2019, Volume 35, Number 2, Page(s) 107-118
Histopathological Changes of Placenta in Meconium Stained Liquor and Its Relevance in Fetal Distress: A Case Control Study
Tanima ROY MONDAL1, Goutam BANDYOPADHYAY2, Sabuj Ghana MUKHOPADHYAY2, Dyuti GANGULY2
1Pathologist, MR Bangur Superspeciality Hospital, KOLKATA, WEST BENGAL, INDIA
2Department of Pathology, Burdwan Medical College, BURDWAN, WEST BENGAL, INDIA
Keywords: Placenta, Histopathology, Meconium stained liquor, Apgar score
Meconium passage during labour is a quite common finding. Studies describing correlation between meconium stained liquor, fetal
distress and specific placental pathology are sparse. This case control study had been designed to ascertain these lacunae of knowledge.
Material and Method:Placentae from 41 cases of otherwise uncomplicated antenatal and intranatal pregnancies with meconium stained liquor
at 37 completed weeks of gestation were studied, both grossly and microscopically, comparing them with controls of 41 cases of clear liquor.
Apgar score of all newborns at 1 minute and 5 minutes were recorded and correlated with histopathological findings.
Results: Both cases and controls were found to be age matched. Meconium stained liquor was associated with more caesarian section than the
clear ones. Significant correlation was found with meconium stained liquor and low Apgar scores. Histopathology of placenta revealed many
statistically significant associations between specific placental histopathology in meconium stained liquor and depressed Apgar score. Evidence
of placental vasculopathy rather than meconium induced placental damage came out as the potential culprit in causing a low Apgar score in this
case control study.
Conclusion: Placental vascular changes have a role in meconium staining of liquor. If timely interventions are taken, the chance of development
of fetal distress is low.
Passage of meconium in-utero is due to bowel peristalsis
and relaxation of anal sphincter. Meconium passage is
especially common in post-term placentas. It is unlikely
to be present before 30 weeks 1
. It is considered normal
in breech deliveries. In the majority, meconium passage
after birth is a sign of physiologic maturity, but it can be
associated with fetal distress when seen before delivery.
There may be presence of some predisposing factors like
maternal hypertension, obstetric cholestasis, multiple
pregnancies, and obstructed labour etc. but meconium
staining also occurs in many uncomplicated pregnancies
and in association with fetal distress, the cause of which is
Fetal distress is assessed by the Apgar score (less than 7 at
1 minute and 5 minutes), cardiotocograph traces, and cord
or fetal scalp blood pH (less than 7.2) etc. Among these,
Apgar score assessment is simple and commonly employed Meconium passage has been significantly associated with
low Apgar scores, cord blood pH of 7.0 or less, respiratory
distress, seizures in the first 24 hours, and the need for
delivery room resuscitation. Neonatal morbidity of all kinds
has been significantly associated with meconium stained
amniotic fluid as compared to clear amniotic fluid 1,2.
Meconium staining of the liquor may be the thin or thick
type. Thick meconium is associated with higher morbidity
and mortality in comparison to clear liquor 3-5. It is also
associated with a higher incidence of emergency caesarean
Meconium aspiration syndrome is a life-threatening
respiratory disease in infants born through meconium
stained amniotic fluid. It is associated with thick
meconium, low Apgar score and non-reassuring fetal heart
rate tracing 3,8. There is some evidence that meconium
may interfere with surfactant production and in high
enough concentrations, have a direct toxic effect on type II pneumocytes, possibly contributing to the meconium
aspiration syndrome 9. All cases of meconium stained
liquor and especially the thick meconium type should
therefore be continuously monitored to prevent serious
Meconium is thought to cause placental and umbilical
cord vasoconstriction along with cerebral and fetal hypoperfusion.
These may be the causes for a major poor
outcome in meconium stained liquor 10,11. Meconium
stained liquor is associated with an increased frequency of
It is not clear that whether meconium staining of liquor is
associated with demonstrable placental pathology which
may give rise to fetal distress, either directly or indirectly,
or whether placental pathology gives rise to meconium
staining and in turn causes fetal distress. It is not discernible
which is the primary event among these variables.
