Ultrasound Note

How to Counsel Parents for Mild Fetal Ventriculomegaly (A Sonographer’s Perspective)

When mild ventriculomegaly is detected during a routine mid-trimester ultrasound, parents often feel immediate anxiety.

As a sonographer with years of clinical experience, I have seen how important careful measurement and thoughtful counseling can be.

This article explains how to approach mild fetal ventriculomegaly from both a technical and counseling perspective.

1. What Is Mild Fetal Ventriculomegaly?

Mild ventriculomegaly is defined as a lateral ventricular atrial width measuring 10–12 mm.

The measurement should be taken:

At the level of the atrium of the lateral ventricle
In a true axial plane
With calipers placed inner-to-inner
Perpendicular to the ventricle walls

Small differences in fetal position can affect the measurement.

Therefore, confirming the plane and repeating the measurement is essential.

2. How Accurate Is the Measurement?

Measurement accuracy is crucial.

Common pitfalls include:

Oblique planes
Measuring outside the atrial level
Fetal head compression due to position

In some cases, waiting and re-scanning after fetal repositioning can change a borderline value.

A 9.8 mm ventricle in a slightly oblique plane may measure 10.2 mm in another — and that changes counseling significantly.

3. Prognosis and Follow-Up

Most cases of isolated mild ventriculomegaly have a favorable outcome.

However, evaluation typically includes:

Detailed anatomical survey
Infection screening (TORCH)
Consideration of fetal MRI
Serial follow-up ultrasound

Progression beyond 12–15 mm increases risk, while stable measurements often correlate with normal neurodevelopment.

Statistics and context matter more than a single number.

4. How to Talk to Parents

Language is powerful.

Instead of saying:

“There is brain enlargement.”

Consider explaining:

“The ventricle measurement is slightly above average. In many cases, babies develop normally, but we recommend follow-up to monitor growth.”

Counseling should:

Avoid alarming terminology
Provide realistic statistics
Emphasize monitoring rather than immediate conclusions

Parents remember tone more than numbers.

Final Thoughts

Mild fetal ventriculomegaly is not simply a measurement — it is a moment of emotional vulnerability for parents.

Technical precision, clinical judgment, and compassionate communication all matter.

As sonographers, we are often the first to detect the finding — and the first to shape how it is understood.

🧬 Trisomy 18 vs Trisomy 21

초음파에서 보이는 사지 소견 차이

두 염색체 이상 모두 사지 이상이 동반될 수 있지만,

양상이 다릅니다.

핵심은:

T18은 “고정된 변형”

T21은 “경미한 soft marker”

1️⃣ 손 소견 비교

🔴 Trisomy 18

Persistent clenched hand
Index finger overlapping 3rd finger
5th finger overlapping 4th finger
고정된 주먹 모양
움직임 거의 없음

👉 구조적 이상 + 기능적 고정

🟢 Trisomy 21

Clinodactyly (5번째 손가락 휘어짐)
Sandal gap (엄지-두번째 발가락 간격 증가)
경미한 단축

👉 손은 움직이고, 고정된 clenched 형태는 아님

2️⃣ 발 소견 비교

🔴 Trisomy 18

Rocker-bottom foot
Overlapping toes
발 모양 왜곡
종종 양측성

구조 자체가 변형된 모습

🟢 Trisomy 21

Sandal gap
경미한 발가락 배열 변화
구조적 변형은 드묾

대개 soft marker 수준

3️⃣ 장골 길이 비교

🔴 Trisomy 18

성장 지연 동반
여러 구조 이상과 함께

🟢 Trisomy 21

Isolated short femur 가능
다른 이상 없으면 단독 soft marker

4️⃣ 패턴 차이

항목	Trisomy 18	Trisomy 21
손	고정된clenched hand	clinodactyly
발	rocker-bottom foot	sandal gap
사지형태	구조적 변형	soft marker 중심
성장	심한 성장지연	경미~ 정상
동반기형	다장기 이상 흔함	심장 이상 흔함

🧠 임상적 사고

Trisomy 18은:

👉 “심각하고 고정된 변형”

👉 다장기 이상 동반

Trisomy 21은:

👉 경미한 구조 변화

👉 soft marker 중심

하나의 손가락 소견만으로 판단하지 않습니다.

