OB Flashcards
What are prenatal diagnostic tests that are available?
- Amniocentesis
- Cordocentesis
- Chronic Villi Sampling
- Ultrasound
- Fetoscopy
- Amniography
- Radiography
Different Amniocentesis procedures include?
- Chromosomal Analysis (Karyotyping)
- Bilirubin Level Determination (In fetal hemolytic
disease) - AFP determination in cases of elevated maternal
serum AFP - Evaluation of fetal lung maturity (LS ratio)
Chronic Villi Sampling Procedures?
- Chromosmal Analysis
2. Biochemical Disorders
Ultrasound Determinations?
- Wide variety of structural malformations
2. Guidance of other procedures
Fetoscopy Procedures?
- Detects hemoglobinopathies/ other disorders via fetal
blood - Directly views fetus
Radiography Procedures?
- Limited to evaluation of fetal skeletal abnormalities RARELY
Amniography Procedures?
- Detection of gross external fetal malformations
- Determination of genitourinary tract disorders
- Determination of gastrointestinal tract disorders
(will swallow contrast in amniotic fluid)
Exam timing for amniocentesis, CVS, and ultrasound?
- Amniocentesis: depends upon the procedure needed and the reason for performing
- CVS: 1st trimester
- Ultrasound: can be performed throughout entire pregnancy, dependant upon reason for performing
Who are “high risk” patients for these examinations?
- Maternal age 35 years old
(Most common, associated with ^ risk of chromosome anomalies) - Previous child with a chromosomal abnormality or positive family history
(Recurrence varies with each anomaly) - Mother is a known carrier for an X linked disorder
(This means the abnormal gene is located on the X chromosome, only MALE offspring are affected, passed from mother to son) - Parent carries to an autosomal recessive disorder that can be diagnosed in utero
(25% recurrence rate if previous child has it) - Positive family history for NTD
(NTD can be inherited as multifactorial disorders)
Potential benefits to mother for detecting?
- Termination
- Prenatal Therapy
- Aiding the obstetrician
- Referral of mother before delivery to centers where neonatology and pediatric services are available
- Prevention of unwarranted life-saving methods on a “unsalvageable” fetus
- Allowing families to make appropriate psychological and social adjustments for birth of an abnormal child
- Relief of anxiety in patients known to be at risk
What is the amniocentesis procedure?
Thin spinal needle is inserted thru maternal abdominal wall with direct real-time U/S guidance. The needle punctures the amnion to enter the amniotic cavity
**Success rate is generally high with low risk
Exam timing for amniocentesis?
- 16-17 weeks (Genetic Amniocentesis)
- 23-24 weeks (DX of Fetal Hemolytic Disease)
- 3rd trimester (Assessment of Fetal Maturity)
Complications of amniocentesis?
- Abortion
- Premature Labor
- Chorioamnionitis
- Transitory episodes of abdominal pain
- Rectus sheath hematoma
- Placental hemorrhage
- Umbilical cord hemorrhage
- Fetal injuries
Reasons for ultrasound assessment?
- Confirm IUP
- Presence of pathology
- Presence of multiple gestations
- Determination of gestational age
- Detection of congenital anomalies
- Placental localization
- Estimation of amniotic fluid volume
- Determination of most appropriate site for amniocentesis
- Determination for depth and angle of entry for needle puncture
Considerations for puncture?
- Placenta should be avoided
- Stay away from fetal head, whenever possible
- Attempt to puncture close to uterine ML to avoid vessels
- Fewer punctures assures less risk
Types of Amniocentesis?
Genetic and Spectrophotometric
What is genetic amniocentesis?
Done 16-17 weeks
Reasons: adequate amount of amniotic fluid and viable cell content is sufficient for culture
Process for genetic amniocentesis?
