Obstetrics Sonography – Second Trimester Fetal Anomaly Scan
Real time B-mode ultrasonography of gravid uterus done.
Rout; Trans abdominal
Date of onset of last menstrual period: Not know.
Last menstrual period: Not Know
Fetal Survey
| Alive intrauterine fetus is seen. | — |
| Fetus | Single |
| Situs | Normal |
| Presentation | Cephalic |
| Fetal activity | Present |
| Cardiac activity | Present |
| Fetal HR | 150 bpm (at the time of scanning). |
| Amniotic fluid | MVP < 5.5 cm. |
| Placentation | Posterior (maturity grade-0). |
| Placental thickness | 25 mm |
| Umbilical cord | Normocoiled 3-vessel cord attached to fetal abdomen. No additional umbilical cord entanglement of either the limbs or the neck. |
Fetal Biometry
| Parameter | Measurement | GA (±1 wk unless noted) |
|---|---|---|
| BPD | 59 mm | 23w06d |
| HC | 212 mm | 23w02d |
| AC | 180 mm | 23w00d |
| FL | 40 mm | 23w01d |
Estimations
| Estimated ultrasound GA | 23 weeks 00 days |
| Estimated ultrasound due date | 01/04/2025 |
| Estimated fetal body weight | 562 gm |
| Date concordance | The dates are congruent (within 2 weeks). |
Contd… p.2
Fetal Anatomical Survey
Head and Neck
“Fetal head visualized in axial planes. Cavum septi pellucidi, midline falx, and thalami identified. Lateral ventricles not dilated. Choroid plexus appears normal. Posterior fossa with cerebellum and cisterna magna within normal limits. No evidence of intracranial malformation.”
| Measurement | Value |
|---|---|
| Biparietal Diameter (BPD) | 56 mm |
| Head Circumference (HC) | 130 mm |
| Occipitofrontal Diameter (OFD) | 65 mm |
| Cisterna Magna (CM) | 9 mm |
| Lateral Ventricle | RA Dim (8 mm) & LA Dim (8 mm) |
| Transcerebellar Diameter (TCD) | 22 mm |
| Cavum Septum Pellucidum (CSP) | 7 mm |
| Skull Shape | Normal |
| Cephalic Index (CI) | 80% |
| Fronto-Occipital Index (FOI) | 78% |
Face
“Fetal face appears normal with well-formed orbits, intact upper lip, nasal bone visualized, and no evidence of cleft lip/palate or facial dysmorphism.”
| Measurement | Value |
|---|---|
| Interorbital Distance (IOD) | 12 mm |
| Orbital Diameter (OD) | Rt. 11 mm & Lt. 11 mm |
| Outer bony margins (OOD/BOD) | 23 mm |
| Nasal Bone Length (NBL) | 10 mm |
| Nuchal Fold Thickness (NFT) | 5 mm |
Thorax
“Fetal thorax appears normal in size and shape with appropriate rib cage configuration. Cardiac axis and position are normal, lungs are homogeneous and appropriately echogenic for gestational age, and no intrathoracic mass or effusion is seen.”
| Measurement | Value |
|---|---|
| Cardiothoracic ratio (CTR) | 0.45–0.55 (heart size relative to thorax) |
| Cardiac axis | ~ 45° ± 20° toward the left |
Contd… p.3
Abdomen
“Fetal abdomen appears normal in contour, with intact abdominal wall. Stomach bubble is visualized in the left upper quadrant. Liver, spleen, and bowel loops appear appropriate for gestational age. Umbilical vein insertion is normal. No evidence of abdominal wall defect or organomegaly.”
| Measurement | Value |
|---|---|
| Abdominal Circumference (AC) | 140 mm |
| Transverse Abdominal Diameter (TAD) | 55 mm |
| Anteroposterior Abdominal Diameter (APAD) | 49 mm |
| Stomach Bubble Size & Position | 14 mm Right side |
| Umbilical Vein / Portal Sinus Measurement | Normal |
| Bowel Echogenicity & Dilatation | Normal |
| Liver & Spleen Size | L-25 mm & Sp-21 mm |
Musculoskeletal System
“Fetal spine appears intact with normal vertebral alignment. Limbs are well visualized with normal bone lengths and echogenicity. No evidence of skeletal dysplasia, limb reduction, or clubfoot noted.”
| Measurement | Value |
|---|---|
| Femur Length (FL) | Rt. 31 mm & Lt. 31 mm |
| Humerus Length (HL) | Rt. 29 mm & Lt. 29 mm |
| Tibia Length | Rt. 27 mm & Lt. 27 mm |
| Fibula Length | Rt. 26 mm & Lt. 26 mm |
| Radius & Ulna Length | Rt. 25 mm & Lt. 25 mm |
| Ulna Length | Rt. 26 mm & Lt. 26 mm |
| Clavicle Length | Rt. 16 mm & Lt. 16 mm |
| Foot Length | Rt. 31 mm & Lt. 31 mm |
| Spinal Alignment | Normal |
Doppler Assessment
“Umbilical artery, middle cerebral artery (MCA), Doppler waveforms demonstrate normal flow patterns with normal resistance indices for gestational age. Umbilical venous flow is continuous and non-pulsatile.”
| Parameter | Umbilical Artery (UA) | MCA | Umbilical Vein (UV) | Uterine Artery |
|---|---|---|---|---|
| S/D | 3.6 (≈ 3.5 – 4.0) |
— | non-pulsatile | — |
| PI | 1.5 (~1.3 – 1.6) |
1.6 (~1.5 – 1.8) |
— | 1.35 (~1.10 – 1.50) |
| RI | 0.70 (~0.68 – 0.74) |
— | — | — |
| PSV | — | 27 cm/s | — | — |
Conclusion
- Single alive intrauterine fetus of 23 wks 00 days.
- No obvious structural fetal defects were seen at this period of gestation.
- Uterine artery screening was negative for Pregnancy induced hypertension (PIH).
Declaration of Doctor conducting Ultrasonography: – I have neither detected nor disclosed the sex of her fetus to anybody in any manner.
Clinical correlation and further investigation are required.
Note
- Ultrasound is modality of diagnosis but it has its own limitations:
- Scan detects structural malformations in up to 60–70% of cases depending on the organ involved.
- Functional abnormalities in the fetus cannot be detected by USG.
- Conditions like trisomy 21 (Down syndrome) may have normal ultrasound findings in 60% cases. Additional tests like serum markers (double test at 10–13 weeks / triple test at 15–20 weeks) will help in detecting more number of cases (70% by triple test / 90% by double test).
- Subtle abnormalities like polydactyly and cleft palate are not looked up in a routine scan, which are surgically correctable after birth.
- Some condition present late in intrauterine life and require serial follow up scans to rule out their presence.
- All the anomalies do not manifest in intrauterine life and may present postnatally for the first time.
- Fetal echocardiography is recommended to assess fetal heart.