There are many questions regarding the cause, effect,
clinical significance and pathologic expression of in-utero
meconium passage which are, as yet, unresolved. In the
majority of infants, meconium passage is a reflection of
physiological immaturity, although in some, it appears
to be associated with adverse stimuli, out of which fetal
distress is a significant factor.
It has also been observed that intra-uterine fetal distress
is the consequence of maternal and fetal vascular
compromise, though the normal placenta has considerable
functional reserve. Placental infarct associated with
crowding ghost-like villi, fetal thrombotic vasculopathy,
intra-villous and peri-villous fibrinoid, placental villous
hypoplasia associated with increased inter-villous spaces
and exaggerated syncytial knots are some of the pathologic
findings associated with fetal and maternal vascular
It is not certain that such factors, to what extent, are
associated with fetal distress and thereby act as potential
causes behind the meconium passage in-utero.
There are many studies which describe meconium induced
fetal distress. A few studies have described placental changes
in meconium stained liquor. However, there are lack of
studies describing correlation of placental histopathology
with fetal distress in meconium stained liquor.
This study has been undertaken to determine the association
between meconium stained liquor with fetal distress and
specific placental pathology in such cases. For this purpose,
macroscopic and microscopic changes of placentae
associated with meconium stained liquor were compared with those in clear liquor in otherwise uncomplicated term
January 2016 to 31st
December 2016, pregnant
mothers in term (37 completed weeks/40 completed weeks
of gestation) with singleton pregnancy, fetus in cephalic
presentation and otherwise with an uncomplicated
antenatal and intranatal period and admitted to the G&O
department of the Burdwan Medical college for safe
confinement were included in the study. Forty-one cases
of meconium stained amniotic fluid were identified. As
controls, 41 cases of clear amniotic fluid matching the
inclusion criteria were also studied.
The information collected were history & clinical
examination (of the mothers in labour), observation (in
the labour room), record review (antenatal card, bed head
ticket) and recorded histopathological findings of the
The parameters were degree of meconium staining (light/
deep), Apgar scores of the newborns, and histopathological
changes in placentae of the cases and controls.
After approval from the ethical committee, we attended
the labour observation room of Gynaecology & Obstetrics
Dept. of Burdwan Medical College. After duly filling up
the consent and case record form (history and clinical
examination), inspection of the pregnant mother in term
gestation with meconium stained liquor took place and the
time of rupture of membrane was noted. Mode of delivery
of the case was decided by the obstetricians and delivery was
done either by vaginal delivery or caesarean section. We
collected the placenta in 10% buffered formalin solution.
Apgar scores of the baby at 1 minute and 5 minutes were
recorded. Thus we collected 41 placentae from thin or thick
meconium stained liquor cases as per availability of such
We collected 41 placentae with clear liquor after vaginal
delivery from age matched control mothers without any
antenatal and intranatal complication. We also noted
Apgar scores of those newborns at 1 minute and 5 minutes.
Apgar score was determined by noting i) color, ii)
respiratory effort, iii) heart rate, iv) muscle tone and
v) reflex irritability. Each variable scores 2 points. The
cumulative score (maximum being 10 and minimum being
0) was graded as follows: No depression (score 7- 10); mild
depression (score 4- 6); and severe depression (score 0- 3)
The color of liquor was graded as- 0 (Clear), 1 (Thin), and
After getting the placentae, gross examinations and
procedures were performed; sections were taken from
different parts of the fixed placentae after one day and
again the sections were fixed in neutral buffered 10%
formalin. Paraffin blocks were prepared after following the
routine histopathological techniques. Staining of sections
(5μ thick) was done with routine Haematoxylin & Eosin
stain. Light microscopic examination was done and results
were noted. Different gross and histopathological changes
were recorded in the histopathological data record form.
