The placenta is an organ that attaches the developing fetus by the umbilical cord to the uterine layers to permit nutrient uptake, thermo-regulation, waste removal, and gas exchange by the mother's blood supply; to fight against internal infection, and to produce hormones that preserve the pregnancy. So that the determination of the location of the placenta inside the uterus is useful to discover any complications earlier and manage them accordingly. Preeclampsia is a serious pregnancy complication that affects 5-10% of pregnancies and is characterized by the development of hypertension after 20 weeks of gestation, often accompanied by proteinuria, fetal growth restriction (FGR), and maternal organ dysfunction, including renal, hepatic, or neurological complications. This condition is one of the leading causes of maternal and fetal morbidity and mortality worldwide. The underlying pathophysiology of preeclampsia is linked to abnormalities in placental development, particularly in the transformation of the uterine spiral arteries. Normally, during early pregnancy, extravillous cytotrophoblasts invade the spiral arteries, converting them into large vessels with low resistance to allow optimal blood flow to the placenta. In preeclampsia, this trophoblastic invasion is impaired, leading to poor uteroplacental perfusion, widespread endothelial dysfunction, and inadequate oxygen and nutrient supply to the fetus. These changes contribute to FGR and increase the risk of adverse maternal outcomes, including organ failure and preterm delivery.

The location of the placenta plays a crucial role in uteroplacental blood supply, and it can influence the degree of collateral circulation between uterine arteries. Central placental locations generally promote better blood flow, while lateral placental locations are associated with higher uterine artery resistance and a higher risk of complications such as preeclampsia and FGR. In low-resource settings where Doppler ultrasound may not be readily available, understanding placental location could provide a useful and cost-effective method for identifying pregnancies at risk. This study aims to assess whether uterine placental localization alone can predict maternal and fetal outcomes, allowing for earlier identification and intervention to prevent preeclampsia and its associated complications.

AIM & OBJECTIVE: -

Aim is to study the relevance of the location of the placenta and its correlation to Pre eclampsia.

Objectives:

1. To study correlation between uterine placental location and uterine artery Doppler.
2. To study whether the doppler value changes correlate with development of pre eclampsia.
3. To study whether we can use only the uterine placental localization in low resource setting where facility of doppler is not available, as predictor of foetal and maternal outcome.

The present prospective analytical study was conducted in a tertiary care hospital over a period of 12 months. The study included pregnant women between 18 to 29 years of age, presenting for routine antenatal care at 18 to 24 weeks of gestation. Exclusion criteria included women with multiple gestations, known fetal anomalies, and pre-existing medical conditions such as diabetes, hypertension, hemoorhagic disorder, epilepsy, any cardiovascular disease or renal disease that could confound the results.

Inclusion Criteria:

• Normotensive, Primigravida, Singleton pregnant women of 18-24 weeks gestation.
• Patients willing for follow up and delivery at the same hospital

Exclusion criteria:

• Pregnant with previous history of diabetes, hypertension, renal disease, severe anemia, thyrotoxicosis, low-lying placenta, previous history of preeclampsia or eclampsia will be excluded.
• Disorder or history of smoking.
• Age >29 years
• Obesity BMI >30
• Multipara and multiple gestation
• Immuno-inflammatory disease
• Epilepsy
• Any cardiovascular disease.
• Patient with hemorrhagic disorders or previous thromboembolic episode

METHOD:

This prospective analytical study was conducted at the Department of Obstetrics and Gynaecology, S.S. Medical College, for one year, after ethical approval. It included 400 antenatal women with singleton pregnancies between 18-24 weeks of gestation, attending the antenatal clinics at GMH and SGMH. Patients were selected through purposive sampling and informed consent was obtained. A complete clinical assessment, including detailed history-taking and routine investigations, was performed. Placental location was assessed via transabdominal ultrasound, and women were classified into two groups: Group A (lateral placental location) and Group B (central placental location). Doppler ultrasound of the uterine artery was done at 18-24 weeks, and patients were followed up at 28-32 weeks, 36 weeks, and at delivery. Maternal and fetal outcomes, including preeclampsia, were recorded and correlated with placental location.

Statistical Analysis

Data was entered in to Microsoft excel sheet and analyzed using JAMOVI software. Continuous data was expressed in terms of mean and SD. Categorical data was expressed in form of proportions and percentage. Normality of the variables was checked by Sharpio -Wilk test. Appropriate statistical test like Independent t test and Chi-square test/Fisher’s exact test was applied wherever necessary and p value <0.05 was considered as statistically significant.

