Role of Ultrasonography and Color Doppler in the Assessment of High-Risk Pregnancies and Their Accuracy in Predicting Fetal Outcome

Introduction Various methods are employed to evaluate the well-being of the fetus in high-risk pregnancies which consists of a biophysical profile (BPP), a non-stress test (NST), and daily fetal movements. Detection of aberrant blood flow in fetoplacental beds has been revolutionized by recent developments in ultrasound technology, such as color Doppler flow velocimetry. The cornerstone of maternal and fetal care is lowering maternal and perinatal mortality and morbidity is antepartum fetal surveillance. Doppler ultrasound is a non-invasive way of obtaining a qualitative and quantitative evaluation of maternal and fetal circulation and is utilized to investigate complications like fetal growth restriction (FGR) and fetal distress. Thus, it is useful in making distinctions between fetuses that are truly growth restricted and small for gestational age and healthy fetuses. The aim of the current study was to determine the role of Doppler indices in high-risk pregnancies and their accuracy in predicting fetal outcomes. Material and methods This prospective cohort study included 90 high-risk pregnancies in the III trimester (after 28 weeks of gestation) on whom ultrasonography and Doppler were performed. Ultrasonography was performed using PHILIPS EPIQ 5, a curvilinear probe of frequency 2-5MHz. Gestational age was determined with a biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femoral length (FL). Placental grading and position were noted. Estimated fetal weight and the amniotic fluid index were calculated. BPP scoring was done. Doppler study was conducted and the findings of Doppler indices that is pulsatility index (PI) and resistive index (RI) of the middle cerebral artery (MCA), umbilical artery (UA), and uterine artery (UTA), and cerebroplacental (CP) ratio in these high-risk pregnancies were documented and compared with standard. The flow patterns in MCA, UA, and UTA were also assessed. These findings were correlated with fetal outcomes. Results Among 90 cases, the common high-risk factor in pregnancy was preeclampsia without severe features (30%). Growth lag was present in 43 (47.8%) participants. Among the study population, HC/AC ratio was increased in 19 (21.1%) participants which indicates asymmetrical intrauterine growth restriction. Adverse fetal outcomes were seen in 59 (65.6%) of the subjects. CP ratio and UA PI had better sensitivity (83.05% and 79.66%, respectively) and positive predictive value (PPV) (87.50% and 90.38%, respectively) in identifying the adverse fetal outcomes. Diagnostic accuracy of CP ratio and UA PI (Accuracy=81.11%) was highest in predicting adverse outcomes than all the other parameters. Conclusion CP ratio and UA PI had better sensitivity, PPV, and diagnostic accuracy in identifying adverse fetal outcomes than other parameters. The study's findings support that the use of color Doppler imaging in high-risk pregnancies will help in the early identification of adverse fetal outcomes and aid in early intervention. This study is non-invasive, simple, safe, and reproducible. This study can also be performed bedside in high risk and unstable patients. This study is required to accurately assess fetal well-being in all high-risk pregnancies in order to improve fetal outcomes and to incorporate this procedure as a part of the protocol for the assessment of fetal well-being in these patients.


Introduction
The incidence of preeclampsia is 8%-10% in pregnant women, according to the National Health Portal of India. In India, the research found that the frequency of hypertensive disorders during pregnancy was 7.8%, with preeclampsia (PE) occurring in 5.4% of the population [1]. Various methods are utilized to evaluate the well-being of fetuses in high-risk pregnancies which include non-stress tests (NST), biophysical profile (BPP), and daily fetal movements. All the above tests are less desirable since they lack a high level of positive predictive value (PPV), sensitivity, and specificity.
The identification of abnormal blood flow in fetoplacental beds has been revolutionized by recent advances in ultrasound (USG) such as Color Doppler flow velocimetry. Early detection of these abnormalities is helpful in determining the optimal time for delivery and early diagnosis of intra-uterine growth restriction (IUGR) which reduces fetal mortality and morbidity.
This technique demonstrates blood flow in uterine arteries (UTAs), umbilical artery (UA), and middle cerebral artery (MCA). This is a non-invasive technique to study uteroplacental and fetoplacental circulations. It is simple, safe, and reproducible. Fetal hypoxia can be assessed with the abnormal wave patterns obtained from these vessels. This method makes it easier to delineate small intracranial vessels resulting in quicker and more accurate examinations. The aim of the current study was to determine the role of Doppler indices in high-risk pregnancies and their accuracy in predicting fetal outcomes.
Fetal growth restriction (FGR) and fetal distress that results due to fetal hypoxemia or asphyxia can be investigated using Doppler velocimetry of uteroplacental and fetoplacental circulations [2]. Thus, it is useful in distinguishing a healthy fetus from a fetus that is truly growth restricted from small for gestational age. Therefore, the current study is important for the accurate assessment of the well-being of fetuses in high-risk pregnancies in order to improve fetal outcomes.

