Gestation Notes PDF

# TEMA 2 GESTACIÓN ## Enfoque EIR - It is a key topic in the EIR exam. - The section on normal pregnancy (in blue cursive) is frequently asked; make sure you understand the physiological changes that occur during pregnancy (including self-care recommendations), how pregnancy is diagnosed, and how t...

# TEMA 2 GESTACIÓN ## Enfoque EIR - It is a key topic in the EIR exam. - The section on normal pregnancy (in blue cursive) is frequently asked; make sure you understand the physiological changes that occur during pregnancy (including self-care recommendations), how pregnancy is diagnosed, and how to calculate the estimated date of delivery. - In embryology, be clear about the different stages of development, the time periods each stage covers, and the primary characteristics of those stages. - Pay close attention to prenatal diagnosis, Rh incompatibility screening, and cardiotocography as a fetal well-being monitoring tool. - Be very clear about the definition of each pregnancy pathology (the most common topics are EHE followed by abortion). - It is crucial to understand which vaccines are contraindicated during pregnancy. ## 2.1. Embriología ### Gametogénesis - Process by which gametes (ova and sperm) are produced and mature for fertilization. ### Ovogenesis - It is the process of forming oocytes. - It takes place in the ovaries and is regulated by the hypothalamic-pituitary-gonadal axis. - It begins during intrauterine life, with the process being suspended in a primary oocyte (2n) until puberty. - During puberty, the primary oocyte completes the division, forming a secondary oocyte (n) and a first polar body. - At ovulation, an LH surge triggers the release of the secondary oocyte to the fallopian tube. - Meiosis II will not be completed, neither will the formation of the ovum and the second polar body, until fertilization occurs. - After a 28-day cycle, only one ovum (with 23 chromosomes: 22X) and three polar bodies are produced. **Remember:** Ovogenesis is not completed until fertilization occurs. ### Espermatogenesis - Continuous process of sperm formation. - It begins at puberty and continues until senescence. - It occurs in the seminiferous tubules of the testes and is regulated by the hypothalamic-pituitary-gonadal axis. - The gonadal endocrine organ is the Leydig cells (testosterone production). - The entire process, from the origination of a spermatogonium to the formation of a mature sperm capable of fertilization, takes about 64 days. - Spermatogonia, with a diploid number of chromosomes (2n), initially reside in seminiferous tubules at birth. - At puberty, they begin meiotic division, forming primary spermatocytes and later secondary spermatocytes. **Before birth:** - **Oogonia:** 46 chromosomes **After birth:** - **Oocyte I:** 46 chromosomes - **Oocyte II:** 23 chromosomes - **Ovum:** 23 chromosomes - **Sperm:** 23 chromosomes **Figure 1. Ovogenesis** - **Primary spermatogonium:** 46 XY - **Primary spermatocyte:** 46 XY - **Secondary spermatocytes:** 23 X and 23 Y - **Spermatids:** 23 X and 23 Y - **Spermiogenesis:** 23 X and 23 Y **Figure 2. Espermatogenesis** - Once spermatids are formed, they undergo a transformation process called **spermiogenesis** to become mature spermatozoa (22X or 22Y). ### **Figure 3. Espermatozoide humano.** - **Head:** - **Acrosome:** - **Nucleus:** - **Centrioles:** - **Filament axial:** - **Mitochondria:** - **Neck:** - **Tail:** ## **Enfermería maternal EM** - Once fertilization occurs, a series of successive mitoses known as **segmentation** or **cleavage,** begins. ### **3.º día:** - **Morula:** composed of 16-32 cells or blastomeras. It moves to the uterus. ### **4.º - 5.º día:** - **Blastocyst:** forms as fluid enters. It is characterized by a prominent cavity and a cell number ranging from 70 to 100. - **Trophoblast:** a peripheral zone forming a layer that will give rise to the placenta. - **Embryonic button:** a compact region that will form the embryo. ### **6.º - 12.