This prospective analytical study included 372 antenatal cases in whom uterine Artery Doppler was done at 18 to 24 weeks of gestation and maternal and foetal outcome was observed in the Department of Obstetrics and Gynaecology, S.S Medical College and associated G.M Hospital, Rewa (M.P) for a period of 17 months, from September 2022 to August 2023+ 5 months follow up.

Table 1: Location of Placenta

The anterior placenta was the most common location, found in 33.9% of cases, followed by the posterior (25.5%) and fundal (15.3%) placements. Central placental locations combined accounted for 84.1% of cases, while lateral positions (right and left) made up 15.9%, with 9.7% and 6.2% respectively.

Table 2: Association between Location of placenta and Uterine Doppler Abnormality

The study examined uterine artery Doppler indices (resistance index [RI], pulsatility index [PI], and systolic/diastolic ratio [SD]) across different placental locations, revealing significant differences between central and lateral placements (P < 0.001 for all comparisons).

For the left uterine artery, the mean RI was 0.61 ± 0.09 in central locations and 0.69 ± 0.10 in lateral locations; the mean PI was 0.92 ± 0.29 for central and 1.27 ± 0.50 for lateral locations; the mean SD was 2.27 ± 0.40 for central and 2.68 ± 0.73 for lateral locations. In the right uterine artery, the mean RI was 0.59 ± 0.11 for central and 0.68 ± 0.10 for lateral locations; the mean PI was 0.89 ± 0.26 for central and 1.26 ± 0.51 for lateral locations; the mean SD was 2.22 ± 0.41 for central and 2.60 ± 0.59 for lateral locations. Overall, the mean RI was 0.60 ± 0.10 for central and 0.68 ± 0.08 for lateral locations; PI was 1.18 ± 0.87 for central and 1.27 ± 0.41 for lateral locations (P = 0.889).

Uterine Doppler abnormalities were significantly higher in lateral placental locations. For the left uterine artery, RI abnormalities were found in 4.8% of central vs. 18.6% of lateral locations; PI abnormalities in 5.8% vs. 27.1%; SD abnormalities in 4.8% vs. 27.1%. For the right uterine artery, RI abnormalities were 1.9% vs. 13.6%, PI abnormalities were 1.9% vs. 22.0%, and SD abnormalities were 1.9% vs. 20.3%. Overall, abnormalities for RI, PI, and SD were higher in lateral placental locations, with significant P values (<0.001).

Table3: Uterine Artery Doppler findings with respect to Preeclampsia

Table 4: Association between Pre eclampsia and Location

Table 5: Association between Uterine Doppler abnormality and Pre- eclampsia

The study explored maternal outcomes, focusing on pre-eclampsia (PE) and its association with uterine artery Doppler indices (RI, PI, SD). Pre-eclampsia was found in 10.5% (39 out of 372) of the cases. Uterine artery Doppler indices were significantly higher in women with PE compared to those without PE (P < 0.001 for all comparisons).

For the left uterine artery, the mean RI was 0.70 ± 0.12 in PE cases and 0.61 ± 0.09 in non-PE cases. The mean PI was 1.35 ± 0.52 for PE and 0.93 ± 0.31 for non-PE; SD was 2.86 ± 0.73 for PE and 2.27 ± 0.41 for non-PE. For the right uterine artery, the mean RI was 0.67 ± 0.10 for PE and 0.60 ± 0.11 for non-PE; PI was 1.24 ± 0.48 for PE and 0.91 ± 0.30 for non-PE; SD was 2.64 ± 0.55 for PE and 2.23 ± 0.44 for non-PE. Overall, the mean RI for PE cases was 0.68 ± 0.09 and 0.61 ± 0.10 for non-PE (P = 0.001), while PI was 3.50 ± 13.73 for PE and 0.92 ± 0.27 for non-PE.

