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Innovative Use of An Amnioport to Maintain Amniotic Fluid Volume In Fetuses with Lower Urinary Tract Obstruction

Saturday, October 20, 2012: 2:03 PM
Grand Ballroom A/B (Hilton Riverside)
William Polzin, MD1, Pramod Reddy, MD2, Timothy Crombleholme, MD3, Mounira Habli, MD1 and Foong-Yen Lim, MD4, (1)Division of Fetal Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, (2)Division of Pediatric Urology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, (3)Department of Pediatric Surgery, Children's Hospital Colorado, Aurora, CO, (4)Division of Pediatric Surgery and Fetal Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH

Purpose:   One of the therapeutic aims of fetal interventions (FI) of lower urinary tract obstruction (LUTO) has been to restore amniotic fluid volume (AFV) in order to promote pulmonary development. Despite several proposed FI, pulmonary hypoplasia due to oligohydramnios remains a major cause of neonatal demise. Recently, a Cochrane review showed that serial amnioinfusion (AI) in fetuses with oligohydramnios due to premature rupture of membranes had an 80% reduction in pulmonary hypoplasia, neonatal demise and sepsis. Serial AI is associated with an increased rate of preterm delivery due to infection, bleeding and chorioamnion separation. The objective of this study was to develop and test the efficacy of an innovative amnioport (AP) utilizing a MediPort system to avoid the complications associated with serial AI in patients with anhydramnios due to LUTO.

Methods: A prospective interventional study was undertaken by our Fetal Care Center. AP was offered to five consecutive LUTO patients with normal karyotype and anhydramnios who opted to undergo FI. The protocol was approved by the IRB, and informed consent was obtained. The AP was placed at the conclusion of the FI, the catheter was tunneled to a subcutaneous pocket where the reservoir was implanted. Post-operative monitoring was performed with serial ultrasounds and AI with lactated ringers solution via the AP was undertaken to maintain the AFV in a normal range.

Results: A total of five patients had AP implanted. At initial presentation, 60% (3/5) had evidence of fetal renal failure by urine analysis, ultrasound and fetal MR imaging. Mean gestational age (GA) at time of placement of the AP was 25 weeks (range 22-30 weeks). The five patients required a total of six AP one was replaced after the catheter became dislodged and was extra-amniotic. The mean volume infused was 384 ml (range 298 457 ml) and the mean number of AI procedures performed was 10.8 (range 2-21). All five fetuses survived the procedure (FI + AP placement) with five live births, two neonate subsequently expired. The mean gestational age at delivery was 33 5/7weeks (range 31-37 weeks). Of the three surviving infants, none required oxygen supplementation, however 66% (2/3) developed renal failure and progressed onto dialysis. In our series, there were no severe maternal complications.

Conclusions: Enhanced fetal monitoring and peri-operative management have permitted improved survival outcomes with FI in the management of fetal LUTO. Failure to replenish the AFV after FI in cases of LUTO is a predictor of fetal renal failure and lethal pulmonary hypoplasia. The proactive placement of an AP to facilitate AI during the remainder of the pregnancy can improve the survival rates. In our experience implantation of the AP and serial AI had minimal morbidity to the mother.