Diagnostic Tests for Amniotic Fluid

Diagnostic Tests for Amniotic Fluid

A. Amniocentesis empty bladder before performing the procedure.

Purpose – obtain a sample of amniotic fluid by inserting a needle through the abdomen into the amniotic sac; fluid is tested for:

1.       Genetic screening- maternal serum alpha feto-protein  test (MSAFP) – 1^st trimester

2.       Determination of fetal maturity primarily by evaluating factors indicative of lung maturity – 3^rd trimester

Testing time – 36 weeks

decreased MSAFP= down syndrome

increase MSAFP = spina bifida or open neural tube defect

Common complication of amniocenthesis – infection

Dangerous complications – spontaneous abortion

3^rd trimester- pre term labor

Important factor to consider for amniocentesis- needle insertion site

Aspiration of yellowish amniotic fluid – jaundice baby

Greenish – meconium

1. Amnioscopy – direct visualization or exam to an intact fetal membrane.
2. Fern Test- determine if amniotic fluid has ruptured or not (blue paper turns green/grey - + ruptured amniotic fluid)
3. Nitrazine Paper Test – diff amniotic fluid & urine.

Paper turns yellow- urine. Paper turns blue green/gray-(+) rupture of amn fluid.

1. Chorion – where placenta is developed

Lecithin Sphingomyelin L/S

Ratio- 2:1 signifies fetal lung maturity not capable for RDS

Shake test – amniotic + saline & shake

Foam test

Phosphatiglyceroli: PG+ definitive test to determine fetal lung maturity

a.       Placenta – (Secundines) Greek – pancake, combination of chorionic villi + deciduas basalis. Size: 500g or ½ kg 

-1 inch thick & 8” diameter

Functions of Placenta:

1.       Respiratory System – beginning of lung function after birth of baby. Simple diffusion

2.       GIT – transport center, glucose transport is facilitated, diffusion more rapid from higher to lower. If mom hypoglycemic, fetus hypoglycemic

3.       Excretory System- artery - carries waste products. Liver of mom detoxifies fetus.

4.       Circulating system – achieved by selective osmosis

5.       Endocrine System – produces hormones

·         Human Chorionic Gonadrophin – maintains corpus luteum alive.

·         Human placental Lactogen or sommamommamotropin Hormone – for mammary gland development. Has a diabetogenic effect – serves as insulin antagonist

·         Relaxin Hormone- causes softening joints & bones

·         estrogen

·         progestin

It serves as a protective barrier against some microorganisms – HIV,HBV