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Question 1
Correct
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Which one of the following statements relating to blood transfusions is not true?
Your Answer: Patients should be transfused to achieve a target haemoglobin of 10 g/dl and a haematocrit of 30%
Explanation:As long as the patient’s Hb level is 7 or higher, transfusion may not be necessary for their management. However, this threshold may vary depending on individual factors such as co-existing medical conditions. It is important to avoid using old blood during massive transfusions as its effectiveness may be compromised.
Blood Products and Cell Saver Devices
Blood products are essential in various medical procedures, especially in cases where patients require transfusions due to anaemia or bleeding. Packed red cells, platelet-rich plasma, platelet concentrate, fresh frozen plasma, and cryoprecipitate are some of the commonly used whole blood fractions. Fresh frozen plasma is usually administered to patients with clotting deficiencies, while cryoprecipitate is a rich source of Factor VIII and fibrinogen. Cross-matching is necessary for all blood products, and cell saver devices are used to collect and re-infuse a patient’s own blood lost during surgery.
Cell saver devices come in two types, those that wash the blood cells before re-infusion and those that do not. The former is more expensive and complicated to operate but reduces the risk of re-infusing contaminated blood. The latter avoids the use of donor blood and may be acceptable to Jehovah’s witnesses. However, it is contraindicated in malignant diseases due to the risk of facilitating disease dissemination.
In some surgical patients, the use of warfarin can pose specific problems and may require the use of specialised blood products. Warfarin reversal can be achieved through the administration of vitamin K, fresh frozen plasma, or human prothrombin complex. Fresh frozen plasma is used less commonly now as a first-line warfarin reversal, and human prothrombin complex is preferred due to its rapid action. However, it should be given with vitamin K as factor 6 has a short half-life.
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This question is part of the following fields:
- Haematology And Oncology
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Question 2
Incorrect
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A 63-year-old woman comes to her physician complaining of bloating, early satiety, change in bowel habit, and weight loss that have been going on for 3 months. During a physical examination, an irregular adnexal mass and shifting dullness are discovered. Her doctor orders a pelvic ultrasound scan, and her serum levels of CA-125 are significantly elevated. She is then referred to the regional gynaecological cancer centre for a staging laparotomy, and her surgeon informs her that her cancer has spread to her lymph nodes.
Which group of lymph nodes is most likely affected by this patient's condition?Your Answer: Deep inguinal lymph nodes
Correct Answer: Para-aortic lymph nodes
Explanation:Metastatic ovarian cancer can be detected in the para-aortic lymph nodes as the ovaries drain to this lymphatic group. This is different from other pelvic organs, which usually drain to the internal and external iliac lymph nodes. The external iliac lymph nodes do not drain the ovary, while the internal iliac lymph nodes do not drain the ovary but drain other pelvic viscera. The deep inguinal lymph nodes drain the clitoris and glans penis, while the superficial inguinal lymph nodes drain the anal canal (below pectinate line), skin below the umbilicus, scrotum, and vulva, but are not significant in the lymphatic drainage of the ovary.
Lymphatic Drainage of Female Reproductive Organs
The lymphatic drainage of the female reproductive organs is a complex system that involves multiple nodal stations. The ovaries drain to the para-aortic lymphatics via the gonadal vessels. The uterine fundus has a lymphatic drainage that runs with the ovarian vessels and may thus drain to the para-aortic nodes. Some drainage may also pass along the round ligament to the inguinal nodes. The body of the uterus drains through lymphatics contained within the broad ligament to the iliac lymph nodes. The cervix drains into three potential nodal stations; laterally through the broad ligament to the external iliac nodes, along the lymphatics of the uterosacral fold to the presacral nodes and posterolaterally along lymphatics lying alongside the uterine vessels to the internal iliac nodes. Understanding the lymphatic drainage of the female reproductive organs is important for the diagnosis and treatment of gynecological cancers.
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This question is part of the following fields:
- Haematology And Oncology
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Question 3
Incorrect
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Which of the following is the least commonly associated with thrombosis in elderly patients?
Your Answer: Use of tourniquets in surgery
Correct Answer: Thrombocytopenia
Explanation:The remaining choices either cause thrombosis by directly promoting it, such as through damage to endothelial cells, or by altering the consistency or flow of blood.
