Case: Oligohydramnios

Question

a) Complication of oligohydramnios

b) How to detect

c) Management

Definition

Reduce in AFI <5 style=""> [additional of vertical amniotic fluid pocket depths volume in four quadrant.] Some specialist may consider AFI <8>

Amniotic fluid production

A) Production of amniotic fluid is from

1. Inward transfer of solute across the amnion with water following passively in early gestation.

2. Water transport across the highly permeable skin of the fetus during the first half of gestation (keratinization of skin at 22-25W)

3. Baby's urination (first starts at 8-11W and is major source of production. it is recycled when baby swallows it)

4. Secretion of large volumes of fluid each day by the fetal lungs after second half of gestation (2nd source)

B) Increase amniotic fluid from 8-43W gestation linearly until 32W (700-800 mL-constant until term)

-C) After 40W, declines at rate 8% per week until 300ml at 42W

Causes

1) PROM or PPROM

2) fetal urinary tract anatomy (renal and ureter most common)

3) Uteroplacental insufficiency

4) Pulmonary hypoplasia

Complication

In the term or post-term gestation, oligohydramnios is frequently associated with thick meconium(a/w Meconium Aspiration), deep decelerations in the fetal heart rate, and the dysmaturity syndrome. One team reported a 13-fold increase in perinatal mortality rate (to 57/1,000) when the sonogram showed amniotic fluid volume to be marginal, and a 47-fold increase (to 188/1,000) with severe oligohydramnios.

In 62 cases of second-trimester oligohydramnios, another team reported a 43% perinatal mortality rate, with lethal pulmonary hypoplasia complicating 33% of cases. If amniotic fluid was essentially absent ("anhydramnios"), 88% had lethal outcomes, compared with 11% of those with moderate fluid reductions.

Diagnosis

- Via ultrasound

Management

Other Investigation

1) intrauterine instillation of dye to diagnose PROM[confirmation if the dye is found in the vagina]

2) Furosemide test to visualize fetal bladder

Others

1) Amnioinfusion of 200 ml Normal saline

2) Maternal rehydration.

3) frequent fetal biophysical testing and appropriately timed delivery

4) Rule out fetal structural and chromosomal anomalies

5) Earlier delivery in baby incompatible with life.

Notes: risk of fetal asphyxia and death is high in IUGR