Polyhydraminios
Polyhydraminios
which is often simply called Hydraminios has been defined as being a quantity
of amniotic fluid which exceeds 1,500mls. The average volume of liquor in the
latter half of pregnancy is between 500 – 1,500ml. The lower li mit of normal
is 500mls of liquor amni while the upper limit of normal is 1,500mls. In most
cases, the excess fluid accumulates gradually (chronic hydramnios) and is only
noticed after 30th week. In a few exceptional cases, hydramnios
occurs earlier and more quickly (acute hydramnios) and many of these cases are
associated with uniovular twins.
Hydramnios
occur more often in multiparae than in primigravidae. The mechanism of
production of liquor amni is not quite understood; consequently the
pathophysiology of hydramnios is obscure. Certain maternal and fetal conditions
are however known to be associated with hydramnios.
Most
times unknown
·
Twin pregnancy particular uniovular twins.
·
Congenital fetal abnormalities, Open neural tube
defect – anencephaly , spinal bifida
·
Oesophageal atresia,
·
Rarely -rhesus isoimmunization, chorioanagioma of
the placenta(rare)
·
Hydrops
fetalis.
·
Maternal diabetes mellitus
·
Occurs at about the 20th week &
comes on suddenly.
·
The fundus reaches the xiphisternum in about 3-4
days.
·
Frequently associated with monozygotic twins.
·
Abdominal pain and vomiting in rare cases.
·
Dyspnoea & indigestion if the uterus is very
much enlarged.
·
Abdomen is large than expected for the duration of
pregnancy.
·
Abdominal muscle may be stretched and oedematous
·
Difficulty in feeling the fetal part and fetal
heart sound may be muffled or inaudible.
·
Fetus is unusually mobile and presentation is
unstable.
·
Oedema of the vulva
·
It is gradual in onset, usually from about the 30th
week of pregnancy.
·
It is the most common type.
·
There is gradual increase in abdominal girth.
·
There are signs of pain, dyspnoea and digestive
discomfort in severe case.
·
Difficult in palpating the fetal part and fetal
heart sound is inaudible.
·
Fluid thrill can be elicited.
·
Abdominal girth increases to about 100cm.
·
Ultrasound scanning
·
Preterm labor
·
Cord presentation and prolapse.
·
Increased incidence of Caesarean section,
mal-presentation may occur.
·
Antepartum hemorrhage – placenta abruption.
·
After delivery, there is risk of post partum
hemorrhage.
·
Raised perinatal mortality
There is
no known method of controlling the production or absorption of amniotic fluid
except that improved control in cases of diabetes may reduce the prevalence of
hydramnios.
1.
The woman may be admitted to a consultant obstetric
unit. Subsequent care depends on condition of the woman, the fetus, the cause
and degree of hydramnios and the stage of pregnancy. Hydramnios without
symptoms and without any evidence of fetal abnormality requires no treatment.
2.
An upright position will help to relieve any
dyspnoea and antacid may be given to relieve heartburn and nausea.
3.
In the presence of gross abnormalities labor should
be induced. Some Obstetrician would draw off part of the liquor by abdominal
amniocentesis before the induction.
4.
Abdominal amniocentesis is particularly suitable in
cases in which the pregnancy is not sufficiently advanced for safe induction
but the patient is in discomfort.
5.
Labour is usually normal but the midwife should be
prepared for the possibility of post partum hemorrhages.
6.
The baby should be carefully examined for
abnormalities and the potency of the oesophagus ascertained by passing
nasogastric tube.
This
means small volume of amniotic fluid. The quantity of amniotic fluid is
markedly diminished, of less than 500ml and sometimes as less as 60ml.
Oligohydramnios
is most often associated with poor placental function and fetal growth
retardation. Severe Oligohydramnios is seen with obstructive lessons of the
fetal urinary tract and with renal agenesis, if diagnosed in early pregnancy.
In some
cases the cause is unknown. The fetus has little room to move and at times will
cause compression deformities e.g. talipes and ankytosis of joints
·
The uterus appears smaller than expected for the
period of gestation.
·
Reduction in fetal movement
·
Intra uterine growth retardation.
·
On palpation, the uterus is small and compact and
fetal parts are easily felt.
·
Ultrasound scanning will confirm diagnosis
The woman
may be admitted to hospital. Check the woman for the possibility of preterm
rupture of the membranes by careful questioning.
When
fetal abnormality is considered not to be lethal, or the cause of the
Oligohydramnios is not known, prophylactic amnioinfusion with normal saline,
Ringer’s lactate or 5% glucose may be performed in order to prevent compression
deformities.
Labour
may be induced because of the possibility of placental insufficiency. Epidural
analgesia may be indicated because uterine contractions are unusually painful
with this condition.
Continuous
fetal heart rate monitoring is desirable as fetus is prone to hypoxia.
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