Prematurity Flashcards
(35 cards)
What is prematurity?
Preterm birth is defined as delivery before 37 completed week’s gestation.
Briefly describe the WHO Classification of prematurity
Preterm birth is defined as delivery before 37 completed week’s gestation. The World Health Organisation defines the different stages of preterm delivery as follows:
- Extreme preterm: before 28 weeks
- Very preterm: 28 to 32 weeks
- Moderate to late preterm: 32 to 37 weeks
What is the most common cause of death in neonates?
Prematurity also remains the number one cause of neonatal death globally, and the number one cause of death in under five year olds.
What can cause preterm delivery?
There are many overlapping causes that can be attributed to premature delivery:
- Around 25% of preterm deliveries are planned due to life threatening conditions affecting either the mother or foetus (pre-eclampsia, renal disease, severe growth restriction etc)
- Approximately 30-40% are due to premature or prelabour rupture of membranes
- Around 25% are due to an emergency event such as placental abruption, eclampsia or severe infection
- Roughly 40% of the cases have no identifiable cause
What are the risk factors for premature delivery?
There are several identified risk factors for premature delivery including (but not limited to):
- Previous preterm delivery
- Multiple pregnancy
- Smoking and illicit drug use in pregnancy
- Being under or overweight in pregnancy
- Early Pregnancy (within 6 months of previous pregnancy)
- Problems involving cervix, uterus or placenta, including infection
- Certain chronic conditions such as diabetes and hypertension
- Physical injury/trauma
Briefly describe the Dubowitz/Ballard Examination
The Dubowitz/Ballard Examination for gestational age is an example of an assessment tool which can be used to estimate neonatal maturity. It uses a combination of external physical and neuromuscular features to determine a score. This is then used to give an estimate of a 2 week window of gestation.
Following stabilisation and transfer to the neonatal unit, there are several baseline investigations that most premature infants might require during their stay, tailored to each individual patient.
What laboratory investigations should be ordered?
- Blood gas
- Urea, creatinine and electrolytes
- Blood culture
- CRP
- Blood group and Direct Coombs Test/ Direct Antiglobulin Test (DCT/DAT)
Why investigate using blood gas?
This is commonly used to help assess the respiratory and metabolic state of the infant and increase or decrease support as needed.
Why investigate using FBC?
Preterm infants are at high risk of infection, thrombocytopenia and anaemia, therefore requiring close observation of their WCC, platelets and RBC.
Why investigate urea, creatinine and electrolytes?
Many units do not perform renal function tests at initial admission, as this is more likely to be reflective of the mother’s electrolyte balance roughly for the first 24 hours of life. However, electrolyte and fluid balance is paramount for neonatal care and close monitoring of renal function helps to tailor management accordingly
Why investigate using blood culture?
Infection can be a risk factor in preterm delivery therefore frequently infants are screened with a blood culture on admission and commenced on intravenous antibiotics. If the baby becomes unwell, they would likely be re-screened as per local protocols.
Why investigate CRP?
In view of the association between prematurity and infection, CRP is checked on admission, and monitored during the child’s stay on the neonatal unit. There is a wide range of protocols for this. NICE guidelines also exist suggesting level thresholds for investigations such as LP. Also, preterm infants are at risk of developing infections for many reasons including immature immune systems, multiple invasive procedures and in dwelling central lines to name a few.
Why investigate blood group and Direct Coombs Test/ Direct Antiglobulin Test (DCT/DAT)?
Many premature infants require a blood transfusion during their stay in the neonatal unit. Almost all (approximately 80%) will develop jaundice in the first week of life. These tests should be checked with admission bloods.
Following stabilisation and transfer to the neonatal unit, there are several baseline investigations that most premature infants might require during their stay, tailored to each individual patient.
What Imaging or invasive tests should be ordered?
- Chest x-ray
- Abdominal x-ray
- Cranial ultrasound scan (CrUSS)
Why investigate using chest x-ray?
Almost all infants born before 32 weeks will need some form of respiratory support. A chest x-ray is needed if an infant shows signs of respiratory distress (tachypnoea, oxygen dependency, increased work of breathing). If a baby is intubated and ventilated, a chest x-ray is required to assess the position of the endotracheal tube.