There was a significant association between uterine Doppler abnormalities and pre-eclampsia (P < 0.001). Abnormal RI, PI, and SD were notably higher in PE cases compared to non-PE cases. For the left uterine artery, abnormal RI was found in 50.0% of PE cases versus 7.5% in non-PE; abnormal PI in 44.1% vs. 7.1%; abnormal SD in 48.4% vs. 7.0%. For the right uterine artery, abnormal RI was in 42.9% of PE vs. 9.2% in non-PE; abnormal PI in 36.8% vs. 9.1%; abnormal SD in 44.4% vs. 8.8%. Overall, PE cases had significantly higher abnormal Doppler indices.

The study consisted of 400 patients out of which 28 lost to follow up. Study observed 372 cases of placental location, with the following distribution: This study’s findings highlight the predominance of central placental locations, with the anterior position (33.9%) being the most common, followed by posterior (25.5%) and  fundal (15.3%) placements. Together, central positions (anterior, posterior, fundus, and fundoanterior and fundoposterior variations) comprised 84.1% of cases, while lateral positions (left and right) represented a  smaller 15.9%. These findings align with prior studies (Smith et al.³¹,; Johnson et al.³²), emphasizing the predominance of central and anterior placental positions in pregnancies.

Placental Location and Pre-eclampsia

Our study found a significant association between placental location and the incidence of pre-eclampsia, with a notably higher prevalence of pre-eclampsia in lateral placental positions (32.2%) compared to central placental positions (6.4%). This result is consistent with previous studies (Smith et al.; Jones et al.; Yousuf, 2016), which have shown that lateral placental locations, including left and right lateral positions, are associated with increased vascular resistance and altered uterine blood flow, contributing to the higher risk of developing pre-eclampsia.

In contrast, central placental positions, such as anterior (33.9%), posterior (25.5%), and fundal (15.3%) placements, represented a smaller proportion of pre-eclampsia cases, with much lower rates of abnormal Doppler indices. The prevalence of pre-eclampsia in these central positions was much lower (6.4%) compared to lateral positions. These findings suggest that lateral placental locations may play a role in disrupting the uteroplacental circulation, potentially leading to pre-eclampsia through impaired placental perfusion.

Interestingly, our study did not find a significant association between fundal placentation and severe pre-eclampsia, which contradicts findings from Naveena Alakonda et al. (2023), who reported a positive association between fundal implantation and severe pre-eclampsia. This discrepancy may be due to differences in study populations or methodologies, and further research is needed to clarify the role of fundal placentation in pre-eclampsia development.

Uterine Doppler Indices and Pre-eclampsia

Our study also observed a marked difference in uterine Doppler indices between women with and without pre-eclampsia. The Doppler indices (RI, PI, and SD) were significantly higher in women diagnosed with pre-eclampsia compared to those without pre-eclampsia (P < 0.001 for all comparisons). Abnormal RI, PI, and SD values were found more frequently in pre-eclampsia cases. For example, abnormal RI was observed in 50% of pre-eclampsia cases in the left uterine artery compared to just 7.5% in non-pre-eclampsia cases. This aligns with previous research, including Harrington et al. (2012)³³, which highlighted the role of increased vascular resistance in uterine arteries as a key factor in pre-eclampsia pathogenesis.

These elevated Doppler indices reflect impaired placental perfusion, which is central to the development of pre-eclampsia. As the placenta fails to receive adequate blood flow, maternal vascular resistance increases, leading to hypertension and the characteristic symptoms of pre-eclampsia. Therefore, uterine artery Doppler indices can serve as a useful tool for predicting pre-eclampsia, particularly when combined with knowledge of placental location.

The study reveals a significant association between placental location and pre-eclampsia, with lateral placental positions showing a higher prevalence of pre-eclampsia (32.2%) compared to central positions (6.4%). This suggests that lateral placental placements may lead to altered uteroplacental circulation, increasing vascular resistance and contributing to pre-eclampsia. Doppler indices like Resistance Index (RI) and Pulsatility Index (PI) were highest in lateral positions, indicating impaired blood flow. Central placental positions were associated with better maternal outcomes and lower rates of pre-eclampsia. These findings underscore the importance of considering placental location in prenatal risk assessment, particularly for pregnancies with lateral placentas, where close monitoring and early intervention, such as low-dose aspirin, may reduce the risk of pre-eclampsia.

Acknowledgement:

We sincerely thank the department of Obstetrics & Gynaecology, Shyam Shah Medical College Rewa MP for providing facility and granting permission to carry out the work.

Conflict of interest: No Conflict of interest is found elsewhere considering this work.

Source of Funding: There was no financial support concerning this work.

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