- The chorionic villi on the medial surface thins and become double lined membranes - the chorionic membrane, the outermost fetal membrane which supports the sac containing amniotic fluid, and the amniotic membrane or amnion, which contains and produces the amniotic fluid itself and phospholipids that initiate production of prostaglandin.
- Fetal urine is present by 10th week.
- Average amount of amniotic fluid is 1000ml at term.
- Hydramnios a excessive amniotic fluid (more than 2000ml) due to inability of the fetus to swallow it.
- Oligohydramnios a reduction in the amount amniotic fluid (300ml) due to disturbed fetal kidney function.
Functions of Amniotic Fluid:
- Shock absorber from external pressure.
- Protects fetus from changes in temperature.
- Medium of excretion.
- Protects the umbilical cord from pressure, protecting fetal oxygenation.
- Specimen
- pH is 7.2, slightly alkaline.
- Specific gravity is 1.005-1.025, slightly heavier than water.
- Clear, color is same as water.
- Green tinged in non-breech is a sign of fetal distress; golden discoloration maybe found to those with hemolytic disease.