Abnormal coagulation can be caused by various factors such as heparin, warfarin, disseminated intravascular coagulation (DIC), and liver disease. Heparin prevents the activation of factors 2, 9, 10, and 11, while warfarin affects the synthesis of factors 2, 7, 9, and 10. DIC affects factors 1, 2, 5, 8, and 11, and liver disease affects factors 1, 2, 5, 7, 9, 10, and 11.
When interpreting blood clotting test results, different disorders can be identified based on the levels of activated partial thromboplastin time (APTT), prothrombin time (PT), and bleeding time. Haemophilia is characterized by increased APTT levels, normal PT levels, and normal bleeding time. On the other hand, von Willebrand’s disease is characterized by increased APTT levels, normal PT levels, and increased bleeding time. Lastly, vitamin K deficiency is characterized by increased APTT and PT levels, and normal bleeding time. Proper interpretation of these results is crucial in diagnosing and treating coagulation disorders.
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This question is part of the following fields:
- Haematology And Oncology
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Question 4
Incorrect
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A 50-year-old patient has discovered a lump in her neck and another one in her groin. She has been experiencing feverish symptoms for several months and has had to change her bedclothes twice in the last week. Upon examination, smooth, firm, enlarged lymph nodes are noted at both sites. The patient's GP is concerned about the possibility of an underlying lymphoma and has referred her to secondary care for further investigations. A CT scan has not revealed any other lymph nodes. What is the most appropriate diagnosis and staging for this patient?
Your Answer: If the histology was suggestive of a low-grade lymphoma she would have a better chance of cure than if it were high-grade
Correct Answer: On biopsy the malignant lymphoid cells would be likely to have many of the characteristics of their parent cells
Explanation:Lymphomas and their Staging
Malignancies that arise from lymphocytes can spread to different lymph node groups due to their ability to retain adhesion and signalling receptors. Lymphomas can present at various sites, including bone marrow, gut, and spleen, as normal trafficking of lymphoid cells occurs through these places. Interestingly, higher-grade lymphomas are easier to cure than lower grade lymphomas, despite initially being associated with a higher mortality rate. On the other hand, low-grade lymphomas may not require immediate treatment, but the disease progresses over time, leading to a poorer prognosis.
To diagnose lymphoma, a biopsy of the affected area, such as a lymph node or bone marrow, is necessary. The Ann Arbor staging system is used to stage lymphomas, with Stage I indicating disease in a single lymph node group and Stage IV indicating extra-nodal involvement other than the spleen. The addition of a ‘B’ signifies the presence of ‘B’ symptoms, which are associated with a poorer prognosis for each disease stage.
From the examination findings, it is evident that the disease is present on both sides of the diaphragm, indicating at least Stage III lymphoma. the staging of lymphomas is crucial in determining the appropriate treatment plan and predicting the patient’s prognosis.
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This question is part of the following fields:
- Haematology And Oncology
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Question 5
Incorrect
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Which of the following processes enables phagocytosis to occur?
Your Answer: Proteolysis
Correct Answer: Opsonisation
Explanation:Phagocytosis is facilitated by opsonisation, which involves coating the micro-organism with antibody, C3b, and specific acute phase proteins. This leads to an increase in phagocytic cell surface receptors on macrophages and neutrophils, which is mediated by pro-inflammatory cytokines. As a result, these cells are able to engulf the micro-organism.
Phagocytosis: The Process of Cell Ingestion
Phagocytosis is the process by which cells ingest foreign materials or pathogens. The first step in this process is opsonisation, where the organism is coated by an antibody. The second step is adhesion to the cell surface, followed by pseudopodial extension to form a phagocytic vacuole. Finally, lysosomes fuse with the vacuole and degrade its contents.
Phagocytosis is an essential process for the immune system to fight off infections and diseases. It is a complex process that involves multiple steps, including opsonisation, adhesion, and pseudopodial extension. The end result is the degradation of the foreign material or pathogen by lysosomes. Understanding the process of phagocytosis is crucial for developing treatments for diseases that involve the immune system.
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This question is part of the following fields:
- Haematology And Oncology
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Question 6
Incorrect
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A 45-year-old individual undergoes a lump excision procedure and upon examination of a histological section, a clump of Reed Sternberg cells is identified by the pathologist. What is the probable diagnosis?
