There is evidence that amniotic fluid arginine vasopressin is a marker for foetal stress in rhesus erythroblastosis.

Abstract

In response to different stress stimuli the foetal neurohypophysis releases arginine vasopressin (AVP). Part of the AVP is cleared from circulation by urinary excretion into the amniotic fluid (AF). Increased AF AVP levels may therefore indicate foetal stress, all the more because AF AVP solely is of foetal origin. We therefore studied AF AVP levels in 13 patients with rhesus erythroblastosis from 22 to 34 weeks of gestation. Twenty-eight patients from 14 to 34 weeks of gestation served as controls. The AVP levels were measured by RIA. Spectral absorption curves were performed and delta/E values determined at 450 nm. Mean AF AVP levels in controls were 2.39 pg/ml and were not normally distributed. There was no significant change in AF AVP levels with different gestational age. If in rhesus erythroblastosis patients the delta/E value was low (n = 7; x = 0.048 +/- 0.007 SE), the AF AVP values were not increased. If the delta/E values were within zone III (n = 6; x = 0.22 +/- 0.035 SE), indicating severe haemolysis, the AF AVP levels were significantly elevated (4.7 pg/ml +/- 0.51 SE; P = 0.001). Linear regression analysis showed a significant correlation between delta/E and AF AVP values (P = 0.05; y = 1.94 +/- 10.88 x). We conclude that there is evidence for the role of AF AVP as a marker for foetal stress in rhesus erythroblastosis.