The fetal outcome in pregnancies with isolated reduced amniotic fluid volume in the third trimester

Hourly fetal urine production rate in isolated oligohydramnios at term

OBJECTIVE

The aim of this study was to evaluate the hourly fetal urine production rate (HFUPR) via three-dimensional ultrasonography in women with isolated oligohydramnios and compare with normal pregnant women at term.

MATERIALS AND METHODS

This was a prospective observational cohort study of 112 women from 34 to 40 6/7 weeks' gestation. They were classified into three groups according to the amniotic fluid index (AFI) and ultrasonographic estimated fetal weight (EFW) as isolated oligohydramnios (defined as AFI below 5% and appropriate EFW corresponding to gestational age) (n = 34) and IUGR (defined as EFW below 5% corresponding to gestational age irrespective amniotic fluid) (n = 17), and normal pregnancy (n = 61). HFUPR was measured using three-dimensional virtual organ computer-aided analysis. Adverse perinatal outcomes in all participants were examined.

RESULTS

There was no significant difference in HFUPR between patients with isolated oligohydramnios and women with normal pregnancies (median, 40.0 mL/h [interquartile range [IQR] 31.0-66.5] vs. 48.6 [31.5-81.2], p = 0.224). HFUPR was significantly decreased in the IUGR group (13.8 mL/h [IQR 10.1-24.8]), compared to the normal pregnancy group (p<0.001) and the isolated oligohydramnios group (p<0.001). HFUPR was significantly decreased in neonates with adverse perinatal outcomes compared to the control (24.7 mL/h [IQR 13.4-47.4] vs. 43.6 [29.8-79.0], p = 0.016).

CONCLUSION

HFUPR was not decreased in patients with isolated oligohydramnios but was decreased in patients with IUGR when compared to normal controls at term.

Isolated oligohydramnios and long-term neurological morbidity of the offspring

This study aimed to assess the association between maternal-isolated oligohydramnios (IO) and offspring long-term neurological complications. A population-based retrospective cohort study was conducted, including all births at a single tertiary medical center in Israel between the years 1991 and 2014. Multiple pregnancies and potential pregnancy complications associated with oligohydramnios were excluded. The computerized obstetrical database was linked with the computerized dataset of all pediatric hospitalizations of the same medical center. Evaluation of cumulative neurological-associated hospitalizations rate over time was compared using a Kaplan-Meier survival curve. The Weibull survival parametric model was conducted to assess the neurological-associated hospitalization risk in the presence of IO, while accounting for potential confounders. A total of 190,259 pregnancies were included in the study, of which 4063 (2.13%) pregnancies were complicated with IO. Total neurological-related hospitalizations were significantly more common in the IO group (3.7% in the IO group and 3.0% in the comparison group, p = 0.005). Pervasive developmental disorder, movement disorders, developmental disorders, and degenerative and demyelization disorders were all specific neurological diagnoses significantly more common in the exposed group. The survival curve demonstrated a significantly higher cumulative hospitalization rate in the exposed group (log-rank p = 0.001). Using a multivariate model adjusting for gestational age, maternal age, and labor induction, an independent association between IO and long-term neurological morbidity of the offspring was observed (adjusted hazard ratio 1.203; 95% CI 1.02-1.42). In summary, a significant association was found between pregnancies complicated by IO and long-term neurological morbidity of the offspring.

Maternal and perinatal outcomes of induction of labor in oligohydramnios at term-a retrospective cohort study

Objective: To evaluate the maternal and perinatal outcomes of labor induction in women at term with oligohydramnios.Methods: A retrospective cohort of women with a singleton pregnancy, who had oligohydramnios at or beyond term (37-42 weeks) and underwent induction of labor for oligohydramnios were studied. Antenatally diagnosed fetal anomalies and intrauterine fetal demise were excluded. The women were categorized into two groups: 1) women with isolated oligohydramnios (n = 166) and 2) women with oligohydramnios associated with other maternal or fetal complications (n = 43). Maternal and perinatal outcomes were collected from the records of all deliveries, data compiled, and appropriate statistical tests were applied.Results: The study included 209 women with mean gestational age of 38.76 ± 1.00 weeks and mean induction-delivery interval of 17.45 ± 8.70 hours (16.98 hours in group 1 versus 19.23 hours in group 2). Most (75%) women delivered vaginally. Only one of the neonates had an Apgar score of less than 7 at 5 min. Average neonatal ICU length of stay was 5.52 days (5.27 days in group 1 versus 6.17 days in group 2). Among all the maternal and neonatal outcomes studied, only the mean birth weights among the two groups was found to be statistically significant (p = 0.0017).Conclusions: Women with isolated oligohydramnios and their neonates were not found to suffer any additional harm due to labor induction at term than women who had oligohydramnios associated with other complications.

