Finding Freddie

Providing an Honest Look at Pregnancy

Common Ultrasound Findings

Courtesy of iVillage.com

by Peg Plumbo, CNM

Your first ultrasound appointment! You’ll probably go in with a mixture of excitement and concern, and you may have many questions, such as:

  • How much can they see?
  • Will they be able to tell me if it’s a girl or boy?
  • Will they be able to tell if anything’s wrong?
  • What if there is something wrong?
  • Will they tell me everything I want to know at the visit, or will I have to wait?
  • Why do I have to have a full bladder?
  • How safe is ultrasound?

Most ultrasound screens are performed at about 18 to 20 weeks because this is an appropriate time for dating the pregnancy and evaluating baby’s structures and organs. The heart is the last organ to develop, and development of two atria and two ventricles should be complete by 18 weeks from the first day of your last period.

Here, some of the words and phrases you’ll come across during your ultrasound:

  • Fetal biometry — measurements of important structures that, when taken together, give an approximation of fetal gestational age
  • Biparietal diameter — measurement made between two points through the baby’s head from about one ear to the other
  • Abdominal circumference — distance around the abdomen at about the level of the umbilicus
  • Femur length — length of the thighbone
  • Structures
    Every ultrasound report done at 18 weeks and beyond will provide an interpretation of baby’s:

    • Brain
      Examining the:
      —Cerebral ventricles — cavities filled with cerebrospinal fluid inside the brain
      —Posterior fossa — a depression on the interior back portion of the base of the skull
      Looking for:
      —Choroids plexus cysts, usually resolved by 28 weeks and rarely associated with chromosomal abnormality (If these cysts persist into the second trimester, suspicion is raised for a chromosomal defect known as Trisomy 18.)
    • Face
    • Looking for clefts and symmetry

    • Spine
    • Looking for completeness and an intact neural tube

    • Heart
    • Looking for the presence of two atria and two ventricles

    • Stomach
    • Looking at size and symmetry

    • Kidneys
    • Looking at size and patency of the ureters to make sure that no obstruction is present

    • Bladder
    • Observing the filling of the bladder and the outflow pathway

    • Abdominal cord insertion
    • Looking at the area where the cord inserts into baby’s abdomen, checking for completeness of the abdominal wall

    • Cord vessels
    • Checking to make sure baby has three vessels running through the cord, two arteries and one vein; two vessel cords may be associated with a higher incidence of congenital defects

    • Arms and hands
    • Checking the number of digits, plus length and symmetry, for the fetus’s particular gestational age

    • Legs and feet
    • Checking the number of toes, the length of the femur to verify gestational age and indications of baby’s feet turning inward or outward

    • Genitals
    • If baby cooperates, fetal gender may be determined as early as 16 weeks, but rarely do ultrasound technicians comment unless they’re very certain; most can be determined by 24 weeks

    • Amniotic fluid
      • The position should be reported, as well as the relationship to the cervical os, or opening. Either an anterior or posterior placenta is normal. If a placenta is next to the cervix (low lying) or covering the cervix (placenta previa), further ultrasounds are done by 32 weeks to make sure that the placenta has been pulled up away from the cervix in the months since the original ultrasound.
      • Comments will be made if any of the pelvic organs of the mother are suspicious for abnormality ‑- for example, if the uterus contains a fibroid or there are cysts on the ovary.
      • Cervical length is noted. Cervical length of less than two and a half centimeters has been reported to be associated with a higher incidence of preterm labor. In this circumstance, the mother will be followed more closely for premature thinning or dilatation.
      • Number of fetuses present
      • Appropriateness of the biometry, size, growth and estimated gestation
      • Confirmation that the fetus is living and that there is heart motion
      • Statement on any abnormalities seen in mother or baby (uterus, ovaries, cervix)
      • In second and third trimesters, a comment on the presentation of the baby (head down or breech)
      • Estimate of volume of amniotic fluid
    • Reporting it as normal, high (hydramnios) or low (oligohyramnios)

      Placenta

      Maternal Anatomy

      Your summary should provide:

      Ultrasound technicians are generally not at liberty to reveal the details of an ultrasound beyond what you and your partner can see for yourselves. If your family physician, obstetrician or perinatologist is not present, he or she will review the tape and dictate a report. The results may be available later the same day or the next day.

      About the Bladder
      If you are having a vaginal ultrasound in the first trimester, you will not need to have a full bladder. But if the scan is performed abdominally, especially in the first or early second trimester, a full bladder is very helpful to the technician. When a pregnancy is in the early stages, it is deep in the pelvis and more difficult to “reach” with ultrasound. A full bladder elevates the uterus a bit and moves the loops of bowel away from the uterus. Ultrasound beams go through water better than air, so structures are more easily discerned.

      A very full bladder, however, can displace baby and make those important structures and organs difficult to see or fully evaluate. Sometimes the technician may ask you to partially empty your bladder ‑- and this can be very uncomfortable! Your clinic staff will let you know how much water to drink and how soon before the scan you should drink it.

      Safety of Ultrasound
      Ultrasound has been studied extensively over 35 years of use. Diagnostic ultrasound uses sound waves at various frequencies, and the low-intensity ranges used in real-time obstetrical scans have never been shown to be harmful to the fetus or mother. Ultrasound, however, should be used only when indicated, and equipment should conform to FDA standards. In recent months, storefront businesses and even kiosks at shopping malls have introduced the “keepsake ultrasound video” and made such scans available to the mass market. Both the American College of Obstetricians and Gynecologists and the Food and Drug Administration have published statements discouraging the use of ultrasound in this way.

      Unless complications arise, research confirms the fact that the use of ultrasound does not change the outcome of a pregnancy and, if you’re given a choice, one scan performed at 16 to 20 weeks meets the standard of care.

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