º día:** - **Implantation:** The blastocyst (30-462 cells) adheres to the secreting endometrium (also called decidua basal) and penetrates it. It is necessary to find blood vessels that will allow the embryo to develop. It typically happens in the fundus or upper third of the uterus. - As the outer layer of the blastocyst comes into contact with the endometrium, it forms two layers: - **Cytotrophoblast:** internal - **Syncytiotrophoblast:** external, which will create gaps between the two layers, filling with maternal blood. **Remember:** - The blastocyst is characterized by a group of cells (70-100) enclosed in a cavity filled with fluid. It is in this blastocyst form that implantation occurs, between days 6 and 12 after fertilization. - **3.º week (day 15 to 21):** - **Gastrulation:** This process involes the formation of the third layer: the mesoderm. This occurs via the migration of ectodermal cells. - These three layers (ectoderm, mesoderm, and endoderm) will give rise to all tissues in the organism. ### **Ectoderm:** - **Central nervous system (SNC) and peripheral nervous system (SN periférico):** - **Epidermis and associated glands (sweat, sebaceous), hair, nails, enamel:** - **Medulla suprarenal:** - **Hypophysis:** - **Head and face connective tissue:** ### **Mesoderm:** - **Heart, blood vessels, lymph vessels:** - **Muscles, bones, cartilage:** - **Connective tissue:** - **Medulla suprarenal:** - **Dermis:** - **Suprarenal cortex:** ### **Endoderm:** - **Epithelium of the digestivesystem (EIR 04, 09) and associated glands (liver, pancreas): * - **Epithelium of the respiratory system and its glands:** - **Epithelium of the urinary system: bladder, urethra:** - **Thyroid, parathyroid:** - **Vagina:** - **Spleen:** - **Thymus:** **Table 1. Embryonic layers.** ### **Figure 4. Fases del periodo preembrionario.** ## **Periodo fetal** - From the 9th week of gestation until birth. - Characterized by the growth and maturation of existing fetal tissues. No new tissues are formed. **Remember:** - **Week 24:** surfactant production begins in type II pneumocytes (EIR 02, 53). - **Week 34:** pulmonary maturity and the suckling-swallowing reflex are achieved. ## **Anejos fetales** ### **Placenta** - An essential organ during pregnancy, responsible for: - Nutrition - Excretion - Respiration - Protection - Regulation - Storage for fetal development. - It originates from the trophoblast. - Produces hormones: hCG, hPL, progesterone, estrogens. - Composed of fetal and maternal components, separated by the placental barrier, which keeps the fetal and maternal circulatory systems distinct and regulates the passage of substances through them. - **Fetal Component:** - Chorionic villi - Chorion/amnion - **Maternal Component:** - **Decidua:** - **Basal Decidua:** Where the blastocyst is implanted. - **Capsular Decidua:** Surrounding the blastocyst. - **Parietal Decidua:** In contact with the rest of the endometrium. **Figure 5. Decidua.** ## **Periodo embrionario** - From the 4th to the 8th week of gestation. - Characterized by organogenesis. - By the end of week 8, all organs are formed. This period is associated with the highest risk of teratogenic effects. ### **Figure 6. Fases del periodo preembrionario.** - **Day 1:** The heart begins to beat. - **Day 22 (Week 6):** The heartbeat can be detected by ultrasound. ## **Enfermería Maternal EM** - **Week 16:** The professional can detect fetal movements with careful palpating. In primiparous women, this occurs between 18-20 weeks; in secundigravidas, it happens between 16-18 weeks, meaning during the second trimester. - **Week 20:** Braxton-Hicks contractions appear, but they are painless and irregular until around week 30. The pregnant woman may notice them starting around week 30. ## **Pruebas de laboratorio** - Detection of gonadotropic hormones in blood and urine. ## **Signos de probabilidad:** - **Alteraciones psicoemotivas:** Increased anxiety, irritability, emotional instability, changes to sleep-wake cycles. - **Quickening:** The mother can feel the fetal