- Desquamated cells are present in amniotic fluid
- Fetal cells culture in approx. 3 weeks
- Harvested cells are examined
- Photographs are taken of chromosomes
- Chromosomes are matched from enlarged photos
- This is called KARYOTYPING
- Diagnosis is made of sex and abnormalities
Results of genetic amniocentesis?
90% are normal
6% are abnormal
*Normal does not mean baby will be free of malformations, because many problems cannot be detected
What is spectrophotometric analysis?
Assesses amniotic fluid bilirubin
- Begins 23-24 weeks
- Reasons: determines severity of fetal hemolytic DZ and provides an indication of fetal maturity
In a normal fetus, the amniotic fluid bilirubin concentration does what?
Decreases along a normal curve and virtually disappears by 36-38 weeks. Bilirubin levels are ELEVATED in a sensitized fetus
What is amniocentesis for fetal maturity?
Different cells can be assessed, but the L/S RATIO is considered to be the most important
*3rd trimester
What is L/S mean?
Lecithin/Sphingomyelin
Certain cells from the fetal ling alveoli produce what?
Surface-active phospholipids to reduce the surface tension of the aveoli, so they dont collapse on expiration
Premature infants do not have the ability to produce these surfactants, so they will develop?
Respiratory Distress Syndrome
Secondary to Hyaline Membrane Disease
L/S Ratios greater than what indicate fetal lung maturity?
> 2
Ratios of 1 indicates immaturity
What is chorionic villus sampling?
Real-time guided biopsy for prenatal diagnosis of fetal disorders in the 1st trimester
Timing of CVS?
Approximately 11 weeks, definately >8 weeks for compression of chorion laeve and only villi in area of chorion frondosum and visualization
Process of CVS?
- Transcervical catheter into uterus or transabdominal puncture into uterine wall
- Catheter is advanced to chorion frondosum under ultrasound guidance
- A plastic syringe applies suction to obtain a small amount of villous tissue
(TransCervical for posterior chorion frondosum and Transabdominal for anterior or fundal chorion frond)
Advantages of CVS?
- Earlier determination of abnormalities (for termination)
- Results within days, rather than weeks
Disadvantages of CVS?
- If unsuccessful, amniocentesis must be performed
(Fibroids most common reason for procedure fail) - Possible hemorrhage, thus abortion
Role of ultrasound during CVS?
- Visualization of and guidance to chorion frondosum
- Documentation and rechecking of fetal heart
What is cordocentesis?
Ultrasoun guided or fetoscope-guided needle puncture of umbilical cord
Purposes of cordocentesis?
- To obtain fetal blood for prenatal diagnosis (diagnostic)
- To transfuse blood to fetus with hemolytic disease (Therapeutic)
Procedure of cordocentesis?
- 22 gauge spinal needle
- Puncture usually at placental cord origin, but can be in free-floating cord
- Umbilical vein is preferred target
Reasons for having Diagnostic cordocentesis?
- Evaluation of fetus for immunologic hemolytic disease
- Rapid karyotyping
- Detection of fetal infection
What is fetoscopy?
Direct visualization of the fetus and umbilical cord using a small bore endoscope
*15-21 weeks
Fetoscopy procedure?
- Fetoscope inserted transabdominally thru uterine wall into amniotic cavity
- Real-time ultrasound used to survey uterus and determine most suitable passage sites
Reasons for fetoscopy?
- Prenatal diagnosis of specific fetal anomalies by direct visualization
- To guide cordocentesis for fetal blood sampling
What is alpha fetoprotein testing?
Measurements of alpha fetoprotein concentration in maternal serum (MSAFP) and amniotic fluid
*15-20
AFP is initially produced by?
Yolk sac, and then by liver
AFP levels can detect?
Open neural tube defects and other congenital anomalies
The highest concentration of AFP is found in?
fetal blood then amniotic fluid then maternal serum
AFP concentrations in all rise gradually until when?
Midtrimester with peak concentrations at 16 weeks
What can be cause of increased MSAFP?
