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AMNIOTIC FLUID. Reasons for testing - To allow antenatal diagnosis of genetic and congenital disorders (15 to 18 weeks) and later in pregnancy (20 to.

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Presentation on theme: "AMNIOTIC FLUID. Reasons for testing - To allow antenatal diagnosis of genetic and congenital disorders (15 to 18 weeks) and later in pregnancy (20 to."— Presentation transcript:

1 AMNIOTIC FLUID

2 Reasons for testing - To allow antenatal diagnosis of genetic and congenital disorders (15 to 18 weeks) and later in pregnancy (20 to 42 weeks) - To assess fetal pulmonary maturity - To assess degree of fetal distress - HDN - Anomalies: UTI, neural tube, intestinal, etc. - Fetal Infections: bacterial, viral, etc.

3 Physiology and composition - Liquid medium that bathes the fetus throughout its gestation - AMNION/amniotic sac – single layer of cuboidal EC

4 Functions of test :- Plays a role in various biochemical processes 4 Disease marker 1 Protects the fetus 2 Enables fetal movement 3 4

5 Formation 1- Initially produced by placenta & amnion 2- Composition is similar to dialysate of plasma 3- As gestation progresses, fetus plays more of an active role in its composition

6 Formation 4. Early in gestation, before skin keratinization 5. Through fetal respiration 6. Latter stages of pregnancy: major constituents come from fetal swallowing & urination 7. Exchange between Amniotic fluid & maternal plasma comes into completion every 2 to 3 hours

7 volume - Increases steadily throughout pregnancy - 25 to 50 ml at 12 weeks’ gestation Max vol = 1100 to 1500 ml at 36 wks’ gestation - Abnormally decreased (oligohydramnios): Congenital malformation & other conditions (e.g. premature rupture of the membranes) - Abnormally increased (hydramnios): Associated w/ decreased fetal swallowing in congenital malformations

8 Specimen collection - Methods 1- Transabdominally 2- Vaginally Increased risk of infection Risk of contamination w/ vaginal cells & bacteria

9 Specimen collection - Timing After 14 wks (depending on purpose) Indications Genetic studies (bet 15 & 18) - To assess health status of fetus (later in preg) in cases of Rh isoimmunization, toxemia & DM - Maturity of fetal pulmonary system

10 Specimen collection Volume: 10 to 20 ml Containers: plastic, why not glass? Cover with aluminum if not colored, why? Transport & storage: ASAP Refrigerate after centrifugation for 5-15 min (24 hours)) Freezing (if storage >24 hrs)

11 Physical examination COLOR Colorless or very pale yellow Distinct yellow or amber – Bilirubin Green – meconium Pinkish to red – blood (e.g. HDN) Brown – severe hemolysis TURBIDITY Slightly turbid due to (fetal cells, hair and secretions

12 Chemical examination - Fern test The Fern Test, used in conjunction with the Nitrazine test, detects the leakage of amniotic fluid from the membranes surrounding the fetus during pregnancy. This phenomenon is in part due to the fluid’s protein and sodium chloride content. A positive test shows the presence of fern-like patterns characteristic of amniotic fluid crystals. The risk may be eliminated by the induction of labor.

13 Negative for crystal fern

14 Positive for crystal fern

15 Chemical examination - FETAL LUNG MATURITY TESTS Lecithin–sphingomyelin ratio Lecithin: major pulmonary surfactant L/S ratio starts out as 1.0, S eventually decreases and L increases <2.0 = fetal lung immaturity - Phosphatidyl glycerol/PG Detectable only in mature fetus

16 Chemical examination - Kleihauer–Betke test Staining technique to identify the presence of maternal or fetal red bloods in amniotic fluid

17 Reference Value 7-7.5PH Colorless to pale yellowColor ClearAppearance Less than 2.0 * MoM = Multiples of the median. α 1 -Fetoprotein AbsentAcetylcholinesterase 1.8–4.0 mg/dL at termCreatinine Less than mg/dL at term Bilirubin Greater than 2:1 at termL/S ratio Present at termPhosphatidylglycerol Normal karyotypeChromosome analysis None seenWhite blood cell count NegativeLeukocyte esterase

18 prepared By:- Abdullah Atallah al-Juhani Majdi Atallah al-Juhani Mahmoud Faleh Alhajoj


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