movements. ## **Diagnóstico de probabilidad - ** **Signs objetivos:** - **Uterine signs:** - **Uterine growth:** The uterus is accessible through palpation starting around week 12 of gestation. It reaches the umbilicus between weeks 20-22. - **Noble-Budin sign:** Globose shape of the uterus with slightly flattened vaginal cavities. - **Piskacek sign:** Asymmetric shape of the uterus due to softening of the implantation site. - **Goodell sign:** Softening of the cervix. - **Hegar sign:** Softening of istmus. The istmus is the anatomical structure connecting the body and the cervix, which forms the lower uterine segment during pregnancy. - **Vulvovaginal signs:** - **Softness, elasticity, and warmth caused by hyperemia:** - **Jacquemier-Chadwick-Johnson sign:** Violet hue of the vulva, vagina, and cervix. - **Osiander pulse:** Palpation of the uterine artery's beat in the vaginal fornices ## **Movimientos fetales:** - The woman will report this, and a health professional can detect it starting around week 16 (primiparous: 18-20 weeks, secundigravida: 16-18 weeks). - **Braxton-Hicks contractions:** They appear early on, are painless, and irregular from week 20 (detected by a health professional), but the pregnant woman will not notice them until around week 30. ## **Membranas ovulares:** - **Chorion:** External layer. It is in contact with the true decidua. - **Amnion:** In contact with the fetus and the amniotic fluid. It is the thickest and most resistant. As the fetus develops, the two layers are attached together. ## **Cordón umbilical;** - Connects the fetus to the placenta. - It attaches to the fetus's side of the placenta. - It contains two arteries carrying deoxygenated blood, and one vein carrying oxygenated blood. - It is wrapped in a layer of Wharton's jelly. - The normal length is about 50-60cm. ## **Amniotic fluid:** - It surrounds the fetus. - It is composed of 98% water and its quantity changes throughout pregnancy, increasing and then decreasing right before delivery. - Its pH is about 7. - Important functions include: - Trauma protection. - Proper fetal positioning. - Proper development of the musculoskeletal system. - Lung maturation. - Development of the digestive system and salivary glands. - Bacteriostatic/bactericidal activity. - Acid-base balance. ## **Defectos congénitos:** - Congenital defect, congenital malformation, and congenital anomaly are synonymous terms used to describe structural, behavioral, functional, or metabolic abnormalities present at birth. - **Types:** - **Malformation:** Happens during organogenesis as the organ is being formed. - **Disruption:** Occurs after organ formation. It is caused by issues such as obstructed blood flow, amniotic bands, etc. - **Deformation:** Caused by mechanical forces that distort the fetal part over time. - **Syndrome:** A group of anomalies that present in the same moment and have a specific common etiology. ## **2.2. Gestación normal** - This is the process of the fetus's development within the uterus. ### **Definition:** - **WHO:** The gestation period begins at the implantation of the conceptus, which occurs between days 12-14 after fertilization. - **FIGO (Fédération Internationale de Gynécologie et d'Obstétrique): ** The gestation period includes all processes related to human reproduction from the implantation of the conceptus until the end of the process. - The starting point for theoretically defining the gestation period has been revised; it used to be considered the beginning of the process. ## **Duration:** - Calculated from the date of fertilization to the time of delivery: 40 weeks or 280 days (10 lunar months) from the first day of the LMP (last menstrual period). ### **Figure 6. Rueda obstétrica.** ## **Estimated Date of Delivery (EDD) or Estimated Date of Confinement (EDC):** ### **Naegele's Formula** - LMP (First day of the last menstrual period) + 7 days - 3 months + 1 year = EDD. ### **Obstetrical wheel.** - This assesses the gestational age based on the LMP. ### **Ultrasound with a vaginal probe during the first trimester.