Is there a relationship to dye determined or ultrasound estimated amniotic fluid volume adjusted percentiles and fetal weight adjusted percentiles?

Amniotic fluid and the clinical relevance of the sonographically estimated amniotic fluid volume: oligohydramnios

The amniotic fluid volume (AFV) is regulated by several systems, including the in-tramembranous pathway, fetal production (fetal urine and lung fluid) and uptake (fetal swallowing), and the balance of fluid movement via osmotic gradients. The normal AFV across gestation has not been clearly defined; consequently, abnormal volumes are also poorly defined. Actual AFVs can be measured by dye dilution techniques and directly measured at cesarean delivery; however, these techniques are time-consuming, are invasive, and require laboratory support, and direct measurement can only be done at cesarean delivery. As a result of these limitations, the AFV is estimated by the amniotic fluid index (AFI), the single deepest pocket, and subjective assessment of the AFV. Unfortunately, sonographic estimates of the AFV correlate poorly with dye-determined or directly measured amniotic fluid. The recent use of color Doppler sonography has not improved the diagnostic accuracy of sonographic estimates of the AFV but instead has led to overdiagnosis of oligohydramnios. The relationship between the fixed cutoffs of an AFI of 5 cm or less and a single deepest pocket of 2 cm or less for identifying adverse pregnancy outcomes is uncertain. The use of the single deepest pocket compared to the AFI to identify oligohydramnios in at-risk pregnancies seems to be a better choice because the use of the AFI leads to an increase in the diagnosis of oligohydramnios, resulting in more labor inductions and cesarean deliveries without any improvement in peripartum outcomes.

Peripartum outcomes of high-risk pregnancies complicated by oligo- and polyhydramnios: a prospective longitudinal study

AIM

To determine pregnancy outcomes in high-risk non-anomalous singleton pregnancies with oligo- and polyhydramnios.

METHODS

In high-risk pregnancies undergoing antenatal testing, the last amniotic fluid index (AFI) prior to delivery in pregnancies with polyhydramnios (>97.5th percentile) and oligohydramnios (<2.5th percentile) was correlated with pregnancy outcomes.

RESULTS

There were 2597 pregnancies with a normal AFI (2.5th-97.5th percentile), 73 with hydramnios (AFI > 97.5th percentile) and 72 with oligohydramnios (<2.5th percentile). Polyhydramnios and oligohydramnios adversely influenced different pregnancy outcomes. Pregnancies with polyhydramnios versus normal AFI were more likely to have: an abnormal tracing influencing delivery (29% vs 17%, odds ratio [OR] = 2.03, 95% confidence interval [CI] 1.19-3.45, P = 0.009), cesarean delivery performed due to fetal labor intolerance (21% vs 7%, OR = 3.89, 95%CI 2.10-7.18, P < 0.001), increased birthweight (P = 0.016), Apgar score <7 at 5 min (8% versus 1%, OR = 6.41, 95%CI 1.12-16.22, P = 0.001) and newborn intensive care unit admission (10% versus 5%, OR = 2.24, 95%CI 1.12-4.49, P = 0.023). Pregnancies with oligohydramnios versus normal AFI had a greater risk of labor induction (18% vs 9%, OR = 3.18, 95%CI 1.62-6.25, P = 0.001), intrauterine growth restriction (25% vs 9%, OR = 3.4, 95%CI 1.94-5.97, P < 0.001) and preterm delivery (29% vs 17%, OR = 1.97, 95%CI 1.17-3.31, P = 0.010).

CONCLUSIONS

Fetal heart rates influencing delivery, cesarean deliveries for fetal labor intolerance, low 5-min Apgar scores, increased neonatal birthweight, and newborn intensive care unit admissions were more common with polyhydramnios. The fetuses of pregnancies complicated by oligohydramnios had a greater risk of labor induction, intrauterine growth restriction and preterm delivery.

Antepartum fetal testing: a critical appraisal

PURPOSE OF REVIEW

Recognition of the fetus at risk for death or damage in utero, quantifying the risk, balancing fetal risk against the risk of neonatal complications from immaturity and determining optimal time and mode of intervention, is a cornerstone of modern perinatal medicine. Antepartum fetal testing is essential in making these crucial decisions. The art and science of fetal assessment is fluid. In this treatise, the evolution of testing is reviewed, test accuracy results examined and suggestions for future applications are considered.

RECENT FINDINGS

Composite testing of a range of fetal biophysical variables is an excellent predictor of fetal acidemia and risk of death or damage. Confusion regarding the optimal means of measuring one of these variables, amniotic fluid volume, has been addressed in the literature and contemporary studies from several independent sources indicate that the amniotic fluid index method should be abandoned in favor of the maximal vertical pocket method. It is becoming increasingly more evident that a spectrum of fetal testing modalities based on interrogation of different aspects of fetal adaptive responses to adversity is preferable in fetal testing. Further it is evident that in some fetal diseases, such as intrauterine growth restriction, fetal condition may change acutely and accordingly best outcome is achieved by much more frequent testing. The question of whether intervention for fetal compromise can prevent subsequent neurological sequelae remains open.

SUMMARY

There has been remarkable advancement in identifying the fetus at risk. The concept of multispectral combined fetal testing including acute biophysical variables, amniotic fluid volume and arterial and venous Doppler flow velocity waveforms is established.

Outcome of children born out of pregnancies complicated by unexplained polyhydramnios

Our aim was to assess the long-term outcomes of infants born out of a pregnancy complicated by unexplained polyhydramnios. We retrospectively analysed a cohort of 173 singleton pregnancies with polyhydramnios. There were 24 singletons with unexplained polyhydramnios, defined as polyhydramnios where prenatal testing was negative. Infants were examined by a paediatrician at a median age of 12 months (range 12-64 months). Of the 24 infants, 19 (79%) had a normal outcome. West syndrome, polyuria and pulmonary stenosis were diagnosed in three children during follow up, while there were two perinatal deaths. Paediatric follow up of children born out of pregnancies complicated by unexplained polyhydramnios should be carried out systematically.