized, discharged orthopedic-operated "high-risk" patients (hip replacement surgery, knee replacement surgery, nailed hip fracture) and assumed "low-risk" patients (diagnostic knee arthroscopy). In addition, the time from the operation to the time when the patients were readmitted with clinically suspected DVT and the distribution of radiologically-confirmed DVT were recorded. Thromboprophylaxis was routinely given for about 10 days to the high-risk groups during the hospital stay but not to patients undergoing knee arthroscopy. During 9 years, the annual incidence of DVT following major procedures was 2.1% (95% CI 1.6-2.6) vs. 0.6% (95% CI 0.2-1.1) after diagnostic knee arthroscopy. Symptoms appeared, on average, 27 (3-150) days after total hip replacement surgery, 36 (3-150) days after nailed hip fracture, 17 (6-30) days after total knee replacement and 1 (1-6) day after knee arthroscopy. In hip-operated patients, 50% of the DVT's were found in the proximal veins vs. 40% following knee arthroplasty.     

Late occurring clinical deep vein thrombosis in joint-operated patients

In a prospective study of 4,840 patients, we determined the annual incidence of clinical deep vein thrombosis (DVT) in mobilized, discharged orthopedic-operated "high-risk" patients (hip replacement surgery, knee replacement surgery, nailed hip fracture) and assumed "low-risk" patients (diagnostic knee arthroscopy). In addition, the time from the operation to the time when the patients were readmitted with clinically suspected DVT and the distribution of radiologically-confirmed DVT were recorded. Thromboprophylaxis was routinely given for about 10 days to the high-risk groups during the hospital stay but not to patients undergoing knee arthroscopy. During 9 years, the annual incidence of DVT following major procedures was 2.1% (95% CI 1.6-2.6) vs. 0.6% (95% CI 0.2-1.1) after diagnostic knee arthroscopy. Symptoms appeared, on average, 27 (3-150) days after total hip replacement surgery, 36 (3-150) days after nailed hip fracture, 17 (6-30) days after total knee replacement and 1 (1-6) day after knee arthroscopy. In hip-operated patients, 50% of the DVTs were found in the proximal veins vs. 40% following knee arthroplasty.     

Late occurring clinical deep vein thrombosis in joint-operated patients

In a prospective study of 4,840 patients, we determined the annual incidence of clinical deep vein thrombosis (DVT) in mobilized, discharged orthopedic-operated "high-risk" patients (hip replacement surgery, knee replacement surgery, nailed hip fracture) and assumed "low-risk" patients (diagnostic knee arthroscopy). In addition, the time from the operation to the time when the patients were readmitted with clinically suspected DVT and the distribution of radiologically-confirmed DVT were recorded. Thromboprophylaxis was routinely given for about 10 days to the high-risk groups during the hospital stay but not to patients undergoing knee arthroscopy. During 9 years, the annual incidence of DVT following major procedures was 2.1% (95% CI 1.6-2.6) vs. 0.6% (95% CI 0.2-1.1) after diagnostic knee arthroscopy. Symptoms appeared, on average, 27 (3-150) days after total hip replacement surgery, 36 (3-150) days after nailed hip fracture, 17 (6-30) days after total knee replacement and 1 (1-6) day after knee arthroscopy. In hip-operated patients, 50% of the DVT's were found in the proximal veins vs. 40% following knee arthroplasty.     

Prevention of deep vein thrombosis after total hip replacement. The effect of low-molecular-weight heparin with spinal and general anaesthesia.

Enoxaparin, a low-molecular-weight heparin, has been used together with spinal or general anaesthesia in a prospective, randomised study of 188 consecutive elective hip replacements. Bilateral venography was performed on all patients on day 13 after operation. Group I (65 patients) received spinal anaesthesia and no immediate injection of enoxaparin. Group II (61 patients) received spinal anaesthesia and 20 mg of enoxaparin one hour after the onset of anaesthesia. Group III (62 patients) was operated on under general anaesthesia and received 40 mg of enoxaparin 12 hours prior to surgery. This group acted as the control group. In all three groups, 40 mg of enoxaparin was given 12 hours after the end of surgery and continued on a once-daily basis. Proximal DVT occurred in 6% of group I, 6.7% of group II and 6.5% of group III, not a significant difference. Distal DVT was present in 11% of group I, 5% of group II and 0% of group III; this was a highly significant difference (p = 0.007). Tolerance was good and the incidence of bleeding low in the three groups. Our results confirm the low rate of DVT in patients operated on under general anaesthesia with the standard procedure of 40 mg of enoxaparin on a once-daily basis started pre-operatively. The 40 mg-dose is also safe and effective in association with spinal anaesthesia if half the dose (20 mg) is injected an hour after the lumbar puncture.