Obstetrics Flashcards
Antenatal screening - Conditions which all pregnant women should be offered screening
Anaemia Bacteriuria Blood group, Rhesus status and anti-red cell antibodies Down's syndrome Fetal anomalies Hepatitis B HIV Neural tube defects Risk factors for pre-eclampsia Syphilis
Antenatal screening - conditions should be offered depending on the history?
Placenta praevia Psychiatric illness Sickle cell disease Tay-Sachs disease Thalassaemia
Amniotic fluid embolism- definition, epidemiology, aetiology, clinical presentation, diagnosis, mx
Definition:
This is when fetal cells/ amniotic fluid enters the mothers bloodstream and stimulates a reaction which results in the signs and symptoms described below.
Epidemiology:
Rare complication of pregnancy associated with a high mortality rate.Incidence 2/ 100,000 in the U.K .
Aetiology:
- Many risk factors have been associated with amniotic fluid embolism but a clear cause has not been proven. A consistent link has been demonstrated with maternal AGE and INDUCTION of labour. It is widely accepted that maternal circulation must be exposed to fetal cells/ amniotic fluid in order for an amniotic fluid embolism to occur. However the precise underlying pathology of this process which leads to the embolism is not well understood, though suggestions have been made about an immune mediated process.
Clinical presentation:
- The majority of cases occur in labour , though they can also occur during caesarean section and after delivery in the immediate postpartum.
- Symptoms include: chills, shivering, sweating, anxiety and coughing.
- Signs include: cyanosis, hypotension, bronchospasms, tachycardia. arrhythmia and myocardial infarction.
Diagnosis:
- Clinical diagnosis of exclusion, as there are not definitive diagnostic tests.
Management:
- Critical care unit by a multidisciplinary team, management is predominantly supportive
A history of sudden collapse occurring soon after a rupture of membranes is suggestive of …
amniotic fluid embolism
Pre-eclampsia- what is it? Predisposes to? High and moderate risk? Features of severe pre-exlampsia?
Pre-eclampsia is a condition seen after 20 weeks gestation characterised by pregnancy-induced hypertension in association with proteinuria (> 0.3g / 24 hours). Oedema used to be third element of the classic triad but is now often not included in the definition as it is not specific
Pre-eclampsia is important as it predisposes to the following problems
- fetal: prematurity, intrauterine growth retardation
- eclampsia
- haemorrhage: placental abruption, intra-abdominal, intra-cerebral
- cardiac failure
- multi-organ failure
NICE divide risk factors into high and moderate risk:
High risk factors:
- hypertensive disease in a previous pregnancy
- chronic kidney disease
- autoimmune disease, such as systemic lupus erythematosus or antiphospholipid syndrome
- type 1 or type 2 diabetes
- chronic hypertension
Moderate risk factors: - first pregnancy - age 40 years or older - pregnancy interval of more than 10 years - body mass index (BMI) of 35 kg/m² or more at first visit - family history of pre-eclampsia - multiple pregnancy (SMOKING NOT A RISK FACTOR)
Features of severe pre-eclampsia:
- hypertension: typically > 170/110 mmHg and proteinuria as above
- proteinuria: dipstick ++/+++
- headache
- visual disturbance
- papilloedema
- RUQ/epigastric pain
- hyperreflexia
- platelet count < 100 * 106/l, abnormal liver enzymes or HELLP syndrome
Perineal tears- Classification
The RCOG has produced guidelines suggesting the following classification of perineal tears:
- first degree: superficial damage with no muscle involvement
- second degree: injury to the perineal muscle, but not involving the anal sphincter
- third degree: injury to perineum involving the anal sphincter complex (external anal sphincter, EAS and internal anal sphincter, IAS):
- 3a: less than 50% of EAS thickness torn
- 3b: more than 50% of EAS thickness torn
- 3c: IAS torn
- fourth degree: injury to perineum involving the anal sphincter complex (EAS and
IAS) and rectal mucosa
Perineal tears - risk factors
Risk factors for perineal tears
- primigravida
- large babies
- precipitant labour
- shoulder dystocia
- forceps delivery
What is Bishop score used for? What does it consist of? Interpretation?
The Bishop score is used to help assess the whether induction of labour will be required.
It has the following components: Cervical position Cervical consistency Cervical effacement Cervical dilation Fetal station
Interpretation:
- a score of < 5 indicates that labour is unlikely to start without induction
- a score of > 9 indicates that labour will most likely commence spontaneously
Magnesium treatment should be started in women with…
How long for?
high risk severe pre-eclampsia, or those with eclampsia
It should be continued for 24 hours after delivery or after last seizure, which ever is later
Eclampsia- what is it? Treatment?
Eclampsia may be defined as the development of seizures in association pre-eclampsia. To recap, pre-eclampsia is defined as:
- condition seen after 20 weeks gestation
- pregnancy-induced hypertension
- proteinuria
Magnesium sulphate is used to both prevent seizures in patients with severe pre-eclampsia and treat seizures once they develop. Guidelines on its use suggest the following:
- should be given once a decision to deliver has been made
in eclampsia an IV bolus of 4g over 5-10 minutes should be given followed by an infusion of 1g / hour
- urine output, reflexes, respiratory rate and oxygen saturations should be monitored during treatment
–respiratory depression can occur: calcium gluconate is the first-line treatment for magnesium sulphate induced respiratory depression
- treatment should continue for 24 hours after last seizure or delivery (around 40% of seizures occur post-partum)
Other important aspects of treating severe pre-eclampsia/eclampsia include fluid restriction to avoid the potentially serious consequences of fluid overload
Group B Streptococcus- risk factors , mx?