🔥 핵심 한 줄

T18은 “형태가 무너진 패턴”

T21은 “부드러운 마커의 조합”

초음파는 차이를 읽는 검사입니다.

🧬 Trisomy 18 (에드워드 증후군)

초음파에서 보이는 대표적인 사지 소견

Trisomy 18은 다장기 기형을 동반하는 염색체 이상입니다.

그중에서도 사지(limb) 소견은 비교적 특징적인 단서를 제공합니다.

하지만 중요한 것은,

하나의 소견이 아니라 “패턴”을 보는 것입니다.

1️⃣ 주먹을 꽉 쥔 손 (Clenched hand)

🔎 가장 대표적인 소견

지속적인 주먹 쥔 자세
검지가 3번째 손가락 위로 겹침
5번째 손가락이 4번째 위로 겹침
반복 스캔에서도 고정된 모습

⚠ 중요한 구분

일시적인 손가락 굴곡은 정상에서도 흔합니다.

하지만,

👉 여러 번 관찰해도

👉 손이 계속 닫혀 있고

👉 손가락이 겹쳐 있는 경우

→ 의심이 높아집니다.

2️⃣ Rocker-bottom foot (볼록 발바닥)

🔎 초음파 특징

발바닥이 과도하게 볼록
talus가 수직화
발 형태 왜곡

이 소견은 Trisomy 18에서 비교적 특징적이며

다른 중증 기형과 동반되는 경우가 많습니다.

3️⃣ Overlapping toes (겹친 발가락)

단순한 curly toe와 다릅니다.

🔎 의심되는 경우

발가락이 명확히 서로 겹침
고정된 위치
양측성
다른 구조 이상 동반

단독 소견은 진단적 의미가 낮습니다.

그러나 다른 기형과 함께 보이면 중요합니다.

4️⃣ 장골 단축 (Short long bones)

경미한 단축이 동반될 수 있습니다.

하지만 Trisomy 18에서는:

단독 short femur보다는
다장기 이상과 함께 나타나는 경우가 많습니다.

5️⃣ Radial ray 이상 (드물지만 가능)

요골 형성 저하
전완 변형

모든 케이스에서 보이는 것은 아닙니다.

🧠 중요한 건 ‘패턴’

Trisomy 18은 거의 항상

다장기 이상을 동반합니다.

자주 함께 보이는 소견:

✔ 심장 기형 (특히 VSD)

✔ 성장지연

✔ 맥락총 낭종 (CPC)

✔ Omphalocele

✔ 주먹 쥔 손

✔ Rocker-bottom foot

👉 단일 사지 소견만으로 진단하지 않습니다.

🚨 언제 의심을 높여야 할까?

고정된 자세
양측성
반복 검사에서도 지속
다른 구조적 이상 동반

이 네 가지가 중요합니다.

📌 핵심 정리

Trisomy 18의 대표적 사지 소견은:

지속적인 clenched hand
손가락 겹침
rocker-bottom foot
겹친 발가락

그러나 초음파 해석은

“한 장면”이 아니라

“전체 구조의 맥락”을 읽는 과정입니다.

🧬 Trisomy 18 (Edwards Syndrome)

Classic Limb Findings on Prenatal Ultrasound

Trisomy 18 is a chromosomal condition associated with multiple structural abnormalities.

Limb findings are among the most characteristic and recognizable ultrasound clues.

Recognizing these patterns helps guide further evaluation and counseling.

1️⃣ Clenched Hands with Overlapping Fingers

🔎 Classic Finding

The most well-known limb sign of Trisomy 18 is:

Persistent clenched hands
Index finger overlapping the 3rd finger
5th finger overlapping the 4th finger

📌 Key Ultrasound Clues

Fingers remain flexed across multiple scans
Fixed position
Limited spontaneous movement

👉 Transient hand flexion is common.

