OBG514 — Reproductive Endocrinology and Fertility: Lecture Note

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This is the complete lecture note for OBG514 Reproductive Endocrinology and Fertility. 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 514 Course title: Reproductive Endocrinology and Fertility Course credit load: 2 Units Series 1: Menstrual Cycle and Disorders • Part 1.1: The Normal Menstrual Cycle o Sub Part 1.1.1: Hormonal regulation of the menstrual cycle o Sub Part 1.1.2: The ovarian cycle o Sub Part 1.1.3: The endometrial cycle • Part 1.2: Menorrhagia and Dysmenorrhoea o Sub Part 1.2.1: Menorrhagia: definition, causes, and evaluation o Sub Part 1.2.2: Management of menorrhagia o Sub Part 1.2.3: Dysmenorrhoea: primary and secondary • Part 1.3: Galactorrhoea and Hirsutism o Sub Part 1.3.1: Galactorrhoea: causes and evaluation o Sub Part 1.3.2: Hirsutism: definition and causes o Sub Part 1.3.3: Polycystic ovarian syndrome • Part 1.4: Abnormal Uterine Bleeding Patterns o Sub Part 1.4.1: Intermenstrual bleeding o Sub Part 1.4.2: Postcoital bleeding o Sub Part 1.4.3: Postmenopausal bleeding Introduction Picture a woman confused and worried after months of unpredictable, heavy periods that have begun to interfere with her work and family life. Understanding her experience begins with a genuinely solid grasp of the normal menstrual cycle itself, the elegant hormonal choreography between hypothalamus, pituitary, and ovary that most women experience monthly without a second thought, before we can properly understand what happens when this cycle goes wrong. This Series lays that essential foundation for the whole of this course on reproductive endocrinology and fertility.

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS The aim of this Series is to equip you with a thorough understanding of the normal menstrual cycle, and the disorders of menorrhagia, dysmenorrhoea, galactorrhoea, hirsutism, polycystic ovarian syndrome, and abnormal uterine bleeding patterns. We shall commence this Series by examining the normal menstrual cycle, its hormonal regulation and the parallel ovarian and endometrial cycles. Next, we will consider menorrhagia and dysmenorrhoea. Following that, our attention turns to galactorrhoea, hirsutism, and polycystic ovarian syndrome. Finally, we will conclude by examining intermenstrual, postcoital, and postmenopausal bleeding. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1: describe the hormonal regulation of the menstrual cycle, • SLO 1.2: describe the ovarian and endometrial cycles, • SLO 1.3: define menorrhagia and describe its causes and evaluation, • SLO 1.4: describe the management of menorrhagia and dysmenorrhoea, • SLO 1.5: describe galactorrhoea and its evaluation, • SLO 1.6: describe hirsutism and polycystic ovarian syndrome, • SLO 1.7: describe the causes and evaluation of intermenstrual and postcoital bleeding, and • SLO 1.8: describe the causes and evaluation of postmenopausal bleeding. 1.1 The Normal Menstrual Cycle 1.1.1 Hormonal regulation of the menstrual cycle The menstrual cycle is regulated by the hypothalamic-pituitary-ovarian axis, beginning with pulsatile secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus, stimulating the anterior pituitary to release follicle-stimulating hormone (FSH) and luteinising hormone (LH), which act on the ovary to drive follicular development, ovulation, and, subsequently, corpus luteum formation and function. A negative and, at one specific point, positive feedback relationship exists between ovarian hormones and the hypothalamic-pituitary axis, with rising oestrogen from the dominant follicle initially exerting negative feedback, then, once a critical threshold is sustained, switching to positive feedback, triggering the LH surge responsible for ovulation, a genuinely elegant