Your Answer: Papillary carcinoma of the thyroid
Correct Answer: Hodgkins lymphoma
Explanation:Understanding Hodgkin’s Lymphoma: Symptoms and Risk Factors
Hodgkin’s lymphoma is a type of cancer that affects the lymphocytes and is characterized by the presence of Reed-Sternberg cells. It is most commonly seen in people in their third and seventh decades of life. There are certain risk factors that increase the likelihood of developing Hodgkin’s lymphoma, such as HIV and the Epstein-Barr virus.
The most common symptom of Hodgkin’s lymphoma is lymphadenopathy, which is the enlargement of lymph nodes. This is usually painless, non-tender, and asymmetrical, and is most commonly seen in the neck, followed by the axillary and inguinal regions. In some cases, alcohol-induced lymph node pain may be present, but this is seen in less than 10% of patients. Other symptoms of Hodgkin’s lymphoma include weight loss, pruritus, night sweats, and fever (Pel-Ebstein). A mediastinal mass may also be present, which can cause symptoms such as coughing. In some cases, Hodgkin’s lymphoma may be found incidentally on a chest x-ray.
When investigating Hodgkin’s lymphoma, normocytic anaemia may be present, which can be caused by factors such as hypersplenism, bone marrow replacement by HL, or Coombs-positive haemolytic anaemia. Eosinophilia may also be present, which is caused by the production of cytokines such as IL-5. LDH levels may also be raised.
In summary, Hodgkin’s lymphoma is a type of cancer that affects the lymphocytes and is characterized by the presence of Reed-Sternberg cells. It is most commonly seen in people in their third and seventh decades of life and is associated with risk factors such as HIV and the Epstein-Barr virus. Symptoms of Hodgkin’s lymphoma include lymphadenopathy, weight loss, pruritus, night sweats, and fever. When investigating Hodgkin’s lymphoma, normocytic anaemia, eosinophilia, and raised LDH levels may be present.
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This question is part of the following fields:
- Haematology And Oncology
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Question 7
Incorrect
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A 55-year-old man is hospitalized after experiencing haematemesis. Upon examination, his prothrombin time is found to be elevated. What could be a possible reason for this anomaly?
Your Answer: Aspirin therapy
Correct Answer: Chronic liver disease
Explanation:The inheritance of Haemophilia A and B is crucial in identifying individuals who are at risk of developing the condition. Haemophilia A and B are genetic disorders that are inherited in an X-linked recessive manner. Haemophilia A is caused by a deficiency in clotting factor VIII, while haemophilia B is caused by a deficiency in clotting factor IX.
On the other hand, haemophilia C, which is caused by a deficiency in clotting factor XI, is primarily inherited in an autosomal recessive manner. In X-linked recessive conditions like haemophilia B, males are more likely to be affected than females. This is because males only need one abnormal copy of the gene, which is carried on the X chromosome, to be affected.
Females, on the other hand, can be carriers of the condition if they carry one normal and one abnormal copy of the gene. While carriers can have clotting abnormalities, these are usually milder than those seen in affected individuals. Men cannot pass the condition to their sons, but they will pass on the abnormal X chromosome to all their daughters, who will be carriers.
Female carriers can pass on the condition to around half their sons, and half their daughters will be carriers. Females can only be affected if they are the offspring of an affected male and a carrier female. In summary, the inheritance of haemophilia A and B is crucial in identifying individuals who are at risk of developing the condition. It also helps in providing appropriate genetic counseling and management for affected individuals and their families.
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This question is part of the following fields:
- Haematology And Oncology
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Question 8
Incorrect
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A 29-year-old man is admitted to the haematology ward for acute lymphocytic leukaemia treatment. You are consulted due to his complaint of supra-pubic pain and frank haematuria. Upon checking his medication, you observe that he is taking cyclophosphamide and suspect that he may have developed haemorrhagic cystitis from this drug.
What is the primary mode of action of cyclophosphamide?Your Answer: Cell cycle arrest and apoptosis
Correct Answer: Cross-linking in DNA
Explanation:Cyclophosphamide is a medication that is used to treat various types of cancer and induce immunosuppression in patients before stem cell transplantation. It works by causing cross-linking in DNA. However, one of the complications of cyclophosphamide treatment is haemorrhagic cystitis. This occurs because when the liver breaks down cyclophosphamide, it releases a toxic metabolite called acrolein. Acrolein is concentrated in the bladder and triggers an inflammatory response that can lead to haemorrhagic cystitis.