Group B Streptococcus (GBS) is the most common cause of early-onset severe infection in the neonatal period. It is thought around 20-40% of mothers have GBS present in their bowel flora and may therefore be thought of as ‘carriers’ of GBS. Infants may be exposed to maternal GBS during labour and subsequently develop potentially serious infections.
Risk factors for Group B Streptococcus (GBS) infection:
- prematurity
- prolonged rupture of the membranes
- previous sibling GBS infection
- maternal pyrexia e.g. secondary to chorioamnionitis
Management
The main points are as follows:
- universal screening for GBS should NOT be offered to all women
- the guidelines also state a maternal request is not an indication for screening
- women who’ve had GBS detected in a previous pregnancy should be informed that their risk of maternal GBS carriage in this pregnancy is 50%. They should be offered maternal intravenous ANTIBIOTIC PROPHYLAXIS (IAP) OR testing in late pregnancy and then antibiotics if still positive
- if women are to have swabs for GBS this should be offered at 35-37 weeks or 3-5 weeks prior to the anticipated delivery date
- maternal intravenous antibiotic prophylaxis should be offered to women with a previous baby with early- or late-onset GBS disease
- maternal intravenous antibiotic prophylaxis should be offered to women in preterm labour regardless of their GBS status
- women with a pyrexia during labour (>38ºC) should also be given intravenous antibiotics
benzylpenicillin is the antibiotic of choice for GBS prophylaxis
Normal laboratory findings in pregnancy?
Reduced urea, reduced creatinine, increased urinary protein loss
(Physiological changes to the circulation results in increased perfusion to the kidneys in pregnancy.)
Pregnancy: physiological changes- what systems are affected
Cardiovascular system Respiratory system Blood Urinary system Biochemical changes Liver Uterus
Pregnancy: physiological changes- cardiovascular system?
- SV up 30%, HR up 15% & cardiac output up 40%
- systolic BP is unaltered
- diastolic BP is reduced in the 1st and 2nd trimester, returning to non-pregnant levels by term
- enlarged uterus may interfere with venous return which can lead to ankle oedema, supine hypotension and varicose veins
Pregnancy: physiological changes- Respiratory system?
- Pulmonary ventilation up by 40%, tidal volume from 500 - 700ml (due to effect of progesterone on respiratory centre)
- Oxygen requirements increase by only 20%, therefore over breathing leads to a fall in pCO2 - this can give rise to a sense of dyspnoea that may be accentuated by elevation of the diaphragm
- BMR up 15% - this may be due to increased thyroxine and adrenocortical hormones - women may hence find warm conditions uncomfortable
Pregnancy: physiological changes- Blood?
- Maternal blood volume up 30%, mostly in 2nd half - red cells up 20% but plasma up 50% Hb falls
- Low grade increase in coagulant activity
- rise in fibrinogen and Factors VII, VIII, X
- fibrinolytic activity is decreased returns to normal after delivery (placental suppression?)
- prepares the mother for placental delivery
- leads to increased risk of thromboembolism
- Platelet count falls
- WCC & ESR rise
Pregnancy: physiological changes- Urinary system?
- blood flow increase by 30%
- GFR increases by 30-60%
- Salt and water reabsorption is increased by elevated sex steroid levels
- Urinary protein losses increase
Pregnancy: physiological changes- Biochemical changes
- Calcium requirements increase during pregnancy
- especially during 3rd trimester + continues into lactation
- calcium is transported actively across the placenta
- serum levels of calcium and phosphate actually fall (with fall in protein)
- ionised levels of calcium remain stable
- Gut absorption of calcium increases substantially - due to increased 1,25 dihydroxy vitamin D
Pregnancy: physiological changes-Liver?
Unlike renal and uterine blood flow, hepatic blood flow doesn’t change
- ALP raised 50% (due to extra production from placenta)
- Albumin levels fall
Pregnancy: physiological changes-Uterus?
100g → 1100g
- hyperplasia → hypertrophy later
- increase in cervical ectropion & discharge
- Braxton-Hicks: non-painful ‘practice contractions’ late in pregnancy (>30 wks)
- retroversion may lead to retention (12-16 wks), usually self corrects
Anomaly scan is when?
18 - 20+6 weeks
Down’s syndrome screening where nuchal scanning is available - when ?
11 - 13+6 weeks
Booking visit - is when?
8 - 12 weeks
Rubella and pregnancy- risks, features, diagnosis, mx
Rubella, also known as German measles, is a viral infection caused by the togavirus. Following the introduction of the MMR vaccine it is now rare. If contracted during pregnancy there is a risk of congenital rubella syndrome. Remember that the incubation period is 14-21 days and individuals are infectious from 7 days before symptoms appear to 4 days after the onset of the rash.
Risk
in first 8-10 weeks risk of damage to fetus is as high as 90%
damage is rare after 16 weeks
Features of congenital rubella syndrome sensorineural deafness congenital cataracts congenital heart disease (e.g. patent ductus arteriosus) growth retardation hepatosplenomegaly purpuric skin lesions 'salt and pepper' chorioretinitis microphthalmia cerebral palsy
Diagnosis
suspected cases should be discussed immediately with the local Health Protection Unit (HPU) as type/timing of investigations may vary
IgM antibodies are raised in women recently exposed to the virus
it should be noted that it is very difficult to distinguish rubella from parvovirus B19 clinically. It is therefore important to also check parvovirus B19 serology as there is a 30% risk of transplacental infection, with a 5-10% risk of fetal loss
Management
suspected cases of rubella in pregnancy should be discussed with the local Health Protection Unit
since 2016, rubella immunity is no longer routinely checked at the booking visit
if a woman is however tested at any point and no immunity is demonstrated they should be advised to keep away from people who might have rubella
non-immune mothers should be offered the MMR vaccination in the post-natal period
MMR vaccines should not be administered to women known to be pregnant or attempting to become pregnant