• Oligohydramnios refers to amniotic fluid volume that is less than expected for gestational age. It is typically diagnosed by ultrasound examination and may be described qualitatively (eg, reduced amniotic fluid volume) or quantitatively (eg, amniotic fluid index ≤5 cm, single deepest pocket <2 cm). • Oligohydramnios may be idiopathic or have a maternal, fetal, or placental cause The fetal prognosis depends on several factors, including the underlying cause, the severity (reduced versus no amniotic fluid), and the gestational age at which oligohydramnios occurs. Because an adequate volume of amniotic fluid is critical to normal fetal movement and lung development and for cushioning the fetus and umbilical cord from uterine compression, pregnancies complicated by oligohydramnios from any cause are at risk for fetal deformation, pulmonary hypoplasia, and umbilical cord compression. • Oligohydramnios is associated with an increased risk for fetal or neonatal death, which may be related to the underlying cause of the reduced amniotic fluid volume or due to sequelae of the reduced amniotic fluid volume. • This topic will discuss issues related to oligohydramnios. Methods of amniotic fluid volume assessment are reviewed separately. • Oligohydramnios occurs when the amniotic fluid is < 5th centile for gestational age. • The most common causes are premature rupture of membranes (often missed by the mother) and placental insufficiency, however structural abnormalities such as renal agenesis should be considered. • Prognosis is linked to gestation at diagnosis and likely development of pulmonary hypoplasia and premature delivery. • Treatment is by optimising gestation of delivery

1. DR ALKA MUKHERJEE
MBBS DGO FICOG FICMCH PGDCR PGDMLS
MA(PSY)

2. INTRODUCTION
• DEFINITION • Oligohydramnios refers to a low level of
amniotic fluid during pregnancy.
• It is defined by an amniotic fluid index that is below
the 5th centile for the gestational age, and is thought to
affect approximately 4.5% of term pregnancies AJOC,
2004.
• AMNIOTIC FLUID VOLUME < 5 th percentile for
gestational age
• SINGLE VERTICAL POCKET < 2 cms • Amniotic fluid
volume of less than 500 mL at 32-36 weeks' gestation 8

3. • Oligohydramnios is a deficient volume of
amniotic fluid; it is associated with maternal
and fetal complications. Diagnosis is by
ultrasonographic measurement of amniotic
fluid volume. Management involves
• Close monitoring and
• Serial ultrasonographic assessments.

5. Amniotic fluid centiles during pregnancy. Polyhydramnios is over the
95th centile, oligohydramnios is below the 5th centile

6. Patho-physiology
• The volume of amniotic fluid increases steadily until 33
weeks of gestation. It plateaus from 33-38 weeks, and then
declines – with the volume of amniotic fluid at term
approximately 500ml.
• It is predominantly comprised of the fetal urine output, with
small contributions from the placenta and some fetal
secretions (e.g. respiratory).
• The fetus breathes and swallows the amniotic fluid. It gets
processed, fills the bladder and is voided, and the cycle
repeats. Problems with any of the structures in this pathway
can lead to either too much or too little fluid.
• Anything that reduces the production of urine, blocks output
from the fetus, or a rupture of the membranes (allowing
amniotic fluid to leak) can lead to oligohydramnios.

9. Aetiology
• The main causes of oligohydramnios are:
• Preterm prelabour rupture of membranes
• Placental insufficiency – resulting in the blood flow
being redistributed to the fetal brain rather than the
abdomen and kidneys. This causes poor urine output.
• Renal agenesis (known as Potter’s syndrome)
• Non-functioning fetal kidneys, e.g. bilateral
multicystic dysplastic kidneys
• Obstructive uropathy
• Genetic/chromosomal anomalies
• Viral infections (although may also cause
polyhydramnios)

10. Diagnosis
• Uterine size is much smaller than
the period of amenorrhoea
• Fewer fetal movements,
• The uterus "full of fetus" because
of scanty liquid,
• Malpresentation (breech)
• Evidences of IUGR of the fetus,
• Oligohydramnios with fetal
symmetric growth retardation is
associated with increased
chromosomal abnormality.

11. Diagnosis of Oligohydramnios
• The diagnosis of oligohydramnios is made via ultrasound
examination. There are two ways of measuring amniotic
fluid; amniotic fluid index (AFI) or maximum pool depth
(MPD). They have similar diagnostic accuracy, however
AFI is more commonly used.
• Sonographic diagnosis is made when largest liquid pool is
less than 2 cm,
• Visualization of normal filling and emptying of fetal
bladder essentially rule out urinary tract abnormality
• Amniotic fluid index is calculated by measuring
maximum cord-free vertical pocket of fluid in four
quadrants of the uterus and adding them together.
• Maximum pool depth is the vertical measurement in any
area.

12. Ultrasound image of normal fetal kidney. In cases of
oligohydramnios, the kidneys should be assessed.

13. • ULTRASOUND - Measure fetal size. Small
babies can result from placental insufficiency,
which also causes oligohydramnios.
• There may also be a rise in pulsatility index of
the umbilical artery Doppler in placental
insufficiency.
• Karyotyping (if appropriate) – particularly in
cases of early and unexplained
oligohydramnios.