👉 Persistent, fixed overlapping is concerning.

2️⃣ Rocker-Bottom Foot

🔎 Appearance

Prominent convex sole
Vertical talus
Abnormal foot contour

Often associated with severe chromosomal or structural abnormalities.

3️⃣ Overlapping Toes

Different from simple curly toes.

Concerning Features:

Clear crossing pattern
Fixed position
Often bilateral
Associated with other anomalies

Overlapping toes alone are not diagnostic,

but in combination with other findings → suspicion increases.

4️⃣ Shortened Long Bones

May be present but usually mild.

Important distinction:

Trisomy 21 → isolated short femur can be common
Trisomy 18 → shortening often accompanies multiple structural anomalies

5️⃣ Radial Ray Abnormalities (Less Common)

Absent or hypoplastic radius
Limited forearm movement

Not universal, but can be seen.

🧠 Pattern Recognition Matters

Trisomy 18 is rarely diagnosed by a single limb finding.

Instead, look for a constellation:

✔ Growth restriction

✔ Cardiac defects (VSD common)

✔ Choroid plexus cyst

✔ Clenched hands

✔ Rocker-bottom feet

✔ Omphalocele

✔ Polyhydramnios

The combination raises suspicion.

🚨 What Makes It Concerning?

Not just the position — but:

Persistence
Fixation
Symmetry
Association with systemic anomalies

One soft marker ≠ diagnosis.

Pattern = risk.

📌 Clinical Takeaway

Classic limb findings in Trisomy 18 include:

Persistent clenched hands
Overlapping fingers
Rocker-bottom feet
Overlapping toes

But interpretation must always consider the entire fetal anatomy and growth pattern.

Ultrasound is about patterns, not isolated images.

NIPT vs Ultrasound

Down Syndrome (Trisomy 21)

Doppler Progression in IUGR

Understanding the Hemodynamic Sequence

Fetal growth restriction (IUGR/FGR) is not a sudden event.

It is a gradual hemodynamic progression.

Doppler allows us to see this progression in stages.

Stage 1: Increased Placental Resistance

Umbilical Artery

PI ↑
S/D ↑
Diastolic flow still present

Placental resistance rises first.

The fetus is still compensating.

Stage 2: Brain-Sparing (Redistribution)

Umbilical Artery

PI further increases

MCA

PI ↓
Diastolic flow ↑

The fetus redistributes blood to the brain.

CPR decreases.

This is compensation phase.

Stage 3: Absent End-Diastolic Flow (AEDF)

Umbilical Artery

No forward flow in diastole

Placental resistance is critically high.

This is no longer mild compensation.

Monitoring must intensify.

Stage 4: Reversed End-Diastolic Flow (REDF)

Umbilical Artery

Diastolic flow reverses

This indicates severe placental insufficiency.

Risk of hypoxia increases significantly.

Stage 5: Ductus Venosus Changes

Ductus Venosus

Increased PI
Absent or reversed A-wave

This reflects cardiac compromise.

Now the issue is no longer only placental —

it involves fetal cardiac function.

Hemodynamic Sequence Summary

Placental Resistance ↑

→ UA PI ↑

→ Brain-sparing (MCA PI ↓)

→ AEDF

→ REDF

→ Ductus venosus abnormality

The sequence is progressive.

Clinical Insight

Not all IUGR cases progress rapidly.

Early-onset IUGR tends to follow Doppler progression more clearly.

Late-onset IUGR may show subtle changes first (often CPR decline).

Trend is more important than a single value.

Technical Reminder

✔ Always confirm abnormal Doppler in multiple planes

✔ Ensure correct angle and sample location

✔ Avoid over-diagnosing from one waveform

✔ Consider gestational age

Doppler is dynamic — interpretation must be dynamic too.

Sonographer’s Note

In IUGR, Doppler tells a story.

At first, the placenta struggles.

Then the fetus adapts.

Eventually, the heart begins to strain.

