|Year : 2020 | Volume
| Issue : 1 | Page : 33-36
Role of amniotic fluid echogenicities in the prediction of fetal outcome
Sheema Posh1, Suhail Rafiq2, Musaib Ahmad Dar2, Rasiq Aslam2, Shabir Ahmad Bhat2
1 Department of Obstretics and Gynaecology, Sheri Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India
2 Department of Radiodiagnosis, Government Medical College, Srinagar, Jammu and Kashmir, India
|Date of Submission||04-Feb-2020|
|Date of Acceptance||30-Apr-2020|
|Date of Web Publication||23-Jun-2020|
Dr. Musaib Ahmad Dar
Government Medical College, Karanagar, Srinagar, Jammu and Kashmir
Source of Support: None, Conflict of Interest: None
Background: The amniotic fluid (AF) is a highly complex and dynamic system that is studied as a data point to interpret fetal well-being. Homogeneously, echogenic AF is due to the presence of innumerable echogenic particles in the fluid and is an uncommon finding. Echogenic AF has been attributed to meconium, blood, and vernix caseosa. The current study was undertaken to evaluate the significance of echogenic AF in the assessment of fetal outcome. Objective: The objective was to study the significance of echogenic AF in the assessment of fetal outcome. Materials and Methods: The present study was a prospective observational study conducted in the Department of Obstetrics and Gynaecology, SKIMS, Soura, Srinagar, from May 2019 to December 2019. A total of 34 participants with ultrasonographic evidence of echogenic liquor were included in the study. They were followed till the delivery for the determination of the fetal outcome. The fetal outcome was studied in terms of Appearance, Pulse, Grimace, Activity, Respiration (APGAR) score; neonatal intensive care unit (NICU) admission rate; and stillbirth rate. Results: Out of 34 participants, 18 participants had vernix caseosa, 8 had meconium, 6 had blood, and 2 had clear liquor amnii. Out of 18 participants with vernix, all 18 fetuses had APGAR score >7/10 with no NICU admission and no stillbirth. Out of eight participants with meconium, six babies had APGAR score <7/10, out of which three had NICU admission, and there was one stillbirth. Out of six participants with blood-stained liquor, four babies had APGAR score <7/10, out of which one had NICU admission, and there was no stillbirth. Conclusion: Our study suggests that when abnormalities of AF exist, appropriate workup to uncover the underlying etiology should be initiated as adverse fetal outcomes are sometimes associated with these variations from normalcy. However, ultrasonography cannot reliably differentiate meconium in AF from other causes of hyperechogenicity. If meconium and blood can be reliably identified prenatally, then it has a significant impact on the fetal outcome. Hence, a change in the management of pregnancy cannot be justified simply due to the detection of hyperechogenic AF.
Keywords: Amniotic fluid, echogenic liquor, appearance, pulse, grimace, activity, respiration score, fetal outcome
|How to cite this article:|
Posh S, Rafiq S, Dar MA, Aslam R, Bhat SA. Role of amniotic fluid echogenicities in the prediction of fetal outcome. J Sci Soc 2020;47:33-6
| Introduction|| |
The aquatic environment of the fetus has long remained an enigma to the patient and their obstetricians. Liquor amnii, a fluid elaborated by amnion (a two-layered extraembryonic membrane formed by the inner ectoderm and outer somatic mesoderm), provides a fluid medium for the early development of the embryo protecting it from concussion, pressure, desiccation, and reminiscent of the aquatic origin of life.
An adequate amount of amniotic fluid (AF) is essential for the normal growth of the fetus for it cushions against all sorts of trauma and agitations. Bacteriostatic properties of AF prevent infection, and it functions as a primary source of fetal nutrients. It creates a physical space for the fetal skeleton to shape normally, promotes fetal lung development, and helps to avert compression of the umbilical cord.
AF is mainly formed from fetal plasma volume, fetal urine, fetal respiratory system, gastrointestinal tract, umbilical cord, and fetal surface of the placenta. The composition of the AF changes with the gestational age with an average pH of 7.2 and specific gravity of 1.0069–1.008.
