Oligohydramnios – How Low Can You Go?

What is Oligohydramnios?

We all know about amniotic fluid by now and how vital it is during these nine months. It should always be at an optimum level and if this level lowers, the condition is known as oligohydramnios.

How is it measured?

In your routine ultrasound, your gynecologist checks for two parameters:

  • amniotic fluid index (AFI) : < 5cm is little and >25 cm is excess.
  • deep pocket measurement: where the single deep pocket (SDP) or maximum vertical pocket (MVP) is most commonly assessed (SDP >7-8 cm may be considered to be polyhydramnios and SDP <2-3 cm as oligohydramnios).

Diagnosis of oligohydramnios :

Apart from the reduced AFI and SDP/MVP values, other symptoms indicating oligohydramnios are:

  • Leaky fluids due to rupture of membranes (checked by sterile speculum test).
  • Reduced movements of the baby.
  • Fluid volume < 500ml (at 33-36 weeks of pregnancy).

Causes of oligohydramnios :

  • Rupture of membranes (leak due to tear in the amniotic membrane)
  • Partial abruption of the placenta
  • Carrying twins
  • Systemic problems in the mother like: Pre-eclampsia, dehydration, diabetes, chronic hypoxia, lupus etc.
  • Medications for the mother: High blood pressure drugs like ACE inhibitors
  • Abnormalities in the developing fetus (especially the urinary system where urine is not properly formed)
  • Pregnancy past the due-date

How does oligohydramnios affect the baby?

Based on when it occurs during pregnancy, the effects on the baby varies

Oligohydramnios during the first half of pregnancy:

The complications seen are:

  • Birth defects due to impaired growth/compression of the developing baby’s organs
  • Miscarriage (within week 20 of pregnancy)
  • Stillbirth (after week 20 of pregnancy)
  • Premature birth (before week 37 of pregnancy)

Oligohydramnios during the second half of pregnancy:

The complications seen are:

  • Premature birth (before week 37 of pregnancy)
  • Slow fetal growth
  • Intrauterine growth restriction (IUGR)

Oligohydramnios during labor:

The complications seen are:

  • The release of meconium in the distressed baby, further leading to respiratory/breathing problems when inhaled
  • Lowered heart rate, increased carbon-di-oxide in the blood and damage to the growing brain leading to defects (caused by the compression of the umbilical cord).

 

 

 

 

 

 

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Aishwarya

Dr. Aishwarya Rajeev has completed her MDS degree and is currently pursuing her PhD. She is an avid reader and loves to teach and write!

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