Welcome to this comprehensive course on the importance of early detection of preeclampsia during pregnancy. Preeclampsia is a complex and potentially life-threatening condition that underscores the need for vigilant prenatal care. Typically emerging after the 20th week of pregnancy, preeclampsia is characterized by high blood pressure and the presence of protein in the urine, often accompanied by significant swelling. The repercussions of severe preeclampsia can be dire, leading to complications such as eclampsia and increased risk of stroke for the mother, as well as developmental challenges for the fetus¹.

Despite its later onset, research highlights the potential for first-trimester screening to predict the likelihood of developing preeclampsia. The root of this condition often lies in the abnormal development of the placenta during early pregnancy, which prompts changes in the mother's blood vessels. As these vessels narrow and become more permeable, they may restrict blood flow, leading to high blood pressure and systemic complications². Understanding these early physiological changes allows healthcare professionals to identify at-risk women, enabling timely interventions.

While the exact causes of preeclampsia remain elusive, genetic and immunological factors, as well as pre-existing medical conditions, seem to play a pivotal role⁵. This course aims to elucidate these complex interactions and equip you with the knowledge to recognize early warning signs, ultimately enhancing pregnancy outcomes. By diving into the latest research and screening techniques, we hope to empower you to make a significant impact in the field of maternal and fetal health.

Risk Factors in Preeclampsia Development

The chart (Figure 1) underscores the complex interplay of genetic and lifestyle factors in assessing preeclampsia risk. Notable genetic predispositions include clotting disorders like factor V Leiden mutation and homozygous MTHFR mutation, especially when multiple thrombophilia is present heightens the risk of preeclampsia. In terms of detection and prediction, early detection of preeclampsia currently stands at 30% with a false positive rate of 5%, indicating the challenges in predictive accuracy. Furthermore, maternal history of hypertension emerges as a more significant predictor of pregnancy-induced hypertension compared to serum parameters and pulsatility index³.

Risk Factors	Description
Metabolic and Glucose Metabolism Disorders	Includes diabetes mellitus and insulin resistance
Assisted Reproductive Techniques	Use of fertility treatments
Obesity is a significant risk factor	Increased Body Mass Index (BMI) >35 kg/m²
Elevated Diastolic Blood Pressure >80 mm Hg	High blood pressure is a prevalent risk factor
Family History of Preeclampsia	Genetic predisposition increases risks
Multiple Pregnancy	Carrying more than one baby
Advanced maternal age	Age Over 40 Years
Preexisting Renal Disease	Existing kidney issues can heighten risks
Clotting Disorders	Includes factor V Leiden mutation, homozygous MTHFR mutation, hyperhomocysteinemia, and the presence of antiphospholipid antibodies
Immunological Factors	Higher risk with the first pregnancy with a new partner; reduced risk in multiparity with the same partner

Figure 1

These findings underscore the critical importance of a holistic approach that integrates both hereditary and lifestyle factors in the management and prediction of preeclampsia⁵. By gaining a comprehensive understanding of these elements, healthcare professionals can improve early detection, provide tailored interventions, and ultimately enhance maternal and fetal health outcomes. Emphasizing both genetic predispositions and lifestyle influences allows for more personalized care and paves the way for future research and innovations in preventing and managing this complex condition³.

Early Detection and Aspirin Therapy

The primary aim of early diagnosis in pregnancy is to start preventive therapy with 100 mg of aspirin before the 16th week, significantly reducing severe preeclampsia risk. Although research continues regarding the optimal aspirin dosage, evidence suggests a range of 70–160 mg may be effective, addressing aspirin resistance seen in 33% of women. Combining aspirin with low-molecular-weight heparin shows additional benefits, especially in cases of hereditary thrombophilia. Early detection relies on a combination of medical history evaluation, assessment of biophysical parameters like blood pressure and arterial stiffness, and analysis of biochemical markers to identify impaired placental function³.

In recent years, the analysis of Uterine artery Doppler waveforms during the second trimester has been thoroughly researched for its ability to predict preeclampsia and fetal growth restriction. Increasing interest has emerged in using this tool during the first trimester. Different measurement methods and impedance indices have been employed to examine the connection between uterine artery Doppler velocimetry and negative pregnancy outcomes. Generally, first-trimester Doppler evaluations of the uterine artery show greater accuracy in forecasting early-onset rather than late-onset preeclampsia. When used alone as a predictor of future conditions, its effectiveness in identifying preeclampsia and fetal growth restriction among low-risk pregnant women is moderate, ranging from 40% to 70%. However, using multiparametric predictive models that combine the first-trimester uterine artery pulsatility index with maternal characteristics and biochemical markers can push the detection rate for early-onset preeclampsia beyond 90%. Determining the best combination of tests and validating them across various patient groups will be the aim of future investigations².

