Anaemia
Haemoglobin in red blood cells carries oxygen around the body and delivers it to tissues and organs. Anaemia is defined as a reduction of haemoglobin concentration, red cell count or packed cell volume to below normal levels. The World Health Organization definition states that anaemia should be considered to exist in adults whose haemoglobin levels are lower than 13 g/100 ml (males) or 12 g/100 ml (females). The US National Cancer Institute considers normal haemoglobin levels to be 12−16 g/100 ml (females) and 14−18 g/100 ml (males).
Patients who are anaemic preoperatively are more likely to be transfused, so it makes sense to try to correct anaemia and iron deficiency preoperatively. For some groups of patients, the impact of this may be limited: in a recent UK study only about 5% of adults awaiting major orthopaedic surgery had microcytic anaemia. A full blood count four to six weeks before the operation allows detection of anaemia in time for the cause to be investigated and for iron replacement to take effect.
Management of iron deficiency anaemia
In anaemia due to iron deficiency, and if there is no sinister underlying cause, ferrous sulphate (conventional dose 200 mg tds: 180 mg of elemental iron) should correct 90% of the deficit in four weeks, whatever the starting haemoglobin. Complete correction takes about six weeks. Iron absorption correlates inversely with ferritin level. Thus, treatment with iron in those without anaemia and with ferritin above 30 mmoI/l will have little effect on iron stores. Compliance with oral iron therapy is poor: symptoms attributed to oral iron may be less when the dose of ferrous sulphate is reduced to 200 mg daily.
Bleeding problems
History
A clinical history of abnormal bleeding (tooth extractions, surgery, menorrhagia or a family history of bleeding) should be investigated.
Abnormal coagulation screen
If a patient admitted for elective surgery or an invasive procedure is found to have an abnormal coagulation screen, i.e. prolonged prothrombin time (PT) or activated partial thromboplastin time (APPT) or a low platelet count, the procedure should be postponed while the cause of the abnormality is identified (see Table 7 below). If there is a known or suspected congenital bleeding disorder, the patient must be managed in conjunction with a haemophilia centre: www.haemophilia.org.uk/
Low platelet count
Bone marrow aspiration and biopsy may be performed in patients with severe thrombocytopenia without platelet support, providing that adequate surface pressure is applied. For lumbar puncture, epidural anaesthesia, gastroscopy and biopsy, insertion of indwelling lines, transbronchial biopsy, liver biopsy, laparotomy or similar procedures, the platelet count should be raised to at least 50 x 109/l. Infuse immediately before the procedure for optimum effectiveness.
For operations in critical sites such as the brain or eyes, the platelet count should be raised to 100 x 109/l. It should not be assumed that the platelet count will rise just because platelet transfusions are given, and a preoperative platelet count should be checked.
Patients on anticoagulants and antiplatelet agents
Many patients awaiting planned surgery are receiving warfarin or other drugs that affect blood coagulation or platelet function. Where it is safe to do so, it is generally advised that such drugs be stopped prior to major surgery, giving sufficient time for their effect on coagulation to decline. This is an issue on which clinical opinions vary; therefore, patients should be managed according to current hospital protocols. A guide is given in Table 7. More information is available in the Better Blood Transfusion Toolkit section of this web site
Table 7 Perioperative haemostasis
Management of patients with abnormal coagulation screens, on anticoagulants or antiplatelet medications |
Abnormal coagulation screen Prolonged prothrombin time or activated partial thromboplastin time | If possible, postpone surgery until the cause of the abnormality is identified. |
Known or suspected congenital bleeding disorder | The patient must be managed in conjunction with a haemophilia centre: www.haemophilia.org |
Low platelet count Bone marrow aspiration and biopsy | May be performed in patients with severe thrombocytopenia without platelet support, with adequate local pressure. |
Lumbar puncture, epidural anaesthesia, endoscopy and biopsy, surgery in non-critical sites | Count should be raised to at least 50 x 109/l. (BCSH Guildeline for ITP (2003) recommends 80 x 109/l for epidural and spinal anaesthesia in pregnancy.) |
Operations in critical sites such as the brain or eyes | Count should be raised to 100 x 109/l. Platelets should be given immediately before the procedure and the count checked before proceeding. |
Medication | Illustrative management plans |
Warfarin Options: - Continue warfarin through surgery, e.g. most dental procedures
- Reduce/stop until INR acceptable
- Stop warfarin until INR normal
- Stop and give ‘bridging’ heparin
| In each case, balance the reason for warfarin treatment against the risk of discontinuing warfarin. There are often locally agreed protocols for management of surgery in patients on anticoagulants, and these should be followed. Refer to BCSH Guidelines on oral anticoagulation (www.bcshguidelines.com) and in the Better Blood Transfusion Toolkit sections 'Appropriate use - pre-operative assessment' and 'Indications for transfusion'). The following are illustrative examples only. |
