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Phase 3a > obs 3 > Flashcards

obs 3 Flashcards

1
Q

What does SGA stand for?

A

small for gestational age

fetus is <10th weight percentile for age (weeks)

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2
Q

what is IUGR?

A

intrauterine growth restriction

fetus unable to achieve genetically predetermined size

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3
Q

what does LBW stand for?

A

low birth weight
birth weight less that 2500g
SGA or prematurity

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4
Q

what are the three classification of small for gestational age fetus?

A

1) normal small fetus - no structural abnormality, normal umbilical doppler and liquor. Not at risk, no special care needed.
2) abnormal small fetus - have chromosomal or structural abnormalities
3) growth restricted fetus - usually results from placental dysfunction. Appropriate treatment or timely delivery may improve prospects.

a significant number of healthy foetuses will be subjected to high-risk protocols and, potentially, iatrogenic prematurity.

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5
Q

what is symmetrical FGR?

A

fetal head and body proportionately small
fatal insults during early development - affect growth process and cell hyperplasia
things like chromosomal disorders

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6
Q

why is asymmetrical FGR and what is caused by?

A 
fatal brain disproportionally large compared to liver 
fatal insult during later development 
usually placental insufficiency 
normal infant brain:live ratio >3 
asymmetrical ratio >6
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7
Q

what are some causes of IUGR?

A

intrinsic: chromosomal aberrations
congenital structural defects
constitutional (genetic heritage)

extrinsic:maternal-placental-fetal infections
uteroplacental perfusion
chronic maternal disease
substrate availability and toxins

fetal causes:multiple pregnancy 
infections 
congenital malformations
extrauterine pregnancy e.g. abdominal 
placental or umbilical cord defects 
chromosomal abnormalities.

placental: uteroplacental insufficiency
- defective trophoblastic invasion/placentation
- lateral insertion of cord
- reduced blood flow to placental bed e.g. pre-eclampsia
- vascular anomaly of placenta and cord - TTTS
- decrease functioning mass - small placenta, abruptio placenta, placenta praaevia, post term pregnancy.

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8
Q

what drugs and medications are associated with FGR?

A 
marijuana 
heroin, methadone 
cocaine 
cigarette smoking 
alcohol 
aminopterin 
cytotoxic drugs 
isotretinoin 
lithium 
oaramethadione
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9
Q

what are the underlying mechanism of IUGR?

A

insufficient gas exchange and nutrient delivery to fetus
maternal disease
- decreased oxygen - carrying capacity e.g. cyanotic heart disease, smoking, haemoglobinopathy
- dysfunctional oxygen delivery system - diabetes with vascular, hypertension, autoimmune conditions
- placental damage - smoking, thrombophilia, autoimmune diseases

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10
Q

what does the placenta transport?

A
  • Gases
  • O2 and CO2 to and from baby.
  • Nutrients (Glucose facilitated diffusion via hexose transporters, Amino acid by active transport, Antibodies IgG not IgM, Bilirubin – conjugated poorly transported, unconjugated from fetus crosses easily
  • Drugs (fetal drug addiction)
  • infectious agents (cytomegalovirus, rubella, measles, microorganisms)
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11
Q

what are some long term consequences of FGR?

A
  • abnormalities (hypothalamic pituitary axis, the CVS)
  • insulin resistance
  • metabolic syndrome
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12
Q

what in the history would you screen for fatal growth restriction?

A 
smoking 
altitude 
malnutrition 
previous FGR
medications 
recreational drugs 
alcohol 
chronic maternal disease 
genetic anomalies (maternal age, fam history, habitual abortion, alpha-fetoprotein
first trimester vaginal bleeding 
parents size
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13
Q

how is fetal growth restriction diagnosed?

A

presence of risk factors
clinical - serial maternal weight , symphysio-funal height assessment
USS - inadequate fetal growth, reduced AFI, placental calcification

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14
Q

what are customised fundal height charts?

A

SFH charts improve sensitivity to detect SGA
non-customised SFH-sensitivity=27%
customised SFH charts-sensitivity=48%

the charts take into account - maternal height, weight, parity and ethnicity.

