Her preductal and postductal
oxygen saturations were 100% and 98%, respectively.
PPHN is suspected when there is a considerable difference between preductal and postductal
oxygen saturation, in combination with severe hypoxaemia that does not improve when the infant is subjected to 100% supplemental oxygen.
In the newborn nursery, her physical exam did not note any murmur, and her congenital cardiac screen was documented as normal (pre- and postductal
saturations 100%) on day two of life.
Also, the ongoing controversy over whether both pre- and postductal
screening is significantly superior to a single postductal
screen  may mean that a single foot saturation screen before discharge is the more practical solution in resource-limited settings.
His CT findings suggested grossly dilated aortic root and ascending aorta, LV hypertrophy, severe postductal
coarctation of aorta, multiple mediastinal posterior chest wall, and paravertebral and intercostal collaterals on either side bypassing coarctation with collaterals channels [Figure 1A].
Early in the process of cardiopulmonary transition immediately after birth and before the closure of the ductus arteriosus the arterial oxygen saturation (SpO2) in the ascending aorta is higher than that in the descending aorta.1 Many studies have documented a difference in oxygen saturation between the upper extremities (pre-ductal) and lower extremities (postductal
) with lower oxygen saturation observed in post-ductal sites within the first hour of life.12
On his magnetic resonance angiography a postductal
coarctation and an aneurysm with a diameter of 6 cm 2 cm below the coarctation were detected (Fig.
The PDA was ligated with a 10 mm clip after ensuring adequate pre- and postductal