They were corroborated with the respective Apgar score to
uncover any relationship between them.
Examination of Placenta
I. Macroscopic examination
Each placenta was examined meticulously as early as
possible after collection following delivery and the findings
were noted in the case record form. Photographs of the
specimen were taken accordingly. The specimen was then
placed in 10% neutral buffered formalin for fixation.
The specimen was examined macroscopically for the
following parameters (13):
The size of the placental disc and umbilical cord, shape,
weight, colour, fetal surface membrane (graded as 0,1 and 2
according to the intensity of meconium staining), maternal
surface, surface vessels and cut surface of the disc and cord.
II. Microscopic examination
Seven sections (14,15) were taken for histopathology of
placenta including three sections from the disc including
fetal and maternal surface, two sections from the fetal
membrane (jelly roll technique) and two sections from the
Microscopically, the following parameters were noted.
1. Intervillous space (IVS): It is graded as 0 (narrow IVS),
1(normal) and 2 (widened IVS )
2. Intravillous fibrinoid and perivillous fibrinoid: In this
study, both are graded as 1 (normal), 2 (mild increase) and
3 (marked increase).
3. Villitis: It is graded as 0 (absent) and 1(present).
4. Syncytial knots (SK): It is increased at term as well as in
hypoxic conditions. It is graded as 1 (up to 5 SK/villous in
the majority of the villi), 2 (5- 10 SK/villous in majority of
the villi) and 3 (>10 SK/ villous in the majority of the villi).
5. Calcification: Focal calcification is considered normal
at term, but excessive calcification may have underlying pathology. In this study it is graded as 0 (no or focal
calcification) and 1 (marked calcification).
6. Infarction: Infarcts are the result of circulatory
disturbances. In this study it is graded as 0 (absent) and 1
7. Fibrosis: Villous stromal fibrosis may occur in hypoxic
conditions. It is graded as 0 (absent) and 1 (present).
8. Blood vessel changes: There may be thrombosis/ avascular
villi/ atrophy of villi/ fetal thrombotic vasculopathy.
In the present study, blood vessel changes are graded as
follows: 0 (no change); 1 (mild changes (focal); 2 (marked
9. Chorion and amnion: Multilayering of amniotic
membrane, ballooning degeneration, necrosis and
chorioamnionitis may be present in various proportions in
meconium staining. The changes are graded as 0 (absent/
no change) and 1 (present).
10. Umbilical cord: There may be funisitis (inflammation
of cord) or cord vasculitis. Changes are graded as 0 (absent)
and 1 (present).
11. Chorangiosis : It may be an incidental finding. It is
considered when there is presence of more than 10 terminal
villi with more than 10 capillaries (actually more than 15
are usually present) involving several areas of placenta. It
may be due to abnormal maturation of villi and hypoxia.
At the end of the study, all the data was compiled and
tabulated. Analysis was done by using suitable statistical
methods (2-tailed t-test and Pearson Chi-square test) and
appropriate software (SPSS v.20).
Minimum maternal age was 19 years and maximum age
was 28 years, mean being 23.11 years. The mean age of
cases was 23.17 years and of controls was 23.05 years. The
difference was not statistically significant. It also proved
that the controls were age matched with the cases. The
mean gestational age of both cases and controls was 37
weeks. Most mothers were primipara, both in cases and
The mean birth weight of babies of cases was 2818.90g.
and of the controls was 2679.88g. The difference was
statistically significant. Higher birth weight was associated
with meconium staining of liquor in comparison to clear
The meconium stained placenta and placenta with clear
meconium was grossly evident (Figure 1,2).
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|Figure 1: Gross photograph of normal placenta, showing
glistening transparent amnion on fetal surface.
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|Figure 2: Gross photograph of a meconium stained placenta with
opaque, gray-brown fetal surface.