- If the fetal body is not covered by a normal integument
- Some body wall defects
- Impaired fetal swallowing
- Increased permeability of fetal kidneys
- Increased placental permeability (Will not cause ^ AFAFP)
- Fetal death
- Multiple gestations
- Gestational age 2 wks or more greater than estimated clinically
What causes increased AFAFP?
Almost all are due to NTD
*Women with elevated MSAFP are offerd amnios to determine AFAFP levels
What causes decreased MSAFP?
- Chromosomal defects (especially trisomies)
- Increased risk of trisomy 21
All of the trisomy disorders represent what?
An extra chromosome on the numbered pair
What does trisomy 13 represent?
A third chromosome on the 13th pair
- RARE disorder with a poor prognosis
- Its recurrence risk is LOW
What are the congenital abnormalities associated with trisomy 13?
- Cranial malformations (Holoprosencephaly: 78%)
- Facial Anomalies (Proboscis/Cleft Lip: 70%)
- Cardiac Defects (Ventriculoseptal defect: 90%)
- Omphalocele or umbilical hernia (40%)
- Renal Malformations (Polycystic kidneys: 31%)
- Limb Malformations (Polydactyly: 70% & Rocker Bottom)
- Symmetric growth retardation in 3rd trimester
- Meningomyelocele RARELY present
What is medical name for trisomy 18?
Edwards syndrome
What is trisomy 18?
ONE of the MOST COMMON chromosomal abnormalities, extra chromosome on pair 18
What is the prognosis of trisomy 18?
Poor
*Survival length=5 days, 90% deceased by 1 year of age
What are the HALLMARK signs for trisomy 18?
- Polyhydramnios
- IUGR (Makes fetus susceptible to premature delivery and fetal distress)
- Congenital Abnormalities
Congenital abnormalities associated with trisomy 18 include?
- Cranial anomalies (Hygromas, Nuchal thick, Enlarged CM, Choroid plexus cyst, “Strawberry shaped cranium)
- Facial malformations (Cleft lip: 10-20%)
- Meningomyeloceles (10-20%)
- Caridac anomalies (congenital heart dz, septal defects: 90%)
- Gastrointestinal disorders (Hernia and omphalocele)
- Renal anomalies (horseshoe)
- Skeletal dysplasia (overlapped index finger over a clenched hand and inward curving of 5th digit: 80%)(Clubfoot or rockerbottom)
What also can be present with trisomy 18?
Small placenta and SUA (80%)
A trisomy 18 fetus is at higher risk for?
- Stillbirth and neonatal death
Fetal movements may be decreased in utero
What is the medical name for trisomy 21?
Downs syndrome
- Present in approximately 1/600 births
- Caused by extra chromosome in number 21
Trisomy 21 is associated with?
Advanced maternal age and low AFP levels
Prognosis of trisomy 21?
Depends on associated anomalies which are present
*Mental retardation is always present
(Common problems: heart failure, respiratory, premature aging and eye problems)
T or F? Many structural anomalies that are present in Down’s are not obvious enough to be detected sonographically
True
Other anomalies that can be identified with trisomy 21?
- Craniofacial: cystic hygroma, round and small ears- 54%
- Heart defects: septal defects- 50%
- Gastrointestinal: duodenal atresia- 30%
- Skeletal: shortened femurs, hypoplasia, and inward curving of middle phalanx of 5th digit- 60%
- Thickened nuchal fold: best measured in 2nd tri- 42%
What is triploidy?
A complete extra set of chromosomes
What is triplody caused by?
Fertilization of 2 sperm. Only about 1% are conceived. Most end in spontaneuos abortion
*Extremely rare to progress to birth
What is triploidy prognosis?
Lethal (survival rate= few hours)
Most common ultrasound finding of triploidy?
- Severe symmetrical IUGR
- Oligohydramnios
- Placental abnormalities (Partial hydaditiform)
- Other sonographic findings are nonspecific)
Triploidy should be considered and karyotping performed anytime there is?