Our role is not just to record numbers —

but to recognize where in the sequence the fetus stands.

Because timing, in obstetrics, changes everything.

Brain-Sparing Effect in Fetal Doppler

When the Fetal Brain Protects Itself

In compromised fetuses, circulation changes before growth does.

Doppler allows us to see compensation

before structural abnormalities appear.

What Is Brain-Sparing?

When placental resistance increases:

Umbilical artery resistance ↑
Oxygen delivery ↓
Fetal body responds

The fetus redistributes blood flow toward vital organs —

especially the brain.

This results in:

Decreased MCA PI
Increased diastolic flow in MCA
“Low resistance” cerebral waveform

This is called the brain-sparing effect.

Doppler Pattern Summary

1️⃣ Umbilical Artery (UA)

PI ↑
S/D ↑
Possible absent or reversed end-diastolic flow

2️⃣ Middle Cerebral Artery (MCA)

PI ↓
PSV may increase
Increased diastolic flow

The key is the relationship between UA and MCA.

The Cerebroplacental Ratio (CPR)

CPR = MCA PI / UA PI

Low CPR suggests redistribution.

Even when growth is borderline normal,

a low CPR may indicate fetal compromise.

Clinical Meaning

Brain-sparing is not reassurance.

It is compensation.

It means:

The fetus is adapting.

But compensation does not last forever.

Persistent brain-sparing is associated with:

IUGR
Hypoxia
Adverse perinatal outcome

Practical Interpretation Flow

If UA PI ↑

→ Check MCA PI

If MCA PI ↓

→ Consider redistribution

If CPR low

→ Closer monitoring required

Never interpret one vessel alone.

Important Technical Reminder

Brain-sparing diagnosis is highly angle-dependent.

✔ Ensure correct MCA sampling

✔ Keep angle as close to 0° as possible

✔ Avoid distal MCA measurement

✔ Repeat abnormal findings

Misalignment can falsely lower PI.

Before diagnosing redistribution,

verify technique.

Sonographer’s Note

Brain-sparing is fascinating —

the fetus protecting its own brain.

But as sonographers,

we must distinguish true redistribution

from technical illusion.

Because sometimes

what looks like compensation

is simply cosine at work.

🫀 HLHS (좌심 저형성 증후군) 정리

1️⃣ HLHS란?

HLHS(Hypoplastic Left Heart Syndrome)는

좌심실(LV), 승모판, 대동맥판, 상행대동맥이 심하게 저형성되어

좌심계가 전신 순환을 담당하지 못하는 심기형입니다.

즉,

좌심실이 매우 작거나 기능이 거의 없고
대동맥이 가늘며
출생 후 ductus가 닫히면 전신 순환이 붕괴됩니다.

2️⃣ 태아 초음파에서 보이는 특징

📌 4-Chamber View

LV가 RV보다 현저히 작음
LV cavity 협소 또는 거의 보이지 않음
승모판 저형성/폐쇄 가능
RV dominance

👉 초기에는 “불균형 AVSD”처럼 보일 수 있음

📌 LVOT View

LVOT continuity 불량
Ascending aorta 매우 작음
대동맥판 협착 또는 폐쇄

📌 3VT View

정상 배열:

MPA > Ao > SVC

HLHS에서는:

MPA가 현저히 큼
Ao가 매우 작게 보임
Ao가 위치가 뒤틀려 보일 수 있음

📌 Aortic Arch

Arch 자체가 hypoplastic
Diameter 감소
Ductal arch가 상대적으로 더 굵어 보임

3️⃣ 왜 DORV처럼 보일 수 있을까?