To reduce the risk of haemorrhagic cystitis, doctors can administer MESNA, a drug that conjugates acrolein and reduces the inflammatory response.
Bleomycin, on the other hand, degrades preformed DNA instead of causing cross-linking. Hydroxyurea inhibits ribonucleotide reductase, which decreases DNA synthesis. 5-Fluorouracil (5-FU) is a pyrimidine analogue that arrests the cell cycle and induces apoptosis. Vincristine inhibits the formation of microtubules.
Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.
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This question is part of the following fields:
- Haematology And Oncology
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Question 9
Incorrect
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A 60-year-old man complains of low back pain that has been bothering him for the past three months. He also experiences shortness of breath with minimal exertion. Upon examination, his ESR is found to be elevated at 100 mm/hr. What is the most probable diagnosis for this patient?
Your Answer: Cellulitis
Correct Answer: Multiple myeloma
Explanation:ESR and its association with diseases
Erythrocyte sedimentation rate (ESR) is a laboratory test that measures the rate at which red blood cells settle in a tube over a period of time. Elevated ESR levels are often associated with inflammatory diseases such as rheumatoid arthritis, systemic lupus erythematosus, and polymyalgia rheumatica. In these conditions, the body’s immune system is activated, leading to inflammation and tissue damage. Malignancies such as myeloma can also cause an increase in ESR levels, particularly in females and with increasing age.
On the other hand, low ESR levels are seen in conditions such as polycythaemia, where there is an excess of red blood cells in the body. It is important to note that ESR is not a specific diagnostic test and must be interpreted in conjunction with other clinical findings. Multiple myeloma, a type of plasma cell neoplasm, is the most common haematological malignancy and can lead to a range of symptoms such as hypercalcaemia, renal failure, anaemia, and bone pain. While it is not curable, advances in treatment have significantly improved the median survival of patients. the association between ESR and various diseases can aid in the diagnosis and management of these conditions.
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This question is part of the following fields:
- Haematology And Oncology
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Question 10
Incorrect
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A 67-year-old woman visits the oncology clinic after being diagnosed with non-metastatic breast cancer. She is started on neoadjuvant chemotherapy using docetaxel.
What is the mechanism of action for this form of chemotherapy?Your Answer: Causes cross-linking in DNA
Correct Answer: Prevents microtubule depolymerisation and disassembly
Explanation:Docetaxel, a taxane chemotherapy agent, works by reducing the amount of free tubulin through the prevention of microtubule depolymerisation and disassembly during the metaphase stage of cell division, ultimately hindering mitosis.
Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.
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This question is part of the following fields:
- Haematology And Oncology
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Question 11
Correct
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A 32-year-old male visits his GP complaining of fatigue. The GP schedules a blood test to rule out anaemia as a possible cause. Typically, where do red blood cells undergo breakdown in the body?
Your Answer: Spleen
Explanation:The spleen is responsible for breaking down most of the red blood cells. This is achieved through the action of macrophages that identify and eliminate old red blood cells. It is worth noting that in a healthy individual, the liver, kidneys, and blood vessels do not participate in the breakdown of red blood cells. Additionally, while the bone marrow plays a crucial role in producing blood cells, it is not involved in the destruction of red blood cells.
Understanding Haemolytic Anaemias by Site
Haemolytic anaemias can be classified by the site of haemolysis, either intravascular or extravascular. In intravascular haemolysis, free haemoglobin is released and binds to haptoglobin. As haptoglobin becomes saturated, haemoglobin binds to albumin forming methaemalbumin, which can be detected by Schumm’s test. Free haemoglobin is then excreted in the urine as haemoglobinuria and haemosiderinuria. Causes of intravascular haemolysis include mismatched blood transfusion, red cell fragmentation due to heart valves, TTP, DIC, HUS, paroxysmal nocturnal haemoglobinuria, and cold autoimmune haemolytic anaemia.
On the other hand, extravascular haemolysis occurs when red blood cells are destroyed by macrophages in the spleen or liver. This type of haemolysis is commonly seen in haemoglobinopathies such as sickle cell anaemia and thalassaemia, hereditary spherocytosis, haemolytic disease of the newborn, and warm autoimmune haemolytic anaemia.
It is important to understand the site of haemolysis in order to properly diagnose and treat haemolytic anaemias. While both intravascular and extravascular haemolysis can lead to anaemia, the underlying causes and treatment approaches may differ.
