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Prenatal Scans and Prognosis: Decoding O/E LHR and Liver Position

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For a baby with congenital diaphragmatic hernia (CDH), prenatal scans measuring lung size (O/E LHR and O/E TFLV) and liver position are vital for predicting severity. A "liver down" position and an O/E LHR over 45% generally indicate a milder case and better prognosis.

Key Takeaways

  • • O/E LHR uses ultrasound to compare your baby's lung size to typical development, helping classify CDH as mild, moderate, or severe.
  • • A fetal MRI calculates Total Fetal Lung Volume (O/E TFLV) to provide a more precise 3D evaluation of the baby's lungs.
  • • A 'liver down' position is a positive indicator, meaning the liver stayed in the abdomen and left more room for lung growth.
  • • A 'liver up' position means the liver has entered the chest, often leading to a more severe CDH diagnosis and restricted lung development.
  • • While prenatal scans accurately measure lung size, they cannot fully predict if a baby will develop pulmonary hypertension after birth.

When your baby is diagnosed with CDH, your medical team uses specialized prenatal scans to try to “see” how well the lungs are growing. While no single measurement can perfectly predict the future, two main factors—lung volume and liver position—provide a valuable roadmap for what to expect after birth [1][2].

Measuring Lung Growth: O/E LHR and O/E TFLV

Because babies grow at different rates, doctors don’t just measure the lung size; they compare it to what is “normal” for a baby at that exact stage of pregnancy.

O/E LHR (Observed-to-Expected Lung-to-Head Ratio)

This is calculated during an ultrasound. The doctor measures the two-dimensional area of the contralateral lung—which is the “good” lung on the side opposite of the hernia. They then divide this measurement by the baby’s head circumference. This result is compared to the “expected” measurement for a healthy baby [3][4].

  • Mild CDH (>45% O/E LHR): Typically associated with high survival rates and a lower need for intensive breathing support [5][6].
  • Moderate CDH (25%–45% O/E LHR): Survival is generally good, but the baby will likely need more significant medical support at birth [5].
  • Severe CDH (<25% O/E LHR): These babies have the most restricted lung growth and are at the highest risk for needing advanced support like ECMO [5][7].

O/E TFLV (Total Fetal Lung Volume)

While ultrasound is great for quick checks, a fetal MRI provides a more detailed 3D look at the total volume of both lungs. The result, called O/E TFLV, is often considered a more precise way to confirm the severity of the condition and help doctors plan for delivery [8][9].

The Importance of Liver Position

The position of the liver is one of the strongest predictors of how a baby will do [1].

  • Liver Down: This means the liver has stayed in the abdomen. This is a very positive sign, as it usually means there is more room in the chest for the lungs to grow [2].
  • Liver Up: This means a portion of the liver has moved through the hole into the chest. Because the liver is a large, solid organ, it can significantly crowd the heart and lungs, often leading to a more severe case of CDH [1][2].

Understanding the Limitations

It is important to remember that these numbers are prognostic markers—they are tools to help doctors prepare, not a final answer [10].

  • Pulmonary Hypertension: These scans are very good at measuring the size of the lungs, but they cannot perfectly predict how the blood vessels in the lungs will behave after birth (pulmonary hypertension) [10][11].
  • Individual Variation: Every baby is different. Some babies with “severe” numbers do better than expected, and some with “mild” numbers may face unexpected challenges [12].

Frequently Asked Questions

What does O/E LHR mean for a CDH diagnosis?
O/E LHR stands for Observed-to-Expected Lung-to-Head Ratio. It is an ultrasound measurement that compares your baby's "good" lung size to what is expected for their gestational age, helping doctors estimate how much the CDH has restricted lung growth.
What is the difference between "liver up" and "liver down" in CDH?
"Liver down" means the baby's liver has remained in the abdomen, which is a positive sign because it leaves more room for the lungs to grow. "Liver up" indicates part of the liver has herniated into the chest, crowding the lungs and heart, usually signaling a more severe case.
How is O/E TFLV different from O/E LHR?
While O/E LHR is calculated using a 2D ultrasound, O/E TFLV (Total Fetal Lung Volume) uses a fetal MRI. The MRI provides a more detailed 3D measurement of both lungs, giving doctors a more precise view to help plan for delivery.
Can prenatal scans predict if my baby will need ECMO?
Prenatal scans can estimate the risk of needing advanced support like ECMO based on lung size. Babies with a severe CDH classification (an O/E LHR under 25%) are at the highest risk, though scans cannot perfectly predict how a baby will breathe after birth.

Questions for Your Doctor

  • • Based on my most recent scan, what is our baby's O/E LHR percentage?
  • • Is our baby's liver currently 'up' in the chest or 'down' in the abdomen?
  • • How do the MRI results (O/E TFLV) compare to what you saw on the ultrasound (O/E LHR)?
  • • Given these numbers, would you classify this as a mild, moderate, or severe case of CDH?
  • • What do these measurements suggest about the likelihood that my baby will need ECMO after birth?
  • • Are there other factors, like heart function or the position of the stomach, that are influencing your outlook?

