False negative oxytocin challenge test
Marcum, R.G.
American Journal of Obstetrics and Gynecology 127(8): 894
1977
ISSN/ISBN: 0002-9378 PMID: 851153 DOI: 10.1016/0002-9378(77)90133-8Document Number: 433272
Recently, the oxytocin challenge test (OCT) has gained increasing prominence in the management of high-risk pregnancies. 1 distinct advantage is its predictive value of intrauterine fetal well-being. Most authors agree that if a negative OCT is obtained the status of the fetus is relatively secure for 1 week. Even so, there have been reports of false negative OCTs. Dr. Freeman (Obstetrics and Gynecology 47: 8, 1976) reported 2 fetal deaths 6 and 7 days after negative OCTs, and Dr. Farahani (Obstetrics and Gynecology 47: 159, 1976) reported 1 fetal death 7 days following a negative OCT. In a Letter to the Editors (American Journal of Obstetrics and Gynecology 123: 106, 1975), Dr. Baskett related 2 additional fetal deaths in utero, preceded 6 1/2 days by negative OCTs. Dr. Klapholtz recorded the earliest fetal death occurring only 6 hours after a negative OCT (Journal of Reproductive Medicine 15: 169, 1975). Our experience of 255 negative OCTs in 140 high-risk patients favorably supports previous data. However, 1 exception has been noted. A primigravid patient with an uncomplicated pregnancy at 43 weeks' gestation by firm dates and third trimester ultrasound examination had initiation of monitoring by OCTs and triweekly estriol determinations. The 1st estriol level was low normal (12 mg/24 hours). An OCT that same evening was negative (data detailed in a figure). The cervix was considered unfavorable for induction of labor. A second 24-hour urinary collection for determination of estriol was begun. 13 hours after the OCT, fetal movement stopped and upon arrival at the hospital, 1 hour later, intrauterine death was confirmed. No fetal, placental, or cord abnormalities were identified after delivery of a normal female infant. (Cord entanglement was not present.) No signs of postmaturity were noted at postmortem examination. Squamous cells were present in the bronchi, and interstitial pulmonary hemorrhage was observed. (This case illustrates a negative OCT followed by fetal death within 14 hours. In contrast, most previously reported intrauterine deaths occurred near the end of the 1-week ''safe period.'') Despite this tragedy, the negative OCT remains as a remarkable indicator of fetal safety. However, it is still necessary to utilize all available aids and to explore new modes of detecting changes in intrauterine fetal status in the high-risk pregnancy.