OBJECTIVE:

To compare the ability to predict adverse intrapartum perinatal outcomes between the determination of pH and lactate by fetal calyceal blood microtomy.

MATERIALS AND METHODS:

Comparative, observational, descriptive and prospective study carried out in pregnant patients, at term, attended from February to October 2019 at the Obstetrics Clinical Management Unit of the Virgen Macarena University Hospital of Seville, Spain. All of them underwent a fetal calyx blood microdrawing during labor and, subsequently, at birth, arterial blood gas analysis of the umbilical cord.

RESULTS:

Of 118 determinations obtained, 99 values corresponding to 81 pregnant women were studied. A significant correlation of 76.6% was found between pH and lactate, although both with low sensitivity and low positive predictive value, high specificity and negative predictive value. When predicting the pH value of the umbilical artery, only the pH of the calyx obtained a significant result.

CONCLUSION:

Due to the high negative predictive value and specificity of fetal calyx pH and lactate determination, it was observed that this is a test that should be applied only when confirmation is required, but not as a screening method for fetal well-being. The pH was superior to lactate in estimating the arterial blood gas result of the umbilical cord.