The major contribution of the ammiotic fluid after 20 weeks of gestations

(Foetal urine): Ref: 37, 214, 218, 464-D Obstetrics - G. Chamberlain 7thAMNIOTIC FLUIDProduced: In early pregnancy, from amnion over placenta and sacLate pregnancy: from fetal urine as wellVolume: Increase to 38 weeks (500 - 1500 ml)50 ml: 12 weeks500 ml: 24 weeks1000 ml: 36 weeksOsmolality: Decreases in late pregnancyCreatinine: Increases in late pregnancyAcid - base: Normally accumulation of CO2 and fixed acid causes a slight reduction in pH (About 7.15 - 7.20)* The foetus drinks about 400 ml of liquer every day at term and equal amount is excreted in the urine* The water in the amniotic fluid is completely changed and replaced in every 3 hours.* Abnormal colour- Meconium stained (green) - Foetal distress Breech or transverse- Golden colour - Rh. Incompatibility- Greenish yellow (Saffron) - Post maturity- Dark coloured - concealed accidental hemorrhage- Dark brown (tobacco juice) - IUD* Amniotic Fluid Index (AFI) - An AFI between 5 and 25 cm is normal and an AFI less than 5 cm (< 10 centile) indicates oligohydramnios and AFI more than 25 cm (> 95 centile for gestational age) indicates Polyhydramnios (464-D)