Nonimmune hydrops fetalis: a heterogeneous disorder and therapeutic challenge

Nonimmune hydrops fetalis part I: etiology and pathophysiology

Nonimmune hydrops fetalis (NIHF) is a condition in which excess fluid has accumulated in the fetal interstitial spaces as a result of one or more nonimmune factors. A plethora of maternal, placental, and fetal disease processes have been associated with NIHF. Knowledge of the various etiologies of NIHF and how the disease process affects fluid homeostasis is important for planning patient care and counseling families of patients diagnosed with nonimmune hydrops fetalis. This article discusses the mechanisms governing fluid distribution in the extracellular spaces, examines the various etiologies associated with NIHF, and describes the pathogenesis of NIHF for each etiologic category.

Nonimmune hydrops fetalis part II: does etiology influence mortality?

Hydrops fetalis is a condition in which there is an excess of total body fluid, primarily within the fetal interstitial spaces. Etymologically, hydrops fetalis is a Latin term meaning "edema of the fetus." In addition to generalized edema, the fetus has at least one of the following: ascites, pericardial effusion, pleural effusion(s), and an abnormally thick (>6 cm) placenta. Hydrops is classified as nonimmune hydrops fetalis (NIHF) when it occurs without evidence of isoimmunization.

Characterization of newborns with nonimmune hydrops fetalis admitted to a neonatal intensive care unit

PURPOSE

To determine the incidence and characteristics of nonimmune hydrops fetalis in the newborn population.

METHOD

A retrospective study of the period between 1996 and 2000, including all newborns with a prenatal or early neonatal diagnosis of nonimmune hydrops fetalis, based on clinical history, physical examination, and laboratory evaluation. The following were analyzed: prenatal follow-up, delivery type, gender, birth weight, gestational age, presence of perinatal asphyxia, nutritional classification, etiopathic diagnosis, length of hospital stay, mortality, and age at death.

RESULTS

A total of 47 newborns with hydrops fetalis (0.42% of live births), 18 (38.3%) with the immune form and 29 (61.7%) with the nonimmune form, were selected for study. The incidence of nonimmune hydrops fetalis was 1 per 414 neonates. Data was obtained from 21 newborns, with the following characteristics: 19 (90.5%) were suspected from prenatal diagnosis, 18 (85.7%) were born by cesarean delivery, 15 (71.4%) were female, and 10 (47.6%) were asphyxiated. The average weight was 2665.9 g, and the average gestational age was 35 3/7 weeks; 14 (66.6%) were preterm; 18 (85.0 %) appropriate delivery time; and 3 (14.3%) were large for gestational age. The etiopathic diagnosis was determined for 62%, which included cardiovascular (19.0%), infectious (9.5%), placental (4.8%), hematologic (4.7%), genitourinary (4.8%), and tumoral causes (4.8%), and there was a combination of causes in 9.5%. The etiology was classified as idiopathic in 38%. The length of hospital stay was 26.6 +/- 23.6 days, and the mortality rate was 52.4%.

CONCLUSIONS

The establishment of a suitable etiopathic diagnosis associated with prenatal detection of nonimmune hydrops fetalis can be an important step in reducing the neonatal mortality rate from this condition.

Extracorporeal life support for nonimmune hydrops fetalis

BACKGROUND/PURPOSE

Most babies born with idiopathic nonimmune hydrops fetalis (NIHF) suffer generalized cardiopulmonary collapse and die despite maximal medical therapy. With reported survival rates of less than 10%, many centers consider NIHF an unsalvageable situation and the babies who have this condition, untreatable. In this study, the authors questioned if the aggressive use of extracorporeal life support (ECLS) could salvage this condition and improve the chances of survival for babies born with NIHF.

METHODS

The Extracorporeal Life Support Organization's (ELSO) neonatal registry was searched for all available information on babies treated for hydrops fetalis. The ELSO records of all hydropic babies were then reviewed to exclude those babies who had identifiable causes of hydrops. Survival statistics were then calculated for the remaining core group of idiopathic NIHF babies before separating them into two groups based on survival. A detailed analysis comparing the survivors with nonsurvivors was then performed.

RESULTS

A total of 28 hydropic babies were identified in the ELSO registry. Four babies were excluded from analysis because of identifiable causes of hydrops (two with congenital diaphragmatic hernia, one with Rh incompatibility, and one with fetal anemia). Of the remaining 24 babies who had NIHF, 54% (13 babies) survived the neonatal period and were discharged from the hospital. Analysis comparing the survivors with the nonsurvivors in our study showed that the groups were similar in their gestational ages, birth weights, Apgar scores and the time to initial intubation. The most distinguishing factor of survival in our study was that the survivors, on average, received ECLS support 3 days sooner than nonsurvivors (mean, 17.5 +/- 1.3 hours of life for survivors v 105 +/- 36.6 hours for nonsurvivors, P < or = .05).

CONCLUSION

Idiopathic NIHF should no longer be considered an untreatable condition but a new indication for ECLS that, when begun early, may significantly improve the chances of survival for these babies previously considered "unsalvageable."