Hydramnios

Question 1

What is amniotic fluid composed of?

Answer 1

98% water and 2% solids (organic and inorganic)
Organic - proteins, carbohydrates, lipids, enzymes, hormones, bilirubin and vitamins
Inorganic - Na, K, Ca, Mg, Cl, Fe, Co, bicarbonate and phosphate

Question 2

What are the functions of amniotic fluid?

Answer 2

Foetal lung, GI and renal development 
Protection of fetus and umbilical cord against pressure and trauma
Barrier against infection
Keeps the temperature consistent 
Acts a lubricant

Question 3

Where does amniotic fluid originate?

Answer 3

Maternal plasma and interstitial fluid that diffuses across the amniochorinic membrane. Later is mainly through placenta
Fetal:
10th week - transudate from fetal serum via skin & umbilical cord
12th week - fetal lungs and urine production by kidneys
16th week - completely dependent on fetal urine

Question 4

How is amniotic fluid decreased?

Answer 4

Fetal swallowing around the 12th week

Question 5

What is the normal volume of amniotic fluid?

Answer 5

12 weeks: 50 ml
24 weeks: 500 ml
36 weeks: 1000 ml
The normal range at term in a singleton pregnancy is large —500–1500 ml

Question 6

What is the definition of polyhydramnios?

Answer 6

Polyhydramnios is an amniotic fluid index of >25cm or a deepest vertical pool of >8cm
Mild - 25cm - 30cm
Moderate - 30cm - 35cm
Severe - >35cm

Question 7

What is the definition of oligohydramnios?

Answer 7

Oligohydramnios is an amniotic fluid index of <5 or a deepest vertical pool of <2cm

Question 8

What is the incidence of polyhydramnios and oligohydramnios?

Answer 8

Oligohydramnios - 4%

Polyhydramnios - 1%

Question 9

What are causes of polyhydramnios?

Answer 9

Idiopathic 66%
Maternal - diabetes 15%

Fetal;
Anencephaly
Neuromuscular abnormality
Oesophageal atresia
Duodenal atresia
Multiple gestations

Question 10

What are causes of oligohydramnios?

Answer 10

Idiopathic

Maternal:
PROM
NSAID use

Fetal:
Renal agensis
Multicystic kidneys
Urinary tract abnormalities
FGR & placental insufficiency

Question 11

What is the presentation of polyhydramnios?

Answer 11

History
• Tenseness of abdomen
• Unable to lie comfortably in any position
• Dyspnoea, indigestion, piles and varicose veins
• Decreased sensation of fetal movements

Examination
• Increased symphysio-fundal height
• Very tense, larger for date uterus
• Difficult to feel any fetal parts
• Difficult to hear FHR
• Possible malpresentation and non-egagement
• Fluid thrill can be elicited.

Question 12

What is the presentation of oligohydramnios?

Answer 12

History
• NSAID use

Examination:
• Decreased symphysio-fundal height
• Uterus small for date
• Foetal poles felt easily (hard to touch)
• FHR easy to hear
• Fetus not ballotable

Question 13

What are 3 differential diagnosis for polyhydramnios?

Answer 13

1 - Multiple pregnancy: laxer feel to uterus and too many fetal parts felt.
2 - Ovarian cyst: uterus and cervix displaced downwards while polyhydramnios elevates pregnancy out of pelvis
3 - Full bladder - caused when uterus is incarcerated in pelvis

Question 14

What investigations would you do for polyhydramnios?

Answer 14

Glucose tolerance test

U/S
Fetal deglutition, esophageal and duodenal atresia, arrhythmias, lung masses
An abnormally large abdominal circumference may be observed with ascites and hydrops fetalis
A macrosomic fetus is observed in association with poorly controlled maternal diabetes

Question 15

What investigations would you do for oligohydramnios?

Answer 15

Screen for PIH and pre-eclampsia
Check for PROM - chronic leak
U/S - Visualize the fetal kidneys, collecting system, and bladder.
U/S - Placental insufficiency

Question 16

What is the management of polyhydramnios?

Answer 16

Depends on cause and severity
• If due to poorly controlled diabetes - treat diabetes
Treat only severe polyhydramnios
• Amniocentesis - 500 - 1000ml over 4-8hrs
• Indomethacin (NSAID, COX 1 &2 inhibitor) showed to be successful in 50% of idiopathic cases
• Schedule weekly or twice weekly perinatal visits and cervical examinations
• Place patients on bed rest to decrease the likelihood of preterm labor
• Perform serial ultrasonography to determine the AFI and document fetal growth

Question 17

What is the management of oligohydramnios?

Answer 17

• Evaluation for PROM by using indigo carmine
• Amnioinfusion
• Maternal bed rest
• Hydration

Question 18

Complications of polyhydramnios?

Answer 18

Antepartum:
• Spontaneous Abortion
• Preterm labour
• Malpresentation

Intepartum: 
• Premature rupture of membranes
• Cord prolapse
• Abruptio placentae
• Postpartum haemorrhage

Feotal Complications
• Prematurity
• Asphyxia due to cord prolapse or placental abruption

Question 19

Fetal complications of oligohydramnios

Answer 19

Abortion
Prematurity
Pulmonary Hypoplasia
Musculoskeletal Deformities
Malpresentations
Fetal distress

Question 20

Maternal complications of oligohydramnios

Answer 20

Increased morbidity
Prolonged labour
Increased risk of operative intervention