Infections and Medical Conditions in Pregnancy

Question 1

Risks of Infection in Pregnancy

Answer 1

Maternal illness can be worse, maternal complications e.g. pre-eclampsia in HIV, preterm labour, vertical transmission, miscarriage, teratogenicity, damage to developing organs e.g. neurological damage.

Question 2

CMV

Answer 2

• A herpes virus transmitted by close contact.
• Vertical transmission occurs in 40%.
• 10% of affected neonates are symptomatic - IUGR, pneumonia, thrombocytopenia and hearing, visual or neurological impairment.
• Mx - ultrasound surveillance and fetal blood sampling at 32 weeks for platelet levels helps to determine the risk of sequalae developing.

Question 3

Herpes Simplex

Answer 3

• DNA virus responsible for most genital herpes.
• Vertical transmission can occur at delivery especially if vesicles are present. More likely if recent primary maternal infection as no immunity is passed to the fetus.
• Mx - a C section is recommended for those delivering within 6 weeks of primary infection and those with genital vesicles.

Question 4

Rubella

Answer 4

• Very rare in the UK due to immunisation.
• Infection in early pregnancy causes deafness, cardiac disease, eye problems and mental retardation. The probability and severity of effects decreases with advancing gestation.
• Mx - TOP if non-immune women develop Rubella before 16 weeks gestation. Screening is routine at booking to identify those in need of vaccination after pregnancy.

Question 5

Toxoplasmosis

Answer 5

• Caused by protozoan parasite toxoplasma gondii found in cat faeces, soil or infected meats.
• Effects - infection more common as pregnancy progresses, causes mental retardatioin, convulsions, seizures and visual impairment.
• Diagnosis - IgM testing following exposure.
• Mx - health education reduces infection, spiramycin is started as soon as diagnosis made.

Question 6

Herpes Zoster

Answer 6

• Rare (0.05%) but can cause severe maternal illness. Teratogenicity only occurs in 1-2%.
• Most common if delivery occurs within 2 days before or 5 days after maternal symptoms.
• Mx - immunoglobulin is used to prevent and aciclovir used to treat the infection.

Question 7

Parvovirus B19

Answer 7

• Causes arthralgia and slapped cheeks in women.
• Effects in fetus - causes anaemia and thrombocytopenia and fetal death in 9%.
• Mx - infected mothers are scanned to look for anaemia and where hydrops is detected in utero transfusion can be administered.

Question 8

Group B streptococcus

Answer 8

• Carried by 25% of women - asymptomatic.
• Effects - fetus is infected following ROM and is more likely during preterm or prolonged labour. Group B strep sepsis occurs in 1 in 500 neonates.
• Mx - known GBS carriers and those at high risk are given IV penicillin throughout labour. Screening is with swabs at 34-36 weeks.

Question 9

Hepatitis B

Answer 9

• DNA virus transmitted by blood products or sex.
• Infection affects 1% of pregnant women in West.
• Effects - vertical transmission occurs at delivery and 90% of neonates become chronic carriers.
• Mx - neonatal immunisation reduces transmission by 90% and maternal screening is rountine in UK.

Question 10

HIV

Answer 10

• Retrovirus that leads to AIDS.
• HIV affects 1% of pregnant women in the UK.
• Effects - increased risk of pre-eclampsia, stillbirth, IUGR and prematurity. Main risk is vertical transmission - commonly occurs beyond 36 weeks, during delivery or breast feeding.
• Mx - infected women should have regular CD4 and viral load tests, prophylaxis against PCP given and HARRT to mother and neonate for 6 weeks, C section and bottle feeding.

Question 11

Syphilis

Answer 11

• STI caused by treponema pallidum.
• Active disease in pregnancy can cause miscarriage, congenital disease or stillbirth.
• Benzylpenicillin can be used safely and will prevent but will not reverse any fetal damage.

Question 12

Mycobacterium Tuberculosis

Answer 12

• Incidence in the UK is increasing.
• BCG vaccine is live and is contraindicated.
• TB infection causes prematurity, IUGR and maternal mortality in the developing world.
• Treatment is with the normal 1st line meds.

Question 13

Listeriosis

Answer 13

• Occurs following ingestion of pate, soft cheeses and prepacked meals - causes non-specific febrile illness in the mother.
• If bacteraemia occurs (0.1%) potentially fatal infection of the fetus may occur.

Question 14

Chlamydia and Gonorrhoea

Answer 14

• During pregnancy Chlamydia occurs in 5% and Gonorrhoea occurs in 0.1%,
• Cause preterm labour and neonatal conjunctivitis.
• Mx - azithromycin or erythromycin for Chlamydia and cephalosporins for Gonorrhoea.

Question 15

Bacterial Vaginosis

Answer 15

• Overgrowth of normal vaginal lactobilli.
• In some cases causes offensive discharge.
• Effects - preterm labour and miscarriage.
• Mx - Clindamycin.

Question 16

Blood Pressure in Pregnancy

Answer 16

• Falls to lowest by 30/15mmHg in second trimester due to decreased vascular resistance.
• Pregnancy induced HTN - when BP rises >140/90 due to transient HTN or pre-eclampsia.
• Pre-existing HTN - when BP is >104/90 before 20 weeks gestation. Increased risk of pre-eclampsia.

