EFFECT OF MATERNAL HYDRATION ON OLIGOHYDRAMNIOS - A COMPARISON OF 3 VOLUME EXPANSION METHODS

Objective: To determine the effect of maternal hydration with intraven ous (IV) isotonic fluid, IV hypotonic fluid, and oral water on amnioti c fluid index (AFI) in women with oligohydramnios. Methods: Patients w ith low AFI and gestational age over 35 weeks without maternal complic ations were randomized into four groups (2 L/2 h IV isotonic fluid, 2 L/2 h IV hypotonic fluid, 2 L/2 h oral water, control). Maternal plasm a osmolality, AFI, hematocrit, and hemoglobin concentration were measu red before and after hydration. Results: Eighty-four patients (n = 21/ group) completed the study without any maternal adverse effects. The m ean increase in AFI after hydration was significantly greater in the I V hypotonic and oral water groups (2.8 +/- 1.9, P < .001; 3.8 +/- 1.9, P < .001, respectively), but not in the IV isotonic group (0.5 +/- 1. 1), compared with the control group (0.5 +/- 1.1). Significant decreas es in maternal hematocrit and hemoglobin concentration were found only after IV isotonic hydration (32.0 +/- 2.9 to 29.5 +/- 2.3, P < .001; 11.0 +/- 1.6 to 10.1 +/- 1.4, P < .001, respectively). Changes in mate rnal osmolality correlated with the changes in AFI in both the IV hypo tonic group (r = .58, P < .001) and oral water group (r = .63, P < .00 1). Conclusion: Maternal hydration with either IV hypotonic fluid or o ral water increases AFI in oligohydramnios. Maternal osmotic change ra ther than maternal volume expansion had a more direct impact on increa sing amniotic fluid volume with short-term acute hydration.(Obstet Gyn ecol 1998;92:525-9. (C) 1998 by The American College of Obstetricians and Gynecologists.).