POLYHYDRAMNIOS - FINAL MBBS REVISION

[lakshmidr]

OVERVIEW
• Polyhydramnios refers to excessive accumulation of amniotic fluid — the fluid that surrounds the baby during pregnancy inside the womb.
• Incidence of polyhydramnios is about 1 to 2 percent of pregnancies and it is associated with increased perinatal mortality and morbidity
• Most cases are mild and occur due to gradual accumulation of amniotic fluid during the second half of pregnancy.
• The earlier during pregnancy that hydramnios occurs, the higher the risk of complications

ETIOLOGY OF POLYHYDRAMNIOS
• Maternal diabetes
• Developmental defect of baby’s digestive system or brain defect
• Blood incompatibility between mother and fetus
• Twin-twin transfusion — wherein one twin receives too much blood and the second twin has reduced blood flow
• Deficiency of red blood cells in the baby (fetal anemia)
• Maternal infection during pregnancy

COMPLICATIONS OF POLYHYDRAMNIOS
• Preterm labour and birth
• Premature rupture of membranes
• Shortness of breath in mother (due to pressure on diaphragm)
• Stillbirth
• Fetal malpresentation
• Big baby if mother is diabetic
• Placental abruption (abruptio placentae) — when the placenta separates from its attachment to the inner layer of the uterus before delivery
• Prolapsed umbilical cord
• Higher risk of C-section delivery
• Hypertensive disorders of pregnancy
• Maternal UTIs
• Excessive hemorrhage due to poor uterine muscle tone following delivery

DIAGNOSIS OF POLYHYDRAMNIOS
1. ULTRASOUND IMAGING
• In suspected cases of hydramnios an ultrasound imaging of the abdomen is done to assess the amniotic fluid volume.
• If initial assessment detects excess amniotic fluid, then a more detailed assessment is performed to determine the single largest pocket of amniotic fluid around the baby. An amniotic fluid volume (AFV) of 8 cm or more is suggestive of hydramnios
• Another method is to measure the four largest amniotic fluid pockets in different parts of the uterus and add these measurements to arrive at the amniotic fluid index (AFI). An AFI of 25 cm or more indicates polyhydramnios
• Additional detailed ultrasound imaging tests to rule out birth defects in the baby

2. MATERNAL BLOOD TESTS
To rule out infections associated with polyhydramnios (TORCH) and gestational diabetes

3. AMNIOCENTESIS
A sample of amniotic fluid is obtained by introducing a needle via the abdomen. The sample contains fetal cells and chemicals secreted by the fetus and analysis of the sample helps to identify chromosomal abnormalities in the fetus

4. NON-STRESS TEST/BIOPHYSICAL PROFILE
These are special tests to determine baby’s heart rate, breathing and tone when it moves (to assess fetal condition/distress)

TREATMENT OF POLYHYDRAMNIOS
• Mild polyhydramnios requires no treatment
• Treatment of maternal infections and management of maternal diabetes
• Drainage of excess amniotic fluid
• Giving Indomethacin to reduce fetal urine production (not advised beyond 28 weeks of gestation)
• In mild polyhydramnios, the pregnancy may proceed uneventfully to term with close monitoring
• In severe hydramnios, appropriate timing of delivery will be decided by the doctor to reduce maternal and fetal complications

TAKEAWAYS
• Polyhydramnios diagnosed by ultrasound
• If positive, further maternal and fetal diagnostic tests are conducted.
• Exclude maternal gestational diabetes and perform maternal ToRCH screening
• Detailed imaging of fetus to rule out birth defects.
• Delivery in a perinatal center under specialist is advised for optimal outcome