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Abnormalities of Fetal Membranes and Amniotic Fluid

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ABNORMALITIES OF FETAL MEMBRANES AND AMNIOTIC FLUID

Abnormalities of fetal membrane

a: Color

1. staning - is obvious within 1 to 3 hr. after meconium passage if the meconium has passed many days before delivery the staning becomes light green or brown.

2. CHORIOAMNIONITIS

-the membrane usually appears diffusely opaque due to neutrophil infiltration.

3. RETROMEMBRANOUS HGE

-the hemorrhage occurred days before delivery. The pigment in the membranes maybe brown or yellow.

b. Texture

1. amnion nodosum - these usually Appears as small nodules on the membrane, seen in pregnancies with oligohydamnios. Microscopy discloses these nodules to be formed of desquamated skin cells

2. Squamous metaplasia -appear as white nodules under

the amnion, not in the surface.

c. Placental insertion

1. circumvallate

-occurs when the membrane insert into the placental surface in a curved border of folded membranes at the margin.

-this folds elevates the membrane in a White rim above the placental surface, antepartum hemorrhage, preterm delivery, perinatal deaths, and fetal malformation were reported To be increased for pregnancies with this placental type.

2. Marginal Insertion

- more common

-the membrane insert into the lacental discs at its margin

- another variant of this circummaginate occurs when the membrane insert away from the placental edge and extend beyond the vascular plate into a white fibrin at the placental edge.

DISORDERS OF AMNIOTIC FLUID

-early in the second trimester the vol occupied by the fetus is about equal to the vol. of the amniotic fluid.

- The fetus does not appear confined within the uterus seen to move freely in a bath of fluid

-Throughout the 2nd and 3rd trimesters,the vol. of the fetus increase in comparison to the vol. of the fetus , and late pregnancy the amount of fluid , and late in pregnancy the amount of fluid appears small in comparison with the fetus.

-normally, amniotic fluid vol. reaches about 10000 ml by 36 weeks, but decreases thereafter

Sonogram has made objective measure of amniotic lluid possible. Two routinely used objective methods are :

1. measurement of a single vertical (SVP) pocket or fluid

2. calculation of the amniotic fluid index .

-The SVP is obtained by measuring the antero- posterior dimension (depth) of the largest pocket of amniotic fluid void of fetal parts or umbilical cord.

-a pocket measuring 2-8 cm is considered normal.

-The AFI is calculated by dividing the

uterus Into four equal segments and

measuring the largest pocket of fluid

(antero posterior measurement

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