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ORIGINAL ARTICLE
Year : 2019  |  Volume : 32  |  Issue : 2  |  Page : 476-482

Predictive value of fetal renal artery Doppler indices in idiopathic oligohydramnios and polyhydramnios


1 Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Obstetrics and Gynecology, El-Galaa Maternity Hospital, Cairo, Egypt

Date of Submission25-Jul-2018
Date of Acceptance02-Sep-2018
Date of Web Publication25-Jun-2019

Correspondence Address:
Kyrillos NF Fahmy
Quesna, Menoufia
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_220_18

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  Abstract 


Objective
The aim of this work was to study the relation of renal artery (RA) and umbilical artery (UA) flow velocity waveforms and amniotic fluid volume in normal pregnancies and those complicated by either polyhydramnios or oligohydramnios.
Background
There is a relation between RA and UA flow velocity waveforms and amniotic fluid volume in normal pregnancies and those complicated by either polyhydramnios or oligohydramnios.
Patients and methods
All patients were enrolled from patients attending the outpatient clinic of El-Galaa Maternity Teaching Hospital. All patients were matched for maternal age, gestational age, and parity at the time of sonography, comparing RA Doppler indices pulsatility index (PI) and resistance index at 22, 28, and 34 weeks in three groups. Group I consisted of 20 patients of normal amniotic fluid index, group II consisted of 20 patients with oligohydramnios, and group III consisted of 20 patients with polyhydramnios.
Results
RA PI values were higher in group II than group I at 22 weeks, 28 weeks, and 34 weeks. The PI value at 28 weeks of gestation was statistically significant (P = 0.016). At 28 weeks of gestation, group II also had higher UA PI and resistance index values than group I.
Conclusion
An increase in RA PI develops in early pregnancy before the development of oligohydramnios. In pregnancies developing polyhydramnios, RA PI was lower.

Keywords: amniotic fluid index, fetal renal artery Doppler, fetal umbilical artery Doppler, oligohydramnios, polyhydramnios


How to cite this article:
Sanad ZF, Abdel Gaied AM, Dawod RM, Mahmoud HS, Fahmy KN. Predictive value of fetal renal artery Doppler indices in idiopathic oligohydramnios and polyhydramnios. Menoufia Med J 2019;32:476-82

How to cite this URL:
Sanad ZF, Abdel Gaied AM, Dawod RM, Mahmoud HS, Fahmy KN. Predictive value of fetal renal artery Doppler indices in idiopathic oligohydramnios and polyhydramnios. Menoufia Med J [serial online] 2019 [cited 2019 Sep 21];32:476-82. Available from: http://www.mmj.eg.net/text.asp?2019/32/2/476/260889




  Introduction Top


In the second and third trimesters of pregnancy, amniotic fluid volume is an indicator of fetal well-being and is an important measurement during antenatal fetal testing. Amniotic fluid volumes have been described as oligohydramnios if the actual volume of the amniotic fluid is less than 500 ml or as polyhydramnios if the volume is more than 2000 ml[1]. However, the definition of normal amniotic fluid has previously been made according to each gestational age. Moore and Cayle[2] published some normative data for amniotic fluid index throughout pregnancy and noted that the mean amniotic fluid index changed weekly. Oligohydramnios or polyhydramnios are characteristic features of structural and functional anomalies and signal to the health care provider that additional assessments or antenatal testing is required[3]. Oligohydramnios has been associated with abnormalities, such as meconium staining, congenital anomalies, growth retardation, dysmaturity, and fetal asphyxia[4],[5]. Polyhydramnios has been associated with fetal structural abnormalities, aneuploidy, and macrosomia[6]. There are many causes of polyhydramnios, such as diabetes mellitus, isoimmunization, fetal infections, and placental abnormalities, but most (50–60%) of the polyhydramnios cases appear to be idiopathic[7]. An increased or decreased amniotic fluid volume is also thought to be a factor in the increased incidence of complications during labor, an approximately twofold increased risk of operative delivery and cesarean section for nonreassuring fetal heart rate patterns, and adverse perinatal outcome[5],[8]. Using ultrasound imaging, the fetal renal circulation can be assessed. Intermittent assessment of renal artery (RA) flow velocity waveforms during the early stages of pregnancy may help in predicting changes in amniotic fluid dynamics. The current study sought to determine the relation of RA and umbilical artery (UA) flow velocity waveforms in normal pregnancies and pregnancies complicated by either polyhydramnios or oligohydramnios.