The mean placental weight of cases was 480.98 g. and of
controls was 487.32g. The difference was statistically
significant. So, here it was evident that lower weight of
placenta was associated with occurrence of meconium
staining of liquor (Table I, Figure 3). In this study there was
no abnormality noted in maternal surface or cut surface of
placenta in either case or control group. No abnormality was seen in gross and microscopical examination of umbilical
cord. Among the meconium stained liquor group, 19.6%
(8/41) cases had thin and 80.4 % (33/41) cases had thick
meconium stained liquor. There was increased incidence
of caesarean section in meconium stained liquor group.
29.3% (12/41) newborns were delivered vaginally and
70.3% (29/41) babies were born through caesarean section.
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|Table I: The differences in mean, 2 standard deviation, and significance of maternal age, birth weight of babies, placental weight and
placental diameter among cases and control group.
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|Figure 3: Box whisker showing range of distribution and mean
values of placental weight of case and control population (n=82).
Salient microscopical findings in this study as observed
from different tables and statistical analysis were increase
in inter-villous space (19.5%), prominence of intra-
(19.5%) and peri-villous fibrinoid (24.4%) (Table II),
exaggerated syncytial knots (26.8%), obvious blood vessel
changes (31.7%), calcification (intra- and peri-villous
as well as within vessel wall) (13.4%) (Table III), villous
fibrosis (7.3%), epithelial hyperplasia in amnion (39%),
evidence of chorio-amnionitis (13.4%) (Table IV, V). The
statistical significance in distinguishing placental changes
from normal control was evaluated (Figure 4-9).
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|Table II: Evaluation of intervilllous space, intervilllous fibrinoid and perivillous fibrinoid.
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|Table III: Depicting incidence of villitis, exaggerated syncytial knots and villous calcification.
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|Table IV: Incidence of villous infarction, fibrosis and blood vessel change in the study population, compared to control.
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|Table V: Depicting changes in Chorion, Amnion and presence of villous chorangiosis as an incidental finding.
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|Figure 4: Normal term placenta showing primary stem villi and
tertiary villi with normal inter-villous space (H&E; x100).
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|Figure 5: The increase in inter-villous space with perivillous
fibrinoid (H&E; x100).
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|Figure 7: Extensive perivillous fibrinoid in meconium stained
liquor (H&E; x100).
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|Figure 8: Exaggerated syncitial knots in meconium stained liquor
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|Figure 9: Fibromuscular sclerosis with intravascular fibrin
thrombi (H&E; x100).
Villitis (6.1%) and infarction (1.2%) were observed in
this study in variable proportions but not statistically
Villous chorangiosis, a peculiar finding in this study,
which was present in 13.4% of cases, was not statistically
significant as it is also observed in control normal placentas
(Table V) (Figure 10).
Unlike in previous studies, there was no obvious change in
the umbilical cord and rarely meconium laden macrophages
in amnion were found in this study.
The Apgar score at 1 minute was as follows: 17.1% (7/41)
were not depressed, even they were associated with
meconium stained liquor. Mild depression was present
in 60.5% (25/41) and severe depression was noted in 22% (9/41) of cases. Apgar score at 5 minutes after delivery
room resuscitation was as follows: No obvious depression
in 73.2% (30/41), mild depression in 24.4% (10/41)
and severe depression in only 2.4% (1/41) of cases. A
significant association was seen between green colored
placenta (meconium) and mild depression of Apgar
score (p-value <0.05) (statistically significant), when a
comparative study was done between the Apgar score and
color of the placentas. A widened inter-villous space was
significantly associated with mild to severe depression,
both at 1 minute and 5 min (p-value < 0.01), which was not observed in control cases. Persistent neonatal depression
was significantly associated with an increase in the amount
of intra-villous and perivillous fibrinoid in the meconium
stained liquor group (p- value <0.002).
No significant association was found with presence or
absence of villitis, in meconium stained liquor and neonatal
depression, evaluated by Apgar score. (p- value >0.094).