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15
Q

what is large for gestational age defined as?

A

above the 90th centile for that gestation

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16
Q

what is macrosomia?

A

BW > 4000g regardless of gestational age

unlike IUGR the morbidity and mortality relate to absolute birth wate rather than centiles

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17
Q

what are the risks of macrosomia?

A 
• Maternal hyperglycaemia during pregnancy
• Previous macrosomic infant
• Pre-pregnancy obesity/excessive maternal weight
gain
• Male fetus
• Post-term gestation
• Parental height and race
• Maternal age < 20 years.
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18
Q

what happens to blood volume during pregnancy?

A

large increase in blood volume from 70ml/kg to 100ml/kg
- eg 70kg lady at booking = blood volume increase from 4900 to 7000ml
plasma volume increases 40-50%
red cell mass increases 20-30% produces relative anaemia.

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19
Q

how does clotting change in pregnancy?

A

pregnancy is a relatively hypercoagulable state, but during pregnancy neither clotting or bleeding times are abnormal

there is a decrease in fibrinolytic activity - these changes tend to prevent excessive bleeding at delivery

fibrinogen is markedly increased
clotting factors increase -

clotting factors increased = II, VII, VIII, X, XI, XII

platelets - the number rises within the normal range

DDimer levels are elevated in pregnancy

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20
Q

what blood products are made from centrifuged blood?

A

Fresh Frozen Plasma.
FFP contains all of the clotting factors normally found in blood at the normal concentrations

Cryoprecipitate is prepared from FFP and contains clotting factors in higher concentrations.

Platelets are prepared by centrifuging the blood more slowly and pooling them together

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21
Q

what bedside test and laboratory tests are done when managing obstetric haemorrhage?

A 
Bedside testing: Serial blood gases
Hb / Hct
Lactate / PH / HCO3
Bedside coagulation testing: ROTEM
Laboratory tests: FBC / coag (take 1 hour)
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22
Q

what is cortisol needed for in the fetus?

A

1-lung compliance and surfactant release, which ensure that spontaneous breathing can occur at birth.
2-in the fetal liver , it induces beta receptor and glycogen deposition to maintain a glucose supply to the neonate after delivery.
3- in the gut it is responsible for villus proliferation and induction of digestive enzymes, which enable the neonate to switch to enteral feeding after birth.

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23
Q

how is the fetal circulation different from adult circulation?

A

1-oxygenation occurs in the placenta not in the lung.
2-the right and left ventricles work in parallel rather than in series.
3-the heart ,brain and the upper body receive blood from the left ventricle , while the placenta and lower body receive blood from both right and left ventricles.

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24
Q

There are modifications in fetal vascularity that ensure that the best , oxygenated blood from the placenta is delivered to the fetal brain, these are:

A

1- the ductus venosus (DV) that shunts blood away from the liver.
2-the foramen ovale, shunts blood from right to left atrium. (trie to bypass the right pumping chamber - so less blood is going to the lungs.
3-the ductus arteriosus (DA) that shunts blood from the pulmonary artery to the aorta - so less blood goes to lungs and more to the body

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25
Q

what does oxygenated blood from the placenta return to the fetus through?

A

the umbilical vein

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26
Q

how does the ductus arteriosus remain patent and how do the DV and DA close at birth?

A

Prior to birth, the DA remains patent due to production of the prostaglandin E2 and prostacyclin which act as local vasodilators,
• Administration of cyclo-oxygenase inhibitor will lead to premature closure of the ductus.
• At birth ,the cessation of umbilical blood flow causes cessation of flow in the ductus venosus , a fall in the right atrium pressure and closure of the foramen ovale.
• Ventilation of the lungs opens the pulmonary circulation, with rapid fall in pulmonary vascular resistance.
• The DA closes functionally within a few days of birth

27
Q

what is persistent fetal circulation?

A

Occurs when there is delayed closure of the DA after birth because the
pulmonary vascular resistance fails to fall despite adequate breathing.
• Results in left to right shunting of blood from the aorta through the DA to the lung.
• The baby remains cyanosed and can suffer from life threatening hypoxia.
• This is mostly occur in premature infants.
• Result in congestion in the pulmonary circulation and reduction in the blood flow to the gastrointestinal tract and brain, that lead to necrotizing enterocolitis and intraventricular haemorrwhat to things can result in pulmonary hypoplasia?ahge.

