產科常見檢查產科常見檢查

R 4 R 4 蔡曉文蔡曉文

Screening for neural tube Screening for neural tube defects and Down syndromedefects and Down syndrome

Screening: identifies individuals whose Screening: identifies individuals whose risk is high for further evaluation.risk is high for further evaluation.

Maternal serum AFP screening: 15-22 Maternal serum AFP screening: 15-22 wks wks

A confirmed increase in maternal A confirmed increase in maternal serum AFP to greater than 2.0 to 2.5 serum AFP to greater than 2.0 to 2.5 MOM indicates increased risk for a MOM indicates increased risk for a fetal NTD or other structural anomaly fetal NTD or other structural anomaly and warrants further evaluation.and warrants further evaluation.

Elevated levels of AFPElevated levels of AFP

Neural tube defectsNeural tube defects Esophageal or intestinal Esophageal or intestinal

obstructionobstruction Cystic hygromaCystic hygroma Abdominal wall defects-Abdominal wall defects-

omphalocele, gastroschiomphalocele, gastroschisissis

Urinary obstructionUrinary obstruction Renal anomalies- polycyRenal anomalies- polycy

stic or absent kidneysstic or absent kidneys

Low birth weightLow birth weight OligohydramniosOligohydramnios Multifetal gestationMultifetal gestation Decreased maternal weiDecreased maternal wei

ghtght

Biochemical screening for Down Biochemical screening for Down syndromesyndrome

Down syndrome: most common cause of congDown syndrome: most common cause of congenital mental retardation; VSD, anterior abdoenital mental retardation; VSD, anterior abdominal wall defects. Typical faces.minal wall defects. Typical faces.

Combination of maternal age, hCG, AFP and uCombination of maternal age, hCG, AFP and uE3( unconjugated estriol)E3( unconjugated estriol)

DS screening was based on maternal age alonDS screening was based on maternal age alone and women aged 35 years and over were offee and women aged 35 years and over were offered amniocentesis.red amniocentesis.

Utilizes two analytes( hCG↑, AFP↓)—double tUtilizes two analytes( hCG↑, AFP↓)—double testest

Triple test: high hCG, low AFP, and low uE3Triple test: high hCG, low AFP, and low uE3

UltrasonographyUltrasonography The mid-trimester anomaly scan: for structurThe mid-trimester anomaly scan: for structur

al abnormality at 18-20 wks.al abnormality at 18-20 wks. Cardiac defect: Four-chamber view identify 6Cardiac defect: Four-chamber view identify 6

0% of severe lesions and a complete fetal car0% of severe lesions and a complete fetal cardiac scan identifies 75% of all cardiac abnordiac scan identifies 75% of all cardiac abnormalities.malities.

NTD: 95% of all spina bifida; The recognized NTD: 95% of all spina bifida; The recognized association of frontal bone scalloping( lemoassociation of frontal bone scalloping( lemon sign) and abnormally shaped cerebellum( n sign) and abnormally shaped cerebellum( banana sign) aids the detection of neural tubbanana sign) aids the detection of neural tube lesions.e lesions.

UltrasonographyUltrasonography Gastrointestinal abnormalities: anterior abdoGastrointestinal abnormalities: anterior abdo

minal wall defect( omphalocele and gastroschiminal wall defect( omphalocele and gastroschisis) at the mid-trimester scan sis) at the mid-trimester scan

obstruction and atresia is more often diagnoseobstruction and atresia is more often diagnosed in late second trimester or the third trimested in late second trimester or the third trimester because of polyhydramnios or an incidental fr because of polyhydramnios or an incidental finding of dilated loops of bowel. inding of dilated loops of bowel.

Thoracic abnormalities: congenital diaphragmThoracic abnormalities: congenital diaphragmatic hernia may be diagnosed in the second triatic hernia may be diagnosed in the second trimester but is usually more apparent in the thirmester but is usually more apparent in the third; usually left-sided.d; usually left-sided.

Nuchal fold translucencyNuchal fold translucencyEdema of the fetal neck, detectable in thEdema of the fetal neck, detectable in th

e first trimester by ultrasound, is associae first trimester by ultrasound, is associated with cardiac defects, Down syndromted with cardiac defects, Down syndrome, and other trisomies. e, and other trisomies.

Performed between 10 and 14 wks.Performed between 10 and 14 wks.Training of personnel and scanning time.Training of personnel and scanning time.

AmniocentesisAmniocentesis

Done between 15 and 20 wks; amniotic fluid containDone between 15 and 20 wks; amniotic fluid contains fetal cells shed from the gut and skin.s fetal cells shed from the gut and skin.

1.1. Chromosomal analysis: most commonly Down syndChromosomal analysis: most commonly Down syndrome testing for maternal age, high risk serum tests rome testing for maternal age, high risk serum tests and ultrasound markers.and ultrasound markers.