  Patients and Methods Top


Informed consent was taken from the patients regarding participation in the study according to policy of the Menoufia University hospitals, which necessitates no harmful procedure to be performed or used for any patient. An approval of the study was taken from El-Galaa Maternity Teaching Hospital.

All patients were subjected to thorough clinical evaluation with emphasis on full medical and surgical history. The clinical examination included general examination (height-weight-vital data) and abdominal examination (inspection size of the abdomen). The laboratory investigations were the usual in the department of obstetrics and gynecology in El-Galaa Maternity Hospital, Cairo, Egypt, for all cases (complete blood count, liver function tests, kidney function tests, prothrombin time, partial thromboplastin time, international normalized ratio, random blood sugar, and ECG).

All patients were enrolled from those attending the outpatient clinic in El-Galaa Teaching Hospital from July 2017 to January 2018 for this case–control study. The inclusion criteria were age of patients between 22 and 45 years, single viable intrauterine pregnancy, and gestational age between 22 and 40 weeks, whereas the exclusion criteria were any patient with additional comorbidities, known fetal congenital malformations, and pregnant women who were diagnosed with fetal karyotype abnormalities by history taken from the patients of prior fetal karyotype abnormalities in previous pregnancies, major fetal anomalies, and fetal renal anomalies.

Sample size was determined by grouping the patients into three groups. The first group was the control one of 20 patients who had normal uterine size and normal amniotic fluid index. The patients with abnormal uterine size in the clinical examination were 189 patients. By ultrasonography, six patients were excluded as they were found to have multiple pregnancies, whereas 183 patients were found to have single pregnancies. By detecting the amniotic fluid index in the single pregnancies patients, 121 normal index patients were excluded, whereas 29 patients found to have oligohydramnios and 33 patients were found to have polyhydramnios. We included 20 patients only from the patients with oligohydramnios, and they were the second group; the other nine patients with oligohydramnios were excluded as they had some abnormalities. We included only 20 patients as well from the patients with polyhydramnios, representing the third group; the other 13 patients with polyhydramnios were excluded as they were found to have some anomalies [Figure 1].
Figure 1: Flow chart of participants.

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Women were divided into three groups:

  1. Group I were included 20 women with normal amniotic fluid
  2. Group II were included 20 women with oligohydramnios
  3. Group III were included 20 women with polyhydramnios.


This is a case–control study. The steps of performance and technique used are as follows:

  1. After fulfillment of the aforementioned criteria and prerequisites, all the eligible patients were divided into three groups:


    1. RA and UA Doppler values were evaluated at 22, 28, and 34 weeks of gestation. Pulsatility index (PI) and resistance index (RI) were recorded, and the amniotic fluid volume was evaluated using Voluson, General Electric (GE), a health care company situated in Vienna, Austria
    2. Fetal biometric measurements were obtained, and placental structure and the amniotic fluid amount were evaluated in four quadrants. After detailed ultrasonography of the fetus, eligible pregnant women were included in the study
    3. Pulsed wave Doppler sonographic studies were performed in the participants placed in the left lateral position with a 3.5-MHz convex transducer. The wall filter was set at the lowest available setting (50–75 Hz) to preserve the end-diastolic component of the waveform
    4. The angle between the ultrasound beam and the direction of blood flow (BF) was maintained below 30°. All recordings were obtained in the absence of fetal breathing and fetal movements. An average of three consecutive Doppler velocity waveforms was used for analysis
    5. For evaluating RA BF, an axial image of the fetal abdomen was obtained at the level of the fetal kidneys. Using color flow Doppler, the renal arteries were evaluated at the level of their origin from the abdominal aorta. The Doppler gate was placed within the lumen in a straight segment of the vessel
    6. A minimum of three consecutive waveforms were used to calculate the PI and RI. The UA Doppler measurements were studied in a free loop of cord, far from the fetus and placenta. PI and RI values were recorded
    7. Amnion fluid volume of less than 2 cm in a single quadrant by vertical measurement or less than 5 cm total in four quadrants was considered to be oligohydramnios[9]
    8. Amnion fluid volume of more than 25 cm total in four quadrants was considered to be polyhydramnios[10].


Statistical analysis

Recorded data were analyzed using the statistical package for social sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean ± SD. Qualitative data were expressed as frequency and percentage.