Why investigate using abdominal x-ray?
Preterm infants are often in need of parenteral nutrition and several intravenous infusions in the first few days and weeks of life. Therefore, central venous and arterial access are usually inserted through the umbilical vein and arteries. An abdominal and chest x-ray are used to assess the position of the umbilical venous and umbilical arterial catheters after insertion. Preterm infants are also at risk of developing necrotising enterocolitis. If this is suspected, an AP and lateral film may be needed to assess for signs of perforation (free air within the abdominal cavity, football sign, pneumatosis intestinalis, immobile bowel loops in repeat x-rays).
Why investigate using cranial ultrasound scan (CrUSS)?
The brains of preterm and very low birth weight infants are at increased risk of neurological insults from haemorrhagic, ischaemic and infective factors. CrUSS is used routinely in infants born at less than 32 weeks to assess for any signs of intraventricular haemorrhage or ischaemic periventricular white matter damage. It has the benefit of being a simple bedside tool which, when used repeatedly and in conjunction with other factors, can help identify those infants most at risk of adverse neurodevelopmental outcomes. This needs to be reviewed with an MRI at a later stage.
In women with a history of preterm birth or an ultrasound demonstrating a cervical length of 25mm or less before 24 weeks gestation…what are the 2 treatment options for delaying birth?
In women with a history of preterm birth or an ultrasound demonstrating a cervical length of 25mm or less before 24 weeks gestation there are two options of trying to delay birth:
- Prophylactic vaginal progesterone: putting a progesterone suppository in the vagina to discourage labour
- Prophylactic cervical cerclage: putting a suture in the cervix to hold it closed
Where preterm labour is suspected or confirmed there are several options for improving the outcomes… what are these options?
Tocolysis with nifedipine: nifedipine is a calcium channel blocker that suppresses labour.
Maternal corticosteroids: can be offered before 35 weeks gestation to reduce neonatal morbidity and mortality.
IV Magnesium sulphate: can be offered before 34 weeks gestation and helps protect the baby’s brain.
Delayed cord clamping or cord milking: can increase the circulating blood volume and haemoglobin in the baby.
Briefly describe the current guidelines for resuscitation in a preterm infant
There is much debate surrounding resuscitation of extreme preterm infants. Current guidelines suggest that if a woman presents in labour at a gestation of:
- Less than 23 weeks then resuscitation should not be performed
- Between 23 and 23+6 weeks then there may be a decision not to start resuscitation in the best interests of the baby, especially if parents have expressed this wish.
- Between 24 and 24+6 weeks, resuscitation should be commenced unless the baby is thought to be severely compromised. Response to initial measures should be considered before the decision is made to commence intensive care.
- After 25 weeks, it is appropriate to resuscitate and start intensive care.
What are the early complications in the preterm infant?
- Respiratory distress syndrome
- Hypothermia
- Hypoglycaemia
- Poor feeding
- Apnoea and bradycardia
- Neonatal jaundice
- Intraventricular haemorrhage
- Retinopathy of prematurity
- Necrotising enterocolitis
- Immature immune system and infection
What are the long complications in the preterm infant?
- Chronic lung disease of prematurity (CLDP)
- Learning and behavioural difficulties
- Susceptibility to infections, particularly respiratory tract infections
- Hearing and visual impairment
- Cerebral palsy
Give examples of respiratory complications in the preterm infant and how these can be managed
Complications:
- Respiratory distress syndrome
- Surfactant deficient lung disease
- Chronic lung disease/ Bronchopulmonary dysplasia
- Recurrent apnoea
Mangement:
- Exogenous surfactant administration
- Endotracheal intubation and mechanical ventilation
- Bilevel positive airway pressure
- Continuous positive airway pressure
- High flow oxygen
- Nasal cannula low flow oxygen
- Ambient incubator oxygen
- Caffeine administration
Give examples of cardiovascular complications in the preterm infant and how these can be managed
Complications:
- Hypotension
- Perfusion abnormalities
- PDA
Management:
- Inotrope infusions (including dopamine, dobutamine, adrenaline, and noradrenaline)
- Fluid management
- Ibuprofen or indomethacin administration
- Ligation of PDA (rare)
