Oligohydramnios Flashcards
What is oligohydramnios?
Oligohydramnios is a condition characterised by reduced amniotic fluid volume, with an amniotic fluid index (AFI) <5 cm or deepest pocket <2 cm.
What are the main functions of amniotic fluid?
Amniotic fluid cushions the fetus, allows for fetal movement, aids lung development, and maintains a stable temperature.
How is oligohydramnios diagnosed?
Diagnosis is made via ultrasound using the amniotic fluid index (AFI) or measurement of the deepest vertical pocket of fluid.
What are the causes of oligohydramnios?
Causes include fetal anomalies (e.g., renal agenesis), placental insufficiency, ruptured membranes, post-term pregnancy, and medications.
What fetal anomalies are associated with oligohydramnios?
Anomalies include bilateral renal agenesis, polycystic kidney disease, and obstructive uropathy.
How does placental insufficiency lead to oligohydramnios?
Placental insufficiency reduces blood flow to the fetus, decreasing urine production and hence amniotic fluid levels.
What maternal conditions can cause oligohydramnios?
Conditions include pre-eclampsia, chronic hypertension, and dehydration.
What medications can lead to oligohydramnios?
Medications such as NSAIDs and ACE inhibitors can reduce amniotic fluid by impairing fetal renal function or placental perfusion.
What are the complications of oligohydramnios for the fetus?
Complications include pulmonary hypoplasia, limb deformities, intrauterine growth restriction (IUGR), and increased risk of stillbirth.
What are the complications of oligohydramnios for labour and delivery?
Complications include umbilical cord compression, abnormal fetal heart rate patterns, and increased risk of operative delivery.
How is oligohydramnios managed antenatally?
Management includes regular ultrasound monitoring, addressing underlying causes, maternal hydration, and consideration of amnioinfusion.
When is delivery indicated in oligohydramnios?
Delivery is indicated if there is evidence of fetal compromise, term pregnancy, or persistent severe oligohydramnios despite management.
What is the role of amnioinfusion in oligohydramnios?
Amnioinfusion involves instilling fluid into the amniotic sac during labour to reduce cord compression and improve fetal heart rate patterns.
How does prolonged oligohydramnios affect lung development?
It can cause pulmonary hypoplasia due to insufficient space for lung expansion and reduced amniotic fluid swallowing.
What are the signs of oligohydramnios on clinical examination?
Signs include reduced symphysis-fundal height and difficulty palpating fetal parts due to lack of cushioning fluid.
What investigations are used in oligohydramnios?
Investigations include ultrasound assessment of amniotic fluid, fetal growth scans, Doppler studies, and maternal blood tests (e.g., infection screening).
What is the role of Doppler studies in oligohydramnios?
Doppler studies assess fetal and placental blood flow, helping to identify placental insufficiency or fetal compromise.
What are the risks of untreated oligohydramnios?
Risks include stillbirth, fetal distress during labour, and long-term musculoskeletal or pulmonary complications.
How is rupture of membranes distinguished from oligohydramnios?
Rupture of membranes is confirmed using tests like amniotic fluid crystallisation (ferning) or nitrazine testing.
What lifestyle modifications can help manage oligohydramnios?
Maternal hydration and avoiding medications that reduce amniotic fluid may help manage oligohydramnios.
What are the differential diagnoses for oligohydramnios?
Differential diagnoses include rupture of membranes, normal variation in fluid levels, and incorrect gestational dating.
What is the prognosis for oligohydramnios?
Prognosis depends on the underlying cause and gestational age at diagnosis; early intervention can improve outcomes.
How is oligohydramnios related to post-term pregnancy?
Post-term pregnancy increases the risk of oligohydramnios due to placental insufficiency and decreased amniotic fluid production.
What psychological support might be needed for women with oligohydramnios?
Women may need counselling to cope with anxiety and uncertainty, particularly if complications or interventions are required.
What is the significance of reduced fetal movements in oligohydramnios?
Reduced movements may indicate fetal distress or compromise, warranting urgent evaluation.