Conducting a UAD in the First Trimester

Here's a step-by-step method for measuring flow velocity waveforms from the uterine artery⁶:

1. Equipment Preparation: Use a 5 or 3.5-MHz curvilinear transabdominal transducer to begin the procedure.

2. Initial Positioning: Start by obtaining a midsagittal section of the uterus and cervical canal.

3. Lateral Movement: Move the transducer laterally until the paracervical vessels are visible.

4. Apply Doppler Imaging: Use color flow Doppler to visualize the uterine arteries. These will appear as aliasing vessels along the side of the cervix.

5. Select Sampling Site: With pulsed wave Doppler, focus on obtaining flow velocity waveforms from the ascending branch of the uterine artery closest to the internal os. This level is ideal for assessment during the first trimester.

Figure 2 An image of a normal uterine artery Doppler waveform typically shows a notch that is usually present in the first trimester.

6. Set the Sampling Gate: Adjust the Doppler sampling gate to 2 mm to capture accurate readings.

7. Optimize Angle of Insonation: Ensure the smallest angle of insonation (<30°) is used to obtain the highest systolic and end-diastolic velocities.

8. Capture Consistent Waveforms: Aim to obtain three consecutive, similar waveforms before proceeding.

9. Measure Pulsatility Index (PI): After obtaining the waveforms, measure the PI and calculate the mean PI by averaging the readings from both sides.

Following these steps ensures accurate measurement and interpretation of the uterine artery flow, particularly effective during the first trimester.

Early Preeclampsia Screening Guidelines

Here's a step-by-step guide for First Trimester Screening for Preeclampsia⁴:

Step 1: Patient Preparation

1. Schedule Appointment: Ensure the screening is scheduled between 11w4d and 13w6d of gestation.

2. Collect,

Patient Information:

Weight	Is patient Diabetic or insulin dependent?
Height	Assisted reproductive use? If so, mark which method.
# of fetuses	# of past pregnancies lasting >24 weeks?
Gestational age of previous pregnancy	Use of Egg donor? Age of donor at egg retrieval?

Clinical History: Mark Yes or No

Previously diagnosed with Preeclampsia?	Systemic Lupus Erythematosus diagnosis?
Family history of Preeclampsia?	Is patient currently smoking?
Chronic hypertension diagnosis?	Antiphospholipid Syndrome (APAS) diagnosis?

Sonographer Information:

CRL date	CRL measurement (45-84mm)
NT (mm) measurement	If twins, chronicity?
Gestational age	LMP/EDD
Sonographer NT Credentials #	Reading MD NT Credentials #

*Measurements should be conducted by a sonographer/provider who is accredited by the Fetal Medicine Foundation or a similar recognized organization. The credential or certification number of the sonographer/provider must be included⁶.

Step 2: Blood Pressure Measurement

1. Equipment: Use a calibrated or validated blood pressure device.

2. Procedure: Ensure the patient is seated comfortably, with the arm supported at heart level. Measure blood pressure twice, ensuring a gap of a few minutes between readings.

3. Record Results:

Right Arm 1____________________mmHg Right Arm 2___________________________mmHg

Left Arm 1_____________________mmHg Left Arm 2____________________________mmHg

Step 3: Ultrasound Assessment

1. Fetal Viability and Gestational Age: Confirm fetal viability and accurately measure the crown-rump length to confirm gestational age. Perform a 1^st trimester screening ultrasound, as usual.

2. Uterine Artery Doppler: Conduct a Doppler ultrasound to assess and measure the pulsatility index of each uterine artery and then calculate the average value. Record findings on form submitted to laboratory.

3. The patient should have a routine blood draw, which will be submitted along with the first trimester screening results. The selected laboratory should provide a specific form for 1st trimester preeclampsia screening⁴.

In the upcoming chapter, we will delve into the development of the uterine artery Doppler waveform during pregnancy and discuss what to expect from the results of the first trimester preeclampsia screening.

Advanced Ultrasound Techniques: Uterine Artery Doppler First Trimester Pre-Eclampsia Screening

Chapter 1: Detecting Preeclampsia: Key Insights Uncovered