Questions for You

  • • How do these numbers make me feel? Am I focused more on the statistics or the care plan?
  • • Have I had both an ultrasound and an MRI to get the most complete picture of my baby's lung volume?
  • • What information from these scans is most important for me to share with my support system?
  • • Do I understand that these numbers are helpful guides but not a 100% guarantee of how my baby will do after birth?

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References

  1. 1

    Antenatal management and outcomes of pregnancies with congenital diaphragmatic hernia.

    Tanacan A, Orgul G, Aydin E, et al.

    Journal of neonatal-perinatal medicine 2020; (13(3)):323-330 doi:10.3233/NPM-190266.

    PMID: 31796690
  2. 2

    Antenatal assessment of liver position, rather than lung-to-head ratio (LHR) or observed/expected LHR, is predictive of outcome in fetuses with isolated left-sided congenital diaphragmatic hernia.

    Straňák Z, Krofta L, Haak LA, et al.

    The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians 2017; (30(1)):74-78 doi:10.3109/14767058.2016.1163539.

    PMID: 27011107
  3. 3

    Reproducibility of fetal lung-to-head ratio in left diaphragmatic hernia across the North American Fetal Therapy Network (NAFTNet).

    Abbasi N, Ryan G, Johnson A, et al.

    Prenatal diagnosis 2019; (39(3)):188-194 doi:10.1002/pd.5413.

    PMID: 30618058
  4. 4

    Standardization of Sonographic Lung-to-Head Ratio Measurements in Isolated Congenital Diaphragmatic Hernia: Impact on the Reproducibility and Efficacy to Predict Outcomes.

    Britto IS, Sananes N, Olutoye OO, et al.

    Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine 2015; (34(10)):1721-7 doi:10.7863/ultra.15.14.11064.

    PMID: 26307118
  5. 5

    Antenatal predictors of outcome in prenatally diagnosed congenital diaphragmatic hernia (CDH).

    Oluyomi-Obi T, Kuret V, Puligandla P, et al.

    Journal of pediatric surgery 2017; (52(5)):881-888 doi:10.1016/j.jpedsurg.2016.12.008.

    PMID: 28095996
  6. 6

    Differences in Outcomes in Prenatally Diagnosed Congenital Diaphragmatic Hernia Compared to Postnatal Detection: A Single-Center Experience.

    Mesas Burgos C, Hammarqvist-Vejde J, Frenckner B, Conner P

    Fetal diagnosis and therapy 2016; (39(4)):241-7 doi:10.1159/000439303.

    PMID: 26431351
  7. 7

    The validity of the observed-to-expected lung-to-head ratio in congenital diaphragmatic hernia in an era of standardized neonatal treatment; a multicenter study.

    Snoek KG, Peters NCJ, van Rosmalen J, et al.

    Prenatal diagnosis 2017; (37(7)):658-665 doi:10.1002/pd.5062.

    PMID: 28453882
  8. 8

    Comparison of prenatal lung volume measurements associated with extracorporeal membrane oxygenation (ECMO) utilization and mortality in congenital diaphragmatic hernia.

    Stanic P, Gavulic A, Jenkins TM, et al.

    Journal of pediatric surgery 2026; 162970 doi:10.1016/j.jpedsurg.2026.162970.

    PMID: 41619847
  9. 9

    Risk-stratification of severity for infants with CDH: Prenatal versus postnatal predictors of outcome.

    Akinkuotu AC, Cruz SM, Abbas PI, et al.

    Journal of pediatric surgery 2016; (51(1)):44-8.

    PMID: 26563530
  10. 10

    Congenital diaphragmatic hernia: Observed/expected lung-to-head ratio as a predictor of long-term morbidity.

    King SK, Alfaraj M, Gaiteiro R, et al.

    Journal of pediatric surgery 2016; (51(5)):699-702.

    PMID: 26932249
  11. 11

    Prenatal prediction of survival in congenital diaphragmatic hernia: An audit of postnatal outcomes.

    Petroze RT, Caminsky NG, Trebichavsky J, et al.

    Journal of pediatric surgery 2019; (54(5)):925-931 doi:10.1016/j.jpedsurg.2019.01.021.

    PMID: 30786991
  12. 12

    Measurements of Lung Size in Ultrasound and Magnetic Resonance Imaging in Congenital Diaphragmatic Hernia - A Comparison of Prenatal Imaging Techniques.

    Schreiner YA, Schmidt JL, Weis M, et al.

    Ultraschall in der Medizin (Stuttgart, Germany : 1980) 2025; (46(6)):585-593 doi:10.1055/a-2525-6117.

    PMID: 40074004

This page explains CDH prenatal scan terminology for educational purposes. Your maternal-fetal medicine specialist is the best source for interpreting your specific ultrasound or MRI results.

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