The following tests were done:

  1. A one-way analysis of variance when comparing between more than two means
  2. Kruskall–Wallis H-test was used for multiple-group comparisons in nonparametric data
  3. χ2-Test of significance was used to compare proportions between two qualitative parameters
  4. The confidence interval was set to 95%, and the margin of error accepted was set to 5%. Therefore, the P value was considered significant as follows:


    1. P value less than 0.05 was considered significant
    2. P value less than 0.001 was considered as highly significant
    3. P value greater than 0.05 was considered insignificant.



  Results Top


There was no statistically significant difference regarding maternal age and parity, whereas there was a highly statistically significant difference between groups according to birth weight.

There was no statistically significant difference between groups according to renal and UA Doppler indices at the gestational age of 22 weeks [Figure 2].
Figure 2: Bar chart between groups according to renal and umbilical artery Doppler indices.

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There was a statistically significant difference between groups according to RA Doppler indices PI and UA Doppler indices RI at the gestational age of 28 weeks [Table 1].
Table 1: Comparison between groups according to renal and umbilical artery Doppler indices in gestational age 28 weeks

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There was a statistically significant difference between groups according to UA Doppler indices PI and RI at the gestational age of 34 weeks [Table 2].
Table 2: Comparison between groups according to renal and umbilical artery Doppler indices in gestational age 34 weeks

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There was a statistically significant difference over the periods through RA Doppler indices PI in group I [Table 3].
Table 3: The extent of the difference over the periods through renal artery Doppler indices (pulsatility index) in each group

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There was a statistically significant difference over the periods through RA Doppler indices RI in group I [Table 4].
Table 4: The extent of the difference over the periods through renal artery Doppler indices (resistance index) in the each group

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There was a statistically significant difference over the periods through UA Doppler indices PI in each group [Table 5].
Table 5: The extent of the difference over the periods through umbilical artery Doppler indices (pulsatility index) in the each group

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There was a statistically significant difference over the periods through UA Doppler indices RI in each group [Figure 3].
Figure 3: Line difference over the periods through umbilical artery Doppler indices (resistance index) in the each group.

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  Discussion Top


Amniotic fluid abnormalities (oligohydramnios and polyhydramnios) are the leading cause of fetal morbidity and mortality. Assessment of amniotic fluid index provides information about the fetal kidneys and allows evaluation of fetal circulation. Thus, starting from the early stages of gestation, intermittent evaluation of RA flow may be used to predict changes of amniotic fluid dynamics. In this study, fetal RA (PI and RI) and UA Doppler (PI and RI) measurements were evaluated at 22, 28, and 34 weeks of gestation to predict amniotic fluid abnormalities.

The total number of pregnant women was 351. Oligohydramnios was observed in 8% of the cases, and nine patients were excluded. Polyhydramnios was observed in 9% of the cases, and 13 patients were excluded.

There were three groups: 20 patients having normal amniotic fluid index, 20 patients with oligohydramnios, and 20 patients with polyhydramnios.

Our results show no statistically significant difference regarding maternal age.

Our results show a high statistically significant difference between groups according to birth weight. Our results show no statistically significant difference between groups according to renal and UA Doppler indices at the gestational age of 22 weeks. Our results show no statistically significant difference between groups according to RA Doppler indices PI and UA Doppler indices RI at the gestational age of 28 weeks. Our results show statistically significant difference between groups according to UA Doppler indices PI and RI at the gestational age of 34 weeks.

When RA Doppler values were compared within each group. Our results show a statistically significant difference over the periods through RA Doppler indices PI in group I (normal amniotic fluid index). Our results show a statistically significant difference over the periods through RA Doppler indices RI in group I (normal amniotic fluid index). Our results show a statistically significant difference over the periods through UA Doppler indices PI in each group. Our results show a statistically significant difference over the periods through UA Doppler indices RI in each group.

Similar results were obtained in a study done by Benzer et al.[11]. Intermittent assessment of RA flow velocity waveforms during the early stages of pregnancy may help in predicting changes in amniotic fluid dynamics. This study sought to determine the relation of RA and UA flow velocity waveforms with normal pregnancies and pregnancies complicated by either polyhydramnios or oligohydramnios. Renal and UA Doppler values were evaluated at 22, 28, and 34 weeks of gestation in 300 low-risk pregnant women with singleton pregnancies. PI and RI were recorded, and the amniotic fluid volume was evaluated. Three groups were formed according to the amniotic fluid volume at birth. Group I consisted of 264 pregnant women with normal amniotic fluid, group II included 30 pregnant women with oligohydramnios, and group III included six pregnant women with polyhydramnios. Doppler parameters were compared between the groups and within each group according to gestational age. RA PI values were higher in group II than group I at 22, 28, and 34 weeks. The PI value at 28 weeks of gestation was statistically significant (P = 0.011). At 28 weeks of gestation, group II also had higher UA PI and RI values than group I.

