Scalp stimulation benefit in predicting of fetal asphyxia

ABSTRACT

The term of fetal asphyxia is accepted when the arterial blood gases are below the 5th percentile value of a normal population pH < 7.12 PO2 < 6.5 PCO2 > 71.2 base deficit < -10 So it is important to differentiate between fetal asphyxia and other terms like Fetal acidosis A pathologic condition characterized by an increased concentration of hydrogen ions in the tissues and in the blood. Fetal hypoxia A pathologic condition characterized by a decreased concentration of oxygen in the tissue and in the blood. Fetal distress unspecific state of fetal jeopardy that may or may not be caused by asphyxia. Clinical indicators of fetal asphyxia 1] Meconium in the amniotic fluid. 2] Low Apgar score. 3] Bad neurologic outcome of the newborn. Biophysical indicators of fetal asphyxia 1] Fetal heart rate monitoring. 2] FHR response to scalp stimulation. 3] FHR response to VAST. Biochemical indicators of fetal asphyxia 1] Fetal-scalp blood gases. 2] Continuous pH measurement. 3] Infra-red light oxymetry. 4] Near infrared spectroscopy. The management of early stages of fetal asphyxia depends on intrauterine resuscitative measures, which consist of 1] Lateral position. 2] Hydration. 3] Administration of oxygen. 4] Discontinuation of oxytocin. 5] Inhibition of uterine activity. In our research we studied 50 women at labor who have non reassuring FHR patterns and the most important results were as follows 1-The presence of meconium in the amniotic fluid is unreliable indicator and it can not be depended on it in predicting of fetal asphyxia, only in the case of severe meconium passage with a sensitivity of 63%. 2-Late decelerations are diagnosed in 58% of cases, and variable decelerations in 38%, but the most important association is the late decelerations with elevated basal FHR with true positive of 72.7%, and true negative of 89.7%. 3-When there is no response to scalp stimulation, the fetus is acidotic or preacidotic in 88% of cases. 4-Poor response is associated in 50% of cases with acidotic or preacidotic fetus. 5-Good response is not associated with any acidotic fetus, and preacidotic fetus is seen in only 7.4% of cases, and the lowest value of pH with good response is 7.232. 6-Scalp stimulation test will suffice the evaluation in 54% of cases. 7-Patients, who are managed by waiting and observation only, have no improvement in FHR pattern, and fetal acidosis is seen in 28.6% of cases. 8-The outcome of patients, who are managed by intrauterine resuscitative measures, is better, but FSST is still the end point in the management of patient with partial improvement. -9-50% of cesarean sections, which are done primarily for nonreassuring FHR pattern, are unwarranted by fetal distress, and only 28.6% of these cesarean sections are for really acidotic fetuses. 10-The dependence on FSST as an indicator to remove to cesarean section in patients, who are managed primarily conservatively, will reduce the rate of this removing from 50% to about 20%, and the usage of fetal scalp sampling will reduce this rate to about 10% only. 11-The specificity of FSST to low P02 is 83%, whereas the sensitivity of this test will reach 73.7%. 12-We can not find any association between the severity of response to FSST and P02 value. 13-All cases of fetal hypercarbia are associated with positive FSST [the sensitivity is 73.7% but the specificity is 100%]. 14-Respiratory acidosis is associated with lower Apgar score at the first and 5th minute in comparing with metabolic acidosis. 15-The very low first minute Apgar score is associated with abnormal fetal pH values in 80% of cases, and with positive FSST in 90% of cases. 16-29.16% of newborns with Apgar score [> 7/10] at the first minute, have abnormal pH values, and 37.5% of those newborns have positive FSST. 17-All newborns with very low Apgar score at 5th minute have abnormal pH values, and positive FSST