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FRS - Obstetrics, Pregnancy Bleeding - Coggle Diagram
FRS - Obstetrics, Pregnancy Bleeding
Placenta Physiology
Development
Day 8 - trophoblast (cytotrophoblast, synctiotrophoblast)
Day 12-15 - primary chorionic villi vegin to form - exchamge between foetal and maternal blood
Day 20-21 - lacunae fuse to form lacunar network
Post Day 21 - decidua basalis ->chorion frondosum forms
Spinal artery invasion
3-12 weeks - invasion or arteries at decidua
14-16 weeks - invasion into upper third of myometrium
20 weeks - invasion of myometrium completed
Coiling of umbilical arteries and vein helps protect from tension and compression of cord
Complications
Spontaneous abortion
Pre-eclampsia - hypertension and proteinuria
Intrauterine growth restriction (IUGR)
Placental function
Gas transfer
Partial pressure gradient
High O2 affinity of HbF
Double Bohr effect (Hb has reduced ability to bind O2 under acidic conditions
Nutrient and waste transfer
Simple diffusion - O2, fatty acids
Facilitated diffusion - glucose, lactate
Active transport - amino acids, iron
Endocytosis - antibodies, LDL
Hormone production
Oestrogen, progesterone - maintains decidue
Oestrogen, HCS, HCG - stimmulates mammary glands
HCG - maintains corpus luteum
Progesterone - inhibits uterine contractions
HCS - promotes energy release for fetus
Relaxin - softens cervix and pelvic ligaments
Immune support of foetus
Maternal IgG cross placenta and protect foetus
Trophoblast cells involved in disguising foetus from maternal immune system
hCG has immunosuppressive effect - prevents recognition of conceptus as foreign body
Placenta Pathology
Abnormal placentation
Marginal insertion - insertion of cord at edge of placenta
Velamentous insertion - cord vessels run in foetal membranes before inserting into placenta - vessels exposed in membrane without protection of Wharton's jelly - more vulnerable to rupture
Vasa previa - vessels run in membranes over cervical os - may lead to stillbirth due to haemorrhage
Placenta succenturiata - placenta has accessory lobe separated by membranes
Placenta circumvallate - basal plate smaller than chorionic plate, trophoblast invades decidua - ridged appearance of placental surface
Abnormal Insertion
Placenta previa - insertion in lower segment of uterus covering/very close to cervical opening - antepartum/postpartum haemorrhage
Placenta accreta - chorionic villi enter myometrium
Placenta increta - invasion deeper into myometrium
Placenta percreta - invades through myomeetrium
Maternal Adaptations to Pregnancy
Cardiovascular
Increased heart rate and stroke volume (SV 1st half, HR 2nd half)
Decreased blood pressure - release of vasodilatory substances, softening of collagen fibres, low resistance through placenta
BP lowest in 2nd trimester, rises in 3rd trimester due to increased RAAS activation (pre-eclampsia - BP disorder)
Uterus expands up and out of pelvic cavity, occupies more space in abdominal cavity
Heart - left acis deviation, reduced PR interval, lead III (small Q wave and inverted T wave), inferolateral leads (ST depression and inverted T wave)
IVC syndrome - heavy gravid uterus compresses on IVC, obstructed venous return, reduced cardiac output
Haematological
Increased blood volume (more plasmat than RBC volume -> haemodilution, anemia)
Increased production of clotting factors
Respiratory
Hyperventilatory state - mainly driven by progesterone
Increased tidal volume is main contributor, increased inspiratory reserve volume
Respiratory alkalosis
Upward shift of diaphragm - decreased FRC, RV, ERV
Outward flaring of lower ribs, relaxin boardens chest and increases subcostal angle
Renal
Dilation due to mechanical pressure (uterus) and hormones (progesterone)
Pressure from enlarged uterus reduces bladder capacity
Pressure from uterus, iliac arteries and ovarian veins complexes compress uterus at pelvic brim - right uterus more dilated, causes urinary stasis, increases risk of UTI and pyelonephritis
Increased progesterone - relacation of smooth muscles in ureters, bladder, blood vessels
Gastrointestinal
Increased appetite - progesterone orexigenic, oestrogen anorexigenic (appetite decreases near term)
Reduced gut motility - progesterone causes generalised smooth muscle relaxation and reduced peristalsis
Morning sickness - N&V caused by hCG and progesterone - acts on vomit centre in hypothalamus, relaxing smooth muscle in stomach - reduced mobility
GGERD, Constipation, Gallstones (biliary stasis from reduced contractility of gallbladder, effects of oestrogen on bile acid transport)
Immune
Reduced chemotaxis - increased risk of gram-negative infection
Reduced NK cell activity - increased risk of listeriosis and toxoplasmosis
Increased monocytes and granulocytes - increased clearance of foetal cells from maternal blood
Increased polymorphs and opsonisation
Reduced Th1, increased Th2
Integumentary
Hyperpigmentation
