Pocket ObGyn – Fetal Ultrasound Anatomy and Echocardiography
See Abbreviations
Basic Second Trimester Ultrasound (Obstet Gynecol 2009;113:451)
- Fetal viability: Fetal cardiac activity (including HR & any abn rhythms)
- Fetal number: In multi gestations, document chorionicity (number of placentas), amnionicity (number of membranes), fetal gender, comparison of fetal size, amniotic
- AFV: Described subjectively or by semiquantitative methods
AFI: Sum of depth (cm) of fluid pockets not containing cord or fetal extremities in each of 4 quadrants of the uterus. Quadrants divided by intersection of umbilicus & linea nigra.
SDP: Vertical depth (cm) of deepest pocket of fluid not containing cord or fetal extremities. Also called MVP, other.
- Placental location: Describing location (anter/post) & relation to internal Endovaginal US should be performed if internal cervical os not clearly visualized. Placental abnormalities (eg, previa) should be followed up w/ 3rd trimester US.
- Umbilical cord: The number of umbilical arteries should be
- CL: Not currently a rec for low-risk Recommendations for CL screening are evolving. Screening CL at anatomy US after 16 w GA is reasonable. Endovaginal US w/ empty bladder more accurate.
- GA: Most accurate in 1st trimester; 2nd trimester determination includes:
BPD: Measured at level of thalamus & cavum septum pellucidum.
HC: More reliable than BPD if head shape flattened or rounded.
AC: Measured at junction of umbilical vein, portal sinus, & stomach. Can compare to BPD to determine symmetric macrosomia or IUGR.
FL: Long axis of femur not including the distal & prox epiphyses.
- EFW: Combination of BPD, HC, AC, & FL to determine
EFW compared to known values to establish %ile & establish macrosomia/IUGR.
Fetal Anatomy Ultrasound (J Ultrasound Med 2010;29:157)
- Routinely performed at 18–20 w Thorough assessment of fetal structures.
Head, face, neck: Cerebellum, choroid plexus, cisterna magna, lateral cerebral ventricles, midline falx, cavum septum pellucidum, upper lip
Chest: Cardiac exam including 4-chamber view & outflow tracts
Abd: Stomach, kidneys, bladder, umbilical cord insertion, umbilical cord vessels
Spine: Including cervical, thoracic, & sacral spine
Extremities: Arms & legs including feet & hands
• Routine screening:
RADIUS trial: 15151 women randomized to screening US vs. US only if other indications; detection rate of 34% vs. 11%, respectively, for fetal anomalies; no change in other outcomes (Am J Obstet Gynecol 1994;171:392).
Eurofetus trial: Large 3-y study revealing 61% sens of US to detect fetal anomalies. Neurologic/urologic anomalies more commonly detected than cardiac (88/89% vs. 20%) (Am J Obstet Gynecol 1999;181:446).
Detection depends on prevalence of anomalies. Detection of anomalies higher in academic compared to community centers. Image quality has improved tremendously since these trials. More anomalies can be identified, though the clinical implications are unclear.
- Aneuploidy screening: US alone not adequate for trisomy 21 (T21) or other Presence or absence of fetal anomalies a/w T21, such as cardiac anomalies & duodenal atresia, confers or ¯ risk, respectively. NT on 1st trimester US identifies risk of aneuploidy. Soft markers: Echogenic bowel, EIF, short femur or humerus, & dilated renal pelvis. Absence of “soft markers” for Down syn on US ¯ a priori risk of T21 or mat serum screening risk by 50%.
Fetal Echocardiography (J Ultrasound Med 2011;30:127)
- CHD: Leading cause of mortality & Prenatal dx offers planning for infant & intervention at birth.
- Indications: Used as adjunct to routine US screening, btw 18 & 22 w
- Mat indications: Autoimmune antibodies, familial inherited cardiac d/o, 1stor 2nd-degree relative w/ CHD or syndromes w/ CHD, IVF, metabolic dz, cardiac teratogen exposure, rubella exposure 1st trimester
- Fetal indications: Abn cardiac screening exam, abn HR or rhythm, fetal chromosomal anomaly, extracardiac anomaly, hydrops, NT, monochorionic twins, unexplained sev polyhydramnios