2.2. DNA analysis for genetic disease.DNA analysis for genetic disease.3.3. Enzyme assays for inborn errors of metabolism.Enzyme assays for inborn errors of metabolism.4.4. Investigation of fetal lung maturity ( lecithin/sphingInvestigation of fetal lung maturity ( lecithin/sphing

omyelin ratio or presence of phyophatidyl glycerol)omyelin ratio or presence of phyophatidyl glycerol)5.5. Bilirubin ( for rhesus iso-immunization)Bilirubin ( for rhesus iso-immunization)

AmniocentesisAmniocentesis

The main risk: miscarriage( <1% procedure-relThe main risk: miscarriage( <1% procedure-related risk)ated risk)

Minor complications: transient vaginal spottinMinor complications: transient vaginal spotting, or amniotic fluid leakage(1%), chorioamniog, or amniotic fluid leakage(1%), chorioamnionitis.nitis.

The risk is higher when the procedure is perforThe risk is higher when the procedure is performed at 14 wks or less( early amniocentesis).med at 14 wks or less( early amniocentesis).

Needle injuries are rare, especially when real-tNeedle injuries are rare, especially when real-time scanning is used.ime scanning is used.

Culture failure is rare with a rate of less than 0.Culture failure is rare with a rate of less than 0.5%. Maternal cell contamination occurs in less 5%. Maternal cell contamination occurs in less than 0.2%than 0.2%

Chorionic villus samplingChorionic villus sampling CVS is performed at 10 to 13 wks; allows earlier and CVS is performed at 10 to 13 wks; allows earlier and

safer methods of pregnancy termination when they safer methods of pregnancy termination when they are abnormal.are abnormal.

Indications:Indications:1.1. Karyotyping when ultrasound findings suggest aneuKaryotyping when ultrasound findings suggest aneu

ploidy.ploidy.2.2. DNA analysis, particularly for haemoglobinopathies DNA analysis, particularly for haemoglobinopathies

and recessive or X-linked disordersand recessive or X-linked disorders ComplicationsComplications1.1. Pregnancy loss- 2-3%Pregnancy loss- 2-3%2.2. Maternal cell contamination lead to false negative rMaternal cell contamination lead to false negative r

esultsesults3.3. Limb reduction deformities: before GA 9 wks.Limb reduction deformities: before GA 9 wks.

Fundal symphyseal heightFundal symphyseal height A useful screening method for detection of the A useful screening method for detection of the

baby that is small or large for gestation.baby that is small or large for gestation. Third trimester: approximate to the number of Third trimester: approximate to the number of

the gestation. The variation is 2 from 20-35 wkthe gestation. The variation is 2 from 20-35 wks, 3 from 36-38 wks, and 4 after that.s, 3 from 36-38 wks, and 4 after that.

Further investigationFurther investigation Limitation: multiple pregnancies, maternal obLimitation: multiple pregnancies, maternal ob

esity, or polyhydramnios. esity, or polyhydramnios.

Fetal movement chartFetal movement chart

The presence of fetal movement is a The presence of fetal movement is a sign of fetal well-being and occurs in sign of fetal well-being and occurs in a cyclical pattern.a cyclical pattern.

High risk pregnancies and those High risk pregnancies and those where a subjective reduction in where a subjective reduction in movements has already been movements has already been reported, the use of fetal movement reported, the use of fetal movement charts( defining normality as 10 charts( defining normality as 10 movements per day) may be of some movements per day) may be of some benefit.benefit.

CardiotocographyCardiotocography Monitoring fluctuations in fetal heart rate oveMonitoring fluctuations in fetal heart rate ove

r time and correlating this with any uterine acr time and correlating this with any uterine activity. ( after 32 weeks)tivity. ( after 32 weeks)

Non stress CTG:Non stress CTG:1.1. baseline 110-160 beats/min with baseline 110-160 beats/min with 2.2. short-term viability around that baseline of bshort-term viability around that baseline of b

etween 5 and 25 beats/min. etween 5 and 25 beats/min. 3.3. At least two accelerations should occur withiAt least two accelerations should occur withi

n each 20 mins( a rise of at least 15 beats lastin each 20 mins( a rise of at least 15 beats lasting for 15 seconds).ng for 15 seconds).

4.4. No deceleration from the baseline.No deceleration from the baseline.

CardiotocographyCardiotocographyUseful means of excluding current Useful means of excluding current

fetal hypoxia and acute compromise.fetal hypoxia and acute compromise.The intermediate and long-term The intermediate and long-term

prognostic value of CTG is poor.prognostic value of CTG is poor.Not be reactive: hypoxia, anemia, Not be reactive: hypoxia, anemia,

infection, medication, cerebral infection, medication, cerebral hemorrhage, maternal metabolic hemorrhage, maternal metabolic disturbance, chromosomal or disturbance, chromosomal or congenital malformation.congenital malformation.