Amniotic fluidPresanted by

Reshma Suzen

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• Amniotic fluid is found in the membranous sac that surrounds the fetus and provides a cushion to protect the fetus

Orgin

Transudation from maternal

circulation

Secretion from amniotic epithelium

Transudation from fetal plasma

Contribution from the fetus

Amniotic fluid volume :

• About 500 mls enter and leave the amniotic sac each hour.

• gradual ↑ up to 36 weeks to around 600 to 1000 ml then↓ after that.

• The normal range is wide but the approximate volumes are:

- 50 ml at 12 weeks

- 400 ml at 20 weeks

- 800 ml at 34 weeks.

- 1L at 36-38 week.

- 600 - 800 ml at term.

compositiona) Organic @ non organic Protein : .3gm % Glucose : 20mg% Urea : 30mg% NPN : 30mg% Uric acid : 4mg% Creatine : 2mg Total lipids : 50mg% hormones

b) Non organic Sodium Sodium chloridec) Suspended particles Lanugo Exfoliate squamous cell Vernix caseosa

Physical features Alkaline Low specific gravity – 1.010 Hypotonic to maternal serum at term Osmolarity – 250 Osmol Colour – in early pregnancy

colourless - at term it become pale

straw colored

Abnormal color Green : meconium stained Golden : Rh incompactability Greenish yellow : post maturity Dark colured : concealed accidental

haemorrhage Dark brown : IUD

Amniotic fluid function:

During pregnancy• Allow room for fetal growth, movement

and development.

• Ingestion into GIT→ growth and maturation.

• Fetal pulmonary development (20 weeks).

• Protects the fetus from trauma.

• Maintains temperature.

• Contains antibacterial activity.

During labor

Dilatation of cervix

Flushes the birth canal by its

antiseptic and bactericidal action

Clinical importance of AF:

• Screening for fetal malformation (serum α-fetoprotien).

• Assessment of fetal well-being (amniotic fluid index).

• Assessment of fetal lung maturity (L/S ratio).

• Diagnosis and follow up of labour.• Diagnosis of PROM

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Tests for the Well-being and Maturity

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Test Normal values at term Significance

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Bilirubin scan 0.025 mg/dl Hemolytic disease

of the newborn

L/S ratio 2.0 Fetal lung maturity

Phosphatidyl- Present Fetal lung maturity

Glycerol

Creatinine 1.3 – 4.0 mg/dl Fetal age

Alpha fetal protein 4.0 mg/dl Neural tube disorders

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Amniotic fluid abnormalities

Oligohydramnios: Defined as reduced amniotic fluid i.e.

amniotic fluid index of 8 cm

Polyhydramnios: Defined as excessive amount of amniotic fluid

of 2000 ml or more (AFI of > 20 cm