Severe IUGR associated with any other congenital anomaly
What is Turners syndrome?
Genetic abnormality marked by the absence of the X or Y sex chromosome
- Most end in spontaneous abortion
- The larger the hygroma, the POORER the prognosis
- Incidence is 1/5000
What gender is associated with Turner’s syndrome?
The infants present as female due to the first X of the pair, but there are mosaics where part of the 2nd chromosome is present
Turners syndrome is characterized by?
- Short stature
- Immature sexual developmental
- Short and webbed neck: cystic hygroma
- Small mandible
- Poor motor skills
- Hearing impairment
- Cubitus valgus: abnormal elbow angle (70%)
Associated sonographic findings of Turners syndromes?
- Cystic hygroma
- Nonimmune hydrops
- Cardiac defects (20%)
- Renal anomalies
- Abnormally-formed ovaries
If the fetus is male what syndrome should be considered?
Noonans syndrome
*Thought to be the male counterpart of Turners
What finding is present with Noonans that is not present with Turners?
Mental retardation
A male fetus with what two things will suggest Noonans?
Nuchal cystic hygroma and congenital heart disease
What is the most common region for cystic hygroma?
Occipital region
- If cystic hygroma is in another area than this, it is usually associated with chromosomal anomalies
- If it is an isolated finding the prognosis is relatively GOOD
What is Meckel-Gruber Syndrome?
Autosomal Recessive Disorder- 25% risk of recurrence
Common associated anomalies with Meckel-Gruber Syndrome?
- Occipital Encephalocele
- Polycystic Kidneys
- Polydactyl
Other anomalies that can be associated with Meckel-Gruber Syndrome
- Facial disorders (30% cleft lip)
- Cranial anomalies (Microcephaly)
- Short limbs
- Ventriculomegaly
- Omphalocele
- Echogenic kidneys
- Oligohydramnios
What syndrome does Meckel-Gruber Syndrome mimic?
Trisomy 13
*AFP will be markedly elevated with Meckel-Gruber
What is Beckwith-Weidemann Syndrome?
Autosomal Dominant Disorder
*Placental Endrocrine Dysfunction- increased levels of growth hormones
Common associated anomalies with Beckwith-Weidemann Syndrome?
- Omphalocele (and other malrotation)
- Macroglossia
- Gigantism
- Hepatosplenomegaly
- Nephromegaly
- Cardiac anomalies
- Diaphragmatic Hernia
Caudal Regression Syndrome is associated with?
Poorly controlled maternal diabetes mellitus
Causes of Caudal Regression Syndrome?
Incomplete development of caudal portion of embryo
Common associated anomalies with Caudal Regression Syndrome?
- Absent lower spine and sacrum
- No bladder
- SUA
- Genital defects
- Renal agenesis
- Oligohydramnios
- Fusion of lower extremities
- Imperforate anus absent rectum
Facts about syndromes?
1/180 births have chromosomal abnormalities
An inherited dominant disorder carries what risk of recurrence?
50%
An inherited recessive disorder carries what risk of recurrence?
25%
X-linked disorders are inherited by?
Boys from their mothers, with a 50% chance of being affected
T or F?
All daughters of affected X-linked males will be carriers
True
What is mosaism?
Gene mutation
May occur in a portion of a cell making it difficult to predict the outcome/affect
What is Amniotic Band Syndrome?
Early rupture of amnion results in amniotic bands that stick, entangle, and disrupt fetal parts resulting in congenital malformations
Ultrasound findings of Amniotic Band Syndrome?
- Abnormal SHEET or BAND that attaches to fetus or flaps with fetal movement
- Restriction of fetal mobility due to entrapment by amniotic band
- Fetal deformities and malformations:
* Extremity amputation
* Edema
* Postural and body wall defects
* Facial clefts
What is medical name for trisomy 13?
Patau
