The use of oxytocin.

Synthetic oxytocin offers a safe and effective means of producing regular uterine activity and has a fairly large therapeutic index; however, the mild antidiuretic and vasoactive properties of oxytocin increase the risk of water intoxication and hypotension. The issue of reduction in cesarean section rates through the use of an active management protocol is being studied actively in the United States and Canada at this time. The authors recommend infusion protocols for the augmentation and induction of labor that use low doses of dilute oxytocin, increased at intervals no more than 40 minutes. Pharmacokinetic and clinical studies support the use of oxytocin in the physiologic range as efficacious and prudent. The longer induction to delivery time demonstrated by some, but not all authors, in our opinion, is a reasonable alternative to avoidable uterine hyperstimulation with the potential for fetal and maternal injury. We advocate the use of the lowest dose necessary to produce adequate uterine contractility and cervical change.

Oxytocin to induce labor.

Oxytocin is a highly successful and safe agent for inducing labor and has a fairly large therapeutic index. It has, however, minimal, but not trivial, antidiuretic and vascular activity when used in large doses. Therefore, to induce labor, low-dose oxytocin dosing regimens that produce efficacious uterine activity and avoid side effects are recommended. Oxytocin should be used in the lowest possible doses necessary to effect a clinical response. Diligence must be exercised when monitoring labor and fetal well-being. Hofbauer, the first to use oxytocin to induce labor, said in 1927 that oxytocin, "with its power of producing regular, rhythmical and forcible uterine contractions, should be regarded as a most beneficent and valuable agent, which, however, should always be employed with care and a realisation of its limitations and dangers." His words remain valid today.

Use of the fetal chest in estimating fetal weight.

OBJECTIVE: This study was designed to develop formulas using the chest circumference instead of the abdominal circumference for estimating fetal weight. STUDY DESIGN: Ultrasonographic measurements of the chest circumference, biparietal diameter, abdominal circumference, humeral length, and femoral length were obtained in 75 term fetuses of uncomplicated pregnancies within 24 hours of delivery. Three equations for fetal weight estimation that used the chest circumference, instead of the abdominal circumference, in combination with the biparietal diameter or the humeral length were developed by regression analysis. RESULTS: The average mean errors of fetal weight estimation for these equations vary from 7.1% to 7.6%. CONCLUSIONS: These equations may be used in predicting the birth weight when the fetal abdomen is altered by certain fetal abnormalities.

Laparoscopic cholecystectomy during pregnancy.

There is a strong association between pregnancy and gallstones. When acute cholecystitis or recurring bouts of biliary colic occur during pregnancy, medical therapy is usually initiated but occasionally fails. Laparoscopic cholecystectomy has recently been described for the treatment of symptomatic cholelithiasis, but many authors consider pregnancy to be an absolute contraindication to this operation. We herein describe the management of markedly symptomatic cholelithiasis during the second trimester of pregnancy using laparoscopic techniques in five patients. Tocolytic medications were administered perioperatively in two patients, and open laparoscopy or the use of an alternative site for insertion of the initial port was used in all patients. Laparoscopic cholecystectomy without cholangiograms was successful in all five patients and postoperative hospitalization ranged from 24 to 48 h. Uncomplicated term delivery has occurred in three of the five patients; in the other two patients, normal pregnancies are continuing. Laparoscopic cholecystectomy can be performed safely during pregnancy, as long as the patient is monitored carefully and specific precautions are observed.

Noninvasive fetal ECG mode fetal heart rate monitoring by adaptive digital filtering.

Beat-to-beat variability (BTBV) of the fetal heart rate (FHR) is considered an indication of the neural integrity and is an important prognostic indicator of fetal well-being. We report the initial evaluation of a recently developed abdominal fetal ECG (AFECG) mode of FHR monitoring using Adaptive Digital Filtering (ADF) to accurately obtain BTBV noninvasively. Five women in labor at term were monitored with the direct fetal scalp electrode (FSE) and simultaneously with the AFECG using ADF. A computer analysis of 3298 seconds (55 minutes) of data provided a one-to-one comparison of the R-R intervals. One analysis of the direct FSE data with a second simultaneous analysis from the same electrode, to serve as control, was compared with the noninvasive AFECG data. The study group has a standard deviation of only 1.50 bpm compared to 0.79 bpm for the control group. The AFECG method agrees with the direct FSE method within 1 bpm for 92.6% of the reported R-R intervals and within 2 bpm for 98.9% of the reported intervals. This new noninvasive AFECG technique with ADF provides a continuous record of instantaneous FHR and BTBV that may be relied upon to provide an accurate continuous clinical record. The reliability of the technique has yet to be determined over a wide range of subjects.

Magnesium tocolysis and neonatal bone abnormalities: a controlled study.

