What are the guidelines for assessing blood pressure in pregnant patients?

Key Points for Blood Pressure Assessment During Pregnancy

The correct position for blood pressure measurement during pregnancy is in the sitting position with the patient's back supported, legs uncrossed, and arm at the level of the right atrium of the heart.

Proper Blood Pressure Measurement Technique in Pregnancy

Patient Positioning

• Patient should be relaxed prior to measurement 1
• After 5 minutes of rest, measure BP with patient in sitting position 1
• Back should be supported and legs uncrossed 1
• Arm should be positioned at the level of the right atrium of the heart 1
• Avoid measuring BP in the left lateral position as this falsely lowers readings 1

Equipment and Technique

• Use a manual auscultatory device or an automated upper-arm cuff device specifically validated for use in pregnancy and preeclampsia 1
• For patients with upper arm circumference ≥33 cm, use a large blood pressure cuff 1
• Korotkoff phase V (disappearance of sound) should be used to determine diastolic blood pressure 1
• Only use Korotkoff phase IV (muffling) if sounds persist at near-zero cuff pressure 1

Diagnostic Criteria for Hypertension in Pregnancy

• Diagnosis requires at least two elevated readings on separate occasions 1, 2
• Hypertension is defined as BP ≥140/90 mmHg 1
• Classification based on timing:
  • Pre-existing hypertension: Present before pregnancy or <20 weeks gestation 1
  • Gestational hypertension: Develops after 20 weeks gestation 1

Advanced Assessment Recommendations

• Consider 24-hour ambulatory BP monitoring or home BP monitoring to:
  • Confirm diagnosis of true hypertension 2
  • Rule out white coat hypertension (affects up to 25% of patients) 2
  • Evaluate patients with diabetes or kidney disease 1

Common Pitfalls to Avoid

• Measuring BP in left lateral position falsely lowers readings 1, 3
• Failing to use appropriate cuff size for larger arm circumferences 1
• Using Korotkoff phase IV instead of phase V for diastolic BP 1
• Not allowing adequate rest time before measurement 1
• Not confirming elevated readings with repeated measurements 1, 2

Additional Considerations

• For patients who cannot sit upright, document the position used during measurement 3
• When using home BP devices, ensure they are validated specifically for pregnancy 2
• Non-pharmacological management should be considered first for mild hypertension (140-150/90-99 mmHg) 1, 2
• Some bed rest in the left lateral position may be beneficial for management of hypertension, but this position should not be used for BP measurement itself 1

Remember that accurate BP measurement is critical for proper diagnosis and management of hypertensive disorders in pregnancy, which affect 5-10% of pregnancies worldwide and can lead to significant maternal and fetal complications 1.