OBG508 — Medical Disorders in Pregnancy: Lecture Note

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This is the complete lecture note for OBG508 Medical Disorders in Pregnancy. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.

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la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Course code: OBG 508 Course title: Medical Disorders in Pregnancy Course credit load: 2 Units Series 1: Haematological Disorders in Pregnancy • Part 1.1: Anaemia in Pregnancy: Definitions, Causes, and Impact o Sub Part 1.1.1: Definitions and classification of anaemia in pregnancy o Sub Part 1.1.2: Causes of anaemia in pregnancy o Sub Part 1.1.3: Impact of anaemia on pregnancy outcome • Part 1.2: Anaemia in Pregnancy: Evaluation and Management o Sub Part 1.2.1: Evaluation of women with anaemia in pregnancy o Sub Part 1.2.2: Management options for anaemia in pregnancy o Sub Part 1.2.3: Prevention of anaemia in pregnancy • Part 1.3: Haemoglobinopathies in Pregnancy o Sub Part 1.3.1: Sickle cell disease in pregnancy o Sub Part 1.3.2: Thalassaemia in pregnancy o Sub Part 1.3.3: Antenatal screening and genetic counselling for haemoglobinopathies • Part 1.4: Disseminated Intravascular Coagulation in Pregnancy o Sub Part 1.4.1: Pathophysiology of DIC in pregnancy o Sub Part 1.4.2: Causes and clinical features of DIC in pregnancy o Sub Part 1.4.3: Diagnosis and management of DIC in pregnancy Introduction

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Picture a woman attending her booking antenatal visit, her blood results returning with a haemoglobin level lower than expected. Understanding whether this reflects the normal physiological changes of pregnancy, a straightforward iron deficiency, or something more complex, such as an inherited haemoglobinopathy, shapes the entire course of her antenatal care. This Series lays the essential foundation for the whole of this course on medical disorders in pregnancy, beginning with the blood itself, before we turn in later Series to the heart, the endocrine system, infection, and the many other medical conditions that can complicate pregnancy. The aim of this Series is to equip you with a thorough understanding of anaemia in pregnancy, its definitions, causes, impact, evaluation, and management, together with haemoglobinopathies and disseminated intravascular coagulation. We shall commence this Series by examining the definitions, causes, and impact of anaemia in pregnancy. Next, we will consider the evaluation and management of anaemia. Following that, our attention turns to haemoglobinopathies in pregnancy, including sickle cell disease, thalassaemia, and antenatal screening. Finally, we will conclude by examining disseminated intravascular coagulation in pregnancy. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1: list the various definitions and causes of anaemia in pregnancy, • SLO 1.2: explain the impact of anaemia in pregnancy on pregnancy outcome, • SLO 1.3: describe how to evaluate women with anaemia in pregnancy, • SLO 1.4: list the various management options of anaemia in pregnancy, • SLO 1.5: describe sickle cell disease and thalassaemia in pregnancy, • SLO 1.6: describe antenatal screening and genetic counselling for haemoglobinopathies, and • SLO 1.7: describe the pathophysiology, causes, and management of disseminated intravascular coagulation in pregnancy. 1.1 Anaemia in Pregnancy: Definitions, Causes, and Impact 1.1.1 Definitions and classification of anaemia in pregnancy

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Anaemia in pregnancy is defined by the World Health Organization as a haemoglobin concentration below 11 grams per decilitre, though this threshold requires careful interpretation given the physiological haemodilution of pregnancy, itself reflecting a proportionally greater rise in plasma volume than red cell mass, meaning a modest fall in haemoglobin concentration during pregnancy is entirely normal and should not automatically be equated with genuine anaemia requiring active treatment. Anaemia is further classified by severity as mild, moderate, or severe according to the specific haemoglobin threshold used by local protocol, and by underlying mechanism as due to reduced red cell production, increased red cell destruction, or blood loss, with this mechanistic classification directly guiding the specific further investigation and, ultimately, the treatment approach most appropriate for an individual woman's particular anaemia. Fill in the blank: Anaemia in pregnancy is defined by the World Health Organization as a haemoglobin concentration below ________ grams per decilitre. Anaemia is classified by underlying mechanism as due to reduced red cell production, increased red cell destruction, or blood ________. 1.1.2 Causes of anaemia in pregnancy Iron deficiency is by far the most common cause of anaemia in pregnancy worldwide and in Nigeria specifically, reflecting the substantially increased iron requirements of pregnancy relative to typical dietary intake, compounded in many Nigerian settings by coexisting causes of blood loss such as hookworm infestation and malaria, together placing pregnant women at genuinely elevated risk of iron deficiency anaemia if intake and supplementation are not actively and consistently addressed. Other significant causes of anaemia in pregnancy include folate deficiency (of particular concern given its established link with neural tube defects), vitamin B12 deficiency, haemoglobinopathies such as sickle cell disease and thalassaemia (discussed in greater depth later in this Series), and, less commonly, other causes including chronic disease and haemolytic anaemia, each carrying somewhat different implications for both maternal management and, in the case of haemoglobinopathies, foetal genetic counselling. Fill in the blank: Iron deficiency is compounded in many Nigerian settings by coexisting causes of blood loss such as ________ infestation and malaria. Folate deficiency in pregnancy is of particular concern given its established link with ________ defects. 1.1.3 Impact of anaemia on pregnancy outcome Anaemia in pregnancy is associated with a range of adverse maternal outcomes, including increased fatigue and reduced functional capacity, an increased risk of postpartum haemorrhage-related complications given reduced physiological reserve to tolerate blood loss, increased susceptibility to infection, and, in severe cases, cardiac decompensation from the additional demand placed on an already anaemic maternal cardiovascular system.