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS physiological mechanism ensuring the precise, coordinated timing central to normal cyclical ovarian function. Fill in the blank: The menstrual cycle is regulated by pulsatile secretion of gonadotropin-releasing hormone from the ________. A sustained rise in oestrogen switches from negative to positive feedback, triggering the LH ________ responsible for ovulation. 1.1.2 The ovarian cycle The ovarian cycle comprises the follicular phase (during which a cohort of ovarian follicles begins development, with typically a single dominant follicle emerging under the influence of FSH), ovulation (release of the mature oocyte, triggered by the LH surge, typically occurring around day 14 of a standard 28-day cycle), and the luteal phase (during which the ruptured follicle transforms into the corpus luteum, secreting progesterone to support the early luteal phase and, should pregnancy occur, the earliest stages of implantation). The luteal phase is characteristically more consistent in duration, typically around 14 days, than the follicular phase, which can vary considerably in length between individual women and between cycles, meaning variation in overall cycle length predominantly reflects variation in the duration of the follicular phase rather than the luteal phase itself. Fill in the blank: Ovulation, release of the mature oocyte, is triggered by the LH surge, typically occurring around day ________ of a standard 28-day cycle. The luteal phase is characteristically more consistent in duration than the ________ phase. 1.1.3 The endometrial cycle The endometrial cycle runs in parallel with, and is driven by, the ovarian cycle, comprising the proliferative phase (endometrial growth under the influence of rising oestrogen from the developing follicle), the secretory phase (further endometrial maturation and glandular secretory activity under the influence of progesterone from the corpus luteum, preparing the endometrium for potential implantation), and, in the absence of pregnancy, menstruation itself. Menstruation results from the abrupt withdrawal of progesterone (and, to a lesser extent, oestrogen) as the corpus luteum regresses in the absence of pregnancy, triggering vasoconstriction of the spiral arteries, endometrial ischaemia, and shedding of the functional endometrial layer, with this entire, remarkably precisely coordinated process then repeating with the onset of the subsequent cycle. Fill in the blank: The endometrial cycle comprises the proliferative phase, the secretory phase, and, in the absence of pregnancy, ________. Menstruation results from the abrupt withdrawal of progesterone as the corpus luteum ________ in the absence of pregnancy.

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.1: The menstrual cycle, showing parallel ovarian and endometrial phases with hormonal changes. Pilot questions 1.1 1. Describe the hormonal regulation of the menstrual cycle by the hypothalamic-pituitary-ovarian axis. (Linked to SLO 1.1) 2. Explain the switch from negative to positive feedback triggering the LH surge. (Linked to SLO 1.1) 3. Describe the phases of the ovarian cycle. (Linked to SLO 1.2) 4. Explain why variation in cycle length predominantly reflects the follicular rather than luteal phase. (Linked to SLO 1.2) 5. Describe the phases of the endometrial cycle and the mechanism of menstruation. (Linked to SLO 1.2) 1.2 Menorrhagia and Dysmenorrhoea 1.2.1 Menorrhagia: definition, causes, and evaluation

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Menorrhagia (heavy menstrual bleeding) describes excessive menstrual blood loss that interferes with a woman's physical, social, emotional, or material quality of life, a genuinely practical, patient-centred definition now generally preferred over historical, precise volumetric thresholds that proved genuinely difficult to apply reliably in routine clinical practice. Causes of menorrhagia include structural causes (uterine fibroids, endometrial polyps, and, less commonly, adenomyosis or malignancy), non-structural causes (ovulatory dysfunction, coagulopathy, and endometrial causes such as disordered local haemostatic mechanisms), and, in a genuinely significant proportion of cases, no specific structural or systemic cause identified, formally classified using the internationally recognised PALM-COEIN system. Fill in the blank: Menorrhagia describes excessive menstrual blood loss that interferes with a woman's physical, social, emotional, or ________ quality of life. Causes of menorrhagia are formally classified using the internationally recognised ________ system. 1.2.2 Management of menorrhagia Evaluation of menorrhagia includes a detailed menstrual history, examination, and, where indicated, transvaginal ultrasound to identify structural causes such as fibroids or polyps, full blood count to assess for associated anaemia, and, in selected cases, endometrial sampling, particularly in women over 45 or with risk factors for endometrial pathology. Management of menorrhagia ranges from medical treatment (the levonorgestrel-releasing intrauterine system as first-line in many guidelines, alongside tranexamic acid, non-steroidal anti-inflammatory drugs, and combined hormonal contraception) to surgical options (endometrial ablation or, for definitive treatment or where fertility is not desired, hysterectomy), with the specific approach genuinely individualised according to the underlying cause, severity, and the woman's own preferences, including any wish to preserve fertility. Fill in the blank: The levonorgestrel-releasing intrauterine system is first-line medical treatment for menorrhagia in many ________. Surgical options for menorrhagia include endometrial ablation or, for definitive treatment, ________. 1.2.3 Dysmenorrhoea: primary and secondary Primary dysmenorrhoea describes painful menstruation without underlying pelvic pathology, reflecting excessive endometrial prostaglandin production driving painful uterine contraction, typically beginning shortly after menarche, and generally responding well to non-steroidal anti-inflammatory drugs, which act by inhibiting prostaglandin synthesis, or combined hormonal contraception. Secondary dysmenorrhoea describes painful menstruation resulting from an identifiable underlying pelvic pathology, most commonly endometriosis or adenomyosis, and less commonly fibroids or pelvic inflammatory disease, typically developing later in reproductive life than primary dysmenorrhoea, with the specific underlying cause requiring targeted investigation and treatment addressing the pathology itself rather than symptomatic pain relief alone.

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: Primary dysmenorrhoea reflects excessive endometrial ________ production driving painful uterine contraction. Secondary dysmenorrhoea most commonly results from endometriosis or ________. Category Key Points Menorrhagia

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