Prematurity (10) Flashcards
What defines prematurity?
Gestational age LESS than 37 weeks
Gestational age less than 37 weeks is defined as?
Prematurity
4 risks for prematurity?
- PPROM
- Intrauterine infections
- Uterine, cervical, placental abnormalities
- Multiple gestations
PPROM
Preterm Premature Rupture of Membranes before 37 weeks
Rupture of Membrane means?
Amniotic membrane spontaneously ruptures
What increases risk for PPROM?
History of PPROM, bleeding during pregnancy and maternal smoking
Chorioamnionitis
Inflammation of the placental membranes
Inflammation of the placental membranes
Chorioamnionitis
Funisitis
Inflammation of fetal umbilical cord
Inflammation of fetal umbilical cord
Funisitis
What histologic correlates are seen with intrauterine infections?
Chorioamnionitis
Funisitis
With prematurity, what are some things that could result?
Neonatal Respiratory Distress Syndrome
Necrotizing Enterocolitis
Sepsis
Intraventricular hemorrhage
Although preterm infants have low birth weight, is it usually proportional to their gestational age?
Yes
Infants who weigh less than 2500g at term are considered?
Undergrown (SGA)
Infants who weigh less than 2500g at term are given the designation?
SGA
Small for Gestational Age
What do SGA infants suffer from?
FGR
Fetal Growth Restriction
What 3 factors can cause FGR and thus SGA?
Maternal
Fetal
Placental
Most common maternal abnormality associated with FGR?
Decreased placental blood flow
What are examples of maternal conditions that can cause decreased placental blood flow and thus FGR?
Pre-eclampsia and Chronic Hypertension
Most common fetal abnormalities associated with FGR?
Congenital anomalies
Infections
If FGR is due to a fetal factor, how will the growth restriction present?
Symmetric
If FGR is due to a placental factor, how will the growth restriction present?
Asymmetrical that spares the brain
Another name for Neonatal Respiratory Distress Syndrome
Hyaline Membrane Disease
Cause of RDS?
Pulmonary immaturity and surfactant deficiency
What stimuli promote surfactant DEFICIENCY?
Insulin and C section
What stimuli promote surfactant synthesis?
Cortisol and Labor
What cells produce surfactant and when is production amplified?
Type 2 alveolar cells after 35 weeks gestation
Decreased surfactant directly causes?
Increased surface tension in the alveoli
Increased surface tension in the alveoli causes?
Atelectasis - collapse of lung tissue due to loss of alveolar spaces
Decreased surfactant causes increased tension and atelectasis. What does that cause?
Hypoventilation and uneven perfusion
Main result of decreased surfactant, increased tension and atelectasis?
HYPOXEMIA AND CO2 RETENTION
Describe the order of events that ensue to get Hypoxemia and CO2 retention with RDS
- Decreased surfactant production
- Increased surface tension in the alveoli
- Atelectasis (collapse of alveoli)
- Hypoventilation and uneven perfusion
= HYPOXEMIA and CO2 RETENTION
Once Hypoxemia and CO2 retention have occurred with RDS, then what ensues?
Acidosis and pulmonary vasoconstriction that damages endothelial and epithelial cells
Acidosis and pulmonary vasoconstriction that damages the pulmonary cells then causes what?
Plasma leaks into the alveoli
If plasma leaks into the alveoli, what is formed?
Fibrin + necrotic cells
Fibrin + necrotic cells =
Hyaline membrane disease
Once Hypoxemia and CO2 Retention occur, describe how hyaline membrane disease is established
- Hypoxemia and CO2 retention
- Acidosis and pulmonary vasoconstriction damages the endothelial and epithelial cells
- Plasma is able to leak into the alveoli
= Fibrin + necrotic cells in the lungs
Once RDS is already taking place, what in the cycle only causes further surfactant deficiency?
Hypoxemia and CO2 Retention
What do the lungs look like with RDS?
Solid, airless, reddish - purple color and they sink in water
Hyaline membrane disease has what characteristic features?
Necrotic tissue inside eosinophilic hyaline membranes made of fibrin
Symptoms of RDS?
Trouble breathing and cyanosis right after birth
How can you tell how much surfactant is present in a child’s lungs?
Measure the phospholipids in the amniotic fluid
An L/S ratio of > ___ indicates mature lungs
2
What are the 2 options to prevent RDS and preterm birth?
- Delay preterm labor
2. Give antenatal steroids to increase maturation of lungs
2 complications that can arise after RDS?
- Retrolental Fibroplasia
2. Bronchopulmonary Dysplasia
Retrolental Fibroplasia
Occurs after RDS
- Increased VEGF –> induces angiogenesis and blood vessel formation that causes lesions on the retina
What is increased with Retrolental Fibroplasia?
VEGF
What cytokines cause Bronchopulmonary Dysplasia?
TNF
IL-6
IL-8
IL-1beta
With Bronchopulmonary Dysplasia, what do the cytokine cause to happen?
Arrest alveolar development = large simplified alveoli
What 3 things are infants who survive RDS at risk for?
- Patent ductus arteriosus
- Intraventricular hemorrhage
- NEC
NEC
Necrotizing Enterocolitis
What are most causes of Necrotizing Enterocolitis associated with?
Introduction of bacteria possible through enteral feeding
What molecule is always increased with NEC?
PAF
platelet activating factor
Describe the process of NEC
- Bacteria entry
- Increased PAF increases permeability and enterocyte apoptosis
- Inflammation with bacteria now inside colon
- Necrosis
- Further bacterial entry
What does increased PAF do?
Increases permeability and enterocyte apoptosis
What portions of the intestines are commonly impacted by NEC?
Terminal ileum, cecum, right colon
What does a segment of intestine look like with NEC?
Distended, gangrenous and with perforations
If perforations are present in the intestine with NEC what can that cause?
Peritonitis
What is always seen on x-ray with NEC?
GAS in the intestines!!!
pneumatosis Intestinalis
Symptoms of NEC?
Bloody stool
Abdominal distention
Circulatory collapse
PNEUMATOSIS INTESTINALIS (GAS) on x-ray!!!!