Question 17

Pre-eclampsia Definition

Answer 17

• Hypertension (>140/90mmHg) and Proteinuria (>0.3g in 24 hours) in 2nd half of pregnancy. It is placental in origin and cured by delivery.
• Affects 6% of nulliparous women and is less common in multiparous women.

Question 18

Pre-eclampsia - Risk Factors

Answer 18

Nulliparity, personal or family hx, older maternal age, chronic hypertension, diabetes, twin pregnancy, AI disease, renal disease or obesity.

Question 19

Pre-eclampsia - Clinical Features

Answer 19

• Hx - usually asymptomatic but headache, visual disturbance, N+V or epigastric pain can occur.
• Examination - oedema and tender epigastrum.

Question 20

Pre-eclampsia - Maternal Complications

Answer 20

• Eclampsia - seizures due to cerebrovascular spasm occurs 0.05%. Mx - magnesium sulphate.
• Cerebrovascular haemorrhage - results from failure of blood flow auto-regulation.
• HELLP syndrome - haemolysis, elevated liver enzymes and low platelet count.
• Renal failure - can require haemodialysis.
• Pulmonary oedema - due to fluid overload.

Question 21

Pre-eclampsia - Fetal Complications

Answer 21

• If occuring between 36 weeks the principle problem is IUGR and in some cases iatrogenic pre-term delivery is required.
• Also increased risk of placental abruption.

Question 22

Pre-eclampsia - Investigations

Answer 22

• Dx - 24 hour protein or protein/creatinine ratio.
• To monitor mother - blood tests for Hb, platelets and LFTs to detect impending HELLP.
• To monitor fetus - USS for growth and CTG.
• Screening - all pregnant women have regular BP monitoring and urinalysis checks.

Question 23

Pre-eclampsia - Mx

Answer 23

• Antihypertensives e.g. Nifidipine or Labetolol.
• IV magnesium sulphate to prevent eclampsia.
• Steroids - if gestation is <34 weeks.
• Delivery can be indicated if gestation >36 wks.
• Post-natal care - it can take up to 24 hours for severe disease to resolve. LFTs, platelet levels and fluid monitoring should continue and BP should be maintained <140/90mmHg.

Question 24

Gestational Diabetes

Answer 24

• Glucose intolerance during pregnancy that resolves following delivery. Diagnosis is by 75g glucose load leading to levels >9 mmol/L.
• Affects 2% of pregnant women
• In addition pre-existing diabetes affects 0.1-0.3% of pregnancy women and they will require increased levels of insulin during pregnancy.

Question 25

Gestational Diabetes - Risk Factors

Answer 25

Hx of gestational DM, FH of diabetes, a fetus >4kg, previous stillbirth, weight >100kg or PCOS.

Question 26

Gestational DM - Maternal Complications

Answer 26

• Increased insulin requirements and aiming for optimum control can result in hypoglycaemia.
• Increased risk of infection e.g UTI, endometrial or wound infections and pre-eclampsia.
• Large fetus results in increased likelihood of instrumental or C section delivery.
• Retinopathy is often worsened by pregnancy.

Question 27

Gestational DM - Fetal Complications

Answer 27

• Congenital abnormalities (e.g. neural tube or cardiac defects) are 3-4 times more common.
• Preterm labour occurs in 10%.
• Fetal lung maturity is decreased.
• Large fetus can lead to shoulder dystocia, birth trauma, fetal compromise or distress.

Question 28

Gestational DM - Management

Answer 28

• High fibre, low carb diet and monitor glucose.
• If preprandial glucose levels are consistently >6mmol/L start insulin therapy - usually long acting at night and 3 x short acting doses.
• Aim to maintain BMs between 4-6 mmol/L.

Question 29

Gestational DM - The Delivery

Answer 29

• Normally arranged for 39 weeks if glucose control has been good. If estimated fetal weight exceeds 4kg elective C section is indicated.
• After delivery the neonate commonly develops hypoglycaemia as insulin levels are high. Respiratory distress syndrome is more common.

Question 30

Gestational DM - The Puerperium

Answer 30

• In pre-existing diabetics insulin doses should quickly be returned to pre-pregnancy levels.
• In gestational diabetics insulin should be stopped.
• A glucose tolerance test is performed after 3 months -50% will develop T2DM within 10 yrs.

Question 31

The Rhesus System

Answer 31

• Consists of 3 gene pairs - Cc, Dd and Ee.
• Individuals who inherit DD or Dd are said to be Rhesus D positive.
• Individuals with other alleles (even dd) recognise the D allele as foreign if exposed.

Question 32

Sensitisation

Answer 32

Delivery, placental abruption and amniocentesis encourage fetal RBCs to enter maternal circulation. If the fetus is D positive the mother will mount an immune response (sensitisation) and produce anti-D antibodies. If the mother is exposed to anti-D in the future a large immune response will occur.

Question 33

Rhesus Haemolytic Disease

Answer 33

• Anti-D antibodies produced by the mother can cross the placenta and bind to fetal RBCs.
• This causes them to be destroyed by the reticulo-endothelial system = haemolytic anaemia.

Question 34

Anti-D

Answer 34

• Exogenous anti-D mops up fetal red blood cells preventing the mothers immune response.
• Anti-D is given to all rhesus negative women at 28 and 36 weeks and after a potentially sensitising event e.g. bleeding and after delivery if the fetus is found to be rhesus D positive.