Oligohydramnios Causes, Symptoms, Radiology, Treatment and Complications

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Oligohydramnios Definition

Oligohydramnios is low amniotic fluid level below 500ml. There are many causes of Oligohydramnios with their complications; whereas Anhydramnios is the complete absence of amniotic fluid this condition is very rare. Incidence of Oligohydramnios is about 1:750 pregnancies.

Oligohydramnios Causes

  1. Severe preeclampsia this causes placental insufficiency
  2. Post-term pregnancy also causes placental insufficiency
  3. Congenital Renal agenesis (detected by empty fetal bladder on serial ultrasonic scanning)
  4. Obstruction of the urinary tract in a fetus (such as in congenital anomalies)
  5. Premature rupture of membranes (PROM)
  6. Drugs such as Indomethacin, Enalapril, Captopril, Lisinopril

Oligohydramnios Pathophysiology

Any cause of placental insufficiency or malformation affecting the urinary tract of a fetus causes Oligohydramnios.

Oligohydramnios Symptoms and signs

  1. Symphysio-Fundal Height (SFH) will be small for gestation age
  2. The fetus is in hyperflexed attitude
  3. Breech presentation is common
  4. Uterus feels full of fetus
  5. Reduced fetal movements

Oligohydramnios Radiology

  1. Ultrasound scan will show small amniotic fluid locules that measures <1x1cm. Ultrasound shows reduced amniotic fluid index of <2cm columns. It is important to exclude congenital anomalies, growth retardation and identify fetal presentation
  2. X-ray will show hyperflexion of the fetal spines

Oligohydramnios Treatment

  1. When Oligohydramnios occurs in post-term, then delivery is indicated
  2. When Oligohydramnios occurs during labour, there is need to check fetal distress as it is more common and if it is found to be present, immediate vaginal or abdominal delivery according to the circumstances should be carried out.

Oligohydramnios Complications

  1. Pulmonary hypoplasia: the amniotic fluid is very important in the development of the lungs as it helps in lung distension, reduction in the amniotic fluid level therefore causes pulmonary hypoplasia.
  2. Abnormal fetal development: causes Intrauterine growth restriction (IUGR) this occurs as a result of compression of uterine wall and adherent fetal parts
  3. Abnormal attitude and presentation of the fetus: breech presentation are common
  4. High rate of fetal abnormalities such as dislocated hips, limps amputation and talipes
  5. High fetal death rate
  6. Causes Preterm labour