Patients with a VTE within the previous three months, patients with AF and previous stroke or TIA or multiple other risk factors, and patients with a mitral valve replacement should be considered for bridging therapy.

The most appropriate bridging therapy in this case would be low-molecular-weight heparin (LMWH), with the last dose given not less than 24 hours prior to the procedure. Warfarin should be discontinued 5 days prior to the procedure. If the INR is still above 3 on the day prior to the procedure, vitamin K should be administered.

Mycoplasma infection causes cold autoimmune haemolytic anaemia (AIHA). The rest of the aforementioned options cause warm AIHA.

AIHA may be divided into ‘warm’ and ‘cold’ types, according to the temperature at which the antibodies best cause haemolysis. It is most commonly idiopathic but may be secondary to a lymphoproliferative disorder, infection, or drugs.

1. Warm AIHA:
In warm AIHA, the antibody (usually IgG) causes haemolysis best at body temperature and tends to occur in extravascular sites, for example, spleen. Management options include steroids, immunosuppression, and splenectomy. It is caused by autoimmune diseases such as SLE (rarely causes mixed-type AIHA), cancers such as lymphomas and CLL, and drugs such as methyldopa.

2. Cold AIHA:
The antibody in cold AIHA is usually IgM and causes haemolysis best at 4°C and occurs more commonly intravascularly. Features may include symptoms of Raynaud’s disease and acrocyanosis. Patients do not respond well to steroids. Cold AIHA is caused by cancers such as lymphomas, and infections such as mycoplasma and EBV.

Polycythaemia vera (PV) is associated with a low ESR.

PV, also known as polycythaemia rubra vera, is a myeloproliferative disorder caused by clonal proliferation of marrow stem cells leading to an increase in red cell volume, often accompanied by overproduction of neutrophils and platelets. It has peak incidence in the sixth decade of life, with typical features including hyperviscosity, pruritus, splenomegaly, haemorrhage (secondary to abnormal platelet function), and plethoric appearance. PV is associated with a low ESR.

Some management options of PV include lose-dose aspirin, venesection (first-line treatment), hydroxyurea (slightly increased risk of secondary leukaemia), and radioactive phosphorus (P-32) therapy.

In PV, thrombotic events are a significant cause of morbidity and mortality. 5–15% of the cases progress to myelofibrosis or acute myeloid leukaemia (AML). The risk of having AML is increased with chemotherapy treatment.

Immune thrombocytopenic purpura (ITP) refers to thrombocytopaenia occurring in the absence of toxic exposure or other diseases associated with low platelets and involves IgG-type antibodies. It is characterised by normal or increased marrow megakaryocytes, shortened platelet survival, and the absence of splenomegaly. Autoimmune haemolytic anaemia (AIHA) occurs commonly in association with ITP. Leukemic transformation, however, does not occur in ITP.

In neonatal ITP, IgG antibodies are passively transferred across the placenta. The infant platelet count may be normal at birth but decreases within 12–24 hours. It is rarely severe enough to induce bleeding diathesis in the infant.

The direct Coombs test will specifically confirm immune-mediated haemolysis occurring post-transfusion in the aforementioned case.

There are two types of Coombs test used in immunohematology and immunology:

1. Direct Coombs test—It confirms autoimmune haemolytic anaemia by detecting antibodies or complement proteins attached to the surface of red blood cells.

2. Indirect Coombs test—It is used in prenatal testing of pregnant women and in testing prior to a blood transfusion. It detects antibodies floating freely in the blood, against foreign red blood cells.

Elevated haemoglobin A2 level is seen in beta thalassaemia trait, whereas, it is typically low in iron deficiency anaemia unless the patient has received a recent blood transfusion.

Low mean corpuscular volume (MCV) and reduced haematocrit (Ht) are encountered in both conditions. Peripheral blood smear is grossly abnormal in both beta thalassaemia and severe iron deficiency anaemia, showing bizarre morphology, target cells, and a small number of nucleated red blood cells.

Exposure to aniline dyes is a risk factor for transitional cell carcinoma. Aniline dyes are used in dyestuffs and pigment manufacturing.

The other aforementioned options are ruled out because:
1. Feed production may expose to aflatoxin (hepatocellular carcinoma).

2. Being a military personnel may expose to mustard gas (lung cancer).

3. Rubber industry may expose to nitrosamines (oesophageal and gastric cancer).

4. Refrigerant production before 1974 may expose to vinyl chloride (hepatic angiosarcoma).

CXR, blood, and urine tests should be carried out initially to exclude an underlying malignancy. If these are normal, a CT scan of abdomen and pelvis should be arranged as the patient’s age is >40 years. Antiphospholipid antibodies should also be checked for the first unprovoked DVT/PE. There is no history, however, to support an inherited thrombophilia.

