What are the recommended orders for a patient at 18 weeks of pregnancy in the 2nd trimester?

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Last updated: September 18, 2025View editorial policy

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Recommended Orders for 18-Week Pregnancy in the 2nd Trimester

At 18 weeks of pregnancy, the recommended orders should include a detailed anatomy ultrasound, screening for gestational diabetes, assessment of fetal growth, and appropriate laboratory tests to monitor maternal health.

Core Recommended Orders

Ultrasound Assessment

  • Detailed anatomy scan (if not already completed)
    • Comprehensive evaluation of fetal anatomy
    • Assessment of placental location and appearance
    • Measurement of amniotic fluid volume
    • Cervical length assessment to screen for preterm birth risk 1

Laboratory Tests

  • Complete blood count to assess for anemia
  • Urinalysis to screen for proteinuria and infection
  • Blood type and antibody screen (if not done in first trimester)
  • Glucose screening test (24-28 weeks, but can be ordered now if high-risk)
  • Thyroid-stimulating hormone levels if clinically indicated 1

Maternal Assessment

  • Blood pressure measurement with appropriate cuff size
  • Weight measurement to track appropriate gestational weight gain
  • Fundal height measurement
  • Assessment for edema or other signs of preeclampsia 1

Specialized Orders Based on Risk Factors

For Patients with Suspected Fetal Growth Restriction

  • Serial umbilical artery Doppler assessment if fetal growth restriction is suspected
  • Weekly umbilical artery Doppler evaluation for severe fetal growth restriction (estimated fetal weight less than 3rd percentile) 1
  • Consider weekly cardiotocography testing if fetal growth restriction is identified 1

For Patients with Obesity

  • Early screening for gestational diabetes (if not already completed)
  • Consider growth scan at 28-32 weeks to aid in detection of late-onset fetal growth restriction
  • Appropriate BP cuff size for accurate measurements 1

For Patients with Previous Complications

  • More frequent monitoring if history of previous adverse pregnancy outcomes
  • Consider additional fetal surveillance based on specific risk factors 1

Nutritional and Supplementation Orders

  • Continue prenatal vitamins with folic acid
    • Standard dose: 0.4-1.0 mg folic acid for low-risk women
    • Higher dose: 4.0 mg folic acid for high-risk women (history of neural tube defects) 2
  • Vitamin D supplementation if deficient
  • Calcium supplementation if indicated 1

Patient Education and Counseling

  • Nutrition counseling for appropriate weight gain during pregnancy
  • Physical activity recommendations (30 minutes of moderate exercise for at least 5 days/week)
  • Discussion of warning signs requiring immediate medical attention:
    • Vaginal bleeding
    • Decreased fetal movement
    • Severe headache
    • Visual disturbances
    • Abdominal pain 1

Follow-up Planning

  • Schedule next prenatal visit in 4 weeks (standard for second trimester)
  • Schedule glucose screening test for 24-28 weeks if not done earlier
  • Plan for additional growth scans if indicated by risk factors
  • Consider anesthesia consultation if BMI >35 1

Special Considerations

  • For patients with previous preterm birth or cervical insufficiency, consider cervical length monitoring
  • For multiple gestations, more frequent monitoring and specialized care is required
  • For patients with chronic medical conditions, coordinate care with relevant specialists 1

Remember that second-trimester vaginal bleeding is associated with increased risk of preterm delivery and adverse outcomes, requiring prompt evaluation and possibly additional monitoring 3.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Pre-conception Folic Acid and Multivitamin Supplementation for the Primary and Secondary Prevention of Neural Tube Defects and Other Folic Acid-Sensitive Congenital Anomalies.

Journal of obstetrics and gynaecology Canada : JOGC = Journal d'obstetrique et gynecologie du Canada : JOGC, 2015

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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