Diseases of the Fetus and Newborn Flashcards
Oligohydramnios
Insufficient amniotic fluid.
Many possile etiologies.
Causes compression of the fetus and leads to pulmonary hypoplasia, which often kills the newborn quickly after birth despite mechanical ventilation.
These infants will also have a “flat” face and club feet.
The Potter Sequence
The inciting event in the Potter Sequence is often renal agenesis, but can be anything that causes decreased fetal urine output.
Respiratory Distress Syndrome of the Newborn
Surfactant deficiency
Causes severe respiratory distress after birth. Most commonly associated with prematurity. Can be prevented by giving a large dose of glucocorticoids prior to deliver (to stimulate surfactant production)
Congenital unilateral diaphragmatic hernia
Will cause severe respiratory distress and unilaterally decreased breath sounds. Bowel sounds may be heard in the affected lung area.
Neonatal goiter
- If syndrome of hyperthyroidism, fetal Grave’s is the likely etiology
- If syndrome of hypothyroidism:
- Maternal propylthiouracil during pregnancy
- Excessive or deficient maternal iodine
- Genetic defect in thyroid hormone production
Fetal hydronephrosis
Commonly detected in the second trimester of pregnancy and usually transient and resolves on its own.
Often unilateral and due to narrowing or kinking of the proximal ureter at the ureteropelvic junction. The UPJ is the last segment of the ureter to canalize, and so has the least structural support.
If undiagnosed prenatally, it may present as a palpable abdominal mass in a newborn representing the enlarged kidney.
Erythroblastosis fetalis
The result of fetal hemolytic anemia due to a sensitized Rh negative mother and an Rh positive fetus.
Transferred anti-Rh IgG will result in hemophagocytosis in the fetal spleen, causing intramedullary hemolysis.
Which types of blood group antigen are capable of causing fetal hemolytic anemia?
Rh factor
Kell antigen
C, c, E, and e antigens
Note that this is because they all have protein components and can stimualte IgG production, unlike the ABO system which stimulates IgM production.
What are the clinical findings of erythroblastosis fetalis?
They are mostly secondary to the anemia (Hgb < 5 g/dL)
How do we avoid erythroblastosis fetalis?
Firstly, we blood type and screen (Coombs) patients at the start of their pregnancy, 28 wks gestation, and delivery. All those who are Rh- are offered Rhogam (Rh-Ig) at 28 wks if a sensitizing event is present.
If the screen / Coombs test is positive, we monitor flow through the fetal MCA by ultrasound. Those with elevated MCA flow can undergo invasive fetal blood sampling and fetal transfusion.
How does Rhogam work?
Rhogam is essentially passive immunization to fetal Rh factor.
300 micrograms of Rhogam protects against 30 mL of fetal Rh+ blood.
It is thought that Rhogam effectively sequesters antigen, preventing it from being processed by the immune system and thus preventing alloimmunization.
The following findings are visualized on ultrasound at a prenatal care visit. Assuming an infectious etiology, what is the most likely agent which caused these abnormalities?
Cytomegalovirus
CMV is the most common congenital infection in the United States, and a consetllation of cerebral calcifications AND ascites is highly suggestive of CMV, especially in a mother who is CMV IgG+
Lumbosacral spina bifida
- Abnormal development of the spine in embryogenesis
- May present as:
- Spina bifida occulta: Small separation of two or more vertebrae, no nerve involvement and therefore no symptoms. Tuft of hair or dimple is often present overlying the lesion.
- Myelomeningocele: aka “Open spiba bifida”. The spinal canal remains open, and may or may not even be covered by skin. Nerves are exposed and protrude into a sac at birth. Often causes walking/mobility problems.
- Risk factors:
- Folate deficiency
- Maternal diabetes
- Maternal obesity
- Elevated body temperature during neurulation
Caudal regression anomaly
- Neural tube defect characterized by abnormal development of the caudal aspect of the vertebral column and the spinal cord
- Results in neurological deficits ranging from bladder and bowel involvement to severe sensory and motor deficits in the lower limbs
- Risk factors:
- Maternal diabetes
Renal tubule dysplasia
- Can be sporadic or caused by ACE inbitors used in the 2nd and 3rd trimesters
- May be unilateral or bilateral
- Kidneys will often be multicystic or misshapen
- On histology, there will be fibrosis between the tubules and islands of cartilage
Fetal alcohol syndrome
-
Early features:
- Microcephaly
- Short palpebral fissure
- Smooth philtrum
- SGA or IUGR
- Sleep and sucking problems
-
Late features:
- Poor coordination
- Speech and language delay
- Attentional problems
Radial dysplasia
- Form of sequence anomaly, in which shortening or absent development of the radius results in hand abnormalities and bowing of the ulna
VACTERL association
- Pattern of abnormalities that tend to co-occur in embryonic development
- Seemingly sporadic with no known cause
- Thought to be related to a mitochondrial defect
Valproate teratogenicity
Valproate interferes with folate metabolism, which in turn interferes with post-translational methylation of the cytoskeleton in neural cells during neural tube closure – particularly during weeks 3-4 of embryogenesis.
So, impaired folate metabolism leads to spina bifida, a result of the failure of the tube to close.