** - Assesses the gestational age by measuring the CRL (crown-rump length). The CRL is the most reliable parameter for accurately calculating the gestation age in the first trimester. ### **Terminology** - **Obstetrical History:** GPAV - **G:** Gravidity: number of pregnancies (including the current one) - **P:** Parity: number of deliveries - **A:** Number of abortions - **V:** Number of living births. - **C:** Number of C-sections. - **E:** Number of ectopic pregnancies. ### **Example:** - **G3P1A1V2C1:** A woman is pregnant. She has had two children, one from a vaginal delivery and another from a C-section. She has also had one abortion. - **G2P1A0V1:** A pregnant woman who has one child born from a vaginal delivery. ## **Gravidity:** - Number of pregnancies, including the current one. - **Nulligravida/nulligesta:** never pregnant - **Primigravida/primigesta:** pregnant for the first time. - **Multigravida/multigesta:** pregnant more than once. ## **Parity:** - Number of vaginal births after 22 weeks of gestation: - **Nullipara:** has never given birth - **Primipara:** has had one vaginal delivery (singleton, twins, live birth or stillbirth, etc.) - **Multipara:** has had more than one vaginal birth. - The term **primipara** is sometimes used interchangeably with **primigesta**, referring to women with a first pregnancy who have not yet given birth. ## **Remember:** - The duration of pregnancy is 40 weeks or 280 days, starting on the first day of the LMP. - We use Naegele's rule to calculate the EDD (Estimated Date of Delivery): - LMP (First day) + 7 days - 3 months + 1 year = EDD. ## **Diagnosis of Pregnancy** ### **Presumptive Diagnosis - Subjective Changes (Suspected or Sympathetic) ** - Reported by the pregnant woman: - **Amenorrhea:** Consider other potential causes of amenorrhea in women of child-bearing age, as pregnancy is the most common cause of secondary amenorrhea. - **Changes in the nervous system:** - Nausea and vomiting. - Changes to the breasts: increased size, sensitivity, tingling, and increased nipple sensitivity. Nipple and areola size and pigmentation will increase. (EIR 05, 83; 203, 3) - Urinary changes: frequent need to urinate, pelvic discomfort. - **Abdominal distention and digestive changes:** excessive salivation, constipation. - **Fatigue** - **Psychoemotional changes:** Anxiety, irritability, unstable moods, changes in the sleep-wake cycle. - **Quickening:** This is the sensation of fetal movements, as reported by the mother. ### **Signs of Probability - Objective Signs:** - They are detected by a health professional. - **Uterine Signs:** - **Uterine Growth:** The uterus is accessible through palpation starting around the 12th week of gestation. The uterus reaches the umbilicus between weeks 20-22. - **Noble-Budin Sign:** The uterus has a globose shape with a slight flattening of the vaginal cavities. - **Piskacek sign:** The uterus has an asymmetric shape due to softening at the implantation site. - **Goodell Sign:** The cervix is softened. - **Hegar Sign:** The isthmus (the anatomical part that connects the body of the uterus and the cervix, which forms the lower uterine segment of the uterus during pregnancy) is softened. ### **Vulvovaginal Signs:** - **Softness, elasticity, and warmth** due to hyperemia (excess blood flow). - **Jacquemier-Chadwick-Johnson Sign:** Violet hue in the vulva, the vagina, and the cervix. - **Osiander Pulse:** Can be palpated with the beat of the uterine artery in the fornix of the vagina. ### **Fetal Movements:: ** - The woman reports them, and a health professional can detect them starting around week 16 (primipara: 18-20 weeks; secundigravida: 16-18 weeks). - **Braxton-Hicks contractions:** They appear early on, are painless, and irregular. They are detected by the health professional starting around week 20, but the pregnant woman probably won't notice them until around week 30. ### **Laboratory tests:** - Detection of gonadotropic hormones in blood and urine.