Pathology of prematurity Flashcards
What age counts as prematurity
<37 weeks
4 common ‘causes’ of prematurity
Chorioamniotitis
Preeclampsia
Chronic villitis
MPVFD
What happens in normal pregnancy implantation to spiral arteries
Trophoblast invades the wall of the spiral arteries in myometrium
Opens up the spiral arteries so they can’t respond to changes in blood pressure
What happens in preeclampsia in terms of the spiral arteries
Failure of invasion
Spiral arteries respond to changes in blood pressure
What is seen in superficial implantation
Trophoblast cells seen in the decidua
What is the decidua
The uterine lining during pregnancy
What histological changes are seen in pre eclampsia
Muscularised arteries
Atherosis (fat) in endothelial wall
Necrosis of the wall
What are the consequences for baby if there is acute chorioamnionitis
Baby born prematurely but not necessary IUGR
What is acute chorioamniotic
Inflammation of foetal membrane
How do placentas appear in MPVFD
Placentas very hard with marbled appearance
What is the histological evidence for MPVFD
Chorionic villi are enclosed in fibrin
What can the cause be for chronic villitis
Viral invasion
Autoimmune
What is chronic villitis
Invasion of villi by lymphocytes
What may babies present with in the short term if born premature
RDS
Lung haemorrhage
Pneumonia
Apnoea of prematurity
What is the foetal response to chorioamniotis
Pneumonia
What is the long term problem from prematurity
Chronic lung disease of infancy
What causes RDS
Lack of surfactant due to biochemical immaturity
How do RDS babies present
Signs of respiratory distress (tachypnoea, expiratory grunting, recession)
What is the onset of RDS
4 hoursa
How do lungs appear in scan of RSD
Lungs appear ground glass shadowing
Spot on black- air bronchogram because air is in bronchus but not in the lung tissue
What % of babies less than 28 weeks have RDS
60
Describe classic presentation of lung morphology
Purple lungs
Liver like consistency
PDA
At what week are first blood vessels seen in lungs
17 weeks
When can babies breathe
25 weeks
What is hilum membrane disease
Manifestation of acute lung injury
Damaged vascular integrity allows fluid to leak into the air spaces
Partial reabsorption leavs proteinaceous material
How does alveolus appear in HMD
Covered in pink proteinaceous material- forms a membrane covering the alveolus therefore causing a barrier to oxygenation
When do macrophages appear to scavenge the hilum membranes
2-3 days
What are the acute complications of HMD
Air leaks due to increased pressure which can lead to pneumothorax
What is pulmonary interstitial emphysema
Air in the interstitium
Increased resp distress due to compression on parenchyma
What is a chronic complication of HMD
Bronchopulmonary dysplasia
What are the 3 stages of lung development
Canalicular stage
Saccular stage
Alveolar stage
What are the features of ‘new’ BPD
- Fewer, larger alveoli and septa
- Arrest in pulmonary alveolar and vascular development
- Abnormalities in VEGF
- Thickened muscular layer of pulmonary arterioles
How do you prevent RDS
Antenatal steroids
Avoidance of intrauterine hypoxia
Prophylactic surfactant treatment
Keep warm, avoid acidosis
When is pulmonary haemorrhage common
In babies with hypoxia
How does pulmonary haemorrhage look histologically
Lumens full of black/ red blood
What is necrotising enterocolitis
Acute bacterial invasion/ inflammation/ necrosis of bowel with gas formation in bowel wall
Risk factors of necrotising entercolitis
Prematurity
Hypoxia
Infection
Enteral feeding
What is first treatment for necrotising enterocolitis
Stop feeds
Antibiotics
Surgery if necessary
Clinical presentation of necrotising enterocolitis
Abdominal distension, tenderness, discolouration
Blood in stool
Generalised collapse
Complications of necrotising enterocolitis
Death Short gut (after surgery) Strictures and late obstruction
What pathological morphology is characteristic of nectrosing enterocolitis
Perforations of ileocecal region Deeply congested mucosa Patchy or diffuse ulceration Dilation of involved segments Dusky serosal surface
Describe the histological signs of NEC
Pneumatosis
Epithelial regrowth and granulation tissue
Fibrosis of muscularisis propria
What are the risk factors for periventricular haemorrhage
Prematurity RDS Pneumothorax Hypercapnia Acidosis Hypotension Instability and handling
What are the complications of intracerebral bleeding
Collapse and death
Loss of brain parenchymal tissue with cyst development
Blockage of CSF circulation leading to hydrocephalus
What is intraventricular haemorrhage often secondary to
Bleeding in germinal matrix
What happens with ventricles that are over distended
Blood dissects into parenchyma
What are the risk factors for IVH
Prematurity Conditions that disturb cerebral blood flow HMD with hypoxia Hypothermia Hypercapnia and acidosis BP instability
What is stage 1 of IVH
Haemorrhage in the matrix
What is stage 2 of IVH
IVH without ventricular dilation
What is stage 3 of IVH
IVH with enlarged ventricles
What is stage 4 of IVH
IVH with parenchymal haemorrhage
What is periventricular leucomalacia
Necrosis of the white matter
What is damaged by periventricular leucomalacia in term babies
The cortex
What are the features of hypoxic ischaemic encephalopathy in full term infants
Bilateral damage to cortical grey matter Shrinkage and gliosis after several weeks Cellular necrosis and apoptosis Capillary proliferation Multifocal ischaemic necrosis
What causes placental abruptions
Interuption of venous return with backward increase in venous pressure and intracranial and intrathoracic haemorrhages
