STRONGSubmersion Therapy for the Reversal of Oligohydramnios; A Non-invasive Gentle Approach

BACKGROUND: The volume of amniotic fluid is relevant clinically as derangements that decrease volume result in a condition known as oligohydramnios, which can have profound implications on perinatal outcome. The incidence of oligohydramnios is 2.3%1,2,3 and measurements of amniotic fluid volume (AFV) has become a standard in fetal surveillance in the evaluation of high risk pregnancies as oligohydramnios is associated with intrauterine growth restriction, respiratory distress syndrome, post-maturity syndrome, and chronic fetal hypoxia. Oligohydramnios may also play a role in fetal malpresentation, umbilical cord compression, meconium staining, and increased operative delivery.3,4, 5,6 Oligohydramnios is commonly defined as an AFV of 5 cm or less. An AFV of 8 cm represents the fifth percentile of normal AFV values.7 It has been observed that delivery in the setting of isolated oligohydramnios, irrespective of an otherwise uncomplicated term gestation free of maternal disease, has become routine thereby increasing maternal morbidity particularly in context of operative delivery or failed inductions. 3 In order to understand oligohydramnios it is first important to understand intrauterine water and progressive changes that occur with normal human gestation. At term, it is reported that total water accumulation is approximately 3.5L, with 2400 mL in the fetus, 400 mL in the placenta, and 700 mL in the amniotic fluid.8 In 1989, Brace and colleagues determined amniotic fluid volume (AFV) as a function of gestational age. They reported an increase in mean values from 30mL at 10weeks to 190mL at 16wks to 780mL at 32-35wks after which time AFV decreases, especially in post-term pregnancies. It is important to realize; however, that the pattern of volume fluctuation as a function of gestational age may vary considerably between individuals. As a general rule AFV increases at a rate of 10ml/wk at the beginning of the fetal period, this rate of expansion increases to 50-60ml/wk from 19 to 25wks at which time a gradual decrease begins to take place until the rate of exchange is zero around 34wks. The pathophysiology of amniotic fluid regulation is not entirely understood at this current date, but it is safe to state that AFV is the integrated sums of the inflow and outflow tracts of the amniotic space.8 Because fluid can move with relative ease between fetal and maternal blood across the placenta and amniotic membranes it stands to reason that a maternal hypovolemia secondary to dehydration would lead to the development of oligohydramnios. This was indeed shown to be the case by Sherer, et al in their 1990 publication. Furthermore, both oral and serum hydration as a way to increase maternal volume have been shown to be effective treatments for oligohydramnios.3,11-16