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This question is part of the following fields:
- Haematology And Oncology
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Question 12
Incorrect
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An 80-year-old male comes to the clinic complaining of worsening low back pain and weight loss. He mentions experiencing difficulty urinating recently and having to wake up at night to urinate. Which anatomical structure would most likely account for his low back pain?
Your Answer: Internal iliac lymphatic channels
Correct Answer: Batson venous plexus
Explanation:The Batson venous plexus is responsible for the majority of bony metastases in cancers commonly associated with bone metastasis, including advanced prostate cancer. This valveless venous plexus has also been linked to bone metastasis in bladder, breast, and, to a lesser extent, lung cancer.
Bone Metastases: Common Tumours and Sites
Bone metastases occur when cancer cells from a primary tumour spread to the bones. The most common tumours that cause bone metastases are prostate, breast, and lung cancer, with prostate cancer being the most frequent. The most common sites for bone metastases are the spine, pelvis, ribs, skull, and long bones.
Aside from bone pain, other features of bone metastases may include pathological fractures, hypercalcaemia, and raised levels of alkaline phosphatase (ALP). Pathological fractures occur when the bone weakens due to the cancer cells, causing it to break. Hypercalcaemia is a condition where there is too much calcium in the blood, which can lead to symptoms such as fatigue, nausea, and confusion. ALP is an enzyme that is produced by bone cells, and its levels can be elevated in the presence of bone metastases.
A common diagnostic tool for bone metastases is an isotope bone scan, which uses technetium-99m labelled diphosphonates that accumulate in the bones. The scan can show multiple irregular foci of high-grade activity in the bones, indicating the presence of metastatic cancer. In the image provided, the bone scan shows multiple osteoblastic metastases in a patient with metastatic prostate cancer.
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This question is part of the following fields:
- Haematology And Oncology
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Question 13
Incorrect
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Which one of the following statements relating to abnormal coagulation is not true?
Your Answer: Cholestatic jaundice can cause vitamin K deficiency
Correct Answer: The prothrombin time is prolonged in Haemophilia A
Explanation:Haemophilia A is characterized by prolonged APTT and reduced levels of factor 8:C, while bleeding time and PT remain normal. Cholestatic jaundice hinders the absorption of vitamin K, which is fat-soluble. Patients who undergo massive transfusions, equivalent to more than 10 units of blood or their entire blood volume, are at risk of thrombocytopenia, as well as deficiencies in factor 5 and 8.
Abnormal coagulation can be caused by various factors such as heparin, warfarin, disseminated intravascular coagulation (DIC), and liver disease. Heparin prevents the activation of factors 2, 9, 10, and 11, while warfarin affects the synthesis of factors 2, 7, 9, and 10. DIC affects factors 1, 2, 5, 8, and 11, and liver disease affects factors 1, 2, 5, 7, 9, 10, and 11.
When interpreting blood clotting test results, different disorders can be identified based on the levels of activated partial thromboplastin time (APTT), prothrombin time (PT), and bleeding time. Haemophilia is characterized by increased APTT levels, normal PT levels, and normal bleeding time. On the other hand, von Willebrand’s disease is characterized by increased APTT levels, normal PT levels, and increased bleeding time. Lastly, vitamin K deficiency is characterized by increased APTT and PT levels, and normal bleeding time. Proper interpretation of these results is crucial in diagnosing and treating coagulation disorders.
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This question is part of the following fields:
- Haematology And Oncology
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Question 14
Correct
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An 80-year-old woman visits her doctor complaining of excessive vaginal bleeding. After undergoing an ultrasound scan and uterine biopsy, it is revealed that she has an endometrial tumor located in the uterine fundus. Which group of nearby lymph nodes will be the primary location for lymphatic metastasis of this tumor?
Your Answer: Para-aortic lymph nodes
Explanation:The lymphatic drainage of the uterine fundus is similar to that of the ovaries, running alongside the ovarian vessels and draining into the para-aortic lymph nodes. Therefore, option 4 is correct. Options 1, 2, and 5 are incorrect as they refer to the drainage of the cervix and uterine body, which is different from that of the uterine fundus. Option 3 is also incorrect as the external iliac lymph nodes are not involved in the drainage of the uterine fundus.
