Preeclampsia is a leading cause of maternal and perinatal morbidity and mortality. It is defined by new-onset hypertension after 20 weeks of gestation, often associated with proteinuria and/or systemic complications such as thrombocytopenia, renal impairment, hepatic dysfunction, neurological symptoms, pulmonary edema, or intrauterine growth restriction. Neurological involvement is particularly severe, as it may progress to eclampsia, intracerebral hemorrhage, or ischemic stroke. Detecting early cerebral hemodynamic changes is therefore essential.

Transcranial Doppler (TCD) is a non-invasive ultrasound technique that measures cerebral blood flow velocities, particularly in the middle cerebral artery (MCA). It provides systolic, diastolic, and mean velocity values, and calculates indices such as pulsatility index (PI), resistance index (RI), cerebral perfusion pressure (CPP), resistance area product (RAP), cerebral flow index (CFI), and Lindegaard index (LI). These parameters can detect impaired cerebral autoregulation, hyperemia, vasospasm, or cerebral hypoperfusion. Although several studies suggest that preeclampsia is associated with altered cerebral hemodynamics, the diagnostic and prognostic role of TCD remains insufficiently defined.

The objective of this prospective, observational, case-control study is to evaluate the diagnostic and prognostic value of TCD in preeclampsia and its complications. The study will be conducted at the Maternity and Neonatology Center of Tunis (Departments of Anesthesia, Intensive Care, and Gynecology-Obstetrics A-D) over six months, from January to June 2025.

Participants will be pregnant women in their third trimester, divided into two groups:

• Group A: preeclamptic women, defined by hypertension and proteinuria after 20 weeks of gestation, or hypertension/proteinuria with at least one severity criterion (hematologic, hepatic, renal, pulmonary, neurological, or fetal).
• Group B: normotensive, non-preeclamptic controls.

Exclusion criteria include chronic hypertension, chronic kidney disease, epilepsy, hematologic disease, cardiac or liver disease, COPD, severe anemia, technical difficulties preventing TCD, loss to follow-up, or diagnostic uncertainty. Women with isolated gestational hypertension will also be excluded.

TCD will be performed via the temporal window using a 2 MHz pulsed Doppler probe, mainly focusing on the MCA. In Group A, measurements will be obtained before and after antihypertensive therapy, before and after magnesium sulfate administration when indicated, and before and after any complications. In Group B, a single TCD will be performed during the third trimester.

The study will compare cerebral blood flow velocities and indices between groups and monitor their evolution over time. Data interpretation will allow classification of findings into patterns such as systemic hypoperfusion, cerebral hypoperfusion with elevated intracranial pressure, hyperemia, or vasospasm.

The expected outcome is to establish whether TCD can serve as a reliable diagnostic and prognostic tool in preeclampsia. The results will contribute to a better understanding of cerebrovascular physiology in this condition and may help identify women at higher risk of neurological or systemic complications. Ultimately, this work aims to highlight TCD as a simple, reproducible, and non-invasive tool for clinical management and risk stratification in preeclampsia.

Preeclampsia is a complex multisystem disorder of pregnancy, and neurological complications are among the most severe outcomes, including eclampsia, cerebrovascular accidents, and altered cerebral perfusion. Understanding cerebral hemodynamics in preeclampsia is essential for early identification of high-risk patients and timely intervention.

Transcranial Doppler (TCD) provides real-time, non-invasive measurements of cerebral blood flow velocities and derived indices, which reflect cerebral autoregulation, vascular resistance, and perfusion pressure. These parameters allow detection of pathophysiological changes such as cerebral hypoperfusion, hyperemia, vasospasm, or elevated intracranial pressure, which are relevant for the management of preeclampsia.

This study is designed as a prospective, observational, case-control investigation to evaluate the diagnostic and prognostic value of TCD in preeclamptic women. It will be conducted over six months at the Maternity and Neonatology Center of Tunis, including the Departments of Anesthesia, Intensive Care, and Gynecology-Obstetrics (A-D).

Eligible participants are women in their third trimester of pregnancy. Women with preexisting conditions affecting cerebral hemodynamics, chronic hypertension, renal, cardiac, hepatic, hematologic disease, COPD, or severe anemia will be excluded. Participants will undergo TCD using a 2 MHz pulsed Doppler probe via the temporal window, primarily assessing the middle cerebral artery.

In preeclamptic patients, serial TCD measurements will be performed to monitor changes before and after antihypertensive therapy, magnesium sulfate administration (if indicated), and any clinical complications. Normotensive control patients will undergo a single TCD assessment. Measured parameters include systolic, diastolic, and mean velocities, as well as resistance and pulsatility indices, cerebral perfusion pressure, cerebral flow index, and Lindegaard index.

Data analysis will focus on identifying hemodynamic patterns associated with increased cerebral risk, and correlating TCD findings with clinical outcomes and therapeutic interventions. This approach aims to evaluate whether TCD can serve as a reliable, non-invasive tool to stratify risk and guide management in preeclamptic women.

The study will contribute to understanding cerebrovascular physiology in preeclampsia and may provide evidence to support the integration of TCD into routine monitoring of high-risk pregnancies, potentially improving maternal and fetal outcomes.

Inclusion Criteria:

• Consenting pregnant women in their third trimester (28 weeks of gestation or more)
• Group A: Patients with preeclampsia, defined as:
• Systolic Blood Pressure (SBP) equal to or greater than 140 mmHg and/or Diastolic Blood Pressure (DBP) equal to or greater than 90 mmHg appearing after 20 weeks of gestation with 24-hour proteinuria equal to or greater than 300 mg/24h, or
• SBP equal to or greater than 140 mmHg and/or DBP equal to or greater than 90 mmHg or 24-hour proteinuria equal to or greater than 300 mg/24h with at least one of the following
• Thrombocytopenia, platelets below 100,000 per cubic millimeter
• Liver cytolysis, AST or ALT more than 2 times normal values
• Hemolytic anemia (schistocytes present, LDH above 600)
• Serum creatinine equal to or greater than 90 micromoles per liter and oliguria equal to or less than 500 milliliters per 24 hours, excluding functional or obstructive causes
• Acute pulmonary edema
• Subcapsular liver hematoma
• Neurological or sensory signs (headache, blurred vision, tinnitus, hyperreflexia, diffuse polykinetic reflexes)
• Eclampsia
• Severe intrauterine growth restriction
• Group B: Healthy, normotensive pregnant women
• SBP less than 140 mmHg and DBP less than 90 mmHg
• No clinical or biological signs of severe preeclampsia
• Negative 24-hour proteinuria test, less than 300 mg/24h, if performed

Exclusion Criteria:

• Multiple pregnancy (twins, triplets, etc.)
• History of significant neurological or cardiovascular disease
• Active infection or major medical complication
• Allergy or contraindication to antihypertensive therapy or magnesium sulfate
• Refusal to provide informed consent

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Pregnant women in their third trimester (28 weeks or more) participating in this study are divided into two groups:

• Group A: Women diagnosed with preeclampsia according to standard clinical and laboratory criteria, including elevated blood pressure and proteinuria, with or without severe features.
• Group B: Healthy, normotensive pregnant women without signs of preeclampsia. Participants are included after providing informed consent and are monitored for cerebral blood flow parameters using transcranial Doppler ultrasound.