Point of Care Ultrasound Screening for Abnormal Fetal Growth During Routine Antenatal Visits

Point of Care Ultrasound Screening for Abnormal Fetal Growth During Routine Antenatal Visits: a Randomized Controlled Trial. MUNN (More Ultrasounds New gaiNs) Trial

Abdominal circumference (AC) in the fetus is the single most useful indicator of fetal growth abnormalities. Measurement of AC as well as DVP do not require extensive training. Our objective is to evaluate if introduction of bedside ultrasound during routine antenatal visits to evaluate fetal AC and amniotic fluid DVP would decrease the false positive rates of fundal height measurement in diagnosing intrauterine growth abnormalities.

The prior studies of routine ultrasound in low risk patients focused on the usual ultrasound evaluation which involves the use of advanced equipment and providers, including trained sonographers and physicians to perform and review the ultrasound, as well as a full examination with multiple fetal measurements and images. A number of recent analyses show that measurement of the abdominal circumference (AC) in the fetus is the single most useful indicator of fetal growth abnormalities. Measurement of AC as well as DVP do not require extensive training, long time to acquire, or expensive ultrasound machines. They can be easily performed in the office by providers who are specifically trained in obtaining these 2 measurements. Therefore, we intended to evaluate if introduction of bedside ultrasound during routine antenatal visits (point of care ultrasound or POC-US) to evaluate fetal AC and amniotic fluid DVP would decrease the false positive rates of fundal height measurement in diagnosing intrauterine growth abnormalities, and would improve the diagnosis of amniotic fluid volume and fetal growth deviations.

Inclusion Criteria:

1. Maternal age ≥ 18 years and ability to give informed consent
2. Singleton gestation
3. Ultrasound examination that confirms or revises the EDD before 22 0/7 weeks of gestational age (ACOG Committee opinion 2017 dating)
4. Gestational age ≥ 24 weeks gestation

Exclusion Criteria:

1. Abnormal aneuploidy screening (1st trimester screening, 2nd trimester screening, integrated screening, NIPT)

2. Fetal chromosomal or genetic abnormalities

3. Fetal malformations or soft markers identified on fetal anatomy survey

4. Current pregnancy is a result of in vitro fertilization

5. Documented uterine bleeding after 24 weeks gestation. Unobserved self-reported bleeding with confirmed intact pregnancy on ultrasound after the bleeding episode is not an exclusion criteria.

6. Uterine/placental abnormalities including uterine malformations (i.e bicornuate uterus, didelpus uterus), abnormal placentation (placenta previa, accreta, percreta), uterine fibroids.

7. Cerclage in the current pregnancy

8. History of intrauterine fetal demise, small for gestational age, macrosomia or shoulder dystocia, or of traumatic delivery

9. Fetal isoimmunization or alloimmunization

10. History of medical complications such as:

    • Cancer (including melanoma but excluding other skin cancers)
    • Endocrine disease including thyroid disease (recently diagnosed or whose medication dose is not stable), adrenal disease, diabetes mellitus (pregestational and gestational).
    • Renal disease with altered renal function (creatinine > 0.9 or proteinuria)
    • Epilepsy or other seizure disorder
    • Any collagen disease (lupus erythematosus, scleroderma, etc.)
    • Active liver disease (acute hepatitis, chronic active hepatitis, persistently abnormal liver enzymes)
    • Hematological disorder including alloimmune and isoimmune thrombocytopenia but excluding mild iron deficiency anemia (Hb > 9 gm/dl). Patients with sickle cell disease are excluded.
    • Chronic pulmonary disease including asthma requiring regular use of medication and active TB. An asthma inhaler used on an as needed basis (PRN) for a cold or an asthma attack is not considered regular use.
    • Heart disease except mitral value prolapse not requiring medication
    • Cardiovascular disorders: chronic hypertension
    • Liver disorders accounting for cholestasis
    • Infectious diseases: HIV, CMV, toxoplasmosis, parvovirus B19 Note that the aforementioned are just examples and any clinical indication for ultrasound examination after 24 weeks is an exclusion.