A nurse is assessing a 28-year-old pregnant client at 32 weeks gestation who presents to the emergency department with complaints of severe headache, blurred vision, and epigastric pain. The client's blood pressure is 160/110 mmHg, and she has 3+ proteinuria. What is the most important assessment the nurse should perform first?

Assessing deep tendon reflexes and clonus is priority to evaluate CNS irritability and seizure risk in severe preeclampsia. Other assessments are important but less urgent.

Clinical Reasoning – Prioritizing Assessment in Preeclampsia with Severe Features

The client’s presentation—32 weeks gestation, severe headache, blurred vision, epigastric pain, blood pressure of 160/110 mmHg, and 3+ proteinuria—meets the diagnostic criteria for preeclampsia with severe features. In this clinical scenario, the nurse must recognize that these signs and symptoms reflect widespread endothelial dysfunction and vasospasm, which increase the risk for a life-threatening complication: eclampsia. Eclampsia is the onset of generalized tonic-clonic seizures in a client with preeclampsia, and its prevention is the immediate priority.

The most important initial assessment is to evaluate for central nervous system (CNS) irritability, which signals a high risk for imminent seizure activity. This is accomplished by assessing deep tendon reflexes (DTRs) and testing for clonus. Hyperreflexia and sustained ankle clonus are clinical indicators of severe CNS hyperexcitability and are often the final warning signs before an eclamptic seizure. Identifying these findings allows the nurse to urgently communicate the need for seizure prophylaxis, typically with magnesium sulfate, and to implement seizure precautions.

The provided case report underscores the critical role of magnesium sulfate in managing eclampsia and severe preeclampsia, while also highlighting a key safety consideration that reinforces the primacy of this neurological assessment. The report describes a patient with eclampsia and coexisting renal impairment who developed magnesium toxicity after receiving a standard magnesium sulfate regimen ^[1]. This illustrates that the therapeutic window for magnesium is narrow, and toxicity is a real and dangerous possibility, particularly when renal function is compromised. The clinical assessment for magnesium toxicity involves monitoring for the progressive loss of DTRs, which is the earliest sign, followed by respiratory depression and cardiac arrest. Therefore, assessing DTRs serves a dual, critical purpose: it first establishes the baseline CNS irritability indicating the need to initiate or continue magnesium sulfate therapy, and then it becomes the primary ongoing assessment to monitor for the drug’s toxic effects once therapy is underway. Without this initial assessment, the nurse cannot safely determine the urgency for treatment or establish a baseline for evaluating the client’s response to magnesium sulfate.

The other options represent important but secondary assessments in this acute presentation. Checking for ankle edema and weight gain (Option 1) relates to fluid retention and is a general assessment for preeclampsia, not the immediate life-threatening complication. Monitoring fetal heart rate patterns (Option 3) is a crucial fetal assessment but does not address the immediate maternal risk of seizure. Evaluating urine output over the past 24 hours (Option 4) is essential for identifying worsening renal function and the risk for oliguria, which, as the case report confirms, increases the risk of magnesium toxicity ^[1]. However, the neurological assessment takes precedence because a seizure can occur rapidly and has immediate, catastrophic consequences for both mother and fetus.