What is the diagnosis for a pregnant patient experiencing hypotension when in a supine position, with blood pressure readings of 88/65, that improves to 116/76 when in a sitting position?

Supine Hypotension Syndrome

The diagnosis is supine hypotension syndrome (Option A), characterized by hypotension in the supine position that resolves with positional change in pregnancy. 1

Pathophysiology

• The enlarged gravid uterus compresses the inferior vena cava when the patient lies supine, particularly after 20 weeks of gestation, decreasing venous return to the heart and subsequently reducing cardiac output. 1

• This aortocaval compression can decrease cardiac output by up to 24% at 32 weeks gestation when supine compared to the left lateral position. 1

• The syndrome represents a spectrum from minimal cardiovascular alterations to severe syncopal shock, with clinical presentation ranging from asymptomatic hypotension to severe symptoms requiring immediate position change. 2

Clinical Presentation in This Case

• Blood pressure drops from 116/76 (sitting) to 88/65 (supine): This represents a systolic drop of 28 mmHg, which exceeds the diagnostic threshold of 15-30 mmHg decrease that defines supine hypotensive syndrome. 3, 2

• The immediate improvement with position change (sitting up) confirms the diagnosis, as this relieves inferior vena cava compression and restores venous return. 1

• Symptoms typically include dizziness, lightheadedness, nausea, and weakness that resolve within minutes of changing position. 2, 4

Why Not the Other Options

• Option C (Orthostatic hypotension) is incorrect because orthostatic hypotension causes blood pressure to drop when moving from lying to sitting/standing positions, whereas this patient's blood pressure increases when sitting up. 5

• Option B (Iron deficiency anemia) is incorrect because while IDA can cause general hypotension and symptoms during pregnancy, it would not cause this dramatic positional variation in blood pressure readings. 3

Clinical Management Implications

• Pregnant patients after 20 weeks gestation should avoid prolonged supine positioning during procedures, examinations, or sleep. 1

• The left lateral position or left pelvic tilt should be maintained during endoscopic procedures, imaging studies, and any prolonged recumbent positioning to prevent aortocaval compression. 1

• During cesarean delivery under spinal anesthesia, women with documented supine hypotensive syndrome have higher risk of severe hypotension and may require more aggressive prophylactic vasopressor therapy. 6

Important Caveats

• Approximately 8-10% of pregnant women develop symptomatic supine hypotensive syndrome, though subclinical hemodynamic changes occur in most pregnant women when supine. 3, 2

• Severe hypotension without maternal symptoms has been reported in rare cases, potentially affecting fetal perfusion despite lack of maternal complaints. 7, 2

• The syndrome can manifest as early as the fifth month of pregnancy in susceptible women, though it is most common in the third trimester. 2