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. 1 2 3 4 Functions of test :- Disease marker Protects the fetus
Enables fetal movement 3
Plays a role in various
biochemical processes 4 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. - Kleihauer–Betke test
Chemical examination
- Kleihauer–Betke test
Staining technique to identify the presence of maternal or fetal red bloods in amniotic fluid

17. Reference Value 7-7.5 PH Colorless to pale yellow Color Clear
Appearance
Less than 2.0 *MoM = Multiples of the median.
α1-Fetoprotein
Absent
Acetylcholinesterase
1.8–4.0 mg/dL at term
Creatinine
Less than mg/dL at term
Bilirubin
Greater than 2:1 at term
L/S ratio
Present at term
Phosphatidylglycerol
Normal karyotype
Chromosome analysis
None seen
White blood cell count
Negative
Leukocyte esterase

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