Amniotic fluid analysis

Dr Rohini C Sane

Professor

Department of Biochemistry

DY Patil Medical College ,EBENE

Amniotic fluid analysis• Liquid produced by membranes & fetus

• Surrounds the fetus throughout pregnancy

• Volume –increases with gestational age( 2weeks –30ml to 350ml (20weeks )---thereafter 500-1000ml

• Clear with some desquamated fetal cells & little lipid

Functions of Amniotic fluid

• It provides physical protection

• Medium for exchange of various chemicals

Diagnostic importance of amniotic fluid• AMNIOCENTESIS –PROCESS BY WHICH AMNIOTIC FLUID COLLECTED FOR

ANALYSIS• Assessment of fetal maturity—cytological staining of fat cells Estimation of creatinine concentration - >1.6mg /dl indicates fetal maturityLung maturity –lecithin –sphingomyelin (l/s) ratio > 2:1 or more indicates normal Lung maturity lecithin –sphingomyelin (l/s) ratio < 2:1 Lung immatureDelay induced delivery till Lung matureINDEX OF SURFACTANT –(SURFACE LOWERING COMPLEX)PREGNANCY ----CELLS LINING ALVEOLI START SYNTHESIZING DIPALMIOTYL LECITHIN,AS LUNG MATURE L/S RATIO INCREASES

EARLY GESTATION PRE TERM

VLOUME 450-1200 ML 500-1400ML

BILIRUBIN < 0.O75 MG/ML < 0.O25 MG/ML

CREATININE 0.8—1.1 MG/DL 1.8-4.0 MG/DL

ESTIROL 10 MICROGRAM /DL >60 MICROGRAM /DL

LECITHIN –SPHINGOMYLIN RATIO

< 1:1 > 2:1

PROTEIN 0.6 -0.24 GM/DL 0.26 -0.19 GM/DL

UREA 18+6MG/DL 30+11MG/DL

URIC ACID 3.7+1 MG/DL 9.9 +2.2 MG/DL

Diagnostic importance of amniotic fluid

• Diagnosis of congenital disorder

• prenatal diagnosis

Chromosomal disorder Down”s syndrome

Metabolic disorder Cystic fibrosis

Sex linked disorder Haemophillia

Enzyme defect Tay sach”s disease

Diagnostic importance of amniotic fluid

• 22-24 WKS OF GESTATION –ESTIMATION OF CHOLINE ESTERASE ISOENZYME ---NEURAL TUBE DEFECTS

• PHENYL ALANINE –PHENYL KETONURIA

• METHYL MALONIC ACID –VITAMIN B12 DEFICIECY –INBORN DEFECT ODD CHAIN FATTY ACID)VALINE,ISOLEUCINE,THREONINE

Diagnostic importance of amniotic fluid

• ASSESSMENT OF HEMOLYTIC DISEASE—ESTIMATION OF BILIRUBIN TO EVALUATE SEVERITY OF HEMOLYTIC DISEASE

• MEASUREMENT OF ALPHA FETO PROTEIN –(AFP)

• NORMAL ---15-40 MICROGRAMS /ML

• < 1.0 MICROGRAMS /ML AT 40WEEKS OF GESTATION ---NEURAL TUBE DEFECT,FETAL DISTRESS ,TURNER”S SYNDROME

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