There is no known cause, and there are usually no symptoms associated with PFO. Treatment is not necessary in most PFO cases.A patent foramen ovale is a small, flaplike opening in the wall between the upper chambers of the heart. The larger the hole, the more likely symptoms are. PFOs, on the other hand, are normal before birth but may fail to close after birth. In the majority of cases, PFO causes no symptoms. In very rare cases, an infant with PFO could have a blue tint to their skin when crying or passing stool. There are usually no symptoms for patent foramen ovale (PFO). Diagnosis: There are usually no symptoms associated with PFO but an imaging test called an echocardiogram can be used to diagnose a PFO. Patent foramen ovale (PFO).