An increase in RA PI develops in early pregnancy before the development of oligohydramnios. In pregnancies developing polyhydramnios, RA PI was lower; however, this study included a small number of women with polyhydramnios.

In comparison with a study done by Akin et al.[12], there were differences between our results and their results. Their aims were to investigate the relationship between fetal RA Doppler results and pregnancy outcomes in patients with idiopathic abnormal amniotic fluid indices. A total of 110 patients without signs of fetal distress were included in the study: 31 idiopathic oligohydramnios and 29 idiopathic polyhydramnios pregnancies (study group) and 50 normal pregnancies (controls). Doppler investigation of the UA and fetal RA was performed in all patients. Fetal RA RI and PI values were measured. Values pertaining to type of birth, newborn weight, and APGAR scores were compared. Average patient age, gravidity, and week of pregnancy were 25 ± 4, 1.6, and 37.4 ± 1, respectively. There were no statistically significant differences between the groups as far as UA SD, PI, and RA SD measurements were concerned. However, in the oligohydramnios group, RA RI and RA PI values were significantly higher than the other two groups. Birth weight in the polyhydramnios group and cesarean section rate owing to fetal distress in the oligohydramnios group were significantly higher.

In the oligohydramnios group, without affecting fetal distress parameters, Doppler USG evaluation identified an increase in the RA resistance. Moreover, in that group, cesarean rate owing to fetal distress during labor was significantly higher than in the remaining two groups. Owing to the predictive potential of values of fetal RA Doppler of fetal outcome, further large sample-sized studies on the subject ought to be carried out.

In comparison with a study done by Akdogan et al.[13], there were differences between our results and their results. The aim of the study was to evaluate the fetal renal BF with color Doppler ultrasonography. Patients with polyhydramnios were investigated for fetal RA PI at the beginning of the treatment and after the conservative treatment in those who reached the normal amniotic fluid index. In this prospective study, 39 fetuses with polyhydramnios were evaluated at gestational weeks 26–36. The fetal development parameters, right and left fetal RA PIs, and amniotic fluid index were measured at the beginning of the treatment in all of these patients. Of these patients, 19 who responded to the conservative treatment were also revaluated when their amniotic fluid index reached normal levels, and statistical analyses were performed for the RA PIs before and after the treatment. In this study, 19 patients fulfilled the inclusion criteria as patients with polyhydramnios who responded to conservative treatment. For these patients, the mean fetal RA PI was 2.08 (range: 1.5–3.0) at the first sonographic examination, and the mean fetal RA PI was 1.94 (range: 1.53–2.69) after the conservative treatment. However, there was no statistically significant difference between these two groups (P = 0.117). In this study, no statistically significant difference was found in the fetal RA PIs of the patients with polyhydramnios before and after the conservative treatment. These results suggest that the RA BF may not have any effect on the RA PI; therefore, these findings indicate that the RA PI cannot be used as a marker in the evaluation of polyhydramnios.

In comparison with a study done by Özkan et al.[14], there were differences between our results and their results. The aim of the study was to investigate the fetal RA impedance and hemodynamics in the context of post-term pregnancy with oligohydramnios, using Doppler indices. Fetal RA Doppler was performed in women at gestational age between 40.1 weeks and 41.3 weeks with singleton pregnancies. The fetal RA Doppler RI, PI, systolic/diastolic ratio (S/D), acceleration time, BF, fetal renal volume, APGAR, and cesarean ratio were measured. Stepwise logistic regression and the two-tailed t test were used to determine whether the Doppler indices correlated with oligohydramnios (amniotic fluid index <5 cm). They studied 84 well-dated, singleton, post-term pregnancies, referenced from the high post-term pregnancy obstetric service. Forty-one (48.1%) patients had oligohydramnios. Patients with oligohydramnios had higher S/D, RI, and acceleration time. The fetal RA BF (FRABF) was lower in patients with oligohydramnios than those without oligohydramnios (P = 0.037). Stepwise logistic regression using RA Doppler indices found FRABF to be the only significant predictor of oligohydramnios: P = 0.012 and P < 0.005 (odds ratio = 0.821, 95% confidence interval = 0.769–0.912).