28
Q

what to things can result in pulmonary hypoplasia?

A

Oligohydramnios and reduced intrathoracic space (daiphragmatic hernia) or chest wall deformities can result in pulmonary hypoplasia, which lead to progressive respiratory failure from birth.

29
Q

what kind of haemoglobin is in the fetus

A

Most haemoglobin in the fetus is the fetal haemoglobin (HbF) that has 2 gamma chains (2 alpha , 2 gamma).

30
Q

when does a switch from fetal to adult Hb occur?

A

90% of fetal Hb is HbF from 10 to 28 wk.
From 28-34 wk a switch to HbA occurs.
At term the ratio of HbF to HbA is 80:20, by 6th month of age only 1% of the Hb is HbF.

31
Q

what is the difference between adult and fetal Hb

A

The HbF had high affinity for oxygen than HbA.

32
Q

what are the TORCH infections and what are they associate with?

A

toxoplasmosis, other (syphilis, varicella-zoster, parvovirus B19), rubella, CMV and herpes infections and are often associated with congenital abnormalities and will often affect the immune system

33
Q

what is indicative of fetal infection in the new born?

A

IgA in the newborn without IgG is indicative of fetal infection.

34
Q

what is the vernix?

A

Vernix ( consisting of desequemated skin cells, cholesterol and glycogen) is covering the skin of fetus in the last wks.
Preterm infants have no vernix and thin skin, this allows a proportionately large amount of insensible water loss.

35
Q

what does the fetus develop with maturation of central nervous system?

A

With maturation of the central nervous system, the fetus develops more complex and well defined behavioral states named 1F-4F

36
Q

what are the different behavioural states?

A

state 1F is similar to quit(non REM)sleep,absence of eye and body movements.

state 2F periodic body and eye movement are present(REM sleep).

state 3F is like quiet wakefulness when there are eye but no body movements.

state 4F body in active ongoing body and eye movement.

37
Q

what two behavioural states will the fetus alternate between?

A

> 80% of time the fetus will alternate between 1F and 2Fstate

38
Q

what is the function amniotic fluid?

A
  • protect the fetus from mechanical injury.
  • permit fetal movement and preventing limbs contracture.
  • prevent adhesions between the fetus and amnion.
  • permit fetal lung development, if there is absence of the fluid especially in the 2nd trimester this will lead to pulmonary hypoplasia.
39
Q

what is the function of the placenta?

A
  1. Protection
  2. Nutrition
  3. Respiration
  4. Excretion
  5. Hormone production
40
Q

what hormones are secreted from the placenta?

A

progesterone
oestrogen
relaxin
lactogen or somatomammotropin

41
Q

what is the role of progesterone secreted from the placenta?

A

– Progesterone provides the stimulus for elevated secretion by the endometrial glands
– Progesterone inhibits myometrial contraction (progesterone block)

42
Q

what is the role of oestrogen secreted from the placenta?

A

The placental estrogens are particularly important during the last part of gestation and in most species signals the early preparturient period

43
Q

what is the role of lactogen / somatomammotropin secreted from the placenta

A

– Promoting the growth of fetus

– Stimulating the mammary gland

44
Q

what is the role of relaxin secreted from the placenta?

A

– Softening of the connective tissue in the cervix
– Promotes elasticity of pelvic ligaments
Can cause too much elasticity leading to pelvic girdle pain (PGP) or symphysis pubis dysfunction (SPD)

45
Q

what is the physiology of parturition?

A

limited space for fetus–> fetus hypothalamus –> fetus ACTH –> fetus cortisol –> placental oestrogen –> uterus PGF2 alpha –>progesterone –> induction of parturition.

46
Q

when can you first see the fetal heart beat?