Moderate/high risk of haemorrhage, low risk of thrombosis e.g. lone atrial fibrillation; thrombosis or embolism > 6 months ago | Stop warfarin day 4 pre-op. Check INR day 1. If < 1.3, proceed. If still too high, give oral or IV vitamin K 1−2 mg (depending on INR and size of patient). Repeat INR on day of surgery. Restart warfarin on evening of operation or first post-operative day. Double maintenance dose first day only. |
Moderate/high risk of haemorrhage, high risk of thrombosis e.g. mechanical heart valve; thrombosis or embolism < 2 months ago | Stop warfarin day 4 pre-op. Check INR daily and start therapeutic dose of low molecular weight heparin (LMWH) when INR falls below therapeutic range. Give last dose 12−24 hours before surgery. Restart LMWH 12−24 hours post-op when haemostasis secure. Restart warfarin (usual dose) when oral intake possible post-op. Stop LMWH when INR in therapeutic range. |
Low risk of haemorrhage, moderate risk of thrombosis e.g. dental procedures, skin biopsy, cataract surgery | Halve normal maintenance dose of warfarin on days 4 to 2 pre-op. Normal dose from day 1 onwards. On day 0 check INR is in surgeon’s acceptable range. INR should be in therapeutic range again by day 2 post-op. |
Surgery needed in > 6 hours | If no acute bleeding, give vitamin K 1−2 mg iv. Check INR at 6 hours. |
Life-threatening bleeding, emergency surgery | Give prothrombin complex (PC) 30−50 units/kg plus vitamin K 1−5 mg iv (dose depending on requirement for continuing anticoagulation and INR). If PC not available, give FFP 15−20 ml/kg (e.g. 4 units in 70 kg adult). Further FFP doses given perioperatively as required. |
Unfractionated heparins (UFH) | Stop iv infusion 6 hours before surgery for full reversal. |
Low molecular weight heparins (NB prolonged half life in renal failure) | Prophylactic dose: stop 8−12 hours pre-operatively. Therapeutic doses: stop 18−24 hours pre-operatively. |
Aspirin* Even if last dose 5 days ago, consider as a cause of bleeding tendency | Preop: General guidance − stop the drug at least 7 days before planned surgery, but note that there may be specific reasons for continuing the drug. Intraop, post-op: Consider platelet transfusion early in a bleeding patient. |
Clopidogrel* Even if last dose 5 days ago, consider as a cause of bleeding tendency | Preop: General guidance − stop the drug at least 7 days before planned surgery, but note that there may be specific reasons for continuing the drug. Intraop, post-op: Consider platelet transfusion early in a bleeding patient. |
Combination of aspirin and clopidogrel* Even if last dose 5 days ago, consider as a cause of bleeding tendency | Preop: General guidance − stop the drug at least 7 days before planned surgery, but note that there may be specific reasons for continuing the drug. Intraop, post-op: Consider platelet transfusion early in a bleeding patient. |
Non-steroidal anti-inflammatory agents Impair platelet function but the effect is reversed when the drug is stopped | Preop: Stop the drugs a few days before surgery if there is no specific indication to continue. |
Note: * A single dose of aspirin (75mg) or clopidogrel causes permanent blockade of platelet receptors and so impairs platelet function for about 5 days. |
[Table 7 resources: View large format or download as Word™ document]
Preoperative autologous blood donation (PABD)
Some patients can donate their own blood − up to four units − in advance of their own planned operation. It can be stored for up to five weeks in controlled blood bank conditions. PABD may be useful for patients for whom it is difficult to provide compatible donor red cells. It is only practicable if the operation scheduled is likely to need red cell transfusion, if the patient is able to attend to have blood collected, and if the initial haemoglobin concentration is > 100 g/l (female) or > 110 g/l (male). There should be sufficient time before surgery to donate at least two units of blood. The date for surgery must be fixed, so the blood does not become outdated. Iron replacement is required.
UK regulations require that autologous blood units are collected, tested, processed, labelled and stored by a registered blood establishment to the same standard as donor blood. Before retransfusion, autologous units must be ABO and RhD grouped and compatibility checked.
Preoperative donation lowers the patient’s haemoglobin level before operation. Administration of epoetin accelerates recovery of haemoglobin after each autologous donation, so that an adult may be able to provide three to five units of blood over about three weeks. Although PABD can reduce the amount of donor (allogeneic) red cells transfused, studies show that the total number of units of red cells transfused (autologous plus allogeneic) is usually greater in those who predonate blood than in a control group. The use of autologous blood should reduce the risks of developing red cell antibodies and of viral infection; however, it does not reduce the risk of bacterial contamination nor does it exclude a risk of the patient receiving wrong blood due to errors.(PMID9521225)(PMID12076491)
Acute normovolaemic haemodilution (ANH)
Several packs of the patient’s blood are withdrawn during induction of anaesthesia and replaced with crystalloid or colloid. The patient’s fresh collected blood can be re-infused during or immediately after the operation. The effectiveness of the procedure is unproven and it appears to be rarely used in the UK.(PMID15104642)(PMID9428843)