USG in Pregnancy Missed Abortion Fetal Echo NTD Abdominal Wall Defects
# **1. MISSED ABORTION – ULTRASOUND FINDINGS**
### **Definition:**
Embryo/fetus has died but is retained in the uterus without symptoms of expulsion.
### **Key USG Features**
| Finding | Description |
| ----------------------------- | ----------------------------------------------- |
| **Absent cardiac activity** | No heartbeat at CRL ≥7 mm (TVS) |
| **CRL criteria** | CRL ≥7 mm with no cardiac activity → diagnostic |
| **MSD criteria** | MSD ≥25 mm with no embryo → diagnostic |
| **Irregular gestational sac** | Collapsed or distorted sac |
| **Discrepancy** | Sac size small for dates |
| **Yolk sac abnormalities** | >6 mm, calcified or irregular |
| **No growth on serial scans** | No increase in CRL or sac after 7 days |
### **Ancillary Signs**
* Subchorionic hematoma
* Echogenic debris inside sac (blood products)
* No double-decidual sign if <6 weeks
### **Management**
* Expectant
* Medical (Mifepristone + Misoprostol)
* Surgical evacuation
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# **2. ULTRASOUND IN EARLY PREGNANCY – DETAILED**
## **2.1 Indications (Very Important)**
* Confirm intrauterine pregnancy
* Confirm viability
* Dating (CRL)
* Pain/bleeding
* Rule out ectopic pregnancy
* Multiple pregnancy & chorionicity
* Evaluate for miscarriage
* Pregnancy of unknown location
* IVF pregnancy follow-up
* Assess uterine anomalies, fibroids
* Gestational trophoblastic disease
* Early fetal anomalies (NT scan)
---
## **2.2 Normal USG Milestones**
| Week | Expected USG Finding |
| ------------- | ----------------------------------- |
| **4–5 w** | Gestational sac |
| **5–5.5 w** | Yolk sac |
| **6 w** | Fetal pole + heartbeat |
| **7–8 w** | Better CRL, cardiac activity strong |
| **11–13+6 w** | NT scan + nasal bone + DV |
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## **2.3 Common Early Pregnancy Diagnoses**
### **A. Anembryonic pregnancy (blighted ovum)**
* MSD ≥25 mm
* No embryo/yolk sac
### **B. Non-viable pregnancy**
* CRL ≥7 mm, no heartbeat
* No embryo after ≥2 weeks post empty sac scan
### **C. Ectopic pregnancy**
* Empty uterus
* Adnexal mass/ring
* Free fluid
* Interstitial line sign
* Live ectopic on TVS
---
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# **3. INDICATIONS & RECOMMENDATIONS FOR OBSTETRIC ULTRASOUND**
### **(Based on ACOG + FOGSI + ISUOG guidelines)**
---
# **A. Recommended Routine Obstetric Ultrasound Schedule**
| Trimester | Timing | Purpose |
| ------------------------ | --------- | --------------------------------- |
| **First Trimester Scan** | 11–13+6 w | Dating, viability, NT, nasal bone |
| **Anomaly Scan (TIFFA)** | 18–22 w | Detailed fetal anatomy |
| **Growth Scan** | 28–32 w | Assess growth, AFI |
| **Late-Term Scan** | 36–38 w | Presentation, placenta, EFW |
---
# **B. Specific Indications**
## **1. Maternal Indications**
* Hypertension, preeclampsia
* Diabetes
* Hypothyroidism
* Epilepsy
* Connective tissue disorders
* Previous CS (accreta screening)
* Poor obstetric history
* Bleeding in pregnancy
## **2. Fetal Indications**
* Suspected congenital anomalies
* FGR suspicion
* Decreased fetal movements
* Non-reassuring NST
* Multiple pregnancy surveillance
* Suspected fetal anemia
## **3. Placental & Cord Indications**
* Low-lying placenta / previa
* Placenta accreta spectrum
* Vasa previa
* Umbilical cord anomalies
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# ------------------------------------
# **4. FETAL ECHOCARDIOGRAPHY – COMPLETE NOTE**
## **4.1 Indications**
**Maternal**
* Diabetes