A

6 weeks

47
Q

at term myometrial contractility is enhanced by a series of molecular processes involving:

A

substantial increase in oxytocin receptors in endometrium and myometrium (MGJ)

endocrine pathway involving the fetal-hypothalamic-pituitary adrenal (HPA) axis and increased output of cortisol

48
Q

Prostaglandins role in parturition?

A

It seems likely that prostaglandins play a significant part in the mechanisms of parturition both at term and preterm.

Concentrations of prostaglandins are increased in the blood, urine and amniotic fluid during labour

Prostaglandins are synthesized by uterine tissues / fetal membranes and increased rates of production occur during labour.

Administration of prostaglandins will induce labour and delivery, whereas inhibition of prostaglandin biosynthesis will delay labour and delivery

Prostaglandin concentrations increase in amniotic fluid prior to myometrial contractions, and the activity of prostaglandin increases in the chorion and amnion at labour.

49
Q

what is cervical ripening and dilatation associated with?

A

Cervical ripening and dilatation are associated with major alterations of the extracellular matrix and the cellular composition of cervical tissue

50
Q

what is cervical ripening

A

the change in the cervix in preparation for pregnancy - stretchy cervix

51
Q

what are the three stages of implantation?

A

Apposition
– Orientation of the blastocyst on the lumen of the
endometrium 

Adhesion
- Interaction between trophoblast cells and luminal epithelial cells in endometrium

Invasion
– Breakdown of connective tissue between luminal
epithelial cells and passage of embryo through to the underlying stroma.

52
Q

what are the benefits of prenatal screening?

A

parental reassurance

it may allow woman to undertake a pregnancy they may not have otherwise undertaken

53
Q

if an abnormality is detected in prenatal screening what are the options?

A 
further testing 
referral 
counselling regarding planned birth or termination 
preparation for special needs child 
altered obstetric management 
facilitated neonatal management.
54
Q

what are the risks associated with prenatal screening and diagnosis?

A

parental anxiety (false positive, true positive)
pregnancy complication s
pregnancy loss

55
Q

who is prenatal screening offered to ?

A

all pregnant woman as >90% of structural and chromosomal abnormalities are born to low risk woman.

56
Q

what are the current screening methods?

A

Integrated Prenatal Screening (IPS)
First trimester screening
Quadruple maternal serum screening

57
Q

What is increased Nuchal Translucency associated with?

A
  • Trisomies 21, 18, 13, triploidy and Turner syndrome
  • Spontaneous fetal loss
  • With normal chromosomes: cardiac defects, diaphragmatic hernia, pulmonary defects, skeletal dysplasias, congenital infection, metabolic/haem disorders, rare single gene disorders
  • Normal pregnancy – chance of a normal birth varies with size of NT measurement
58
Q

what is done for combined screening???

A

Nuchal Translucency measurement 11 to 13 weeks

T1 serum markers (PAPP-A, free beta hCG

NTD screening with MS-AFP and/or USS is still recommend in T2

59
Q

what are non-invasive methods of chromosomal evaluation?

A 
Fetal cells from maternal blood 
preimplantation embryos (PGD)
60
Q

what are invasive methods of chromosomal evaluation?

A

amniotic fluid (amniocentesis)
placenta (chorionic villus tissue)
Fetal blood

61
Q

what are the complications of amniocentesis?

A

pregnancy loss 0.3 - 1%

Leakage of amniotic fluid (better prognosis than spontaneous leakage)
Amnionitis
Vaginal bleeding
 Needle puncture of the fetus
Long term complications:
Respiratory distress??
Isoimmunization??
62
Q

what increases the risk of amniocentesis?

A

Needle larger than 18g
Multiple needle insertion
Discoloration of the fluid
High AFP, multiple late miscarriages, previous vaginal bleeding

63
Q

what is non-invasive prenatal testing (NIPT)?

A

it is new technology
it is a single blood test that uses cutting-edge technology to screen pregnant women for chromosome problems, as early as 10-weeks in pregnancy.

64
Q

who can be offered NIPT?

A

Maternal age-related risks
Positive results on maternal serum screening
Abnormal ultrasound finding(s)
Prior pregnancy with aneuploidy
Parental Robertsonian translocation involving one of the tested chromosomes

Phase 3a (41 decks)

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