This study was conducted to investigate the relationship between maternal administration of intravenous (IV) magnesium sulfate and radiographic abnormality of neonatal long bones. Eleven neonates in the exposed group were born to mothers who had received IV magnesium tocolysis for more than 7 days. Two gestational age-matched unexposed neonates were selected for each member of the exposed group. Initial chest radiographs of exposed and unexposed neonates were reviewed in random sequence by a pediatric radiologist who was blinded to exposure status. On evaluation of the proximal humeri, six neonates had radiographic abnormalities consisting of transverse radiolucent and/or sclerotic bands; all six were in the exposed group. The difference in radiographic findings between the exposed and unexposed groups was statistically significant (P less than .001). These results support the existence of a causal relationship between prolonged IV magnesium tocolysis and abnormal fetal bone mineralization. Further study is needed to elucidate the mechanism and clinical significance of these bone changes.

Acute fatty liver of pregnancy associated with preeclampsia: management of hepatic failure with postpartum liver transplantation.

Acute fatty liver of pregnancy is a potentially fatal disorder. We report a patient complicated by preeclampsia, coagulopathy, encephalopathy, and hepatorenal syndrome successfully managed by postpartum hepatic transplantation.

A comparison of the effect of epidural, general, and no anesthesia on funic acid-base values by stage of labor and type of delivery.

The effect of epidural anesthesia on neonatal acid-base status, before, during, and after labor, was determined by review of funic blood-gas values from 142 women with normal term pregnancies and normal fetal heart rate patterns. Funic acid-base parameters were compared by type of anesthesia when stratified by mode of delivery (vaginal, cesarean section in the active phase of labor, or elective cesarean section). Use of epidural analgesia for vaginal delivery was associated with significantly longer labor, lower umbilical arterial pH, higher arterial PCO2 and arterial bicarbonate values. In women who had cesarean section in the active phase of labor, use of epidural anesthesia was associated with significantly lower arterial and venous PO2 values when compared with women who received general anesthesia. Patients who had elective cesarean section with epidural anesthesia had funic acid-base values similar to women who had general anesthesia. Epidural analgesia-anesthesia offers no clear advantage to the uncompromised term fetus.

A prospective comparison of hourly and quarter-hourly oxytocin dose increase intervals for the induction of labor at term.

Fifty-two women undergoing labor induction and vaginal delivery at term were randomized between two oxytocin infusion protocols, involving hourly versus quarter-hourly increases in dose. Potential differences were sought of duration of labor, amount of uterine activity generated, and amount of oxytocin required. Starting at 0.5 mU/minute, oxytocin infusion was increased regularly in small increments every hour or every 15 minutes, according to group assignment. No differences were observed in potentially confounding clinical and demographic factors between the groups, including time to ruptured membranes. There were no clinically or statistically significant differences found for the duration of any phase or stage of labor, quantitative assessment of uterine activity, incidence of hyperstimulation, or neonatal outcome. The average dose of oxytocin used was lower in the hourly than in the quarter-hourly, protocol (4.4 versus 6.7 mU/minute; P less than .005). Significantly fewer patients on the hourly protocol required a maximum infusion rate exceeding 8 mU/minute (P less than .05). More patients on the hourly protocol either had oxytocin discontinued completely or were maintained at 4 mU/minute or less during the active phase of labor (P less than .05 and P less than .001, respectively). We conclude that a slower rate of increase in oxytocin administration via continuous infusion results in no prolongation of any phase of induced labor, while permitting lower infusion rates of the drug.

Clinical use of the Kleihauer-Betke test.

Results of all Kleihauer-Betke (KB) tests performed in 1988, at a center with 4,201 deliveries, were reviewed. Two hundred and twenty-seven tests were performed on maternal specimens from 205 patients. Eighteen (8.8%) of the 205 patients had positive test results. Medical records were available for 147 (71.7%) of the patients, including 17 of the 18 patients with a positive result. Indications for testing were: vaginal bleeding (33%), maternal trauma (31%), unexplained fetal death (5%), Rh incompatibility (3%), fetal distress (3%), and miscellaneous (24%). Most of the tests were performed antepartum. In only one case, and without clear benefit, did the KB test prompt a clinical intervention. At least two of the 18 patients with positive test results had probable false positive results due to maternal hemoglobin F. Such false positive KB test results may be misleading. Further evaluation of the role of the KB test in obstetrical management is needed.

The intrapartum management of the breech presentation.

In many cases of breech presentation, a trial of labor is practical and safe among carefully selected parturients. Anesthesia and full neonatal support should be available. Described is the protocol in use at several large institutions that maintain a Cesarean rate for breech presentation in the 60 to 70 per cent range which is approximately 25 per cent lower than the national rate. The development of this protocol as well as its highlights in clinical application are described and highlighted in this report.

Prophylactic amnioinfusion during labor complicated by meconium: a preliminary report.