Lymphatic Drainage of Female Reproductive Organs
The lymphatic drainage of the female reproductive organs is a complex system that involves multiple nodal stations. The ovaries drain to the para-aortic lymphatics via the gonadal vessels. The uterine fundus has a lymphatic drainage that runs with the ovarian vessels and may thus drain to the para-aortic nodes. Some drainage may also pass along the round ligament to the inguinal nodes. The body of the uterus drains through lymphatics contained within the broad ligament to the iliac lymph nodes. The cervix drains into three potential nodal stations; laterally through the broad ligament to the external iliac nodes, along the lymphatics of the uterosacral fold to the presacral nodes and posterolaterally along lymphatics lying alongside the uterine vessels to the internal iliac nodes. Understanding the lymphatic drainage of the female reproductive organs is important for the diagnosis and treatment of gynecological cancers.
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This question is part of the following fields:
- Haematology And Oncology
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Question 15
Incorrect
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A 3-year-old child is experiencing recurrent infections that are difficult to clear, leading to suspicion of an immunodeficiency. The clinical immunologist orders an immunological profile, which reveals low CD3+ cells, normal CD20+ cells, and normal CD68+ cells. The child's medical history includes surgical repair of a cleft palate and Tetralogy of Fallot within the first year of life. Which pharyngeal pouches are involved in the development of the structure implicated in this child's immunodeficiency?
Your Answer: Second alone
Correct Answer: Third and fourth
Explanation:The thymus is derived from the third and fourth pharyngeal pouches during development.
In a child with normal levels of B-cells and monocytes but no T-cells, the underlying issue is likely located in the thymus as this is where T-cells are produced. This suggests that the thymus is the structure responsible for the child’s condition.
The child’s medical history, including a conotruncal heart defect and cleft palate, suggests a possible diagnosis of DiGeorge syndrome.
During development, the first pouch gives rise to the Eustachian tube, middle ear, mastoid antrum, and inner tympanic membrane. The second pouch forms the middle ear and palatine tonsils. The third pouch develops into the thymus and inferior parathyroid glands, while the fourth pouch gives rise to the superior parathyroid glands, thymus, thyroid C-cells, muscles, and cartilage of the larynx. The fifth pouch is a rudimentary structure that becomes part of the fourth pouch, and the sixth pouch forms the muscles and cartilage of the larynx.
The Thymus Gland: Development, Structure, and Function
The thymus gland is an encapsulated organ that develops from the third and fourth pharyngeal pouches. It descends to the anterior superior mediastinum and is subdivided into lobules, each consisting of a cortex and a medulla. The cortex is made up of tightly packed lymphocytes, while the medulla is mostly composed of epithelial cells. Hassall’s corpuscles, which are concentrically arranged medullary epithelial cells that may surround a keratinized center, are also present.
The inferior parathyroid glands, which also develop from the third pharyngeal pouch, may be located with the thymus gland. The thymus gland’s arterial supply comes from the internal mammary artery or pericardiophrenic arteries, while its venous drainage is to the left brachiocephalic vein. The thymus gland plays a crucial role in the development and maturation of T-cells, which are essential for the immune system’s proper functioning.
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This question is part of the following fields:
- Haematology And Oncology
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Question 16
Incorrect
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A 57-year-old man with stable angina undergoes an angiogram and is found to have a 60% stenosis of the left main artery. The surgeons recommend a coronary artery bypass procedure. Which structure is likely to be supplied by the vessel used in this procedure?
Your Answer: Thyroid gland
Correct Answer: Thymus gland
Explanation:The thymus receives its arterial supply from either the internal mammary artery or the pericardiophrenic arteries.
During coronary artery bypass surgery, the internal thoracic artery, also referred to as the internal mammary artery, is utilized.
The Thymus Gland: Development, Structure, and Function
The thymus gland is an encapsulated organ that develops from the third and fourth pharyngeal pouches. It descends to the anterior superior mediastinum and is subdivided into lobules, each consisting of a cortex and a medulla. The cortex is made up of tightly packed lymphocytes, while the medulla is mostly composed of epithelial cells. Hassall’s corpuscles, which are concentrically arranged medullary epithelial cells that may surround a keratinized center, are also present.