The National Institute for Health and Care Excellence (NICE) published guidelines in 2012 for the investigation and management of DVT. If a patient is suspected of having DVT, a two-level DVT Wells score should be used:

DVT likely: 2 points or more
DVT unlikely: 1 point or less

This system of points is based on the following clinical features:
1. Active cancer (treatment ongoing, within six months, or palliative)—1
2. Paralysis, paresis, or recent plaster immobilisation of the lower extremities—1
3. Recently bedridden for three days or more, or major surgery within 12 weeks requiring general or regional anaesthesia—1
4. Localised tenderness along the distribution of the deep venous system—1
5. Entire leg swollen—1
6. Calf swelling at least three cms larger than the asymptomatic side—1
7. Pitting oedema confined to the symptomatic leg—1
8. Collateral superficial veins (non-varicose)—1
9. Previously documented DVT—1
10. An alternative diagnosis is at least as likely as DVT—2

If two points or more—DVT is ‘likely’
If one point or less—DVT is ‘unlikely’

Management

1. LMWH or fondaparinux should be given initially after a DVT is diagnosed.
2. A vitamin K antagonist such as warfarin should be given within 24 hours of the diagnosis.
3. LMWH or fondaparinux should be continued for at least five days or until the international normalised ratio (INR) is 2.0 or above for at least 24 hours. LMWH or fondaparinux is given at the same time as warfarin until the INR is in the therapeutic range.
4. Warfarin should be continued for at least three months. At three months, clinicians should assess the risks and benefits of extending the treatment.
5. Consider extending warfarin beyond three months for patients with unprovoked proximal DVT if their risk of VTE recurrence is high and there is no additional risk of major bleeding. This essentially means that if there is no obvious cause or provoking factor (surgery, trauma, significant immobility, etc.), it may be implied that the patient has a tendency to thrombose and should be given treatment longer than the normal of three months. In practice, most clinicians give six months of warfarin for patients with an unprovoked DVT/PE.
6. For patients with active cancer, LMWH should be used for six months.

As both malignancy and thrombophilia are obvious risk factors for DVT, therefore, all patients with unprovoked DVT/PE who are not already known to have cancer should undergo the following investigations:
1. Physical examination (guided by the patient’s full history)
2. Chest X-ray
3. Blood tests (full blood count, serum calcium, and liver function tests) and urinalysis
4. Testing for antiphospholipid antibodies
5. Testing for hereditary thrombophilia in patients who have had unprovoked DVT/PE and have a first-degree relative who has a history of DVT/PE.

This patient meets the diagnostic criteria for neutropenic sepsis, which is a relatively common complication of cancer therapy – usually chemotherapy occurring 7–14 days after. It is defined as a neutrophil count of <0.5 x 10^9/L in a patient undergoing anticancer treatment and who has either a temperature higher than 38°C or has other features consistent with clinically significant sepsis. Management approach is the same as mentioned in this case. However, if the patient still remains unwell, then an antifungal such as amphotericin B is started after risk-stratifying the patient and carrying out investigations (e.g. HRCT and Aspergillus PCR) to determine the likelihood of systemic fungal infection.

The diagnosis for the aforementioned case is thrombotic thrombocytopenic purpura (TTP). TTP is classically characterised as a pentad of thrombocytopaenia, microvascular haemolysis, fluctuating neurological signs, renal impairment, and fever.

The differential diagnosis for severe thrombocytopaenia is immune thrombocytopenic purpura (ITP). ITP is more common than TTP. However, a patient of ITP would not present with the range of symptoms seen in this scenario.

In TTP, there is deficiency of a protease which breaks down large multimers of von Willebrand factor. This leads to abnormally large and sticky multimers of von Willebrand factor which cause platelets to clump within the vessels.

Untreated TTP has a mortality rate of up to 90%. Therefore, rapid plasma exchange (PEX) may be a life-saving intervention. Platelet transfusion in TTP is only indicated if there is an ongoing life-threatening bleed. Intravenous methylprednisolone is indicated after treatment with PEX has been completed. There is no current role of intravenous immunoglobulin in the routine management of TTP. However, there have been reports of its successful use in PEX- and steroid-refractory cases. Intravenous argatroban is indicated in heparin-induced thrombocytopaenia (HIT), but there is no history of recent heparin administration or hospitalisation in this patient nor are the clinical signs consistent with HIT.

Management options for TTP include PEX as the treatment of choice. Steroids and immunosuppressants are also given. Antibiotics are not recommended as they may worsen the outcome of the disease. For cases resistant to PEX and pharmacologic therapy, vincristine is given.