The echogenicity of AF indirectly represents the size, number, and distribution of particles in AF and in turn turbidity of AF. This could give rise to the ultrasound detection of echogenic particles, also known as AF sludge or appearance of a homogeneously echogenic AF. AF “sludge” is dense aggregates of particulate matter. In the first- and second-trimester ultrasound imaging, the presence of such particulate matter in AF is seen in approximately 4%. It is associated with intraamniotic bleeding, and the acrania–anencephaly sequence is also observed in women with higher concentrations of maternal serum alpha-fetoprotein. By the third trimester, the incidence rises to about 80% and has been mainly attributed to the presence of vernix caseosa and/or meconium., Vernix caseosa is a complex fatty substance derived from the desquamated epithelial cells and sebaceous material. Congenital conditions associated with particulate matter in the AF include harlequin ichthyosis and epidermolysis bullosa letalis.
Homogeneously, echogenic AF is due to the presence of innumerable echogenic particles in the fluid and is an uncommon finding. In most cases, this is due to the presence of vernix caseosa in AF; however, in minority of cases, this could be due to meconium or blood [Figure 1] and [Figure 2].,,, The ultrasound diagnosis of echogenic or meconium AF could be made if the following criteria are met:
|Figure 1: Ultrasound image showing evidence of coarse echoes within amniotic fluid. A sample meconium-stained liquor was collected in a plastic container during delivery|
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|Figure 2: Ultrasound image showing evidence of diffuse echoes within amniotic fluid. A sample of blood-stained liquor was collected in a plastic container due to small retroplacental hematoma|
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- Diffuse echoes within the amniotic cavity
- Clear contrast between the AF and the umbilical vessels. Normally, there is no clear contrast between clear/anechoic liquor and anechoic lumen of the umbilical vessels. In the presence of echoes within liquor, there is a contrast between echogenic liquor and anechoic lumen of vessels.
- Layering in the more dependent areas of the uterus
- Thus, it appears prudent to evaluate AF during any assessment of fetal status whether as a part of the antenatal testing protocol or in the labor suite.
| Materials and Methods|| |
A prospective study was conducted in the Department of Obstetrics and Gynecology at SKIMS Maternity Hospital, Srinagar, from May 2019 to December 2019. A total of 34 pregnant women with gestational age between 37 weeks and 39 weeks without any medical and obstetric complications were enrolled in the study with ultrasonographic evidence of echogenic liquor. History and examination details were noted. All necessary Antenatal checkup (ANC) investigations, nonstress tests, and ultrasound examinations were done to see the fetal well-being, congenital anomalies, AF index, and echogenicities in liquor. The patients were delivered either vaginally or by a cesarean section and were followed till 7 days after delivery. The condition of babies was assessed by the Appearance, Pulse, Grimace, Activity, Respiration (APGAR) score at birth, need for neonatal neonatal intensive care unit (NICU) admissions, and stillbirths.
- Patients who were sure of their last menstrual period
- Gestational age between 37 and 39 weeks
- Singleton pregnancy
- Amniotic fluid index (AFI) between 8 cm and 15 cm
- Ultrasound documented echogenic liquor
- Normal fetal Doppler indices.
- Gestational age <37 weeks and >39 weeks
- Oligohydramnios or polyhydramnios
- Multiple gestation
- Premature rupture of membranes
- Any medical or obstetric complication of pregnancy
- Congenital anomaly in the fetus.
Data were analyzed using the IBM SPSS statistical software (SPSS South Asia (P) Ltd, Bangalore, India). Categorical variables described in terms of frequency. P value was calculated to assess the level of significance using Chi-square test with P < 0.05 being statistically significant. We calculated the level of significance between echogenic liquor (for vernix caseosa and meconium) and APGAR score. Statistical significance between echogenic liquor and blood-stained liquor, echogenic liquor and NICU admission, and echogenic liquor and stillbirth could not be calculated due to very less number of patients.
| Results|| |
The present study was undertaken to study the outcome of term pregnancy with echogenic AF.
Out of 34 participants, 18 participants had vernix caseosa, 8 had meconium-stained liquor, 6 had blood-stained liquor, and 2 had clear liquor [Table 1].
|Table 1: Liquor characteristics in patients with echogenic liquor (n=34)|
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Out of 18 participants with vernix, all fetuses had APGAR score >7/10 [Table 2] and [Figure 3] with no NICU admission and no stillbirth. Vernix was associated with positive fetal outcome (APGAR values >7/10) (P < 0.01).
Out of eight participants with meconium, two babies had APGAR score >7/10 [green bar in [Figure 3] and six babies had APGAR score <7/10 [blue bar in [Figure 3], out of which three had NICU admission [yellow bar in [Figure 3], and there was one stillbirth [Table 3] and [Figure 3]. Meconium was associated with negative fetal outcome (APGAR values <7/10) (P < 0.01).
