This was a prospective observational study approved by institutional ethical review board in St. John's Medical College Hospital, Bangalore. Consecutive 100 patients presenting to the hospital, who fulfilled the criteria were included in the study. Patients with age of more than 18 years undergoing abdominopelvic cancer surgery were eligible whereas patients with current or past VTE were excluded. Informed consent was taken from all the patients. At inclusion in to study detailed history, co-morbidities, type of cancer and nature of surgery and VTE risk assessment will be recorded. Subjects will be grouped under different groups, according to the DVT prophylaxis treatment given by each discipline. Group 1 was patients who received no prophylaxis, Group 2 was those who received some form of prophylaxis. Patients receiving standard 7-10 days of anti-coagulation were included in Group 3, whereas Group 4 consisted of patients receiving extended prophylaxis for 4 weeks. Study subject were reassessed between second and third week for the development of DVT by Doppler scan, in case of clinical suspicion any time Doppler scan can be taken. Compression Doppler Ultrasonography (CDU) was performed by Radiologists in the department of Radiology using linear probe 7-12 MHz. Veins of both lower limbs were studied as iliofemoral, femoropopliteal segments and the distal veins. Hypoechoic filling defects with non-compressible veins were diagnosed as deep vein thrombosis.

Descriptive statistics were reported using mean and standard deviation for the continuous variables, number and percentage for the categorical variables. Chi-square test was done to test the association between categorical variables. Analysis of variance was done to compare the means between outcomes. P value less than 0.05 was considered statistically significant.

All the analyses were done using SPSS version 20.0.

There was a female preponderance in the study population, with 69 out of the 100 patients being female and 31 being males Table 1. Majority of the participants be aged below 60 years (71%) and 29% aged above 60 years with mean age of 51.7. The body mass index of the patients was analyzed and found that 45 patients had BMI below 22kg/m³ and 55 had BMI above 22kg/m³.

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Majority of our study group patient (73%) received pharmacological and mechanical prophylaxis according to the standard guidelines. Study also revealed that none of the patient were received extended pharmacological prophylaxis and 24 patient received pharmacological prophylaxis but it was not according to standard recommendation as far as the dosage, duration and pre-operative prophylaxis are concerned. Four patients developed deep vein thrombosis during the screening period. Among those who developed DVT three received standard pharmacological thromboprophylxis for 7- 10 days or more and remaining one was in group 2 received pharmacological thromboprophylxis, not as recommended as per dosage and preoperative prophylaxis Table 2. But statistical analysis this data was not significant (P value-0.16).

Duration of the surgery was grouped into less than 2 hours, 2 to 5 hours and more than 5 hours. Duration of 71 surgeries was found to be between 2 to 5 hours Figure 1.

Three drugs were mainly used in the pharmacological prophylaxis; Enoxaparin, Daltaparin, Heparin (unfractionated). Of 97 patients who received pharmacological prophylaxis, 43 received Enoxaparin, 42 received Daltaparin, and 12 received Heparin. The incidence of postoperative DVT was almost double in Daltaparin group as compared to enoxaparin and conventional Heparin.

Commonest malignancy in the study was gynaecological in origin (39%) with cervical cancer 13%. Gastrointestinal cancer was next common with 33% in incidence.

Analysis of type of surgery verses outcome have shown that one patient developed DVT among 85 patients who underwent curative surgery for abdominopelvic caner, of 15 patients who underwent palliative surgery three developed DVT Table 3. Statistical analysis on type of surgery and DVT is significant with p value of 0.01. On subset analysis, age of the patients who had DVT was more than 50 years, GI malignancy was common (75%), two patients received preoperative chemotherapy and they received prophylaxis for an average of 11 days.

Among the patient developed deep vein thrombosis, three developed after discharge while one developed during hospital stay on post-operative day 10. Iliofemoral Deep vein thrombosis was seen in one patient whereas other three patients were found to have femoropopliteal segment involvement. All these patients were asymptomatic and none were worked up for Pulmonary embolism in view of haemodynamical stability.

In our study the average age of patients was 51.7 which is much lower than the world literature 12.

Hypertension and Diabetes were the most commonly associated co-morbidities however, a direct relation between these and the development of DVT was not evaluated as review of literature doesn’t implicate it.

Despite of evidence in favor of thromboprophylxis for Cancer surgeries, most centers are not following the same. The ESSENTIAL trial demonstrated that 75% of patients undergoing major cancer surgery did not receive appropriate extended venous thromboembolism prophylaxis. All the patients in our study who were eligible for thromboprophylaxis, received it, which is in good compliance with the standard guidelines 13, 14.

In our study 90% of the study population received both mechanical and pharmacological prophylaxis as the combined regimen of pharmacologic and mechanical prophylaxis may improve efficacy, especially in the highest-risk patients 9. The incidence of DVT, PE, and total VTE within 1 month following surgery varied widely across a spectrum of cancer diagnoses, ranging from 0.19%, 0.12%, and 0.28% for breast resection to 6.1%, 2.4%, and 7.3%, respectively for esophagectomy 15. In another study, among 1,015,598 cancer patients, 34,357 (3.4%) were diagnosed with deep venous thrombosis and 11,515 with pulmonary embolism (PE) (1.1%) for an overall VTE rate of 4.1% 12. Our study has same incidence of DVT similar to the above studies. Interestingly, a multi-centric study from India involving 300 patients showed that only 48% received thromboprophylaxis and none developed DVT, which is not comparable to our study. The possible difference could be that this study only did look at symptomatic patients and the real number of cases would have been missed as many DVT are asymptomatic 16.

The rate of late VTE is estimated to be between 10% and 20%. A meta-analysis of two studies using dalteparin or enoxaparin has shown that prolonging thromboprophylaxis for a further 3 weeks significantly reduces the risk of late occurring VTE by 62% 17.

In our study, majority of the DVT (3/ 4) occurred in patients undergoing palliative surgery; this data statistical analysis was significant with p value of 0.01.

Our main finding was that pharmacological prophylaxis for week after surgery for abdominal or pelvic cancer significantly reduced the frequency of postoperative venous thromboembolism but extended prophylaxis may benefit patients undergoing palliative surgery for the same.

It is a small study, Cancer specific VTE assessment scoring would have been better than Wells score.