HLHS에서는:

LV가 거의 기능을 못 함
RV가 systemic circulation 담당
Ao가 작고 RV 쪽에서 기시하는 것처럼 보일 수 있음
Outflow가 합쳐진 것처럼 보이는 착시

👉 특히 RV dominant AVSD 동반 시 감별이 매우 어려움

4️⃣ 감별 포인트 (DORV vs HLHS)

항목	DORV	HLHS
LV 크기	존재	매우작음
Asc Ao	정상~약간작음	매우작음
RV 역할	주로폐순환	전신순환담당
Ductal 중요도	상대적	필수

5️⃣ 실전 체크 포인트

✔ RV dominant 보이면 LV 직경 정량 비교

✔ Ao/MPA 비율 반드시 확인

✔ LVOT continuity 집요하게 보기

✔ 3VT에서 Ao 크기 비교

✔ Ductal arch 반드시 separate로 확인

✔ 자세 불량 시 확정 진단 보류 가능

6️⃣ 임상적 의미

출생 후:

ductus 의존성 순환
Prostaglandin 유지 필요
단계적 수술 (Norwood → Glenn → Fontan)

예후는 수술 전략과 해부학적 세부 구조에 따라 달라집니다.

HLHS는 단순히 “좌심실이 작은 병”이 아니라, 전신 순환이 우심실과 ductus에 의존하는 치명적인 구조적 이상이다. 특히 RV dominant 소견이 보일 경우, DORV와의 감별을 위해 대동맥 크기와 ductal arch를 반드시 확인해야 한다.

🦶 Isolated 4th Curly Toe at 22 Weeks

Normal Variant or Something to Worry About?

Case Summary

Gestational age: 22 weeks 3 days
Examination: Detailed second-trimester ultrasound
Finding: Flexed appearance of the right 4th toe

Ultrasound Findings

Flexion of the right 4th toe
Other toes aligned normally
Normal foot length and shape
No rocker-bottom configuration
No syndactyly
Long bones within normal range
No additional structural abnormalities

👉 Isolated finding

What Is a Curly Toe?

A curly toe refers to a flexed or slightly underlapping toe appearance.

In fetal ultrasound, this can be seen due to:

Intrauterine positioning
Transient muscular tone
Normal anatomical variation

The 4th toe, in particular, may appear flexed because of its anatomical alignment and scanning angle.

Is It a Soft Marker?

Isolated curly toe is not considered a strong soft marker for chromosomal abnormalities.

However, further evaluation is important when:

Multiple anomalies are present
Persistent overlapping toes are observed
Fixed deformity is suspected
Associated skeletal abnormalities exist

In this case, no additional abnormalities were identified.

What Should Be Checked?

When a curved toe is seen, the examiner should assess:

✔ Overall toe alignment

✔ Foot contour

✔ Long bone measurements

✔ Presence of other structural anomalies

✔ Fetal growth pattern

Context is everything.

Counseling Perspective

When isolated and not associated with other findings, a curly toe is most often:

Positional
Benign
Likely to resolve or remain clinically insignificant

Follow-up imaging can help confirm stability.

🔎 Clinical Takeaway

Not every unusual image represents pathology.

Ultrasound interpretation requires pattern recognition and context.

An isolated 4th curly toe at mid-gestation is usually a normal variant.

22주 정밀초음파에서 보인 4th Curly Toe — 정상 변이일까?

1️⃣ 기본 정보

임신 주수: 22주 3일
검사: 정밀 초음파
관찰 소견: 우측 4번째 발가락 굴곡 소견

2️⃣ 초음파 소견

우측 발에서 4번째 발가락이 굴곡된 모습 관찰
다른 발가락 배열은 비교적 정상 정렬
발 길이 및 발바닥 형태 정상
Long bone 길이 정상 범위
명확한 overlapping toes 소견은 아님
고정된 변형인지 여부는 추적 필요

👉 단독 isolated finding

3️⃣ Curly Toe란?

Curly toe는 발가락이 굴곡(flexion)되어 보이는 상태로,

태아기 초음파에서 비교적 흔하게 관찰될 수 있습니다.

대부분은:

자궁 내 자세 영향
일시적인 위치 변화
출생 후 자연 교정

으로 이어집니다.

특히 4번째 발가락은

구조적으로 굴곡이 잘 보일 수 있는 위치입니다.

