MORPHOLOGICAL AND HISTOLOGICAL VARIATIONS OF HUMAN PLACENTA IN HYPERTENSIVE DISORDERS OF PREGNANCY

Address for Correspondence: Dr. Siva Sree Ranga. M.K., Siva Sree Sadanam, Vellarada, Thiruvananthapuram Dist. Kerala, India. PIN 695 505; Mobile: 9447696069; E-Mail: sivasreeranga@gmail.com Background: Hypertensive disorders of pregnancy form leading cause of maternal as well as foetal morbidity and mortality. Many disorders of pregnancy are associated with gross pathological changes in placenta, the feto-maternal organ which is vital for maintaining pregnancy and for promoting growth of the fetus. Materials and Methods: A cross sectional study was conducted among placentae from thirty pregnant mothers with hypertension and thirty mothers with uncomplicated pregnancy in the Department of Obstetrics and Gynaecology, Dr.Somervell Memorial CSI Medical College, Karakonam. The gross morphological and histological examination of placentae was done. Results: The placental weight, diameter and thickness were reduced in the hypertensive group. The hypertensive placentae showed more incidence of infarction, retroplacental haematoma and calcification. Histologically, hypertensive placentae showed large number of syncytial knots, cytotrophoblastic proliferation, fibrinoid necrosis and villus hyalinization. New born babies of hypertensive group had reduced birth weight and low Apgar score. Conclusion: Hypertensive disorders of pregnancy show significant differences in various parameters of placental morphology and histology. Hypertensive disorders of pregnancy adversely influence the foetal outcome.

INTRODUCTION organ for maintaining pregnancy and promoting development of the fetus [1]. The intrauterine existence of fetus is dependent on this vital organ. The hypertensivedisorders of pregnancy are responsible for 5-8 % of all maternal deaths [2]. Hypertensive disorders of pregnancy are also The human placenta is an intrauterine fusion of fetal and maternal tissues for the purpose of physiological transfer of nutrients and oxygen from mother to fetus and transfer of waste products of metabolism from fetus to mother for continuation of fetal life. Placenta is the vital strongly associated with foetal growth retardation and prematurity leading to perinatal morbidity and mortality. Placenta has drawn attention as valuable indicator for foetal and maternal diseases [3]. Many disorders of pregnancy which are associated with high perinatal morbidity and mortality have shown gross pathological changes in placenta 1 . Many maternal diseases or disorders bring about changes in placenta at morphological and microscopic level. Abnormal placenta adversely affects the fetal outcome [4]. As placenta is the mirrorof maternal and foetal status,complications like hypertension in pregnancy has reflected in the placenta in a significant way both macroscopically and microscopically [5][6][7][8].
Though a wide variety of morphologic changes has been reported in the placentae of hypertensive pregnancies, the definitive pathogenesis of these structural abnormalities, their correlation with placental function and their relationship to fetal and maternal outcome have not been studied in rural areas of South Size, Shape, Surface Area and thickness of placentae, marginal veins for any thrombus, number of cotyledons, condition of membranes, presence of infarction, calcifications and site of insertion of umbilical cord were noted. The weightof the placenta was taken using standard weighing machine. Tissues were taken from the following placental sites for histological studies:--Near the insertion of the umbilical cord -Margins -12, 3, 6, 9 o' clock positions -Centre of the placenta -Fibrotic area if any -Infarcted area if any -Umbilical cord at placental junction and cut end Placental tissues were stained and examined under microscope for number of syncytial knots, cytotrophoblastic cellular proliferation, fibrinoid necrosis, endothelial proliferation, calcified and hyalinised villous spots in the hypertensive group in comparison to normotensive group. The newborn babies were examined for congenital anomalies. Neonatal outcome in the form of birth weight, Apgar score, need for neonatal resuscitation and admission to Newborn Intensive Care Unit were noted. Feto-placental weight ratio was calculated in each case. Statistical analysis was made using Student's T Test and Chi Square Test The study group comprised placentae from thirty pregnancies with hypertension. The controlgroup comprised thirty placentae from pregnant mothers with normal blood pressure, without proteinuria and without edema. The mean age of hypertensive mothers was 25.6 ± 3.8 years The mean age of non hypertensive mothers 24.6 ± 3.3 years. The two groups were not significantly different (P>0.05).

