Significance of Sporadic Deceleration During Antepartum Testing in Term Pregnancies

Abstract

We have investigated the significance of single sporadic deceleration during reactive nonstress testing in normal pregnancies at term. A prospective study was performed during a 1-year period including 4742 nonstress tests performed between the 38th and 42nd weeks of pregnancy in patients referred to our department for antepartum testing and without any complication or pathology. Nonstress test (NST) was carried out with the patient lying on her left side, and was defined as reactive if at least two accelerations of 15 beats/min (bpm) or more lasting 15 sec were observed in a 20-min period. Sporadic deceleration was defined as a decrease in the fetal heart rate to less than 90 bpm or a decrease of 40 bpm below the baseline, lasting at least 2 min. The sporadic deceleration was considered as single when only one appeared in the first 20 min of monitoring and repeated when observed again once in at least one subsequent monitoring. Thirty-four cases of single sporadic deceleration were observed among women with reactive NST. In 14 cases there were repeated sporadic decelerations. The patients were divided into two groups according to the presence or absence of repeated decelerations. Outcomes of patients with repeated sporadic decelerations were compared with a group of 34 patients where sporadic decelerations were not observed during the antepartum testing. A significantly higher percentage of pathological fetal heart rate traces during labor were observed in the group of repeated decelerations. In conclusion the presence of repeated sporadic decelerations during a reactive NST suggests that the cause of cord compromise is persistent and recurrent cord compression is possible. Therefore, in these cases an increased fetal risk could be expected.

Single sporadic deceleration during reactive nonstress test – clinical significance and risk for cesarean delivery

“…Most SSDs are most likely variable decelerations, that are caused by temporary cord compression [9].…”

“…Variable decelerations are common during fetal heart rate monitoring and may be seen in up to 50% of NSTs [8]. The evidence regarding the clinical signi cance of a single sporadic variable deceleration (SSD) during fetal heart rate tracing during reactive NST is scarce, and previous studies have yielded con icting results [8, [9][10][11][12][13][14][15]. Therefore, the optimal management of SSD during NST for a fetus without other signs of fetal compromise has not been established.…”

Sporadic fetal heart rate decelerations associated with electrocortical changes in fetal lambs

“…2 The incidence of non-reassuring fetal conditions during labor is significantly higher in these fetuses with sporadic decelerations when compared to the normal parturient population. 1,2 Moreover, major, sporadic FHR decelerations may also be associated with relatively trivial behavioral changes in physiologically normal human fetuses. 3 Additional studies in fetal humans 4-6 and sheep 7,8 have found that vibroacoustic stimulation can alter fetal behavioral states associated with benign FHR decelerations.…”

“…In human fetuses, the occurrence of a single sporadic deceleration at gestational ages of 32–42 weeks is not an alarming sign, providing the non‐stress test (NST) and/or contraction stress test (CST) are reassuring 1 . However, the presence of repeated sporadic decelerations during a reactive NST suggests that cord compromise is persistent and recurrent cord compression can occur 2 . The incidence of non‐reassuring fetal conditions during labor is significantly higher in these fetuses with sporadic decelerations when compared to the normal parturient population 1,2 .…”

“…However, the presence of repeated sporadic decelerations during a reactive NST suggests that cord compromise is persistent and recurrent cord compression can occur 2 . The incidence of non‐reassuring fetal conditions during labor is significantly higher in these fetuses with sporadic decelerations when compared to the normal parturient population 1,2 . Moreover, major, sporadic FHR decelerations may also be associated with relatively trivial behavioral changes in physiologically normal human fetuses 3 .…”