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Perinatal Outcome After Diagnosis of Oligohydramnious at Term


1 Department of Obstetrics and Gynecology, Tehran University of Medical Sciences Tehran, Tehran, IR Iran
2 Zabol Medicinal Plants Research Center, University of Medical Sciences, Zabol, IR Iran
3 Nursing and Midwifery School, Zabol Medical Sciences University, Zabol, IR Iran
*Corresponding Author: Khadije Rezaie Keikhaie, Department of Obstetrics and Gynecology, Tehran University of Medical Sciences Tehran, Tehran, IR Iran. Tel: +98-9158535428,, E-mail: rezaie.khadije@ymail.com.
Iranian Red Crescent Medical Journal. 16(5): e11772 , DOI: 10.5812/ircmj.11772
Article Type: Research Article; Received: Apr 25, 2013; Accepted: May 18, 2013; epub: May 5, 2014; collection: May 2014

Abstract


Background: Oligohydramnious is a threatening condition to fetal health for which some treatment are available, and some are under evaluation. Oligohydramnious, is associated with increased pregnancy complications, congenital anomalies, and perinatal mortality. There is an inverse relationship between the amniotic fluid index (AFI), and the adverse perinatal outcome. Oligohydramnious is clinical condition characterized by amniotic fluid index (AFI) of 5 cm or less. Its incidence is 3-5% of all the pregnancies an accurate and reproducible method of determining abnormality in amniotic fluid volume (AFI) is sonographic assessment of amniotic fluid index (AFI). It often increases the risk of small-for gestational age (SGA) and also the incidence of cesarean section, meconium stained, low Apgar score and neonatal intensive care unit (NICU) admission.

Objectives: This study aimed to analyze the fetal outcome in low-risk pregnant women with oligohydramnious at term. This is a prospective, descriptive study.

Materials and Methods: The study was conducted at Amiralmomenin Hospital in Zabol for a period of 8 months from March 27, 2012 to November 05, 2012. It included 100 pregnant women diagnosed with the AFI of 5 cm or less at term. Control group included 300 pregnant women with AFI more than 8cm. Comparison was done between the two groups. Detailed data, regarding the fetal and pregnancy outcome, were recorded in terms of fetal weight, Apgar score at 1 and 5 min, using chi-square and p value.

Results: Mode of delivery, NICU admission neonatal death and induction of labor. Oligohydramnious is associated with a high rate of pregnancy complications and increased perinatal morbidity and mortality. Women with oligohydramnious usually have low-birth babies.

Conclusion: However, we can expect a safe and good outcome for pregnant women with oligohydramnious, should proper fetal surveillance and regular antenatal care visits be prepared.

Keywords: Amniotic Fluid Index; Apgar Score; Birth Weight

1. Background


Amniotic Fluid (AF) is an important component of pregnancy sac and helps fetal development. Amniotic Fluid has a number of prominent functions like protects the fetus from trauma, maintains body temperature and development of musculoskeletal system by permitting fetal movements, growth and development of intestinal tract (by swallowing amniotic fluid), and it provides essential nutrients to fetus (1). There is a gradual increase in its volume with advancing gestation until approximately 31-33 week followed by a significant decrease toward and beyond the estimated date of confinement. At term (37 week and beyond ) the average volume is approximately 750 mL, but volume decrease rapidly after the 40th week (2). Oligohydramnious was defined as an amniotic fluid index (AFI) ≤ 5 cm (3, 4). In 1990, Moore and Cayle defined oligohydramnious as an AFI below the 5th percentile for the gestational age (5). Its incidence is 2.3% of all the pregnancies (6). In 2005, Leeman et al. reported that oligohydramnious occurs in about 1% to 5% of pregnancies at term (7). Assessment of amniotic fluid volume by ultrasonography is more reliable (8). It is calculated as the sum of the deepest vertical dimension in each quadrant of the uterus (2, 9).

Oligohydramnious is associated with increased pregnancy complications, congenital anomalies and perinatal mortality (6) and it may be associated with uteroplacental insufficiency, idiopathic fetal growth restriction (IUGR), premature rupture of the fetal membranous, fetal hypoxia , meconium stained fluid and or postmaturity syndrome (10). Oligohydramnious can also be an idiopathic finding in a woman who had low risk pregnancies and no medical or fetal complication (7). Sequel of oligohydramnious can be fetal demise, pulmonary hypoplasia, facial and skeletal deformities. Reduced amniotic fluid may predispose to umbilical cord occlusion and increase the risk of fetal hypoxemia and will affect the Apgar score of baby at birth (11). It has been observed that antepartum or intrapartum AFI ≤ 5 cm is associated with a significant increase in risk of lower segment caesarean section for fetal distress and low Apgar score at 5 minute (Apgar score < 5) (12). Patients with AFI ≤ 5 cm should be admitted to the hospital (13). Determination of the optimal time of delivery is necessary and labor should not be prolonged (14). Oligohydramnious is the late sign of malnutrition. Inadequate nutrition is the second important cause of IUGR and associated complications (15). Current local practices rely heavily on AFI estimation, particularly in the management of prolonged pregnancy and IUGR (16-18). The role of AFI as an isolated predictor on the fetal outcome needs to be checked not only in prolonged pregnancies, but also in other frequency managed high-risk pregnancies.