Materials And Methods
This is a prospective cohort study conducted at a tertiary hospital, R. L. Jalappa Hospital and Research Center in Kolar, Karnataka, India, over a period of 18 months (January 2021 and July 2022). All singleton pregnancies beyond 28 weeks of gestation (third trimester) deemed by investigators to be at high risks like preeclampsia, eclampsia, and gestational diabetes mellitus (GDM) were included in the study. Pregnancies with any congenital anomalies and multiple pregnancies were excluded from the study.
The sample size was calculated as 87 using master software version 2.0. The study was approved by the institutional ethics committee of Sri Devaraj Urs Medical College, Kolar, Karnataka, India (approval number: SDUMC/KLR/IEC/603/2020-21). Written informed consent was obtained from all the study participants and only those participants willing to sign the informed consent were included in the study. The risks and benefits involved in the study and the voluntary nature of participation were explained before obtaining consent. The confidentiality of the study was maintained.
A detailed history was taken from all the patients meeting the inclusion criteria and referred to the Department of Radiodiagnosis. Patients were subjected to ultrasonography examination and a Doppler study. The equipment used was PHILIPS EPIQ 5G system with a pulsed wave, continuous wave, and HPR Doppler with dual sector transducer. The scan was performed using 2D real-time USG with a C5-1 MHz convex sector transducer. Gestational age was determined with a biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femoral length (FL). Placental grading and position were noted. Estimated fetal weight and the amniotic fluid index were calculated. BPP scoring was done. Doppler study was conducted and the findings of Doppler indices like pulsatility index (PI) and resistive index (RI) of the MCA, UA, and UTA, and cerebroplacental (CP) ratio in these high-risk pregnancies was documented and compared with standard. The flow patterns in MCA, UA, and UTA were also assessed. This was correlated with fetal outcomes. The data were entered into a Microsoft Excel sheet and the SPSS 22 version (IBM Corp., Armonk, NY) of the software was used to analyze the data. The sensitivity, specificity, PPV, NPV, and diagnostic accuracy of each Doppler indices in predicting the adverse fetal outcome are calculated.

Results
A total of 90 subjects were included in the study, of which the maximum number of cases were in the age group between 21 and 25 years (39 participants; 43.3%), followed by 26-30 years (26 participants; 28.9%), less than 20 years (15 participants; 16.7%) and least number of cases were seen beyond 30 years (10 participants; 11.1%). The age distribution based on maternal age is shown in Table 1. The mean age group of subjects was 25.4 years and the age group ranged between 18 and 37 years. A total of 49 (54.4%) participants were multigravida and formed the majority of the study population, while 41 (45.6%) patients were primigravida.   Oligohydramnios was seen in 37 (41.1%) participants and six (6.7%) participants had polyhydramnios. Growth lag was present in 43 (47.8%) participants while, HC/AC ratio was increased in 19 (21.1%) participants which indicates that these participants had asymmetrical IUGR.

High-risk conditions
Early diastolic notching in uterine artery   Reversal of CP ratio was seen in 52 (57.8%) subjects. Distribution of subjects based on CP ratio in all highrisk pregnancies is shown in Table 6.  Fetoplacental insufficiency was seen in 57 (63.3%) cases and P-value < 0.001, there was a statistically significant difference found between fetoplacental insufficiency and outcome. Uteroplacental insufficiency was seen in 62 (68.9%) cases and P-value 0.016, there was a statistically significant difference found between uteroplacental insufficiency and outcome.
Among the study population, 31 subjects underwent normal vaginal delivery (NVD) in 31 (34.4%) and 59 (65.5%) underwent lower segment cesarean section. Adverse fetal outcomes were seen in 59 (65.6%) of the subjects. The distribution of subjects according to maternal complication and outcome is shown in Table 7 and PE with severe features had the highest adverse outcomes. P-value was <0.001, there was a statistically significant difference found between complication and outcome.

