Pregnancy and Screening Flashcards
What nervous system results in uterine ‘cramping’ (menstruation) and uterine contractions (labour)?
ANS (via hormes)
What nervous system results in pelvic floor muscle contraction (eg. during sneezing)?
Somatic motor
What nervous system results in feeling pain from the adnexae and uterus?
Visceral afferents
What nervous system results in feeling pain from the vagina?
Visceral afferents (pelvic parts) Somatic sensory (perineum)
What nervous system results in feeling pain from the perineum?
Somatic sensory
What do the visceral afferents supplying the superior aspect of the pelvic organs (touching the peritoneum) run alongside?
Sympathetic fibres
Where do the visceral afferents supplying the superior aspect of the pelvic organs (touching the peritoneum) enter the spinal cord?
T11-L2
Where is pain from the superior aspect of the pelvic organs (touching the peritoneum) perceived?
Suprapubic
What do the visceral afferents supplying the inferior aspect of the pelvic organs (not touching the peritoneum) run alongside?
Parasympathetic fibres
Where do the visceral afferents supplying the inferior aspect of the pelvic organs (not touching the peritoneum) enter the spinal cord?
S2, S3 and S4
Where is pain from the inferior aspect of the pelvic organs (not touching the peritoneum) perceived?
In the S2, S3 and S4 dermatome - ie. Perineum
What nerves supply structures above the levator ani (crossing from pelvis to perineum)?
Visceral afferents
PNS
S2, S3 and S4
What nerves supply structures below the levator ani (crossing from pelvis to perineum)?
Somatic sensory
Pudendal nerve
S2, S3 and S4
What organs, in the female, have visceral afferents that enter the spinal cord between T11-L2?
Uterine tubes
Uterus
Ovaries
What organs, in the female, have visceral afferents that enter the spinal cord between S2-S4?
Cervix
Superior vagina
What nerve supplies the organs in the female in the perineum:
- Inferior vagina
- Perineal muscles
- Glands
- Skin
Pudendal nerve (S2-S4)
What does spinal anaesthesia result in in terms of the ANS?
Blockade of sympathetic tone to all lower limb arterioles resulting in vasodilation: - Skin looks flushed - Warm lower limbs - Reduced sweating Hypotenstion
What does the pudendal nerve have a role in the motor control of?
External anal sphincter
External urethral sphincters
What will a pudendal nerve block anaesthetise?
Majority of the perineum
How does the pudendal nerve exit the pelvis?
Greater sciatic foramen
Where does the pudendal nerve pass in relation to the sacrospinous ligament?
Posterior
How does the pudendal nerve enter the pelvis again?
Lesser sciatic foramen
Where is the pudendal canal?
Within obturator fascia
What does the pudendal canal run alongside?
Internal pudendal artery and vein
Nerve to obturator internus
Where does the pudendal nerve crosee?
Lateral aspect of the sacrospinous ligament
What can be used as a landmark for a pudendal nerve block?
Ischial spine
When is a pudendal nerve block used?
During labour:
- Forceps delivery
- Painful vaginal delivery
When repairing tears or an episiotomy
What can happen to the pudendal during labour?
Can be stretched
What can result from pudendal nerve damage or sphincter damage during labour
Weakened pelvic floor
Faecal incontinence
What is a first degree perineal terar?
Laceration limited to fourchette and perineal skin/vaginal mucose
What is a second degree perineal tear?
Extends to perineal muscles and fascia (not anal sphincter)
What is a third degree perineal tear?
Anal sphincter torn:
- 3a = <50% of external anal sphincter thickness
- 3b = >50% of external anal sphincter
- 3c = Internal anal sphincter
When is the first booking appointment in pregnancy?
12 weeks
What is done at the booking appointment in pregnancy
FBC Antibodies and Rhesus Glucose Syphilis Rubella USS: - Confirm viability, number of foetuses and gestation
What tests are done at the 16 week visit?
Alpha-fetoprotein OR Triple test: - AFP - Oestriol - Beta-hCG
What test is done at 18 weeks?
Ultrasound
When is Anti-D given and when would it be given?
28 weeks
If mother is Rh negative
When is a biophysical score calculated?
If pregnancy lasting longer than 40 weeks AND no induction of labour
What examinations are done at follow-up visits?
BP and urinalysis Symphysis-Fundal height Lie and presentation Engagement of presenting part Foetal heart auscultation
How can the risk of Down’s Syndrome be assessed in the first trimester?