Definition of “spontaneous abortion”
Loss of a fetal pregnancy before 20 wks gestation
Characteristics of the newborn with Down syndrome
- Flattened nasal bridge
- Small, rotated, cup-shaped ears
- Sandal gap toes
- Protruding tongue
- Hypotonia
- Simian creases
- Oblique palpebral fissures
Four characteristics of a healthy newborn that requires no additional resuscitation
- Full-term
- Spontaneous breathing and crying
- Clear amnionic fluid with no evidence of meconium
- Good muscle tone
Apgar score
Taken every 5 minutes until 20 minutes, and continuing if the 20 minute score is below 7.
Immediate post-delivery care of the neonate
- Dry the infant off
- Keep it warm (skin-skin contact with mom or warm blanket)
- Clamp cord, wait 30 seconds, cut cord and obtain cord blood
- Assess neonate vital signs
- Continue repeating assessment every 30 minutes until stable for 2 hours
Immediate skin-skin contact of the infant with the mother accomplishes two goals:
- Keeping the baby warm
- Increasing the successfulness of breast feeding (infant is more likely to breast feed if this is done)
Standard transitional post-delivery care of the neonate
- Intraocular erythromycin (prevent gonococcal ophthalmia neonatorum)
- Shot of vitamin K
- Monitoring of stool and urinary patterns
What should you suspect of a neonate does not pass stool within the first 24 hours?
Imperforate anus
Color of neonatal stool
First 2-3 days: greenish brown, tar-like
After breastfeeding for a while: yellow, semisolid
Hyperbilirubinemia in newborns
- Almost all newborns have some neonatal jaundice
- However, we want to ensure that this dissipates:
- Within the first 24 hours, we take
Kernicterus and bilirubin encephalopathy are usually associated with bilirubin levels above. . .
. . . 25 mg/dL
Which infants are at risk for kernicterus and bilirubin encephalopathy?
- Late-preterm infants (EGA 35-36+9)
- Criggler-Najjar syndrome
- UDP-glucoronyltransferase absent (type I) or reduced (type II) at birth.
- Type II responds to phenobarbital by upregulating. Type I there is nothing to upregulate.
Umbilical cord blood gas
- Umbilical arterial blood gas is most important, but both should be taken if possible
- Acidemia of the neonate is defined as umbilical arterial blood pH < 7.20
- Fetal asphyxia is defined as impaired placental gas exchanged leading to progressive hypoxemia and hypercapnia with significant metabolic acidosis (usually arterial bicarb <12). pH < 7.00 and 5 minute apgar score < 5 with evidence of encephalopathy and multiorgan dysfunction.
Talipes equinovarus
- Aka clubfoot
- Risk factors: oligohydramnios, smoking during pregnancy, family history, genetic factors
- Can impair walking and cause arthritis if untreated
- Therapy:
- 1st line: Ponseti method – form of physical therapy involving stretching and casting
- 2nd line: Surgical correction
Erb’s and Klumpke’s Palsies
Beckwith-Wiedemann syndrome
- Hallmarks are omphalocele (exomphalos), macroglossia, and macrosomia (gigantism)
- Prenatal presentation: Polyhydramnios and macrosomia
- “Big belly button, big tongue, big baby”
- Increased risk for certain tumors: Wilm’s tumor and hepatoblastoma
- 85% sporadic, 15% familial
- Risk factors: Subfertility, use of assistive reprodutive technology
Ebstein’s anomaly
Teratogenic effect of lithium during pregnancy
Duodenal atresia
- Strongly associated with fetal Down syndrome
- Cysts that can be seen on fetal ultrasound in the right and left abdomen (Double bubble sign: one is the stomach, other is the duodenum)
- Results in a blockage (atresia) that stops food or fluid from leaving the baby’s stomach
- Will require neonatal surgery to remove this obstruction
Velamentous cord insertion
Umbilical vessels separate from the cord before reaching the placenta, protected only by a thin fold of amnion instead of by the cord or the placenta itself.
Increased susceptibility to tearing.
Elevated risk for this in monochorionic twin pregnancies
Bloom syndrome
Bloom syndrome (BSyn) is a rare genetic disorder characterized by short stature; a sun-sensitive, red rash that occurs primarily over the nose and cheeks; mild immune deficiency with increased susceptibility to infections; insulin resistance that resembles type 2 diabetes; and most importantly, a markedly increased susceptibility to many types of cancer, especially leukemia, lymphoma and gastrointestinal tract tumors.
Russel-Silver syndrome
IUGR, poor growth after birth, a relatively large head size, a triangular facial appearance, a prominent forehead (looking from the side of the face), body asymmetry and significant feeding difficulties
Cretinism
- Congenital thyroid deficiency
- IUGR, congenital hypothyroidism, physical deformities, learning disability
Gastroschisis
Birth defect in which the baby’s intestines extend outside of the abdomen through a hole next to the belly button
Associated with IUGR as a fetus
Omphalocele
Also known as exomphalos, is a birth defect of the abdominal (belly) wall. The infant’s intestines, liver, or other organs stick outside of the belly through the belly button. The organs are covered in a thin, nearly transparent sac that hardly ever is open or broken.
Associated with IUGR as a fetus