14. Any abnormality seen on USG
E.g. FGR (estimated fetal weight < 10% for GA)—
• Unless previously done, perform a detailed fetal
anatomic survey -
• Serial ultrasound evaluations of the following: (1) Fetal
growth with Doppler velocimetry (every 3- 4 weeks) (2)
Biophysical profile with or without non-stress test
(weekly) along with umbilical artery Dopplers
• One course of antenatal corticosteroids between 24 and
34 weeks of gestation in the week before delivery is
expected
• Delivery at 38-39 weeks or sooner if abnormal results of
antepartum testing or co

15. • Consider a repeat fetal structural survey to
rule out possible missed a fetal malformation
• Non-stress test (NST)
• and AFI (or biophysical profile) once or twice
weekly until delivery
• For women with idiopathic oligo-hydramnios,
we suggest delivery at 36 to 37 completed
weeks of gestation rather than expectant
management

16. • Undetected fetal anomaly - A repeat
detailed sonographic evaluation
• Recommend offering karyotype analysis in
if knowledge of the karyotype will affect
management
• Spontaneous Bradycardia - Prolonged fetal
monitoring on labor and delivery triage
unit

18. Clinical Assessment
• Oligohydramnios is a diagnosis made via
ultrasound examination. Therefore, the clinical
assessment of the patient is directed at
establishing any underlying cause:
• History
– Inquire about symptoms of leaking fluid and feeling
damp all the time (often described as new urinary
incontinence).
• Examination
– Measure the symphysis fundal height.
– Perform a speculum examination (can a ‘pool’ of
liquor be seen in the vagina?).

21. • When considering ruptured membranes as a
cause for oligohydramnios, a bedside test
can be performed to detect the presence of
IGFBP-1 (insulin-like growth factor binding
protein-1) in the vagina.
• This protein is found in amniotic fluid, and if
detected, is strongly suggestive of membrane
rupture. The test is particularly useful if the
diagnosis is unclear.

22. Management
• The management of oligohydramnios is
largely dependent on the underlying
cause. The two most common causes are
rupture of the membranes and placental
insufficiency.

23. • Ruptured Membranes
• If oligohydramnios is due to ruptured
membranes, labour is likely to commence within
24-48 hours in most pregnancies.
• In cases of preterm rupture of membranes (i.e.
before 37 weeks’ gestation), and where labour
doesn’t start automatically, induction of labour
should be considered around 34-36 weeks (in the
absence of infection).
• A course of steroids should be given to aid fetal
lung development, and antibiotics to reduce the
risk of ascending infection.

24. Placental Insufficiency
• In women where oligohydramnios is caused
by placental insufficiency, the timing of
delivery depends on a number of factors:
• Rate of fetal growth
• Umbilical artery and middle cerebral artery
Doppler scans
• Cardiotocography
• These babies are likely to be delivered before
36-37 weeks

25. • Fetal death
• Intrauterine growth restriction
• Limb contractures (if
oligohydramnios begins early
in the pregnancy)
• Delayed or incomplete lung
maturation (if oligohydramnios
begins early in the pregnancy)
• Inability of the fetus to
tolerate labor, leading to the
need for cesarean delivery
• Risk of complications depends
on how much amniotic fluid is
present and what the cause is.
•Complications may include cord
compression, musculoskeletal
abnormalities such as facial distortion
and clubfoot, pulmonary
hypoplasia and intrauterine growth
restriction.
•Amnion nodosum is frequently also
present (nodules on the fetal surface
of the amnion
•The use of oligohydramnios as a
predictor of gestational complications
is controversial.
•Potter syndrome is a condition
caused by oligohydramnios. Affected
fetuses develop pulmonary
hypoplasia, limb deformities, and
characteristic facies. Bilateral agenesis
of the fetal kidneys is the most
common cause due to the lack of fetal
urine.
Complications

26. Treatment
• Serial ultrasonography to determine AFI and monitor fetal
growth
• Nonstress testing or biophysical profile
• Ultrasonography should be done at least once every 4 weeks
(every 2 weeks if growth is restricted) to monitor fetal growth.
The AFI should be measured at least once a week
• Most experts recommend fetal monitoring with nonstress
testing or biophysical profile at least once a week and delivery
at 36 to 37 weeks/6 days if oligohydramnios is isolated and
uncomplicated However, this approach has not been proved to
prevent fetal death.
• Also, optimal time for delivery is controversial and can vary
based on patient characteristics and fetal complications.

27. Treatment
• A Cochrane review concluded that "simple maternal
hydration appears to increase amniotic fluid volume and
may be beneficial in the management of oligohydramnios
and prevention of oligohydramnios during labour or prior
to external cephalic version."
• In severe cases oligohydramnios may be treated
with amnioinfusion during labor to prevent umbilical cord
compression. There is uncertainty about the procedure's
safety and efficacy, and it is recommended that it should
only be performed in centres specialising in invasive fetal
medicine and in the context of a multidisciplinary team
• In case of congenital lower urinary tract obstruction, fetal
surgery seems to improve survival, according to
a randomized yet small study.

28. • Prognosis
• Oligohydramnios in the second trimester carries a poor
prognosis.
• In the majority of these cases, there is premature rupture of
membranes (which may or may not be associated with
infection), with subsequent premature delivery and pulmonary
hypoplasia – which can cause significant respiratory distress at
birth
• When oligohydramnios is associated
with placental insufficiency, there is also a higher rate
of preterm deliveries (usually through planned induction of
labour). These cases will carry a poorer prognosis than that of
a normally grown fetus.
• Amniotic fluid also allows the fetus move its limbs in utero
(exercise). Without this, the fetus can develop severe muscle
contractures – which may lead to disability despite
physiotherapy after birth.

31. • Oligohydramnios can be caused by uteroplacental
insufficiency, drugs, fetal abnormalities, or premature
rupture of membranes.
• It can cause problems in the fetus (eg, growth
restriction, limb contractures, death, delayed lung
maturation, inability to tolerate labor).
• If oligohydramnios is suspected, determine the amniotic
fluid index and test for possible causes (including doing
a comprehensive ultrasonographic evaluation).
• Do ultrasonography a least once every 4 weeks, and
consider fetal monitoring at least once a week and
delivery at term (although optimal time for delivery
varies).
Summary