Parity Hypertension Non Hypertension
There was no significant difference between the hypertensive and nonhypertensive groups in respect of maternal parity (P>0.05).     [9] found that the number of cotyledons were almost same in hypertensive and non hypertensive groups. The Foeto placental ratio of the two groups were 5.5± 1.9 and 5.6±0.7 respectively. This finding was not statistically significant (P>0.05). Insertion of Placenta: Udaina et al (2004) [5] and Majumdar Setal (2005) [6] observed that marginal insertion of cord was significantly associated with hypertensive placentae.
In the hypertensive group of the present study, five placentae showed abnormal insertion of cord. Among them, four placentae showed marginal insertion (Fig.1) and one showed velamentous insertion while the placentae of normotensive group showed central insertion of umbilical cord. There was insignificant association between insertion of umbilical cord and hypertension in pregnancy (P>0.05) in this study.  63.3% of placentae from hypertensive mothers showed fibrinoid necrosis (Fig.6) and there was no incidence among the non hypertensive group. The difference showed very high statistical significance (P<0.001). Udainia et al (2004) [5] reported that fibrinoid necrosis,endothelial proliferation of arteries and hyalinization probably leads to placental insufficiency and ultimately to foetal growth retardation  .7) and the same of their counterpart in Nonhypertensive group was 23.3% ( Fig. 3-5).
The difference is statistically highly significant (p<0.01).
A study by Majumdar etal [6] showed histological findings like cytotrophoblastic cellular proliferation, syncytial knot formation and fibrin plaque formation in greater amount in hypertensive placentae. Babies of such mothers were mostly small for date. Villus hyalinization (Fig.9) was observed among 16.7% placentae of hypertensive group where as none was observed among of placentae of normotensive group. This difference was statistically very highly significant (P<0.001). A study done by Aparna N et al (2011) [19] concluded that gross abnormalities and villous lesions were significant in placentae of normotensive patients. The incidence of infarction among the hypertensive placentae was 36.7% and the same of the non hypertensives was 6.7%. The observed difference between the two groups was statistically highly significant (P<0.01).  [21] found structural changes such as significant number of syncytial knots, areas of fibrinoid necrosis, areas of medial coat proliferation of medium sized blood vessels, areas of calcification, and areas of hyalinization in hypertensive placentae. A significant increase in syncytial knot formation in placental villi indicates disturbance in the hormonal factors, which may lead toaltered morphometry of placenta resulting in Pregnancy induced hypertension in the mother and to low birth weight in the new born.

CONCLUSION
It may be concluded that hypertensive disorders of pregnancy show significant differences in various parameters of placental morphology and histology. Hypertensive disorders of pregnancy adversely influence foetal outcome. The placentae of mothers with hypertensive disorders of pregnancy show presence of retroplacental haematoma and infarction which may lead to placental insufficiency. This can lead to both foetal and maternal morbidity and mortality. Placenta has a great potential to provide valuable information in the case of an adverse foetal outcome.
Recommendations: Further studies may be required in different settings with larger sample size. More precise intervention strategies may be devised that can contribute to more effective management of the condition in the future. It will help to bring down the fetal and maternal mortality and morbidity.
Present study has been planned to record the morphology and histology of placentae of hypertensive disorders of pregnancy and to compare the findings with those of placentae of normal pregnancy. A group of thirty pregnant ladies with uncomplicated normal pregnancy and another group of thirty pregnant mothers with hypertension comparable in age and parity were selected from Department of Obstetrics and Gynaecology, Dr.SM CSI Medical College, Karakonam. The placentae were collected immediately after delivery from both the groups and morphological and histological findings were compared.