The reliability of the result of the umbilical cord pH.

In modern obstetrical practice, the pH of the umbilical cord blood is considered as a parameter of neonatal morbidity and, by implication, as a retrospective evaluation of the quality of obstetrical care [3, 5]. In order to determine the pH, blood has to be taken from the umbilical vessels, stored and analysed. Various factors during these procedures (heparin concentration, temperature of storage, time-lapse from birth to blood sampling) influence the ultimate results of the pH. In a first study we compared the outcomes when blood was sampled and tested immediately post partum with three other procedures (sampled later and stored at room temperature, sampled from a late clamped, cool-stored segment of the umbilical cord, and sampled from the chorionic vessels of the cool-stored placenta). In a second study we investigated various factors separately (storing of blood in syringes and in segments of the cord, at room temperature and at 0 °C, early or late clamping, and sampling from the chorionic vessels of the placenta)