4️⃣ 우리가 반드시 확인해야 할 것

발가락 굴곡이 보일 때는 다음을 함께 평가합니다:

✔ 다른 발가락 정렬

✔ 발바닥 아치 형태

✔ Rocker-bottom foot 여부

✔ Syndactyly 여부

✔ 장골 길이

✔ 다른 구조적 이상 동반 여부

이 케이스에서는

동반 기형은 관찰되지 않았습니다.

5️⃣ Soft Marker일까?

일반적으로 isolated curly toe는

염색체 이상과의 직접적인 연관성은 낮습니다.

하지만

여러 소견이 함께 있을 경우
지속적이고 고정된 overlapping toe일 경우

→ 추가 평가가 필요합니다.

현재 케이스는 단독 소견이며

임상적으로 의미가 크지 않을 가능성이 높습니다.

6️⃣ 환자 설명 관점

“현재 보이는 발가락 굴곡은 대부분 태아 자세에 따른 일시적인 모습일 가능성이 높습니다. 다른 이상 소견은 보이지 않으며, 추적 관찰을 통해 변화 여부를 확인하겠습니다.”

7️⃣ 교육적 포인트

작은 변이를 과잉 해석하지 않는다.
단독 소견인지 반드시 확인한다.
‘구조’와 ‘패턴’을 함께 본다.
follow-up의 중요성.

📌 Take Home Message

Isolated 4th curly toe는

대부분 정상 변이에 가깝습니다.

초음파는 “이상 찾기”가 아니라

“맥락을 읽는 검사”입니다.

🧠 Case Review

Small CSP + Suspected Horseshoe Kidney + Borderline Oligohydramnios at 22+5 Weeks

1️⃣ Background

Gestational age: 22 weeks 5 days
Indication: Detailed second-trimester anatomy scan
No known prior abnormalities

2️⃣ Key Ultrasound Findings

🧠 Central Nervous System

Cavum Septi Pellucidi (CSP) appears small
No ventriculomegaly
Posterior fossa structures grossly normal
Corpus callosum not fully assessed in mid-sagittal plane

🔎 Recommendation: Dedicated mid-sagittal view for corpus callosum evaluation

🩺 Renal Findings

Both kidneys appear low-lying
Suspicious midline fusion anterior to the aorta
Renal isthmus suspected on transverse view

➡ Suspicion: Horseshoe kidney

💧 Amniotic Fluid

AFI: 6.7 cm
Borderline oligohydramnios

🔎 Fetal bladder visualized

🔎 Follow-up fluid trend recommended

3️⃣ Clinical Significance

This is not a single-marker case.

The combination of:

Small CSP
Possible horseshoe kidney
Borderline AFI

Raises the question of:

Isolated incidental findings
vs
Underlying midline developmental issue
vs
Chromosomal or syndromic association

4️⃣ Differential Considerations

① Isolated Horseshoe Kidney

Often good prognosis
May be incidental

② Midline Developmental Spectrum

Small CSP may warrant corpus callosum assessment
Evaluate septal integrity and callosal length

③ Chromosomal Association

Horseshoe kidney reported in Trisomy 18
Consider soft markers review
Genetic counseling if additional findings emerge

④ Renal Function & Fluid Correlation

Borderline AFI may reflect:
- Measurement variability
- Early placental insufficiency
- Subtle renal functional issue

Trend is more important than single measurement.

5️⃣ What Should Be Rechecked?

✔ Detailed mid-sagittal brain view

✔ Corpus callosum morphology

✔ Outflow tracts & aortic arch

✔ Renal isthmus confirmation with color Doppler

✔ Serial AFI

6️⃣ Educational Take-Home Points

Small CSP alone does not equal pathology.
Horseshoe kidney is frequently benign when isolated.
Borderline AFI should be interpreted in context.
Multisystem minor findings require structured thinking.
Follow-up imaging may be more valuable than immediate labeling.

7️⃣ Final Thought

Ultrasound is not about detecting abnormalities.

It is about understanding patterns.

Sometimes, the question is not

“Is this abnormal?”

But

“Is this connected?”