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 excluding  

fetal parts and umbilical cord) in each  

quadrant and adding the 4 numbers  

together.

- The AFI varies with gestational age, but  

as a rule of thumb, the normal AFI falls  

between 10 - 24 cm after 30 weeks  

gestational age.

1. Oligohydramnios

-diminished amniotic fluid volume  

-severe if AFI is less than 2cm and carries a perenatal mortality 40 - 50 times than that of normal pregnancies.  

autopsy findings in these fetuses showed  

either bilateral renal agenesis, bilateral  

cystic dysplasia, or unilateral agenesis  

with dysplasia. a few had minor urinary  

abnormalities.

 

for those fetuses who survived,  

adhesions, between the amnion and fetal  

parts cause serious deformities including  

amputation.

 

Subjected to pressure from all sides , a fetus assumes a peculiar appearance , musculoskeletal deformities such as clubfoot are observed.

when amniotic fluid is scant, pulmonary  

hypoplasia is common. Possible causes  

include thoracic compression, lack of  

fetal breathing movement which include  

lung inflow, and failure to retain amniotic  

fluid or increased outflow with impaired  

lung development.

Cause of olygohydramnios

PREGNANCY RELATED

Premature Rapture of Membrane

Postdate Pregnancy

Intrauterine Infection

Placental Insufficiency or Abruption

 

FETAL GENITOURINARY ANOMALIES

Renal Atresia

Bilateral Renal Anomalies

Bladder Outlet Obstruction

Posterior Urethral Valves

 

FETAL CHROMOSOME ANOMALIES INTRAUTERINE GROWTHRESTRICTION PHARMACEUTICAL CAUSES

Prostaglandin Synthetase inhibitors.

Angiotensin-Converting Enzyme Inhibitors.

IDIOPHATIC 

2. Polyhydramnios

- Defined as excess of amniotic fluid of more than 2000 ml.

Cause of Polyhydramnios

Idiopathic (60% - 70%) 

Fetal Macrosomia ( with or without diabetes

Maternal Diabetes Mellitus 

Intrauterine Infection 

Twin-twin Transfusion 

Fetal Anomalies

CNS disorder affecting swallowing

Gastrointestinal atresia and Obstruction

Fetal Masses

Cardiovascular Anomalies

Hydrops Fetalis

Musculoskeletal anomalies affecting  

Fetal movement  

-Thank you-

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