In oligohydramnios, in the context of post-term pregnancies, there is an increased resistance in the fetal renal vascular bed. The reduced FRABF suggests that increased arterial impedance is an important factor in the development of oligohydramnios. This study supports the idea of increased vascular resistance in the fetal renal bed in patients in post-term.


  Conclusion Top


There is a statistica significant decrease in PI in the control group (normal AFI at 22, 28, and 34 weeks). An increase in RA PI develops in early pregnancy before the development of oligohydramnios. In pregnancies developing polyhydramnios, RA PI was lower.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Magann EF, Nolan TE, Hess LW, Martin RW, Whitworth NS, Morrison JC. Measurement of amniotic fluid volume: accuracy of ultrasonography techniques. Am J Obstet Gynecol 1992; 167:1533–1537.  Back to cited text no. 1
    
2.
Moore TR, Cayle JE. The amniotic fluid index in normal human pregnancy. Am J Obstet Gynecol 1990; 162:1168.  Back to cited text no. 2
    
3.
Magann EF, Chauhan SP, Sanderson M, McKelvey S, Dahlke JD, Morrison JC. Amniotic fluid volume in normal pregnancy: comparison of two different normative datasets. J Obstet Gynaecol Res 2012; 38: 364–370.  Back to cited text no. 3
    
4.
Moore TR. Amniotic fluid dynamics reflect fetal and maternal health and disease. Obstet Gynecol 2010; 116:759.  Back to cited text no. 4
    
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Rossi AC, Prefumo F. Perinatal outcomes of isolated oligohydramnios at term and post-term pregnancy: a systematic review of literature with meta-analysis. Eur J Obstet Gynecol Reprod Biol 2013; 169:149–154.  Back to cited text no. 5
    
6.
Magann EF, Doherty D, Lutegendorf MA, Magann MI, Chauhan SP, Morrison JC. Peripartum outcomes of high risk pregnancies complicated by oligoand polyhydramnios: a prospective longitudinal study. J Obstet Gynaecol Res 2010; 36:268.  Back to cited text no. 6
    
7.
Magann EF, Chauhan SP, Doherty DA, Lutgendorf MA, Magann MI, Morrison JC. A review of idiopathic hydramnios and pregnancy outcomes. Obstet Gynecol Surv 2007; 62:795–802.  Back to cited text no. 7
    
8.
Guin G, Punekar S, Lele A, Khare S. A prospective clinical study of feto-maternal outcome in pregnancies with abnormal liquor volume. J Obstet Gynaecol India 2011; 61:652–655.  Back to cited text no. 8
    
9.
Rutherford SE, Phelan JP, Smith CV, Jacobs N. The fourquadrant assessment of amniotic fluid volume: an adjunct to antepartum fetal heart rate testing. Obstet Gynecol 1987; 70:353–356.  Back to cited text no. 9
    
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Brady K, Polzin WJ, Kopelman JN, Read JA. Risk of chromosomal abnormalities in patients with idiopathic polyhydramnios. Obstet Gynecol 1992; 79: 234–238.  Back to cited text no. 10
    
11.
Benzer N, Pekin AT, Yılmaz SA, Kerimoǧlu OS, Doǧan NU, Çelik C. Predictive value of second and third trimester fetal renal artery Doppler indices in idiopathic oligohydramnios and polyhydramnios in low-risk pregnancies: a longitudinal study. J Obstet Gynaecol Res 2015; 41:523–528.  Back to cited text no. 11
    
12.
Akin I, Uysal A, Uysal F, Öztekin O. Applicability of fetal renal artery Doppler values in determining pregnancy outcome and type of delivery in idiopathic oligohydramnios and polyhydramnios pregnancies. Ginekol Pol 2013; 84:950-954.  Back to cited text no. 12
    
13.
Akdogan M, İpek A, Kurt A, Sayit AT, Karaoglanoglu M. Renal artery Doppler findings in the patients with polyhydramnios before and after the conservative treatment. Eurasian J Med 2015; 47:85–90.  Back to cited text no. 13
    
14.
Özkan MB, Özkan E, Emiroglu B, Özkaya E. Doppler study of the fetal renal artery in oligohydramnios with post-term pregnancy. J Med Ultrasound 2014; 22:18e21.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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