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Cancer and major surgery both raise the risk of blood clots in the legs and lungs. Before the operation the team should assess your risk of clots and of bleeding, use stockings or leg pumps, and usually give blood-thinning injections. After major cancer surgery in the abdomen or pelvis these are often continued at home for four weeks, because many clots happen after discharge.
NICE NG89 (2018, updated 2019) asks for every surgical patient's VTE and bleeding risk to be assessed on admission with a published tool and reassessed at consultant review or when their condition changes. For abdominal (gastrointestinal, gynaecological, urological) surgery at increased risk, mechanical prophylaxis (anti-embolism stockings or intermittent pneumatic compression) starts on admission and continues until mobility returns, and LMWH or fondaparinux is added for at least 7 days where clot risk outweighs bleeding risk. NICE says to consider extending pharmacological prophylaxis to 28 days after major cancer surgery in the abdomen. For thoracic surgery the same pattern is 'consider'. ASCO (2023 update) added apixaban and rivaroxaban as options for extended prophylaxis after cancer surgery, with a weak recommendation. The Cochrane review (2019; 7 RCTs, 1728 participants, benign and malignant disease) found extended LMWH reduced VTE after major abdominal or pelvic surgery from 13.2% to 5.3% (OR 0.38, 95% CI 0.26 to 0.54, moderate-quality evidence), mostly clots found by scanning, with no difference in bleeding or mortality. Before discharge, people should be shown how to inject and dispose of needles, told how long to continue, and told the signs of DVT, pulmonary embolism and bleeding.
Why: Prevention is only worth its bleeding risk in people whose clot risk is high enough, and a structured tool means nobody is missed.
“Assess all surgical and trauma patients to identify the risk of VTE and bleeding:”
NICE 2018 · [2018, amended 2021]
Why: People who understand why they need the injections and stockings are more likely to keep using them.
“For people admitted to hospital who are at increased risk of VTE, give them and their family members or carers (as appropriate) verbal and written information on the following before offering VTE prophylaxis:”
NICE 2018 · [2018]
Why: Squeezing the legs keeps blood moving while you are less active, without any bleeding risk.
“Start mechanical VTE prophylaxis on admission for people undergoing abdominal surgery. Choose either:”
NICE 2018 · [2018]
Why: Badly fitting stockings can cause pressure sores, and they are unsafe with some skin and arterial conditions.
“Ensure that people who need anti-embolism stockings have their legs measured and that they are provided with the correct size of stocking. Anti-embolism stockings should be fitted and patients shown how to use them by staff trained in their use.”
NICE 2018 · [2010]
Why: Blood-thinning injections reduce clots after major surgery more than stockings alone.
“Add pharmacological VTE prophylaxis for a minimum of 7 days for people undergoing abdominal surgery whose risk of VTE outweighs their risk of bleeding, taking into account individual patient factors and according to clinical judgement.”
NICE 2018 · [2018]
Why: A blood thinner given too close to placing or removing an epidural catheter can cause bleeding around the spinal cord.
“If regional anaesthesia is used, plan the timing of pharmacological VTE prophylaxis to minimise the risk of epidural haematoma.”
NICE 2018 · [2010]
Why: Cancer keeps clot risk high for weeks after surgery, and many clots appear after people have gone home.
“Consider extending pharmacological VTE prophylaxis to 28 days postoperatively for people who have had major cancer surgery in the abdomen.”
NICE 2018 · [2018]
Why: A new bleed, a return to theatre or a fall in platelets can change whether blood thinners are still safe.
“Reassess all medical, surgical and trauma patients for risk of VTE and bleeding at the point of consultant review or if their clinical condition changes.”
NICE 2018 · [2018]
Why: Four weeks of daily injections at home only work if people know how to do them and why to finish the course.
“Give people discharged with VTE prophylaxis and their family members or carers (as appropriate) verbal and written information on:”
NICE 2018 · [2018]
Why: Calf pain or swelling, sudden breathlessness or chest pain need urgent treatment.
“the importance of seeking help if DVT, pulmonary embolism or other adverse events are suspected.”
NICE 2018 · [2018]
How care is usually carried out, read from the guidelines and standards cited. Your own team's protocol and their judgement come first; this page is for understanding it, not for doing it yourself.
Risk assessment for VTE and bleeding on admission, mechanical prophylaxis from admission, LMWH or fondaparinux for at least 7 days after abdominal surgery, and extended pharmacological prophylaxis to 28 days after major abdominal or pelvic cancer surgery (NICE NG89 'consider' [2018]; Cochrane 2019, moderate-quality evidence that it reduces VTE without increasing bleeding or mortality). ASCO 2023 adds apixaban or rivaroxaban tablets as options for the extended course, with a weak recommendation, where NICE names only LMWH or fondaparinux. Most of the reduction in the trials is in clots found by scanning; symptomatic VTE fell from 1.0% to 0.1%, a difference that did not reach significance.
NICE 2018 · Cochrane Database of Systematic Reviews 2019 · ASCO (Journal of Clinical Oncology) 2023
Where it differs: Replaces four weeks of daily injections with an oral factor Xa inhibitor after cancer surgery.
Evidence: ASCO 2023 added both as options with a weak strength of recommendation, on two randomised trials that its abstract describes as having important limitations but suggesting safety and effectiveness. NICE NG89 does not list them for abdominal surgery.
Blood clots after a major operation for bowel, gynaecological or other abdominal cancer often appear after discharge. Extending preventive blood thinners to four weeks roughly halved clots in pooled trials without more major bleeding, and professional societies recommend it, yet among 23,527 older Americans having bowel cancer surgery in 2016 and 2017, 4.7 per cent received it.
| Recommendation | Grade, as printed | Source |
|---|---|---|
| Offer VTE prophylaxis for abdominal surgery at increased risk “Offer VTE prophylaxis to people undergoing abdominal (gastrointestinal, gynaecological, urological) surgery who are at increased risk of VTE.” | [2018] (NICE does not grade) | NICE 2018 |
| Consider extending pharmacological prophylaxis to 28 days after major abdominal cancer surgery | [2018] (NICE does not grade) | NICE 2018 |
| Extended LMWH reduced VTE from 13.2% to 5.3% after major abdominal or pelvic surgery | moderate-quality evidence | Cochrane Database of Systematic Reviews 2019 |
| Apixaban and rivaroxaban as options for extended prophylaxis after cancer surgery “Apixaban and rivaroxaban were added as options for extended pharmacologic thromboprophylaxis after cancer surgery, with a weak strength of recommendation.” | weak strength of recommendation | ASCO (Journal of Clinical Oncology) 2023 |
| Consider prophylaxis for thoracic surgery at increased risk “Consider VTE prophylaxis for people undergoing thoracic surgery who are at increased risk of VTE.” | [2018] (NICE does not grade) | NICE 2018 |
Shares Four weeks of blood-clot prevention after major abdominal or pelvic cancer surgery, Gastric & gastro-oesophageal junction cancer, Pancreatic ductal adenocarcinoma, Colorectal cancer.
Shares Colorectal cancer.
Shares Gastric & gastro-oesophageal junction cancer, Pancreatic ductal adenocarcinoma, Colorectal cancer.
Shares Gastric & gastro-oesophageal junction cancer, Ovarian cancer, Pancreatic ductal adenocarcinoma.
Shares Venous thromboembolism (VTE), Cancer-associated thrombosis prevention and treatment.
Shares Cancer-associated thrombosis prevention and treatment, Gastric & gastro-oesophageal junction cancer, Pancreatic ductal adenocarcinoma, Colorectal cancer.