Correlation Between Placental Histomorphology and Umbilical Cord Coiling Index in Preeclampsia

BACKGROUND Preeclampsia is a common hypertensive disorder of pregnancy and one of the leading causes of maternal health complications and death globally. Both preeclampsia and abnormal umbilical coiling have been reported to alter the structure of the placenta significantly. Cases of preeclampsia and either of the two abnormal coiling states; hypercoiling or hypocoiling, occurring in the same pregnancy have been documented. The type of abnormal coiling associated with preeclampsia varies in different populations. The extent of changes in the placenta in preeclampsia coupled with either of the two is unknown. The current study aimed at determining which of the coiling state significantly alters the structure of the placentae of mothers with preeclampsia and therefore, predisposes them to more adverse perinatal outcomes. METHODs An unmatched case-control study was carried out in Kenyatta National Hospital labor ward and maternity theatre. Seventy (70) placentae from mothers with diagnosis of preeclampsia (cases) and mothers without complicated pregnancy (controls) were collected. The length of the cord and the number of coils was measured to calculate the coiling index. A gross placental examination was carried out followed by biopsy and tissue processing for light microscopy. Slides were photographed and several histological features analyzed in the terminal villi. Data from this study was input into SPSS (Version 21.0) where mean values, standard deviations, and frequency tables were obtained. Appropriate parametric and non-parametric tests were used where needed. A P-value of <0.05 was considered statistically significant. RESULTS In the current study, the mean umbilical cord coiling index (UCI) in cases and controls was 0.40 ± 0.18 and 0.22 ± 0.08 coils/cm respectively. Cases had a significantly greater UCI than controls (P = < 0.001). All placentae in the case hypocoiled subdivision had infarctions and were meconium stained. The mean placental weight was 519 g and 578 g respectively in cases and controls and the difference was found to be significant (p = 0.031). In cases and controls, the gross placental volume was 542 cm3 and 638 cm3, respectively. There was a significant difference in placental volume between cases and controls, and between subdivisions (p = < 0.001 and 0.028 respectively). The case hypocoiled subdivision had the highest absolute volume of villous stroma, fibrin deposition, syncytial knots and the lowest fetal capillary surface area. CONCLUSION Hypocoiling was associated with alteration of the structure of the placenta in preeclampsia more than it was observed in hypercoiling. Early detection of hypocoiling using ultrasound in pregnancies complicated with preeclampsia may help clinicians in identification of cases that warrant close antenatal and intrapartum monitoring thus reducing adverse perinatal outcomes.