Role of Ultrasound-Based Prenatal Prediction of Pulmonary Function in Congenital Diaphragmatic Hernia: Does It Have Prognostic Significance Postnatally?

Background and objectives: The incidence of congenital diaphragmatic hernia (CDH) in India is 1 in 1000. About 60 % of these are isolated, and the survival prognosis in them depends upon the quantum of contralateral functional lung. Out of the various pulmonary and extrapulmonary sonological predictors, observed to expected lung-head ratio (O/E LHR) is an efficient gestation-independent predictor of pulmonary function. This study was carried out to see the correlation of this prenatal predictor with the postnatal outcome depending on the pulmonary function.

Methodology: This study was carried out at Apollo Center of Fetal Medicine, New Delhi, from January 2009 to December 2015. A total of 14 fetuses with isolated left-sided CDH were included. The contralateral lung area was measured in 2D transverse view of the thorax at the level of four-chamber view of the heart by tracing method. The obtained value (square mm) was then divided by the expected mean lung area at that gestation and multiplied with 100 to express O/E LHR as percentage. These were then classified as severe (O/E LHR <25 %), moderate (25-45 %) or mild (>45 %) varieties of CDH. The parents to be were counselled for termination or continuation of pregnancy based on severity of CDH and total lung area. The patients were followed up for obstetrical and neonatal outcome till the time of first postoperative visit (diaphragmatic repair).

Results: The survival correlation in mild cases was 100 % (n = 5 out of 5) and 50 % in moderate cases (n = 2 out of 4), and both severe cases were terminated. There was a significant difference (p < 0.01) in the survival rate in the mild versus severe cases.

Conclusions: The prenatal predictor for postnatal pulmonary function correlates well with the neonatal outcome and hence is an important tool in prenatal counseling and triaging those who require termination of pregnancy versus expectant management. An obstetrician who is a first point of contact to the pregnant women can understand this and use it for counseling and differentiating the patients who need termination with regard to CDH.