Multiples

  • First trimester ultrasound is ideal for establishing fetal number, amnionicity, and chorionicity.
    • Determine number of yolk sacs.
    • Determine number of placentas.
    • Determine number of amniotic sacs.
  • Evaluate dividing membrane
    • Is there “Twin Peak” sign seen? This indicates separate sacs and placentas seen in Dichorionic/ Diamniotic twins.
    • Thick membrane suggests Dichorionic gestation
      • >2mm
    • Thin suggests Monochorionic gestation.
      • <2mm
  • Determine location and presentation of “A”, “B”, “C”, etc.
  • Document a cine clip to show position and presentation.
    • The fetus or sac closest to the internal cervical os is “A”
  • Determine gender of fetuses when able.
  • Largest vertical pocket is used unless Monochorionic/Monoamniotic twins.
    • Measured in sagittal plane, deepest pocket for each baby with free-floating membrane visualized and documented.
    • Fluid pockets should be roughly equal for each baby.
  • Fetal growth measurements should be concordant.
    • Discordant fetal growth is a difference of at least 20%.
    • To calculate the discordance, subtract smallest fetal weight from the largest weight (in grams), then divide the resulting number by the weight of the largest fetus (in grams).

  • TTTS

    • MC/DA twins will be evaluated at each visit for TTTS.
    • TTTS eval is performed every 2 weeks, unless signs of TTTS are present, or as ordered by physician.
      • NOTE: A transvaginal sono will be performed at each visit in combination with the TTTS evaluation. fFN with be collected when appropriate.
    • Findings will be documented in body of ultrasound report using the MO/DI TTTS evaluation impression.
    • Document FHR for both fetuses using M-mode.
    • Determine fetal positions and differentiate “A” from “B”.
    • Image free floating membrane with fluid on both sides.
      • One image needs to have color flow Doppler.
    • Measure largest vertical pocket of fluid for each twin.
    • Observe for fetal activity, along with breathing movements, when indicated.
    • Image the following for each fetus:
      • Cranium, to R/O scalp edema.
      • Chest to R/O pleural and/or pericardial effusion.
      • Abdomen to R/O ascites and demonstrate presence or absence of full stomach.
      • Bladder fullness.
    • Obtain UA Dopplers, MCA Dopplers, and DV Dopplers after 16 weeks.