Striae gravidarum - wide violaceous linear marks on abdomen, breasts, thighs - eventually fase to silvery white after pregnancy
Pruitus
Acne - increased sebaceous gland secretions due to increased androgens
Prickly heat/rash - due to increased dilation of cutaneous blood vessels and activity of eccrine sweat glands
Minor disorders - pruitus and discomfort - pruitic folliculitis, polymorphic eruptoon of pregnancy
Severe disorders - pruitus, fever, lethargy - impetigo herpetiformis, pemphigoid getationis
Hormones of Pregnancy
Syncytiotrophoblast cells - hCG, hCS, hPL
Ovaries and placenta - oestrogen
Corpus luteum and placenta - progesterone
Obstetric anatomy and terminologies
Pelvic inlet
True ostetric conjugate - sacral promontory to upper and inner border of pubic symphysis
Diagonal conjugate - sacral promontory to lower border of pubic symphysis
Transverse diameter - between furthest 2 points of iliopectineal line
Oblique diameter - sacroiliac joint to opposite iliopectineal eminence
Pelvic outlet
Anteroposterior diameter - tip of coccyx to lwoest part of pubic symphysis
Bispinous diameter - between tips of ischial spines
Bituberous diameter - between ischial tuberosities
Pelvis types
Gynecoid
Android
Anthropoid
Platypelloid
Foetal bones
Sutures
Coronal - separates frontal from parietal bones
Sagittal - separates 2 parietal bones
Lamboid - separates occipital from parietal bones
Fontanelles
Anterior - junction of sagittal and coronal sutures - diamond shaped
Posterior - junction of sagittal and lamboid sutures - triangular shaped
Regions of head
Sinciput
Bregma - anterior fontanelle
Vertex - between anterior and posterior fontanelles
Occiput - behind posterior fontanelles
Terminologies
Foetal lie - relationship between foetal spine and maternal spine
Attitude - relationship of foetal head to its spine
Presentation - anatomical part of foetus at lower segment of pelvis
Caput - localised swlling which can ccur on foetal scalp due to pressure from cervix or pelvic inlet
Moulding - ability of foetal skull bones to be compressed
Physiology of Labour
Initiation
Uterus becomes more sensitive to oxytocin as term approaches
Sensitivity increased by oestrogen, decreased by progesterone
Increased DHEA production (increases oestrogen), increased cortisol production (increases prostaglandins)
Foetal cortisol inhibits progesterone - reduces its inhibitory effects on uterus - initiation of contraction
Ferguson reflex - more cervical pressure from contraction - greater increase of oxytocin
Mechanism
Dilatation
Birth
Afterbirth delivery
1st stage - latent phase,, active phase
2nd stage - engagement, flexion, descent, internal rotation, extension, external rotation, expulsion
3rd - placental delivery
Episiotomy - cut in perineum to enlarge vaginal introitus to allow easier delivert
Right mediolateral preferable to midline
Pathology of Labour
Abnormal progress in Labour
Power - efficiency of uterine contractions
1st stage - good and efficient contractions for cervical dilatation
2nd stage - contractions and maternal effort for descent, rotation, delivery
Passage - size and shape of maternal bony pelvis and soft tissues
Cephalic pelvic disproportion - disparity between dimensions of foetal head and maternal pelvis - precludes vaginal delivery
Absolute = true mechanical obstruction
Relative - difficulties of foetus navigating through pelvis
Passenger - size of foetal head, presentation and position of foetus
Macrosomia - large foetal size - uncontrolled diabetes during pregnancy
Bydrocephalus - CSF accumulation in brain
Malpresentation - breech, transverse, brow, face, compound
Head extension - extreme extension increases diameter
Asynclitism - lateral tilting of foetal head
Complications of Pre-term labour
Respiratory distress syndrome - lung hypoplasia due to late in-utero development and lack of surfactant production - alveolar collapse - most common complication
Intra-ventricular haemorrhage - bleeding in germinal matrix due to high risk of vessel rupture
Germinal matrix - highly cellular and hihghly vascularised refion in the brain out from which cells migrate during brain development - normally regresses towards term
Bronchopulmonary dysplasia - premature infants require long-term oxygen after receiving prolonged mechanical ventilation
Prolonged high O2 delivery - inflammation, scarring of lung
Patent ductus arteriosus - remnant of foetal circulation - left to right shunt
Necrotising enterocolitis - loss of mucosal integrity and bacteria involvement - bowel necrosis
Retinopathy of prematurity - retinal damage due to relative ischaemia between vascularised and non-vascularised areas after resuscitation
Development of genital organs
Sex determination
MIS - causes Mullerian (paramesonephric) ducts to degenerate
Testosterone - Wolffian (mesonephric) ducts to develop
Gonads
Medial part of urogenital ridge becomes genital ridge - gives rise to gonads