2. Objectives


The purpose of this study was to assess low amniotic as a predictor of perinatal outcome at low-risk pregnancies at term.

3. Materials and Methods


This case-control prospective study was conducted at Amiralmomenin hospital in Zabol for a period of 8 months from March 27, 2012 to November 05, 2012. Pregnant women were divided into two groups. 100 consecutive pregnant women with AFI ≤ 5 cm with low risk pregnancies at term were included in group A, then 300 pregnant women with AFI ≥ 5 cm and AFI ≤ 20 cm were included in group B. Inclusion criteria were women with singleton, term, non-anomalous pregnancies with intact membrane evidence of IUGR, previous cesarean section, post-term pregnancies, previous perinatal loss, recurrent missed abortion, medical disorder like diabetes mellitus, hypertension, and cardiac disease were excluded from this study. Both groups were matched for age, parity, gestational age and intact membranes. All women were followed up until delivery and pregnancy and perinatal outcome were recorded using chi-square (x2), and P value was calculated to determine the statistical significance.

4. Result


During the study period, there were 100 Patient with AFI ≤ 5cm and 300 Patient with AFI > 5 cm. Maximum numbers of women were in the age group of 25-35 year (46.9%). About 49% of women in oligohydramnious group were primigravida. Cesarean section was done in 20.2% of participants in group A and in 8.6% of the women in the control group (Table 1).

Table 1.
Pregnancy and Perinatal Outcome a,b

There was a significant difference regarding the cesarean section rate between two groups. So that the odds ratio in oligohydramnious group was 2.79:1 with respect to the control group. Also, the cause of cesarean section was statistically different between two groups so that the fetal distress in oligohydramnious group 4.01 times greater than control group. There was an increased incidence of SGA among women with oligohydramnious and control groups, so that in oligohydramnious group, SGA was 1.91% greater than the control group. There was statistically significant difference in the rate of labor induction between two groups, so that the induction of labor in oligohydramnious group was 3.22 times greater than control group and There was no difference in incidence of instrument delivery (Apgar score < 7 at 0 and 5 minutes) between two groups and also no difference found regarding the length of stage in NICU.

5. Discussion


Estimation of amniotic fluid volume is an integral part of antenatal surveillance (19). Low volume of amniotic fluid carries an increased risk of intrapartum complications at high-risk pregnancies (6, 20). Relationship between sonography detected oligohydramnious and perinatal morbidity, and mortality has been well established by Manning and Platt (21). Garmel et al. reported that 67% of women with oligohydramnious were nulliparous (22), likewise Jandial et al. reported that 66% of women were nulliparous (23). While we observed that 49% of our studied women were primigravida. Chauhan et al. (12) concluded that AFI < 5 cm is associated with increased risk of caesarean section for fetal distress and low Apgar Score at 5 minutes. In this study, 20.2% of women were delivered by caesarean section. Results of Umber (24) and Jandial et al. (23) showed a significant increase in the incidence of caesarean section and nonreassuring fetal heart rate in women with low AFI. In this study, 20.2% of women were delivered by caesarean section. Sarno et al. (25) noted a significantly higher rate of fetal distress and low Apgar score in women with AFI of 5 cm. Golan et al. (26) reported a low Apgar score at 5 minutes in 4.6 babies in contrast to a figure of 9.9% noted by us. Casey et al. (6) reported 6.4% perinatal death, while we conducted in 5.9% perinatal death. Meconium staining is an indicator of fetal distress and has its own complication in the newborn. In this study, there was no significant difference in the incidence of meconium between two groups. These results were consistent with certain studies (24, 27). To conclude, oligohydramnious is associated with high rate of pregnancy complications and increase perinatal morbidity and mortality. We believe that assessment of AFI antepartum, and intrapartum would help to identify women who need more antepartum surveillance for pregnancy complications. Women with oligohydramnious usually have low-birth weight babies but can expect the safe and good outcome for which proper fetal surveillance and regular antenatal care visits are required.

Acknowledgments

Researchers are grateful to all the patients who participated in the research study, which may not have been done without their assistance.

References


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Table 1.

Pregnancy and Perinatal Outcome a,b

Oligohydramnious GroupControl Group
Caesarean section20 (20.2)26 (8.6)
Distress9 (8.9)7 (2.4)
Birth weight less than 2.5 kg29 (29)53 (17.6)
Induction42 (42)38 (12.6)
Apgar scoreless than 7 at 5 minutes8 (4.7)14 (4.7)
Use by(1) 13 (1)
Admitted to the NICU(1) 10 (0)
a Abbreviation: NICU, neonatal intensive care unit.
b Data are presented as number No. (%).