Discussion
Studies using perinatal Doppler velocimetry are able to identify fetuses who are at risk of having adverse outcomes, allowing for prompt intervention. It is challenging to analyze each parameter independently with different research because the definition of adverse fetal outcomes is not fixed. Since various clinical factors and the Doppler results were taken into consideration for patient management in the current study, it is possible that fetal outcomes will differ from that of other studies. We studied the role of color Doppler and USG in high-risk pregnancies. Doppler finding's predictive value in various high-risk pregnancies was studied and its significance in the management of fetal outcomes was established.
In the current study, out of 90 (100%) patients, most of the patients were in the age group 21-25 years (39/43.3%). In the current study, the mean age was 25.4 years, ranging between 18 and 37 years in the study population. Age ranged from 19 to 35 years and the mean was calculated as 26.73 years in a study conducted by Gaikwad et al. which is similar to our study [3]. A similar finding was found in a study by Kavitha et al. where most of the patients were in the age group 26-30 years (n=80) followed by 20-25 years (n=60) [4].
According to complications, out of 90 (100%) majority of the patients had PE without severe features (27/30%), followed by eclampsia (24/26.7%), GDM (21/23.3%), PE with severe features (18/20%). A statistically significant difference was found between complication and outcome with a p-value of <0.001. This is similar to the study of Aparna et al. about 90% of patients at risk had PE and 6% had gestational diabetes [5]. In our study, out of the 90 patients, 54.4% were multigravidas and the rest were primigravidas.
In our study, most of the patients (55/61.1%) were in >36 weeks of the gestation period, followed by 25 (27.8%) of the patients who were in 32-36 weeks and 10 (11.1%) were in 28-32 weeks. Aparna et al. had patients with a gestational age of 28 to 37 weeks [5].
In the present study, the sensitivity, specificity, NPV, PPV, and diagnostic accuracy for MCA RI in predicting adverse outcomes were 40.68%, 87.10%, 43.55, 85.71%, and 56.67%, respectively. Gaikwad et al. also studied the fetal MCA through Doppler studies; MCA RI was found to be abnormal in 25.6% of patients. It was discovered that MCA RI had the highest specificity of 100% for predicting unfavorable outcomes. Additionally, MCA RI was found to have a PPV of 100% for predicting unfavorable outcomes [3].

Study
The CP ratio is considered abnormal if the ratio is <1. The index will reflect a mild increase in placental resistance with mild reductions in fetal brain vascular resistance. An abnormal CP ratio reflects the redistribution of cardiac output to the cerebral circulation and has been associated with intrapartum fetal distress.
In the present study, out of 90 (100%) patients, the majority of patients (52/57.8%) had reversed fetal CP ratio. A sensitivity of 79.66%, specificity of 83.87%, NPV of 68.42%, PPV of 90.38% and accuracy of 81.11% for CP ratio in predicting adverse outcome was observed in the present study. In a similar study by Lakshmi et al., it was found that the CP ratio has 90% sensitivity and 94% PPV [8]. CP ratio has the highest specificity and PPV of 90.32% and 83.33% respectively in identifying adverse perinatal outcomes as seen in Gaikwad et al. study [3].
In 2010, Bansal et al. did a study on the role of pan vessel Doppler studies in high-risk pregnancies. Their conclusion was similar to our study, women with aberrant Doppler indices had higher rates of LSCS (78%), low Apgar scores, and LBW and NICU admissions (36%) [16]. In 2010, Urmila and Beena did a study on triple vessel wave patterns in high-risk and normal pregnancies. They came to the same conclusion as ours; in the study group, there was an increased incidence of LSCS and NICU admissions as compared to the control group [17].
In a 2016 study on color Doppler ultrasonography in high-risk pregnancies, Amin et al. found that perinatal mortality and morbidity were 41.3% and 23.9%, respectively, among 46 pregnancies with abnormal Doppler waveforms, in comparison with patients having normal Doppler waveforms, had 3.7% (mortality) and 11.1% (morbidity) [18].
In a study conducted by Kirkinen et al., it was discovered that Doppler investigations had advanced significantly and were now acknowledged as a crucial examination to forecast heart failure in hypoxic fetuses. In 83 low-risk and 84 high-risk pregnancies, the pulsed Doppler method was utilized to record the blood flow velocity waveforms from fetal intracranial arteries. In typical cases, the waveform's RI decreased as the pregnancy progressed, and these arteries continued forward flow. A low RI had a 57% sensitivity and 94% specificity for predicting the birth of an infant that was small for dates and/or the subsequent development of a cardiotocographic abnormality [19].

Conclusions
CP ratio and UA PI had better sensitivity and PPV in identifying unfavorable outcomes. Diagnostic accuracy of CP ratio and UA PI was highest in predicting adverse outcomes. The study's findings support that the use of color Doppler imaging in high-risk pregnancies will help in the early identification of adverse fetal outcomes and aid in early intervention. This is a non-invasive technique to study uteroplacental and fetoplacental circulation. This study is simple, safe, and reproducible. This study can also be performed bedside in high risk and unstable patients. This study is required to accurately assess fetal well-being in all high-risk pregnancies in order to improve fetal outcomes and to incorporate this procedure as a part of the protocol for the assessment of fetal well-being in these patients.