Determine Fetal Situs step by Step:

🫀 Detecting Fetal Situs According to Guideline


🔹 Step 1: Determine Fetal Lie & Presentation

প্রথমে fetus-এর অবস্থান নির্ণয় করুন:

✔ Cephalic / Breech / Transverse
✔ Spine কোথায় আছে
✔ Head orientation

👉 এটি right-left orientation বুঝতে সাহায্য করে।


🔹 Step 2: Obtain Transverse View of Fetal Abdomen

Fetal abdomen-এর transverse section নিন।

Normal findings:

✔ Stomach → left side
✔ Descending aorta → left posterior
✔ Inferior vena cava (IVC) → right anterior

👉 এটি normal abdominal situs নির্দেশ করে।


🔹 Step 3: Evaluate Cardiac Position

Thoracic transverse view-এ:

✔ Heart left chest-এ আছে কিনা
✔ Apex left দিকে pointing করছে কিনা

Normal:

  • Levocardia
  • Cardiac axis ≈ 45° ± 20°

🔹 Step 4: Assess Cardiac Situs

Cardiac chambers abdominal situs-এর সাথে consistent কিনা দেখুন।

Normal Situs Solitus:

✔ Right atrium → right side
✔ Left atrium → left side


🔹 Step 5: Look for Situs Abnormalities

🔴 Situs Inversus

  • Stomach right side
  • Apex right side

🔴 Heterotaxy Syndrome

  • Abnormal arrangement
  • Interrupted IVC
  • Complex CHD association

🔹 Step 6: Confirm Sequential Segmental Analysis

Guideline অনুযায়ী assess করুন:

✔ Situs
✔ Atrioventricular connection
✔ Ventriculoarterial connection


⚠️ Important Guideline Points

✔ Always start from abdomen
✔ Never directly start from heart
✔ Determine right-left orientation carefully
✔ Confirm aorta and IVC position


📌 Common Mistakes

❌ Fetal lie ignore করা
❌ Only cardiac apex দেখে decision
❌ Abdomen না দেখে cardiac situs বলা


🫀 Normal Situs Pattern

StructurePosition
StomachLeft
AortaLeft posterior
IVCRight anterior
Cardiac apexLeft

👨‍⚕️ ডা. মোহাম্মদ নিজাম উদ্দিন

Dr. Mohammed Nizam Uddin

MBBS, BCS (H), MD (Cardiology)
Post Doctoral Training in Cardiac Intervention
Advanced Fellowship in Fetal Cardiology & Intervention

Associate Professor & Senior Consultant (Cardiology)
Clinical & Interventional Cardiologist
Pioneer Fetal Cardiologist & Fetal Echocardiography Expert


Detecting Fetal Situs According to Guideline

Determination of fetal situs is the most important initial step in fetal echocardiography. Incorrect situs assessment may lead to major diagnostic errors. Therefore, a systematic guideline-based approach is essential.


🔹 Step 1: Determine Fetal Lie & Presentation

First identify:

✔ Cephalic / Breech / Transverse lie
✔ Spine position
✔ Head orientation

👉 This helps establish fetal right-left orientation.


🔹 Step 2: Obtain Transverse Abdominal View

Take a transverse section of the fetal abdomen.

Normal findings:

✔ Stomach on left side
✔ Descending aorta left posterior
✔ Inferior vena cava (IVC) right anterior

👉 These findings indicate normal abdominal situs.


🔹 Step 3: Assess Cardiac Position

On thoracic transverse view:

✔ Heart located in left chest
✔ Cardiac apex pointing left

Normal:

  • Levocardia
  • Cardiac axis ≈ 45° ± 20°

🔹 Step 4: Evaluate Cardiac Situs

Assess whether atrial arrangement corresponds to abdominal situs.

Situs Solitus:

✔ Right atrium on right
✔ Left atrium on left


🔹 Step 5: Identify Situs Abnormalities

🔴 Situs Inversus

  • Stomach on right
  • Apex on right

🔴 Heterotaxy Syndrome

  • Abnormal organ arrangement
  • Interrupted IVC
  • Associated complex CHD

🔹 Step 6: Perform Sequential Segmental Analysis

Guideline-based evaluation includes:

✔ Situs
✔ Atrioventricular connections
✔ Ventriculoarterial connections


⚠️ Important Guideline Principles

✔ Always begin from abdomen
✔ Never start directly from heart
✔ Carefully determine right-left orientation
✔ Confirm aorta and IVC relationship


📌 Common Errors

❌ Ignoring fetal lie
❌ Diagnosing situs only by cardiac apex
❌ Skipping abdominal evaluation


🫀 Normal Situs Pattern

StructurePosition
StomachLeft
AortaLeft posterior
IVCRight anterior
Cardiac apexLeft

👨‍⚕️ Dr. Mohammed Nizam Uddin

MBBS, BCS (H), MD (Cardiology)
Post Doctoral Training in Cardiac Intervention
Advanced Fellowship in Fetal Cardiology & Intervention

Associate Professor & Senior Consultant (Cardiology)
Clinical & Interventional Cardiologist
Pioneer Fetal Cardiologist & Fetal Echocardiography Expert

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