Exaggerated syncytial knots (Figure 8), though a feature
of post-maturity, were also observed in hypoxic state, as
revealed from above analysis, showing p-value <0.05 , which
is statistically significant. Wide areas of heterotrophic calcification may be the end result of villous atrophy and
fibrosis, leading to maternal and fetal hypoperfusion, is
significantly associated in cases of meconium-stained
liquor and associated neonatal depression (p- value <0.05
which is statistically significant). Blood vessel changes were
a noticeable finding, in this study population (Cases=41),
with a significant association with both 1 min. and 5 min.
Apgar score (p- value <0.05; which is also statistically
Fibro-muscular sclerosis with vascular obstruction (46.3%)
(Figure 9) was seen in a substantial population of cases
(19/41), which was statistically significant (p-value<0.05)
finding (Table VI). We have observed that mild to severe
depression were always associated with meconium stained
liquor. Though this figure is statistically significant
(Pearson’s Chi- square test), but actually we had selected
our controls as normal placenta at birth in an otherwise
normal vaginal delivery. So, this finding is not significant
in respect to our study population.
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|Table VI: The association between different changes of placentas (macroscopical and microscopical) and Apgar score of newborns.
Meconium is the bile-stained intestinal content of the
fetus. It is often admixed with mucus. Meconium is present
in the small bowel of fetuses long before mid-gestation
but is usually not eliminated until after birth. The risk
factors for meconium stained amniotic fluid are both
maternal and fetal. The maternal factors are hypertension,
gestational diabetes mellitus, maternal chronic respiratory
or cardiovascular diseases, post term pregnancy,
preeclampsia, and eclampsia. The fetal factors include
oligohydramnios, intrauterine growth restriction, and poor
biophysical profile 16
. Meconium staining is an indicator
of increased perinatal morbidity, though many cases
may have normal outcome. Meconium passage has been significantly associated with parameters of fetal distress
including low Apgar scores, umbilical artery pH of 7.0 or
less, respiratory distress, seizures in the first 24 h, and need
for delivery room resuscitation 1
. It may cause meconium
aspiration syndrome, characterized by life threatening
respiratory distress. Fetal distress is defined as compromise
of a fetus during the antepartum period (before labor) or
intrapartum period (during the birth process). The term
fetal distress is commonly used to describe fetal hypoxia
(low oxygen levels in the fetus), which can result in fetal
damage or death if it is not reversed or if the fetus is not
The mean age of the mothers in this study is 23.11 years
(23.17 in the meconium group and 23.05 in the clear
liquor group). There is no significant difference in the
mean age between case and control population (by 2 tailed
significance test the value is 0.805). In this study, 46.3% of
the mothers in the meconium stained liquor group (19/41)
and 43.9% (18/41) of the mothers in the clear liquor group
were primipara. So, there is similarity of parity between
cases and controls. However, Osava et al. 17 found higher
incidence of meconium stained liquor in primipara in
comparison to clear liquor cases in their study. Klufio et al.
18 found positive significant association between grand
multiparty and meconium stained liquor. In the present
study, mean and most frequently occurring gestational
age in both meconium and clear liquor group is 37 weeks
and the average birth weight (BW) of babies is 2749.39 g..
The mean BW in meconium group was 2818.90 g. and in
clear liquor group it is 2679.88 g.. So, the BW is little higher
in meconium group, having no statistical significance.
However, Zhu et al. 20 noted in their study that birth
weight was higher in meconium stained amniotic fluid
group than that in clear amniotic fluid group (P < 0.001).
However, Khazardoost et al.. 8 found that neonatal birth
weight was lower in the meconium stained liquor cases.
Odongo et al. 21, however, found no significant difference
in the mean birth weights of the infants born to women in
36 meconium stained liquor cases and 41 clear liquor cases
(3359.72 g. and 3260.24 g. respectively, p-value: 0.282). This
study also showed similar results on statistical analysis. In
the present study, the mean placental weight of the case
population was 480.98 g. and of the control population is
487.32 g. In this study, we found 19.6% thin meconium
liquor and 80.4 % thick meconium liquor among the cases.