* SLE/anti-Ro/anti-La antibodies
* Phenylketonuria
* Teratogenic drug exposure (lithium, valproate)
**Fetal**
* Increased NT (>3.5 mm)
* Abnormal cardiac views on anomaly scan
* Arrhythmias
* Non-immune hydrops
* Single umbilical artery
**Family**
* Previous baby with CHD
* Parental CHD
---
## **4.2 Recommended Timing**
* **Optimal: 22–24 weeks**
* Can be done 18–22 weeks in high-risk
---
## **4.3 What Radiology Evaluates (Core Views)**
* **4-chamber view**
* **LVOT & RVOT**
* **3-vessel view**
* **Aortic & ductal arch**
* **IVC–SVC anatomy**
* **Ventricular function & ejection patterns**
---
## **4.4 Common Diagnoses on Fetal Echo**
* Ventricular septal defect
* Atrioventricular septal defect
* Tetralogy of Fallot
* Transposition of great arteries
* Hypoplastic left heart
* Coarctation of aorta
* Arrhythmias (heart block, tachycardia)
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# **5. NEURAL TUBE DEFECTS – ULTRASOUND DETAILS**
### **Types**
1. **Anencephaly**
2. **Spina bifida (open/closed)**
3. **Encephalocele**
4. **Meningocele / Myelomeningocele**
---
## **5.1 USG Findings**
### **A. Anencephaly**
* Absence of cranial vault
* “Frog-eye sign”
* Polyhydramnios
* Seen as early as **11 weeks**
### **B. Spina Bifida (Open)**
**Cranial markers (high-yield):**
* **Lemon sign** (frontal bone scalloping)
* **Banana sign** (cerebellum curved)
* **Ventriculomegaly**
**Spinal markers:**
* Splaying of posterior elements
* Cystic sac with neural tissue (myelomeningocele)
### **C. Encephalocele**
* Extracranial mass with bony defect
* Usually occipital
* May contain brain tissue (poor prognosis)
---
## **5.2 Management**
* Anomaly confirmation
* MRI
* Folic acid counseling
* Consider MTP based on gestation
* Neonatal neurosurgery (if operable)
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# **6. ABDOMINAL WALL DEFECTS – ULTRASOUND DETAILS**
## **6.1 Gastroschisis**
* Para-umbilical (usually right-sided) defect
* **Free-floating bowel loops outside abdomen**
* No covering membrane
* Normal cord insertion
* No chromosomal association
* Associated: bowel edema, oligohydramnios
### **Management**
* Serial growth + AFI
* Deliver at 37 weeks
* Neonatal surgery
---
## **6.2 Omphalocele**
* Midline herniation at base of umbilical cord
* **Membrane-covered sac**
* Contains bowel ± liver
* High association with:
* Trisomy 13 & 18
* Cardiac defects
### **Management**
* Fetal echo mandatory
* Karyotyping/NIPT
* Delivery at tertiary center
* Surgical repair
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## **6.3 Body Stalk Anomaly**
* Severe defect
* Absent umbilical cord
* Fetus attached to placenta
* Incompatible with life
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# **7. HIGH-YIELD TABLES**
## **USG Criteria for Non-Viable Pregnancy**
| Feature | Cutoff |
| ----------------------------------------------- | ---------- |
| CRL without heartbeat | ≥7 mm |
| MSD without embryo | ≥25 mm |
| No heartbeat after 11 days of yolk sac presence | Diagnostic |
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## **Differentiating Abdominal Wall Defects**
| Feature | Gastroschisis | Omphalocele |
| -------------------- | ----------------------- | ----------- |
| Location | Right of cord insertion | Midline |
| Covering membrane | **Absent** | **Present** |
| Cord insertion | Normal | Into sac |
| Chromosomal risk | Low | High |
| Contains liver | Rare | Common |
| Additional anomalies | Rare | Common |
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