Clinical value of intrapartum fetal pulse oximetry incases complicated with meconium-stained amnioticfluidTo the Editors: We read with interest the article byCarbonne et al. (Carbonne B, Langer B, Goffinet F,

Audibert F, Tardif D, Le Gouieff F, et al. Multicenterstudy on the clinical value of fetal pulse oximetry. Am JObstet Gynecol 1997;177:593-8), who observed a highnegative predictive value and specificity of both intra­partum fetal pulse oximetry and fetal blood analysis foran arterial umbilical pH $;7.15 and for an abnormal

neonatal outcome at a 7.20 threshold for fetal scalp pHand 30% for fetal oxygen saturation.

In our department we monitored 58 singleton, term

deliveries with fetal pulse oximetry, and a good correla­tion was found between simultaneous fetal oximetryreadings and scalp pH values obtained at 5 minutes be­fore birth as well as acid-base parameters of the umbilicalartery samples taken immediately after delivery (correla­tion between fetal oxygen saturation and scalp pH, r =0.62; umbilical artery pH, r = 0.68; umbilical artery oxy­gen saturation, r = 0.78; umbilical artery base excess, r =0.65, respectively).

To date, fetal scalp blood sampling is a widely ac­cepted direct method for intrapartum assessment of fetalacid-base status and is highly indicated if meconium­stained amniotic fluid is associated with abnormal fetal

heart rate patterns on cardiotocography! A growing bodyof evidence suggests that fetal oxygen saturation moni­toring may be an additional method for the evaluation offetal well-being during labor and might be of clinicalvalue in our decision making as to whether to performan immediate operative intervention or to avoid an un­necessary instrumental delivery-

In patients with meconium-stained amniotic fluidneonatal outcome was improved by intrapartum prophy­lactic amnioinfusion compared with standard obstetriccare.f

In our practice transcervical amnioinfusion was ap­plied in 18 cases of pregnancies complicated with thickmeconium and abnormal fetal heart rate tracings duringlabor. Fetal pulse oximetry was used as an adjunct to car­diotocography and fetal blood analysis, and in 14 cases inspite of a preacidotic scalp blood pH value obtained dur­ing the first stage of labor, a reassuring fetal oxygen satu­ration ~30% enabled us to prevent an unnecessary ce­sarean section. The neonatal outcome was uneventful.

In accordance with previous reports, our data suggestthat intrapartum fetal pulse oximetry could potentiallybe used as a new modality in combination with amnioin-

1100 May 1998

LETTERS TO THE EDITORS

fusion and routine monitoring techniques during laborto reduce instrumental deliveries and improve perinatal

outcome.Istvan SzabO, MD, PhD, Laszlo Halvax, MD, and Tibor

Kiss, MDDepartment,of Obstetrics and Gynecology, University Medical School ofPees, Pees, Edesanyak u 17.H-7624, Hungary

REFERENCES

1. Baker PN, Kilby MD, Murray H. An assessment of the use ofmeconium alone as an indication for fetal blood sampling.Obstet GynecoI1992;80:792-6.

2. Elchalal D, Weissman A, AbramovY, Abramov D, Weinstein D.Intrapartum fetal pulse oximetry: present and future. Int JGynaecol Obstet 1995;50:131-7.

3. Cialone PR, Sherer DM, Ryan RM, Sinkin RA, Abramowicz JS.Amnioinfusion during labor complicated by particulate meco­nium-stained amniotic fluid decreases neonatal morbidity. AmJObstet GynecoI1994;170:842-9.

6/8/89472

ReplyTo the Editors: We thank Szabo et al. for their interest inour article. Although this was not the main objective of

our study, we share their interest in fetal pulse oximetryin case of meconium-stained amniotic fluid. I, 2 Further

analysis of the data from the French multicenter studysuggests no influence of meconium on fetal oxygen satu­

ration readings obtained by pulse oximetry (SP02)' con­trary to the observations byJohnson et aJ.3We observedno significant difference in Spo2 in fetuses with clear am­niotic fluid (43.8% ± 9.1% at the end of first stage oflabor, n = 93) compared with fetuses with meconium(41.9% ± 8.7% at the end of the first stage, n = 57; differ­ence not significant). On the other hand, the rare fetuses(n = 3) in whom meconium aspiration syndrome devel­oped in this study had a significant drop in Sp02 duringlabor compared with others (44.7% ± 8.0% at inclusionand 27.0% ± 8.5% at the end of the first stage, p< 0.05).

In this latter group scalp blood pH and acid-base balanceat birth were in the normal range and not different fromthe other groups, suggesting that meconium aspirationsyndrome may occur in situations of acute hypoxia with­out fetal acidosis.

However, the benefits of the clinical use of pulseoximetry in this particular condition remain to be con­firmed prospectively. Although some complications ofmeconium-stained amniotic fluid such as meconium as­piration syndrome are paticularly severe, they are alsoparticularly rare, whereas many pathologic cases are nec­essary to properly assess the predictive value of a newmonitoring technique. Observing a good correlation be-

American Journal of Obstetrics and Gynecology