Meconium stained liquor is associated with increased
incidence of caesarean section, as noted in the studies by
Arulkumaran et al. 4, Shaikh et al. 6, Osava et al. .17,
Odongo et al.21, Khatree et al. 22, and Klufio et al. 18.
Similarly, in the present study, there is increased caesarean section rate among meconium stained liquor group: 29.3%
delivered vaginally and 70.7% delivered by caesarean
section. But, in contrast, in a study by Kumari et al. 7 60%
patients delivered through normal vaginal delivery and
40% through caesarean section among meconium stained
liquor cases. Microscopically, free meconium consists of
amorphous green-brown material and anucleate squames.
The amniotic epithelium exposed to meconium shows
degenerative changes including heaping, stratification,
ballooning degeneration and eventually nuclear pyknosis
and necrosis. With time, meconium is engulfed by
macrophages in the amnion, chorion, and deciduas.
Meconium is usually scant in the umbilical cord due to the
paucity of macrophages. To investigate whether meconium
causes vasoconstriction, Altshuler et al. 10 tested umbilical
vein tissue with an isometric transducer connected to a
polygraph. They hypothesized that meconium may cause
placental and umbilical cord vasoconstriction, cerebral
and other fetal hypoperfusion, and major poor outcome.
According to Ziadie M.11, meconium induced changes to
placenta may be graded depending upon the exposure time
of meconium mainly by the presence of meconium filled
macrophages in the placental membranes. This study had
shown significant association between meconium stained
liquor and neonatal depression evaluated by Apgar score.
Apgar score was devised in 1952 by the eponymous Dr.
Virginia Apgar as a simple and repeatable method for
quickly and summarily assesses the health of newborn
children immediately after birth and to diagnose fetal
distress at birth 23. Apgar was an anesthesiologist who
developed the score in order to ascertain the effects of
obstetric anesthesia on babies. It has a continuous value in
detecting fetal distress at birth for many years 24,25.
From that time, numerous studies 19,26-31 have
demonstrated lower 1 and 5 minute APGAR scores in cases
of thick meconium and increased incidence of caeserean
sections and maternal and perinatal foetal morbidity. In
our study, 1 minute Apgar score shows no depression in
17.1%, mild depression in 60.9% and severe depression in
22% cases of meconium stained liquor. Mild and severe
depression is present in meconium stained liquor group
only. All clear liquor cases (controls) have no depression.
At 5 minutes Apgar score no depression was observed in
73.2% of newborns, mild depression in 24.4% and severe
depression in 2.4% of meconium stained liquor. Mild and
severe depression is present in meconium stained liquor
cases only. These findings are statistically significant. So,
both 1 and 5 minutes Apgar scores are lower (denoting
depression) in meconium stained liquor group in comparison to clear liquor. Similarly, Misao et al. 2 noted
increased incidence of low Apgar score in their study.
Arulkumaran et al. 4 also found low 1 minute Apgar
score and more admission of the newborns in special baby
care unit. Zhu et al. 20 noted average Apgar score in
meconium stained amniotic fluid group was lower than that
in normal amniotic fluid group (P = 0.001). Ramchandra et
al. 5 found higher incidence of low Apgar score (0-7) at
one minute in study group as compared to the control, but
no significant difference was found in the Apgar score at 5
A significant association was also noted between Apgar
score and several microscopical changes in placentas of
meconium stained liquor.
When association between Apgar score (both at 1 and 5
minutes) and placental changes are assessed, it is seen
that color of placenta, color of membrane and most of
the microscopical changes noted here, are significantly
higher in meconium group in comparison to clear group,
except villitis and infarction. Most changes are related to
villous structures. These are increase in intervillous space,
intravillous fibrinoid, perivillous fibrinoid, calcification,
fibrosis, syncytial knots, blood vessel changes (especially,
fetal thrombotic vasculopathy). These changes are
statistically significant (p- value: <0.05) in meconium
stained liquor group in comparison to clear liquor group.