Nuchal thickness (NT):
- Measure skin thickness behind foetal neck (USS)
- Measured at 11-13+6 weeks
- Combined with bCG and PAPP-A
How can the risk of Down’s Syndrome be assessed in the second trimester?
Blood sample at 15-20 weeks
Assay of hCG and AFP
How is the personal risk of a foetus having Down’s Syndrome calculated?
Incorporate with maternal age and gestation
If there is a high risk (>1:250) of Down’s Syndrome, what is done?
Amniocentesis
What does a lower AFP level indicate?
Increased risk of Down’s Syndrome
What does a lower level of hCG indicate?
Reduced risk of Down’s Syndrome
When is amniocentesis usually carried out?
After 15 weeks
What is the miscarriage rate of amniocentesis?
1%
When is chorionic villus sampling carried out?
After 12 weeks
What is the miscarriage rate of chorionic villus sampling?
2%
What can result in a small babe?
Pre-term delivery
Small for gestational age:
- Intra-Uterine Growth Restriction (IUGR)
- Constitutionally small
Between what dates is a pre-term delivery?
24 and 36+6
What is the prevalence of pre-term delivery?
6-7%
What is the survival rate for a baby born at 24 weeks?
20-30%
What is the survival rate for a baby born at 27 weeks?
80%
What is the survival rate for a baby born at 32 weeks?
> 95%
What can cause ‘over-distension’ and result in pre-term birth?
Multiple pregnancy
Polyhydramnios
What intercurrent illness can result in pre-term birth?
Pyelonephritis/UTI
Appendicitis
Pneumonia
What else can result in pre-term birth?
Infection
Placental abruption
Cervical incompetence
Idiopathy
What is the risk of pre-term labour after 1 previous PTL?
20%
What is the risk of pre-term labour after 2 previous PTLs?
40%
What is the risk of pre-term labour in a multiple pregnancy?
50%
What parity increases the risk of pre-term labour?
=0 or >5
What BMI can increase the risk of pre-term labour?
<20
Why do 25% of pre-term infants have a planned C-section?
Severe pre-eclampsia
Kidney disease
Poor foetal development
What emergency events are responsible for 25% of pre-term infants?
Placental abruption
Infection
Eclampsia
What proportion of pre-term infants have an unknown cause?
Idiopathi
What proportion of pre-term infants are due to premature rupture of membranes?
20%
How is small for gestational age defined?
Birthweight <10th centile for gestation corrected for maternal:
- Height
- Weight
- Foetal sex
- Birth order
What vertically transmitted infections can result in IUGR?
Rubella
CMV
Toxoplasmosis
What congenital abnormalities can result in IUGR?
Renal agenesis
What chromosomal abnormality can result in IUGR?
Down’s syndrome
What uteroplacental factors, secondary to hypertension (pre-eclampsia), can result in IUGR?
Placental infarcts
Placental abruption
Placental insuffiency
What uteroplacental factors, not secondary to hypertension, can result in IUGR?
Uterine malformations
Multiple gestation
What are the two types of IUGR?
Symmetrical: - Small head and abdomen Asymmetrical: - Normal head - Small abdomen
What risks does IUGR pose during labour?
Hypoxia +/or death
What are some post-natal consequences of IUGR?
Hypoglycaemia Effects of asphyxia Hypothermmia Polycythaemia Hyperbilirubinaemia Abnormal neurodevelopment
What are the clinical features of poor growth?
Predisposing factors
Fundal height less than expected
Reduced liquor
Reduced foetal movements
How can the growth of a baby be assessed?
Head circumference in mm
Abdominal circumference in mm
What are the two traces on cardiotocography?
Upper:
- Foetal heart rate
Lower:
- Uterine contraction pattern
In cardiotocography, what does the DR (from the mnemonic DR C BRaVADO) mean?
Define risk:
- Low or
- High
In cardiotocography, what does the C (from the mnemonic DR C BRaVADO) mean?
Contractions:
- Comment on frequency
In cardiotocography, what does the BRa (from the mnemonic DR C BRaVADO) mean?
Baseline foetal heart Rate:
- Should be 120-160 bpm
In cardiotocography, what does the V (from the mnemonic DR C BRaVADO) mean?
Variability:
- HR should vary by 10-15 bpm
- Persistent reduced (<5 bpm) indicates potential asphyxia (?sedative/analgesic drugs)
In cardiotocography, what does the A (from the mnemonic DR C BRaVADO) mean?