The inferior parathyroid glands, which also develop from the third pharyngeal pouch, may be located with the thymus gland. The thymus gland’s arterial supply comes from the internal mammary artery or pericardiophrenic arteries, while its venous drainage is to the left brachiocephalic vein. The thymus gland plays a crucial role in the development and maturation of T-cells, which are essential for the immune system’s proper functioning.
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This question is part of the following fields:
- Haematology And Oncology
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Question 17
Correct
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A 45-year-old woman is hospitalized with cholestasis caused by a stone lodged at the ampulla of vater. Which test is the most indicative of a bleeding tendency during ERCP in this specific scenario?
Your Answer: Prothrombin time
Explanation:The clotting factors that are dependent on vitamin K include 2, 7, 9, and 10, which can be accurately measured through the prothrombin time test. On the other hand, factors 8, 9, 11, and 12 are tested through the APTT, which can also be affected by vitamin K deficiency, but is usually associated with severe liver disease. Platelet function is measured through the bleeding time test. Additionally, jaundice can impair the production of vitamin K dependent clotting factors.
Abnormal coagulation can be caused by various factors such as heparin, warfarin, disseminated intravascular coagulation (DIC), and liver disease. Heparin prevents the activation of factors 2, 9, 10, and 11, while warfarin affects the synthesis of factors 2, 7, 9, and 10. DIC affects factors 1, 2, 5, 8, and 11, and liver disease affects factors 1, 2, 5, 7, 9, 10, and 11.
When interpreting blood clotting test results, different disorders can be identified based on the levels of activated partial thromboplastin time (APTT), prothrombin time (PT), and bleeding time. Haemophilia is characterized by increased APTT levels, normal PT levels, and normal bleeding time. On the other hand, von Willebrand’s disease is characterized by increased APTT levels, normal PT levels, and increased bleeding time. Lastly, vitamin K deficiency is characterized by increased APTT and PT levels, and normal bleeding time. Proper interpretation of these results is crucial in diagnosing and treating coagulation disorders.
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This question is part of the following fields:
- Haematology And Oncology
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Question 18
Incorrect
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You are developing a research project to evaluate the impact of a novel anticoagulant on the coagulation cascade. Your focus is on the intrinsic pathway. What parameter will you measure?
Your Answer: Prothrombin time (PT)
Correct Answer: aPTT
Explanation:The aPTT time is the most effective way to evaluate the intrinsic pathway of the clotting cascade. If the aPTT time is prolonged, it may indicate haemophilia or the use of heparin.
To assess the extrinsic pathway, the prothrombin time (PT) is the preferred measurement.
The thrombin time is a test that evaluates the formation of fibrin from fibrinogen in plasma. It can be prolonged by heparin, fibrin degradation products, and fibrinogen deficiency.
A 50:50 mixing study is utilized to determine whether a prolonged PT or aPTT is caused by a factor deficiency or a factor inhibitor.
The Coagulation Cascade: Two Pathways to Fibrin Formation
The coagulation cascade is a complex process that leads to the formation of a blood clot. There are two pathways that can lead to fibrin formation: the intrinsic pathway and the extrinsic pathway. The intrinsic pathway involves components that are already present in the blood and has a minor role in clotting. It is initiated by subendothelial damage, such as collagen, which leads to the formation of the primary complex on collagen by high-molecular-weight kininogen (HMWK), prekallikrein, and Factor 12. This complex activates Factor 11, which in turn activates Factor 9. Factor 9, along with its co-factor Factor 8a, forms the tenase complex, which activates Factor 10.
The extrinsic pathway, on the other hand, requires tissue factor released by damaged tissue. This pathway is initiated by tissue damage, which leads to the binding of Factor 7 to tissue factor. This complex activates Factor 9, which works with Factor 8 to activate Factor 10. Both pathways converge at the common pathway, where activated Factor 10 causes the conversion of prothrombin to thrombin. Thrombin hydrolyses fibrinogen peptide bonds to form fibrin and also activates factor 8 to form links between fibrin molecules.
Finally, fibrinolysis occurs, which is the process of clot resorption. Plasminogen is converted to plasmin to facilitate this process. It is important to note that certain factors are involved in both pathways, such as Factor 10, and that some factors are vitamin K dependent, such as Factors 2, 7, 9, and 10. The intrinsic pathway can be assessed by measuring the activated partial thromboplastin time (APTT), while the extrinsic pathway can be assessed by measuring the prothrombin time (PT).