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Foetal and neonatal outcomes associated with maternal anaemia include an increased risk of low birth weight, preterm birth, and, in severe maternal anaemia specifically, intrauterine growth restriction, reflecting the reduced oxygen-carrying capacity available to support optimal placental function and foetal growth, together underscoring why anaemia in pregnancy should never be regarded as a purely maternal issue but rather as a condition with genuinely significant, direct implications for the developing foetus as well. Fill in the blank: Anaemia in pregnancy increases the risk of postpartum haemorrhage-related complications given reduced physiological ________ to tolerate blood loss. Severe maternal anaemia is associated with an increased risk of intrauterine growth ________. Cause Relative Frequency Key Features Iron Deficiency Anaemia Most common (≈75%) Microcytic, hypochromic; low ferritin; responds to iron supplementation Folate Deficiency Anaemia Less common Macrocytic; megaloblastic changes; associated with poor diet, multiple pregnancies Vitamin B12 Deficiency Anaemia Rare Macrocytic; neurological symptoms; seen in strict vegetarians or malabsorption Anaemia of Chronic Disease Occasional Normocytic, normochromic; associated with chronic infections/inflammation Haemoglobinopathies (e.g., Sickle Cell, Thalassaemia) Region-specific prevalence Genetic; microcytic or normocytic; requires specialized management Acute Blood Loss (e.g., antepartum/postpartum haemorrhage) Important but less frequent Sudden drop in Hb; hypovolaemia; requires urgent transfusion Other Causes Rare Aplastic anaemia, bone marrow suppression, chronic renal disease Table 1.1: Causes of anaemia in pregnancy and their key features. Pilot questions 1.1 1. Define anaemia in pregnancy according to the World Health Organization threshold. (Linked to SLO 1.1) 2. Describe the classification of anaemia in pregnancy by underlying mechanism. (Linked to SLO 1.1) 3. List the causes of anaemia in pregnancy. (Linked to SLO 1.1)

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 4. Describe the maternal complications associated with anaemia in pregnancy. (Linked to SLO 1.2) 5. Describe the foetal and neonatal outcomes associated with maternal anaemia. (Linked to SLO 1.2) 1.2 Anaemia in Pregnancy: Evaluation and Management 1.2.1 Evaluation of women with anaemia in pregnancy Evaluation of anaemia in pregnancy begins with a full blood count, including red cell indices, which provide valuable initial diagnostic clues, given that microcytic anaemia is suggestive of iron deficiency or thalassaemia, macrocytic anaemia is suggestive of folate or vitamin B12 deficiency, and normocytic anaemia may reflect early iron deficiency, chronic disease, or an acute process such as haemolysis or blood loss. Further targeted investigation is guided by these initial findings and includes serum ferritin (the most reliable marker of iron stores), folate and vitamin B12 levels where macrocytosis is present, haemoglobin electrophoresis where a haemoglobinopathy is suspected on the basis of ethnicity, family history, or unexplained microcytic anaemia unresponsive to iron, and, where indicated, further investigation for an underlying cause of blood loss. Fill in the blank: Microcytic anaemia is suggestive of iron deficiency or ________, while macrocytic anaemia is suggestive of folate or vitamin B12 deficiency. Serum ________ is the most reliable marker of iron stores in the evaluation of anaemia. 1.2.2 Management options for anaemia in pregnancy Oral iron supplementation is the first-line treatment for confirmed iron deficiency anaemia in pregnancy, generally well tolerated though sometimes limited by gastrointestinal side effects including nausea and constipation, with intravenous iron considered where oral therapy is poorly tolerated, ineffective, or where a more rapid correction of anaemia is genuinely required, such as approaching term or before an anticipated significant

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