Gross and Micro anatomical Study of Placenta from Normal and Hypertensive Pregnancies

Introduction: The examination of placenta gives a clear idea of what had happened with fetus, when it was in the mother’s womb. The changes in placenta of women with pregnancy induced hypertension and normal pregnancies can be compared. Objective: This study was done to find out differences in gross structure and histology between normal and hypertensive placentas. Methods: Placenta from case and control group was collected from the Gynecology and Obstetrics Department of B.P.Koirala Institute of Health Sciences, Dharan. The histology slides were prepared, examined and parameters was collected. Results: The mean weight of placenta in control group was 469.5±148.9gm and in case group was 375.50 ± 109.08gm which was statistically significant. The histological observation of syncytial knot, hyalinized villi, stromal fibrosis, necrosis, hemorrhage and calcification in placenta was significantly higher in case group than that of in normotensive group. Conclusions: It is concluded that, in hypertension complicating pregnancy, with increase of severity, there is decrease in morphology and increase in abnormal histological changes of placenta. So, the reduction in placental morphological parameters and histological changes might be the reason for retarded growth of baby with increased complication of hypertension.


INTRODUCTION
The placenta is the chief regulator of nutrient supply to the growing embryo during gestation. 1 Pregnancy induced hypertension (PIH) is a sustained rise of blood pressure to 140/90 mm Hg or more on at least two occasions 4 or more hours apart beyond the 20th week of pregnancy or during the first 24 hours after delivery in a previously normotensive woman. 2 The hypertensive disorders complicating pregnancies are quite common. Fetal distress, intrauterine fetal deaths and placental abnormalities are common in pregnancy induced hypertension. 3 It is a leading cause of maternal and perinatal morbidity and mortality. 4 It usually develops after 20 weeks of gestation and resolves after delivery of placenta. 5 The condition complicates 2-8% of pregnancies. 6 Pregnancy induced hypertension is very common in our country and to the best of my knowledge of investigation, little or no work is done here to evaluate placental changes in this condition. This study was designed to evaluate changes in placenta of women with pregnancy induced hypertension and compare these with placenta of normal pregnancies.

METHODS
This study was a case control study. For this study, sample was collected from Gynecology and Obstetrics Department of B.P. Koirala Institute of Health Sciences, Dharan in one year (August 2014 to August 2015). A total of 100 placentas of 50 from normotensive and 50 from hypertensive pregnant women were collected. For this study, proportional quota sampling of purposive sampling method was used. Inclusion criteria included full term pregnant women (Gestational week 36-40). Exclusion criteria was pregnant women having complication other than pregnancy induced hypertension like gestational diabetes mellitus, acquired immune-deficiency syndrome (AIDS, Hepatitis). The experimental procedures were explained verbally and written informed consent was obtained before enrollment. The study was ethically approved by Institutional Ethics Committee.
The collected specimen was dried. The membrane and umbilical cord was trimmed. The measurement for weight, diameter and thickness were noted. The insertion of umbilical cord was observed. Each specimen was labeled separately and then transferred to 10% formal saline solution for fixation. For histological examination, the permanent slides of the placental tissues for its histopathological evaluation was prepared; the preserved placentas were processed by fixation, dehydration, clearing and impregnation. Embedding and microtomy was done. The slides were stained by H&E stain and microscopy was done.
The collected data was entered in Microsoft Excel 2010 and converted into SPSS 16.0 for statistical analysis. For Descriptive Statistics, mean, SD % and proportion was calculated along with graphical and tabulated presentation. For inferential statistics, Chi-Square and Independent T-test were applied to find out the significant difference between hypertensive and non-hypertensive placenta at 95% confidence interval where probability value (P) is 0.05.

RESULTS
Mean weight, diameter, thickness and number of cotyledon were 375.50 gm, 13.86 cm, 1.12 cm and 15.40 in case group and 469.5gm, 14.83cm, 1.69cm and 17.76 in control group respectively. These shows statistically significant value. However, there was no significant difference of insertion of cord between case and control. Table 2 shows that the weight, diameter, thickness and cotyledon of placenta are decreasing with increase of severity of PIH.   There was significant increase of syncytial knot, hyalinization, stromal fibrosis, necrosis, calcification and hemorrhage (84%, 66%, 92%, 36%, 58% and 60% respectively) in case group than in control group (38%, 18%, 42%, 16%, 20% and 24% respectively) ( Table 3).
The severity of PIH has direct relation with the abnormal changes in histology of placenta. Syncytial knot was found 84.61% of total PIH, 88.24% of total Pre-eclampsia and 100% of total eclampsia.

DISCUSSION
The anatomical and pathological examinations and assessments are becoming more precise and considered as an indirect or non-invasive method for the study of human placenta. 7 In present study, the mean weight of placenta in control group was 469.5±148.9gm and in case group was 375.50 ± 109.08gm which was statistically significant. The mean placental diameter in case group was 13.86 ± 1.49 cm which was statistically reduced than that of control group (14.83±1.57cm). Mean placental thickness was 1.69±0.37cms in control group and 1.12 ± 0.22cms in hypertensive group.
In control group, mean number of cotyledon was 17.76±3.50 whereas in case group, it was 15.40± 2.71, which showed statistically significant value. Udaina and Jain also found placental weight in control group 495.05gm and 405.67 in case group which was higher than present study. 8 Similarly, Modi et al. also reported weight <400gm; volume <400ml; thickness <2cm and diameter <18cm of placenta in PIH 9 which supports the findings of present study.
A similar study by Baloch et al. found that the placental weight and the diameter from hypertensive group were significantly less than that from normotensive group, whereas they found statistically no significant differences in number of cotyledons and central thickness in both groups. 10 which is different from the present study as number of cotyledon and mean thickness of placenta from hypertensive group is significantly reduced than control group.

CONCLUSIONS
From this study, it is concluded that the weight, diameter and thickness and cotyledon of placenta are significantly reduced in hypertensive group than in normotensive group. In histological finding there are significant increase in syncytial knot, hyalinization, stromal fibrosis, necrosis, hemorrhage and calcification in hypertensive group than that of normotensive group.
The study also concluded that, with increase of severity, there is decrease in morphology and increase in abnormal histological changes of placenta. So, the reduction in placental morphological parameters and increased histological changes might be the reason for fetal growth retardation in preeclampsia. Higher incidence of PIH is mostly due to malnutrition, ignorance, lack of adequate health education, and medical care. If proper medical care is given during antenatal period and labor, then further risk to mother and fetus can be reduced.