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This question is part of the following fields:
- Haematology And Oncology
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Question 19
Incorrect
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Which one of the following statements relating to malignant mesothelioma is not true?
Your Answer: It may be treated by extrapleural pneumonectomy.
Correct Answer: It is linked to cigarette smoking independent of asbestos exposure.
Explanation:This type of cancer is not associated with smoking cigarettes. The preferred treatment option is a complete removal of the tumor if caught early. Radiation therapy is commonly administered before or after surgery, but this type of cancer is not highly responsive to radiation. The most effective treatment involves a combination of chemotherapy drugs, with many regimens utilizing cisplatin.
Occupational cancers are responsible for 5.3% of cancer deaths, with men being more affected than women. The most common types of cancer in men include mesothelioma, bladder cancer, non-melanoma skin cancer, lung cancer, and sino-nasal cancer. Occupations that have a high risk of developing tumors include those in the construction industry, coal tar and pitch workers, miners, metalworkers, asbestos workers, and those in the rubber industry. Shift work has also been linked to breast cancer in women.
The latency period between exposure to carcinogens and the development of cancer is typically 15 years for solid tumors and 20 years for leukemia. Many occupational cancers are rare, such as sino-nasal cancer, which is linked to wood dust exposure and is not strongly associated with smoking. Another rare occupational tumor is angiosarcoma of the liver, which is linked to working with vinyl chloride. In non-occupational contexts, these tumors are extremely rare.
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This question is part of the following fields:
- Haematology And Oncology
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Question 20
Incorrect
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A 29-year-old woman is a few minutes into receiving a blood transfusion after experiencing a postpartum haemorrhage when she experiences intense chest and abdominal pain. Her temperature has risen to 38.1ÂșC, and her BP is 80/60 mmHg. The medical team suspects that she is having an acute reaction to the blood product transfusion.
What is the underlying mechanism of the probable transfusion reaction?Your Answer: Fluid overload
Correct Answer: Host IgM antibody destruction of ABO-incompatible red blood cells (RBCs)
Explanation:The correct mechanism of acute haemolytic transfusion reactions is the destruction of ABO-incompatible red blood cells (RBCs) by host IgM antibodies. These reactions typically occur due to human error in giving patients ABO-incompatible blood products. Symptoms include hypotension, fever, and abdominal and/or chest pain.
Fluid overload, host anti-IgA antibodies reacting against donor IgA, and host antibodies reacting with donor white cell fragments are all incorrect mechanisms for acute haemolytic transfusion reactions. These mechanisms are associated with transfusion-associated circulatory overload (TACO), anaphylaxis to blood products in patients with IgA deficiency, and non-haemolytic febrile reactions, respectively. These conditions present with different symptoms and are not associated with the rapid onset of hypotension and abdominal pain seen in acute haemolytic transfusion reactions.
Blood product transfusion complications can be categorized into immunological, infective, and other complications. Immunological complications include acute haemolytic reactions, non-haemolytic febrile reactions, and allergic/anaphylaxis reactions. Infective complications may arise due to transmission of vCJD, although measures have been taken to minimize this risk. Other complications include transfusion-related acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), hyperkalaemia, iron overload, and clotting.
Non-haemolytic febrile reactions are thought to be caused by antibodies reacting with white cell fragments in the blood product and cytokines that have leaked from the blood cell during storage. These reactions may occur in 1-2% of red cell transfusions and 10-30% of platelet transfusions. Minor allergic reactions may also occur due to foreign plasma proteins, while anaphylaxis may be caused by patients with IgA deficiency who have anti-IgA antibodies.
Acute haemolytic transfusion reaction is a serious complication that results from a mismatch of blood group (ABO) which causes massive intravascular haemolysis. Symptoms begin minutes after the transfusion is started and include a fever, abdominal and chest pain, agitation, and hypotension. Treatment should include immediate transfusion termination, generous fluid resuscitation with saline solution, and informing the lab. Complications include disseminated intravascular coagulation and renal failure.
TRALI is a rare but potentially fatal complication of blood transfusion that is characterized by the development of hypoxaemia/acute respiratory distress syndrome within 6 hours of transfusion. On the other hand, TACO is a relatively common reaction due to fluid overload resulting in pulmonary oedema. As well as features of pulmonary oedema, the patient may also be hypertensive, a key difference from patients with TRALI.
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This question is part of the following fields:
- Haematology And Oncology
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