Anhydramnios

Anhydramnios is a term where there is a complete or near-complete lack of amniotic fluid (sometimes referred to as "liquor volume").

Pathology

Anhydramnios can result in a number of situations:

• fetal renal tract anomalies
  • Potter syndrome (bilateral renal agenesis): most common 
  • large ureterocoele: if capable of causing bilateral renal tract obstruction ⁶
  • posterior urethral valves: with severe/complete obstruction ¹
• preterm premature rupture of membranes (PPROM)
• placental insufficiency ⁴
• silent uterine rupture ⁴
• nimesulide therapy (single report only ⁵)
• chemotherapeutic agents administered during pregnancy
  • trastuzumab/paclitaxel ³

Radiographic features

Antenatal ultrasound

Typically shows a complete absence of amniotic fluid around the fetus. Color Doppler interrogation may be of value in selected cases when loops of cord around the fetus mimic amniotic fluid ². However demonstration of vascularity within the same can help differentiate the loops from amniotic fluid. Visualization of fetal structures can sometimes be very difficult due to the absence of amniotic fluid.

Complications

• fetal akinesia deformation sequence with the development of pulmonary hypoplasia if anhydramnios has been present for a long period

See also

• oligohydramnios