Though, villitis (6.1%) and infarction (1.2%) are not
statistically significant (p- value: >0.05) in this study. No
change was noted in umbilical cord both in control group
In the fetal membrane, (i.e.: amnion and chorion) we
found multi-layering of amniotic epithelium in significant
number of the cases (Amnion epithelial hyperplasia)
and chorio-amnionitis in 15 cases, which are statistically
significant findings (p- value: <0.05) in meconium group
in comparison to clear liquor group. However, meconium
laden macrophages in amnion or chorion are noted in only
3 cases of meconium stained liquor, may be because of early
intervention in a tertiary care center. Necrosis or ballooning
degeneration of chorion and amnion are not found in any
cases of study population. Villous chorangiosis is a peculiar
finding in this study. It is present in 13.4% of total cases
(72.7% in meconium stained liquor group and 27.3% in
clear liquor group). But the finding is not statistically
significant (p- value: 0.067 (>0.05)). But, Altshuler 32
found it to be a sign of neonatal morbidity and mortality. A
study by Kaspar et al. 33, described 9 different pathologic
lesions of the placenta. Among those, the frequency of
villous vascular thrombosis (25.4%), infarcts (38%), acute chorioamnionitis (20%), villous edema (9.1%) and villitis
(14.5%) was significantly higher in the group with longer
meconium exposure. Somewhat closely we have also found
many changes in villi. Though in our study, villous oedema
is not present; villitis and infarction are not significant
finding in the present study. Kariniemi et al. found
that meconium in the amniotic fluid seem to be associated
with placental rather than with umbilical insufficiency. In
this study we also found similar type of findings.
This study also suggests, that vascular changes in villous
structures are possibly present due to placental insufficiency,
causal factor for fetal distress and meconium passage,
either due to maternal or due to fetal hypoperfusion,
and not the effect of long standing meconium exposure.
Redline et al. 35, Sienko and Altshuler 36, Altshuler et
al. 37, demonstrated muscle necrosis of umbilical vessels
with prolonged meconium exposure. Ziadie 11 described
meconium laden pigmented macrophages with apoptotic
like nuclei present in different parts of placenta. However,
this study did not show this type of microscopical feature,
significantly. We found more changes in villi, fewer changes
in amnion and chorion, no change in umbilical cord at all.
It had previously been observed that intra-uterine fetal
distress is the consequences of maternal and fetal vascular
compromise, though the normal placenta has considerable
functional reserve 1. This study also revealed that various
placental changes observed in meconium stained liquor
and associated neonatal outcome are mostly the features of
fetal thrombotic vasculopathy as well as fetal and maternal
hypoperfusion. Intra-villous and peri-villous fibrinoid,
increase inter-villous space, fibro-muscular sclerosis of
fetal vessels with or without calcification and luminal
obstruction as observed in this study are the features of
In conclusion, we can postulate that, villi changes
of placenta, most importantly arises out of vascular
compromise in villi may be the primary cause which gives
rise to fetal distress and thereby passage of meconium in
utero, possibly arises out of chronic placental hypoxia.
Fetal thrombotic vasculopathy, characterized by increased
intra- and peri- villous fibrinoid, exaggerated syncytial
knots, villous fibrosis and fibro-muscular sclerosis may be
the cause behind chronic placental hypoxia. The changes
which are described in various studies, like changes in
umbilical cord and fetal membrane are not present in this
study, may be due to early intervention of the meconium
stained liquor cases and thus changes associated with
chronic meconium exposure were not detected in this small
study group. Elaborate cross-sectional study is necessary for further comments regarding placental changes in
meconium exposure with time and its effect on neonatal
The authors thank all staffs of Department of Pathology,
Burdwan Medical College for support and help in this
The authors confirm that they are all employee of
Government of West Bengal, India and have no corporate
affiliations. No funding has been received to do this
CONFLICT of INTEREST
The authors declare no conflict of interest.
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Ellenson LH, Ronnett BM, editors. Blaustein’s Pathology of the
female genital tract. 6th ed. New York: Springer; 2011. 999- 1074.
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