Polyhydramnios Flashcards
Define Polyhydramnios
- AFV of 2,000 mL or greater at term
- DVP is greater than or equal to 8 cm
- AFI is above the 95th percentile for the particular gestational age
- AFI is more than or equal 25 cm
Degrees of polyhydramnios are based on
he measurement of the largest vertical pocket of liquor.
What is mild polyhydramnios
Largest vertical pocket of liquor measures 8–11 cm
AFI: 25.0–29.9 cm
What is moderate polyhydramnios
Largest vertical pocket of liquor measures 12–15 cm
AFI: 30–34.9 cm
What is severe polyhydramnios
Largest vertical pocket of liquor measures >16 cm
AFI: >35
What is the incidence of polyhydramnios
0.2-3.9%
Define the course of amniotic fluid when it starts increasing, reaching plateau and declining
- ** Increases up to: 33 Weeks
- Plateau: 33-38 Weeks
- Declining: 38-42 Weeks**
Factors affect Amniotic fluid balance
amniotic fluid production
* fetal urine production
* secretions from the respiratory tract
* oral secretions
amniotic fluid removal
* fetal swallowing
fluid dynamics across the membranes
* transfer across the placenta, umbilical cord, and fetal skin (intramembranous flow)
* across the fetal membranes (transmembranous flow)
Abnormality of these mechanisms leads to excessive accumulation of AF.
Methods for assessment of amniotic fluid
Ultrasound evaluation of the amount of amniotic fluid:
* deepest vertical pocket (DVP)
or
* amniotic fluid index (AFI)
The AFI is calculated by
obtaining a sum of the vertical dimensions of four quadrants of the uterus without any cord ot limb meausred
Normal: 5-25
DVP is calculated by
(Single deepest pocket) the largest visible pocket of amniotic fluid without any limb or cord measured
Normal: 2-8 cm
Most common cause of polyhydramnios in sigleton pregnancy
Idiopathic 60%
Most common fetal complication of mother uses lithium
Fetal nephrogenic diabetes insipidus
Most common Known cause of polyhydramnios in sigleton pregnancy
Maternal Diabetes
How Maternal DM causes polyhydramnios
Pederson’s Hypothesis:
Maternal Hyperglycemia leads to fetal hyperglycemia and hyper-insulinemia leading to polyuria by osmotic action