The purpose of this prospective and randomized study is to evaluate the safety and efficacy of prophylactic transcervical amnioinfusion in the management of labor complicated by meconium. A preexisting intrauterine pressure catheter was used for amnioinfusion. The incidence of thick meconium was significantly lower after amnioinfusion, compared with standard management (5% versus 62% p less than 0.0005). This was also demonstrated with spectrophotometry. Significant differences between the amnioinfusion group and the control group were found for the following: arterial cord pH less than 7.20 (16% versus 38%, p less than 0.05); meconium more than trace below the vocal cords at delivery (0% versus 29%, p less than 0.05) and need for positive pressure ventilation at birth (16% versus 48%, p less than 0.05). No complications related to amnioinfusion were observed. We conclude that (1) transcervical amnioinfusion during labor complicated by meconium is a simple and apparently safe procedure, and that (2) amnioinfusion effectively decreases the frequency of thick meconium, the frequency of neonatal acidemia, the frequency of more than trace meconium below the vocal cords, and the need for positive pressure ventilation.

Fetal vibro-acoustic stimulation: magnitude and duration of fetal heart rate accelerations as a marker of fetal health.

The relationship between intrapartum fetal acid-base status and fetal heart rate (FHR) response to vibro-acoustic stimulation was investigated in 100 patients. Fetal heart rate responses were classified into three groups: acceleration of 15 or more beats per minute lasting 15 or more seconds, acceleration of ten or more beats per minute lasting 10 seconds but less than 15 beats per minute and 15 seconds, or no acceleration. The mean fetal scalp blood pH was 7.29 in both groups with acceleratory responses, and such responses were highly predictive (98-100%) of scalp pH 7.20 or above. The mean pH value for the no-acceleration group (7.22) was significantly lower than the mean pH value for both groups with an acceleratory response (P less than .05), and the lack of response to the stimulus detected 90-100% of fetuses with a pH below 7.20. This sensitivity was reduced to 45% in the detection of fetuses with pH less than 7.25.

Oxytocin for the induction of labor.

The obstetric benefits and dangers of using oxytocin to promote uterine activity have long been appreciated. The induction of labor should be undertaken when the positive reasons for delivery outweigh the risks of allowing the pregnancy to continue. Over the years, recognition of the pharmacokinetics of oxytocin has led to modifications in how it is administered for the induction of labor. Most would agree that it should be used in the lowest possible dose that will provide a safe as well as efficacious process of labor for both patients: the woman and her fetus. The sensitivity of the uterus to oxytocin varies with gestational age and from individual to individual. Likewise, each fetus exhibits its own tolerance to the effects of this drug. Close surveillance of each patient's uterine activity response and labor curve and of her fetus's heart rate response is an essential part of the induction of labor.

An assessment of the first decade's experience with antepartum fetal heart rate testing.

The utility of antepartum fetal heart rate (APFHR) monitoring (nonstress test and the contraction stress test) was evaluated for a 10-year interval from 1974 through 1983. The number of high-risk patients evaluated increased from 2.9 to 25.1% of all deliveries. The decade's perinatal mortality rate differed from 22.4 per 1000 in the nontested population to 11.8 per 1000 in the tested population; the stillbirth rate differed from 11.1 per 1000 to 5.4 per 1000 uncorrected, 2.2 per 1000 corrected, and perinatal morbidity also differed from 26.1 per 1000 to 24.9 per 1000 (NS). Improvement statistics appear to plateau by the fourth year. An abnormal APFHR test was associated with a lethal congenital anomaly in 2.54% of patients (versus 0.5 to 1.5% in the general population). Evaluation for the presence of congenital anomalies appears to be indicated in the fetus with an abnormal APFHR test. A lower stillbirth rate occurred within 4 days of a normal APFHR test (0.027%) compared with a test interval of 5 to 7 days (0.11%). Thus, APFHR testing performed twice weekly may offer a better outcome for the fetus at risk than once weekly testing. This report confirms that the chief value of APFHR testing is its ability to identify the normal healthy fetus. These tests are somewhat less accurate at identification of the sick fetus. The nonstress test and contraction stress test were found to be of similar clinical predictive value.

Human fetal oxygenation (tcPo2), heart rate variability and uterine activity following maternal administration of meperidine.

Fetal tcPo2 levels were measured in 10 patients following maternal administration of 50 mg of meperidine by intravenous route. About 3 minutes following injection of meperidine, tcPo2 values started to decline to reach the lowest value of 37 +/- 25% by 7 mins of injection. tcPo2 values recovered by about 15 mins following injection. These changes in fetal tcPo2 levels preceded transient minimal increase in FHR variability. The increase in FHR variability was followed immediately by a decrease in the indices of the FHR variability. The uterine activity began to decline below the predicted positive slope values shortly following injection of meperidine. This decline was maximum 15 mins post-injection, subsequently establishing a trajectory toward the positive values expected for unmedicated labor. Two patients receiving 25 mg intravenous meperidine demonstrated no decline in tcPo2 levels; however, in the patient receiving 75 mg of intravenous meperidine, the changes noted were similar to those observed following 50 mg of meperidine.