Delivery mode and perinatal outcomes after diagnosis of oligohydramnios at term in China

Objective: The purpose of this study is to assess the incidence of oligohydramnios at term and evaluate whether the mode of delivery in patients with oligohydramnios influences perinatal outcomes in China.Methods: A cross-sectional survey of all deliveries in 39 hospitals in China from 1 January 2011-31 December 2011 was evaluated for the mode of delivery and perinatal outcomes in women with oligohydramnios compared to those without known oligohydramnios after excluding preterm births, polyhydramnios, and oligohydramnios secondary to premature rupture of membranes.Results: Oligohydramnios complicated 3954 (4.4%) of the 89,050 pregnancies, analyzed. Pregnancy cases with oligohydramnios compared those without known oligohydramnios had a significantly higher incidence of preexisting or gestational diabetes mellitus, fetal growth restriction, nonreassuring fetal heart tracings, obesity and malpresentation (p<.001). The cesarean delivery (CD) rate was significantly higher in pregnancies with identified oligohydramnios compared to those without (84.4 versus 54.7%; p<.001). Furthermore, in 2/3 of these CD in pregnancies with oligohydramnios, the identification of oligohydramnios was the only indication for the CD. In pregnancies with oligohydramnios, vaginal delivery did not significantly increase the risks of adverse outcomes compared to vaginal delivery without oligohydramnios, except postpartum complication.Conclusion: CD is not indicated in term pregnancies with isolated oligohydramnios. Vaginal delivery of oligohydramnios is not associated with increased perinatal mortality.

Short-term outcome among term singleton infants with intrapartum oligohydramnios

AIM

To evaluate rates of early short-term neonatal complications among term singleton newborn infants with oligohydramnios.

METHODS

Retrospective data were collected on 456 term infants with prenatal diagnosis of oligohydramnios and on matched controls, including information on maternal condition and on infant perinatal complications.

RESULTS

Infants in the study group were born with lower birthweight and were SGA compared with those in the control group. Rates of renal malformations were significantly higher in the study group compared with the controls (15-3.3% and 3-0.7%, respectively; p = 0.007). Among the severe oligohydramnios subgroup (Amniotic Fluid Index <2), renal anomalies were even more prevalent compared to other infants with oligohydramnios and to the controls (6-9.8%, 9-2.3% and 3-0.7%, respectively; p < 0.001). The incidence of skeletal deformities (developmental dislocation of hip and torticollis) was higher among the study group.

CONCLUSION

Term infants with oligohydramnios that was detected near birth are associated with a greater prevalence of renal malformations (mostly mild hydronephrosis) as well as congenital torticollis and developmental dislocated hips compared with controls. Postnatal renal evaluation should be considered in infants with severe oligohydramnios.

Perinatal outcome in pregnancies complicated by isolated oligohydramnios diagnosed before 37 weeks of gestation

OBJECTIVE

To analyze pregnancy outcome in cases of isolated oligohydramnios at preterm.

METHODS

A retrospective cohort study of singleton pregnancies diagnosed with isolated oligohydramnios at preterm (n = 108). Pregnancy outcome was compared with a matched control group of low-risk preterm pregnancies with normal levels of amniotic fluid in a 3:1 ratio (n = 324).

RESULTS

Pregnancies complicated by isolated oligohydramnios were characterized by a higher rate of preterm deliveries (26.9% vs 12.3%, P < .001), most of which were iatrogenic, and a higher rate of labor induction and cesarean delivery. Neonates with isolated oligohydramnios were characterized by a lower birthweight and a higher rate of neonatal morbidity. These differences were eliminated when the analysis was limited to the subgroup of pregnancies with isolated oligohydramnios that were managed expectantly and delivered spontaneously at term.

CONCLUSION

Adverse pregnancy outcome in cases of isolated oligohydramnios diagnosed at <37 weeks appears to be related to a considerable degree to iatrogenic prematurity.

Obstetricians' attitudes towards ‘isolated’ oligohydramnios at term

Oligohydramnios at term in the absence of maternal and fetal complications poses a dilemma in management. It is one of the major indications for antenatal surveillance and induction of labour. There is a growing body of evidence that oligohydramnios in the absence of maternal or fetal risk factors ('isolated' oligohydramnios) is not associated with an adverse perinatal outcome. In this study, we surveyed the management of isolated oligohydramnios at term in a tertiary referral maternity unit. Out of 92 women who were scanned at term, 22 (24%) women had isolated oligohydramnios. A greater tendency to intervene in such cases was noted with 10 (45%) women having labour induced, while one (4.5%) had an elective caesarean section. Emergency caesarean section rates were also higher in the oligohydramnios group (13.5%) than in a low risk group (6%). There was no increased perinatal morbidity when compared with pregnancies managed expectantly.

Cesarean delivery for fetal distress: rate and risk factors

The objective of this article was to review the recent English language literature on cesarean delivery for fetal distress to determine its incidence, diagnostic tests, and the contributing factors to this obstetric complications. A PubMed search (1990-2000) with items of "cesarean, fetal distress," "cesarean, non-reassuring fetal heart rate," "cesarean, neonatal acidosis," and "cesarean, umbilical arterial pH," was undertaken. Reports, letters to the editor, focus on anomalous fetuses, and papers not specifically focused on this topic were excluded. Of the 392 articles that the search yielded, 169 met the inclusion criteria. Based on 37 reports with more than 1,000 patients each, the overall risk of prompt cesarean delivery for fetal concern was 3.1% (43,340 of 13,989,74). The risk exceeded 20% in patients with moderate/severe asthma, severe hypothyroidism, severe preeclampsia, and postterm or fetal growth restricted fetuses with abnormal Doppler studies. Use of likelihood ratios suggests that Doppler of the umbilical artery is a superior diagnostic test to amniotic fluid index in identifying parturients at risk for cesarean for non-reassuring fetal heart rate tracing. Although several risk factors increase the need for cesarean delivery for fetal distress, in general, most are unpreventable.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to estimate the incidence of cesarean delivery for non-reassuring fetal heart rate tracing, outline potential diagnostic tests that are useful for the detection of fetal distress, and summarize medical and obstetric conditions that place patients at risk for cesarean delivery for fetal distress.