Primordial germ cells formation and migration - develops in wall of yolk sac, migrate along dorsal mesentery of hindgut - invade genital ridges
Lateral part of urogenital ridge becomes nephrogenic cord - kidneys
Descent of ovary
Females - overies descend into pelvis
part between ovary and uterus - pvarian ligament
part between uterus and labia majora - round ligament
Males - testes descend into scrotum
Mesonephric duct - male genital tract
Mullerian duct - female genital tract
Female embryo - no testosterone produced (usually by Leydig cells), no MIS (cranial parts of paramesonephric ducts -> uterine tubes, caudal parts fuse -> uterine canal)
Vagina dual origin
Upper 1/3 vagina - uterine canal
Lower 2/3 vagina - urogenital sinus
Pathology - genital birth defects
Defective development of uterus
MRKH Syndreome - mullerian agenesis - complete absence of reproductive tract
Congenital uterine defects
Unicornuate - developmental arrest of 1 mullerian duct
Didelphic / double uterus - complete non-fusion of mullerian ducts (2 vaginas, simultaneous pregnancies)
Bicornuate uterus - partial fusion of mullerian ducts
Septate uterus - fusion but failure of midline remodelling or reabsorption of tissue
Arcuate uterus - small indent in midline of uterus
Defective development of vagina
Transverse vaginal septum - due to failure of degeneration of vaginal plate, associated with shortened vagina
Imperforate hymen - failure of perforation after birth
Disorders of sexual development
Androgen insensitivity syndrome (46XY) - androgen receptor mutation in genetic males - presence of SRY (mullerian ducts regress), no response to testosterone (wolffian ducts degenerate)
Swyer syndrome (46XY) - SRY gene mutation, gonadal dysgenesis, phenotypically female
Female pseudo-intersexuality (46XX) - genetic female, masculinisation of female external genitalia - most commonly caused by CAH
Male pseudo-intersexuality (46XY) - genetic male - underdeveloped male external genitalia - due to inadequate production of testosterone
Normal foetal growth and development
Cardiovascular system
Foramen ovale - connects right and left atria - blood bypasses right ventricle
Ductus arteriosus - connects pulmonary artery to aorta - bypasses pulmonary circulation
Ductus venosus - shunt passing oxygenated blood from umbilical vein to IVC - bypasses hepatic circulation
Nervous system
Telencephalon - cerebrum, basal ganglia
Diencephalon - thalamus, hypothalamus
Mesencephalon - tectum, tegmentum
Metencephalon - pons, cerebellum
Myelencephalon - medualla oblongata
Amniotic fluid
Polyhydramnios - increased amniotic fluid volume
Oligohydramnios - decreased amniotic fluid volume
Assessment of gestational age
First day of LMP + 1 year - 3 months + 7 days
Symphysis-fundal height after 12 weeks of gestation
Ultrasound before 13+6 weeks - crown rump length
Ultrasound after 13+6 weeks - biparietal diameter - head circumference
Early pregnancy bleeding
Types of miscarriages
Missed = foetus stops growing (dies) but body does not detect - hormones continue to be produced
Threatened - possibility of miscarriage, can salvage
Inevitable - pregnancy still intact and miscarriage has not started yet but will happen
Incomplete - in process of being passed out
Complete - completely passed out
Septic - infection
Ectopic pregnancies
Congenital foetal abnormalities
Small for gestational age - foetal weight <10th percentile
Constitutionally small
non-placenta-mediated growth restriction - structura/chromosomal anomalies, inborn errors of metabolism, foetal infections
Placenta-mediated growth restriction
IUGR
Early vs late onset (32 weeks)
Symmetric - restriction affects all growth parameters, normal head:abdomen / femur:abdomen ratio - poor prognosis
Asymmetric - utero-placental insufficiency - extrinsic influences
Foetal macrosomia - foetal weight >90th percentile
Disorders
Down syndrome - meiotic nondisjunction
Rpnertsonian translocation - long arm of chromosome 21 gets attached to another chromosome, t(14;21)
Mosaicism - anaphase lag of chromosome 211 in trisomy somatic cell, nondisjunction event in diploid somatic cell during early cell division
Structural congenital defects
Congenital heart defects
Neural tube defects - anencephaly and myelomeningocele
Amdominal wall defects - exomphalos/omphalocele - gastroschisis
Lung disorders - diaphragmatic hernia
Genitourinary - polycystic kidney disease
Spina bifida - myelomeningocele - failed closure of caudal end of neural tube
Anencephaly - failed closure of rostral end of neural tube - incomplete formation of brain, skull
Maternal infecton - TORCH
Toxoplasmosis (parasite)
Others
Rubella
Cytomegalovirus
Herpes simplex virus (HSV)
Teratogens
Foetal alcohol syndrome - growth restriction, facial stigmata, permenant CNS damage, primary cognitive and functional disabilities
Antiepileptic drugs
Neural tube - valproate, carbamazepine
Cleft lip / palate - carbamazepine, penytoin, phenobarbitone
Congenital heart defects + urogenital defects - valproate, phenytoin, phenobarbitone