Longitudinal measurement of amniotic fluid index in term pregnancies and its association with intrapartum fetal distress.

OBJECTIVE: The aim of the present study was to evaluate the dynamic changes in serially obtained amniotic fluid index values and to determine any association with intrapartum fetal distress in a term population. MATERIALS AND METHODS: All patients, > or = 40 weeks of gestational age, evaluated at the Institute of Obstetrics and Gynecology, 'G. Salesi' Hospital, University of Ancona, between January 1, 1994, and December 31, 1995, participated in this longitudinal study. Women with an amniotic fluid index of > 50 mm, who also demonstrated a reactive nonstress test, underwent semiweekly amniotic fluid assessment until spontaneous labor. After 42 gestational weeks, the patients underwent an elective induction of labor. All patients were managed with continuous electronic fetal heart rate monitoring throughout labor. The incidence of intrapartum fetal distress, and meconium staining of amniotic fluid were evaluated with respect to the amniotic fluid index. RESULTS: Of the 117 patients that were evaluated by ultrasound, 83 women had multiple amniotic fluid index measurements and were enrolled in the study. A serial decrease in amniotic fluid index was documented in 54 women; the mean decrease per week was 20.7 +/- 15.4%. An increase in amniotic fluid index was noted in 17, while 11 women showed no change in amniotic fluid index over time. The 14 patients who underwent cesarean section for fetal distress had a significantly lower amniotic fluid index (p < 0.001) at the last sonographic examination than the normal outcome group. Significant differences were also observed for a serial decrease in the amniotic fluid index within a week (p < 0.001). The sensitivity and specificity of the 30% serial decrease in the amniotic fluid index cutoff point, with respect to intrapartum fetal distress were 86 and 93%, respectively. CONCLUSION: Longitudinal measurement of the amniotic fluid index seems to be an effective method in predicting intrapartum fetal distress in a term population.

Prophylactic transabdominal amnioinfusion in oligohydramnios for preterm premature rupture of membranes: increase of amniotic fluid index during latency period.

OBJECTIVE: This study was designed to: (i) evaluate the effect of amnioinfusion on the latency period in patients with oligohydramnios for preterm premature rupture of membranes, and (ii) to investigate the relationship between changes in the amniotic fluid index and fetal heart rate short-term variability by computerized Hewlett-Packard cardiotocography, longitudinally estimated before and after prophylactic amnioinfusion. MATERIALS AND METHODS: All singleton pregnancies with prolonged premature rupture of membranes after 25 weeks of gestation and seen at the Institute of Obstetrics and Gynecology, University of Ancona (Italy), between January 1994 and June 1995 were included in the study. Transabdominal amnioinfusion with 150-350 ml warmed normal saline (25-50 ml/min) was performed at weekly intervals. Amniotic fluid volume was assessed ultrasonographically by means of the four-quadrant technique on a weekly basis before and after each amnioinfusion, as well as the short-term variability by a Hewlett-Packard computerized cardiotocographic system. RESULTS: 18 women were enrolled and underwent prophylactic transabdominal amnioinfusion at weekly intervals until delivery. Eighteen controls, who did not undergo prophylactic amnioinfusion, were recruited from our 1992-1993 series and included in the study. The median interval between premature rupture of membranes and delivery was 3.0 weeks (range 1-8 weeks), with an average delivery age of 33.0 weeks (range 27-36 weeks). The latency period was significantly longer in patients who underwent prophylactic amnioinfusion (mean +/- SD, 4.1 +/- 1.7 weeks) than in controls(1.7 +/- 1.0 weeks; p < 0.001). An increase in both the weekly amniotic fluid index (linear regression analysis r = 0.8, p = 0.03) and the weekly short-term variability (linear regression analysis r = 0.82, p = 0.02) was observed among patients who underwent prophylactic amnioinfusion. A direct relationship was observed between the amniotic fluid index and short-term variability (linear regression analysis r = 0.54, p = 0.04). The mean values of fetal movements recorded by computerized tomography during the 20 min of observation significantly increased after amnioinfusion in comparison with those before it (2.6 +/- 0.9 and 0.9 +/- 0.7 respectively; p = 0.001). CONCLUSION: The present study has shown a positive effect of prophylactic transabdominal amnioinfusion on the latency period in patients with preterm premature rupture of membranes and oligohydramnios. Among the patients who underwent amnioinfusion, an interesting improvement in fetal heart rate short-term variability was associated with the progressive increase in amniotic fluid volume, as an expression of fetal well-being.