Accelerations:
- Increased due to contractions and returning to baseline before end of contraction is normal
- > =15 bpm change for >=15 secs is healthy
In cardiotocography, what does the D (from the mnemonic DR C BRaVADO) mean?
Decelerations:
- Early decels. coincide with contractions
- Late decels. have lowest point after contraction
- Variable
What kind of decelerations are most associated with asphyxia?
Late
In cardiotocography, what does the O (from the mnemonic DR C BRaVADO) mean?
Overall; is it:
- Reassuring
- Non-reassuring
What does a biophysical profile consider?
Movement Tone Foetal breathing movements Liquor volume Heart rate
How is a biophysical profile assessed?
USS
What does each component of the biophysical profile score?
0 or 2
What scores indicate what in a biophysical profile?
8 - 10 = Satisfactory
4 - 6 = Repeat
0 - 2 = Deliver
What are the common causes of a large for dates pregnancy?
Wrong dates
Multiple pregnancy
Diabetes
Polyhydramnios
What is polyhydramnios?
Excess amniotic fluid
How can polyhydramnios arise?
Monochorionic twin pregnancy Foetal anomaly Maternal diabetes Hydrops foetalis: - Rh isoimmunisation - Infections (erythrovirus B19) Idiopathic
What are the symptoms of polyhydramnios?
Discomfort
Labour
Membrane rupture
Cord prolapse
How is polyhydramnios diagnosed?
Clinical
USS
What is the incidence of spontaneous twins?
1:80
What is the incidence of spontaneous triplets?
1:10,000
What does zygosity refer to?
Number of eggs fertilised
What does chorionicty refer to?
Placental membrane pattern
What percentage of dizygotic twins are a dichorionic/diamniotic pregnancy?
100%
What fraction of monozygotic twins are a dichorionic/diamniotic pregnancy?
~1/3
What fraction of monozygotic twins are a monochorionic/diamniotic pregnancy?
~2/3
What fraction of monozygotic twins are a monochorionic/monomniotic pregnancy?
~1%
What is the USS sign of dichorionic twins?
Twin-peaks sign (lambda sign) at 12 weeks gestation
What is the USS sign of monochorionic/diamniotic twins?
T-sign
What can help infer zygosity?
Sex of the twins (same sex = monozygotic)
How can a multiple pregnancy be diagnosed?
12 week USS Exaggerated pregnancy symptoms (eg. Hyperemesis) High alpha-fetoprotein Large for dates uterus Feeling more than two foetal poles
What are some complications of multiple pregnancy?
Congenital anomalies Pre-term labour Growth restriction Pre-eclampsia APH Twin-to-twin transfusion
How is a multiple pregnancy managed?
More frequent antenatal visits
Detailed anomaly scan at 18 weeks
Regular scans from 28 weeks for growth
Routine iron supplementation
How are triplets or more delivered?
C-section
How are twins delivered?
If one is cephalic aim for vaginal
~50% risk of C-section
Epidural anaesthesia
What is gestational diabetes
Carbohydrate intolerance resulting in hyperglycaemia of variable severity with onset or first recognition during pregnancy
What is the incidence of gestational diabetes?
2-18%
In what ethnic groups is gestational diabetes more common?
South Asian (India/Pakistan/Bangladesh)
Middle East
Black Caribbean
How does gestational diabetes arise?
- Placental hormones
- Relative insulin deficiency/resistance
- Aberrant fuel mixture:
- Glucose
- Amino acids
- Lipids - Above compounds go to placenta
- Hyperinsulinaemia
What does foetal metabolic programming in gestational diabetes result in an increased risk of?
Obesity
Insulin resistance
Diabetes
What is Freinkels hypothesis?
Abnormal maternal mixture of metabolites gain access to developing foetus modifying phenotypic gene expression in developing cells
What does foetal hyperinsulinaemia result in?
Reduced arterial oxygen Increased EPO (polycythaemia)
What is gestational diabetes screening based on?
Risk factors
Random blood glucose at:
- Booking
- 28 weeks gestation
How is gestational diabetes diagnosed?
Glucose tolerance test:
- Fasting >=5.1 mmol/L
- 2 hour glucose >=8.5 mmol/L
What are some risk factors for gestational diabetes?
FHx of diabetes Previous big baby Previous unexplained stillbirth Recurrent glycosuria Maternal obesity Previous gestational diabetes
What are the complications of pre-existing diabetes in pregnancy?
Congenital abnormalities
Miscarriage
Intrauterine death