Out of six participants with blood-stained liquor, one baby had APGAR score >7/10 [green bar in [Figure 3] and five babies had APGAR score <7/10 [blue bar in [Figure 3], out of which two had NICU admissions [yellow bar in [Figure 3], and there was no stillbirth [Table 4] and [Figure 3]. Four patients with blood-stained liquor had marginal placental site abruption, one had evidence of scar dehiscence, and in one case, we found no cause for blood-stained liquor.
| Discussion|| |
According to our study, the most common cause of echogenic liquor was vernix caseosa, followed by meconium. This is in accordance with the study conducted by Shreejana Shrestha et al., who reported vernix (81.4%) and meconium (18.6%) as the most common causes of echogenic liquor. We studied 34 patients with echogenic liquor in our study. This sample size was achieved as about 70–80 patients visit our outpatient department each day since there are only two tertiary care centers at our place and up to 20–30 patients deliver per day. The normal sonographic appearance of AF is an anechogenic image surrounding the fetus and the umbilical cord. Echogenic AF was first reported in two postdated pregnancies and diagnosed as meconium. Hyperechogenic AF is an uncommon finding that is commonly due to the presence of vernix, though in some cases, it is associated with the presence of meconium or blood creating a dilemma for the management of these patients.,,, However, a review by Sepúlveda and Quiroz indicated that the finding of hyperechoic AF refers more often to a considerable amount of vernix rather than meconium. However, they suggested amniocentesis or amnioscopy to rule out the presence of meconium.
A retrospective study by Brown et al. described echogenic AF during the third trimester as an unreliable indicator of meconium or blood in AF. Nineteen such cases were investigated with amniocentesis. One case of meconium (5%) was detected and the remaining 95% had vernix. Similarly, Petrikovsky et al. prospectively studied 19 cases of twin pregnancies, each with one amniotic sac containing echogenic AF and the other containing anechoic AF. Only one case (5%) of meconium was detected in the echogenic group compared to 4 (21%) in the anechoic group.
In our study, six patients had evidence of blood-stained liquor. Khaleghian in 1983 reported blood as a cause of echogenic AF in the second trimester.
Two of the cases with echogenic liquor on ultrasound which were later found to have clear liquor on delivery are most likely due to nonusage of tissue harmonic imaging on ultrasound, which helps in better delineation of clear and echogenic liquor due to better contrast resolution and reduced artifacts.
In our study, out of eight cases with meconium-stained liquor, six infants had APGAR score <7/10, out of which three had NICU admission, and there was one stillbirth. This is in accordance with a study done by Rajlaxmi et al. who reported that neonatal outcome was poor in terms of low APGAR score at birth, birth asphyxia, meconium aspiration syndrome (MAS), and increased neonatal admission in patients with meconium-stained liquor. One cause of stillbirth in meconium-stained liquor was attributed to birth asphyxia secondary to MAS that occurs due to complete occlusion of bronchiolar and alveolar spaces.
In our study, out of six cases with blood-stained liquor, four infants had APGAR score <7/10, out of which one had NICU admission. Most of the cases of blood-stained liquor were due to marginal placental abruption. Marginal placental abruption has been associated with neonatal asphyxia with decreased APGAR score as per the study done by Downe et al.
In the initial reports, where echogenic amniotic fluid had been diagnosed by ultrasonography, further evaluation by amniocentesis or amnioscopy was recommended.
Amniocentesis is also not without risk, as it may give rise to infections and induce labor or result in miscarriage. It should be noted that ultrasonography cannot reliably differentiate meconium or blood in AF from other causes of hyperechogenicity; however, ultrasonic finding of an echogenic AF at term in a normal pregnancy can be a predictor of meconium and adverse pregnancy outcomes. If meconium and blood can be identified prenatally, then it has a significant impact on the neonatal outcome.
| Conclusion|| |
Our study suggests that echogenicity in the AF can be due to the presence of innumerable echogenic particles in the fluid. In most cases, this is due to the presence of vernix caseosa which is associated with good fetal outcome; however, in minority of cases, this could be due to meconium or blood. Since meconium or blood-stained liquor cannot be ruled out on ultrasound, it is suggested that direct AF visualization by amniocentesis or amnioscopy is recommended or fetal monitoring by nonstress test and/or biophysical profile is an alternative option.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]