Is amnioinfusion for intrapartum variable decelerations effective? Evaluation of the total deceleration area: A retrospective cohort study.

Objective: Data regarding the efficiency of amnioinfusion in the presence of recurrent variable decelerations (VD) are limited. Total deceleration area (TDA) has been shown to be a useful indicator of both intrapartum fetal acid-base status and neonatal morbidity. The aim of the present study was to evaluate the effectiveness of amnioinfusion during labor for decreasing the TDA in deliveries complicated by recurrent VD.

Methods: Departmental protocol is to perform amnioinfusion after 30 min of recurrent VD, if decelerations continue despite intrauterine resuscitation. Electronic fetal monitoring of these labors was analyzed. TDA was calculated for 30 min before and after amnioinfusion, as the sum of the area under the curve for each deceleration using the formula (heart rate change in BPM*time in seconds)/2.

Results: Among 131 deliveries, 44.3% resulted in vaginal delivery, 22.1% in vacuum extraction, and 33.6% in cesarean delivery (CD). Patients who had CD had higher rates of nulliparity (P = 0.004), meconium (P = 0.017), and fever (P = 0.034). Median TDA before amnioinfusion was 8430 (505-14 321) versus 3591 (1297-7371) after amnioinfusion, P < 0.001. Amnioinfusion led to a 57.4% reduction in median TDA, regardless of umbilical cord entanglement, although the decrease was more substantial without cord entanglement (74.0% vs. 51.8%). Amnioinfusion reduced TDA in both nulliparas (59.4%, P < 0.001) and multiparas (59.0%, P < 0.001). In a subgroup of patients with normal amniotic fluid index upon admission to labor, amnioinfusion also decreased TDA (median TDA 9189 [5322-14 774] before amnioinfusion and 3621 [1321-7581] after, P < 0.001).

Conclusions: Amnioinfusion effectively reduced TDA in deliveries complicated with recurrent VD and can be used to alleviate intrapartum VD regardless of parity, amniotic fluid volume or cord entanglement. Prospective trials would help elucidate the clinical significance of post-amnioinfusion reduction in the TDA and maternal and fetal outcomes.