Michael K. Yancey

The use of the polymerase chain reaction to detect bacteria in amniotic fluid in pregnancies complicated by preterm labor

OBJECTIVES The purpose of this investigation was to determine the feasibility of using the polymerase chain reaction to detect bacteria in amniotic fluid and to compare pregnancy outcomes in subsets of women categorized by amniotic fluid culture, polymerase chain reaction, and interleukin-6 findings. STUDY DESIGN Amniotic fluid from 54 pregnancies with preterm labor and no clinical evidence of intraamniotic infection was evaluated with use of the polymerase chain reaction, interleukin-6, and bacterial culture. Gestational age, newborn weight, and time between amniocentesis and delivery were compared between subsets of women categorized by these tests. RESULTS With use of the polymerase chain reaction <100 bacteria per milliliter could be detected in amniotic fluid. A total of 55.5% of the amniotic fluid samples were polymerase chain reaction positive, whereas 9.2% of culture results were positive. Birth weights and gestational age at delivery were less and time from amniocentesis to delivery was shorter in the polymerase chain reaction-positive group (p < 0.05). Nine samples (15%) had elevated interleukin-6 concentrations; of these, six were polymerase chain reaction positive. CONCLUSIONS The polymerase chain reaction is a sensitive means of detecting bacteria in amniotic fluid. These results provide further evidence of an association between preterm delivery and intraamniotic infection. Not all amniotic fluid samples with elevated interleukin-6 levels have bacteria detectable by the polymerase chain reaction. We anticipate that the polymerase chain reaction will provide another avenue for the detection of bacteria in amniotic fluid.

A critique of the new recommendations for weight gain in pregnancy

Recent Institute of Medicine recommendations for weight gain in pregnancy advocate a marked increase over prior guidelines, and for reasons that must be questioned. The objectives of these new guidelines are to reduce perinatal mortality, prematurity, and fetal growth retardation. Evidence of a causal relationship between less maternal weight gain and these adverse outcomes is lacking. In addition, the consequences of increased pregnancy weight gain have been incompletely assessed. The risk-to-benefit ratio may be prohibitive. The new recommendations, which will be considered by many to be clinical guidelines, fall short of the formulation criteria recommended by the United States Preventive Services Task Force.

Labor epidural analgesia and intrapartum maternal hyperthermia.

Abstract Objective: To determine if labor epidural analgesia (LEA) is associated with intrapartum hyperthermia. Materials and methods: Retrospective cohort analysis of nulliparous women with term gestations in spontaneous labor delivered during a 12-month period immediately before the availability of on-demand LEA (Before group) and a similar group of nulliparas delivered after LEA was available on request (After group). Primary outcome variables were maximal intrapartum temperatures of 99.5°F or higher or 100.4°F or higher. Logistic regression analysis was used to control for duration of labor and ruptured membranes and for the number of vaginal examinations. Results: The frequency of LEA use increased from 1.2% in the Before period to 83.6% in the After period. Using logistic regression, when compared with women in the Before period, women in the After period were more likely to have an intrapartum temperature of 99.5°F (RR 4.4, 95% CI 2/8. 6/9) or 100.4°F or higher (RR 19.2, 95% CI 5.7, 65.0). Conclusion: The use of LEA is associated with a clinically significant increase in the incidence of intrapartum hyperthermia. ∗ . Outcome Variable Before (N = 487) After (N = 391) RR (95% CI) Mean admission temperature 97.9 ± 0.8 97.8 ± 0.8 Mean maximum temperature 98.6 ± 0.7 99.0 ± 1.1 ∗ Temperature ≥ 99.5°F (%) 39 (8.0) 103 (26.0) ∗ 3.3 (2.3, 4.6) Temperature ≥ 100.4°F (%) 5 (1.0%) 41 (10.5) ∗ 10.3 (4.1, 25.9) ∗ P

Parvovirus B19 infections in pregnancy

Parvovirus B19 is the viral agent that causes the childhood exanthum erythema infectiosum, or fifth disease. Approximately 50% of pregnant women are seropositive for this agent and thus immune to primary infection. However, acute infection may develop in seronegative pregnant women exposed to B19. Acute B19 infections during pregnancy have been associated with miscarriage and hydrops fetalis. This latter condition is amenable to fetal therapy via intrauterine transfusion.

The effect of placental removal method on the incidence of postcesarean infections

OBJECTIVE Our purpose was to determine whether the incidence of postoperative endometritis and wound infection is associated with the method of placental removal at the time of cesarean section. STUDY DESIGN Parturients undergoing cesarean delivery were prospectively randomized to have the placenta removed manually or spontaneously. Patients were excluded from participation if they had received intrapartum prophylactic antibiotics or had been determined to have chorioamnionitis. After delivery of the infant women in the manual group had the placenta extracted by the primary surgeon, whereas women in the spontaneous group had the placenta delivered by gentle traction on the umbilical cord. All study subjects received perioperative prophylactic antibiotics. The primary outcome variable was a postcesarean infection, defined as postecsarean endometritis or wound cellulitis requiring drainage and antibiotic therapy. RESULTS A total of 333 women were enrolled in the investigation, with 165 assigned to the manual removal group and 168 allocated to have spontaneous removal. There were no statistically significant differences in mean gestational age, frequency or duration of ruptured membranes, frequency or duration of labor, or mean number of vaginal examinations between the two study groups. Postoperative infections occurred in 25 of 168 (15%) women in the spontaneous delivery group compared with 44 of 165 (27%) women in which the placenta was manually extracted (relative risk 0.6, 95% confidence interval 0.4 to 0.9, p = 0.01). Subset analysis of patients delivered with ruptured membranes similarly demonstrated a statistically significant reduction in the incidence of postoperative infections with spontaneous placental removal compared with manual extraction (20% vs. 38%, relative risk 0.5, 95% confidence interval 0.3 to 0.9, p = 0.02). There was a similar trend toward a reduction in postdelivery infections associated with spontaneous placental removal in women with intact membranes; however, this difference did not attain statistical significance. CONCLUSIONS Spontaneous delivery of the placenta after cesarean delivery is associated with a decrease in the incidence of postcesarean infections.

Observations on labor epidural analgesia and operative delivery rates

OBJECTIVE Our purpose was to compare operative vaginal and abdominal delivery rates in a large population before and after on-demand labor epidural analgesia became available. STUDY DESIGN We retrospectively compared patients who gave birth during a 20-month period immediately before the introduction of an on-demand labor epidural analgesia service with those who gave birth during a 20-month period after the epidural usage rate had reached a plateau at approximately 60%. Operative vaginal and cesarean delivery rates were stratified according to parity and history of prior cesarean delivery. RESULTS A total of 4859 women gave birth during the study period when on-demand epidural analgesia was available, and 4778 women gave birth in the study period before the availability of on-demand epidural analgesia. Comparisons between the women with and those without on-demand availability of epidural analgesia demonstrated no statistically significant differences in the rate of spontaneous vaginal delivery (69.5% vs 68.3%), the overall cesarean delivery rate (19.0% vs 19.4%), the primary cesarean delivery rate (13.2% vs 13.4%), or the operative vaginal delivery rate (11.1% vs 11.9%) between the 2 periods. There were no statistically significant differences in mean gestational age at the time of delivery between the 2 groups, whereas there were statistically significant increases in the proportion of nulliparous women and in mean birth weight during the on-demand epidural period. Analysis after substratification of the study groups according to parity also revealed no statistically significant differences in the primary cesarean delivery rate or the proportion of women undergoing vaginal delivery. The sample size was adequate to exclude a 2% increase in the primary cesarean delivery rate between the 2 periods with 80% power. Subgroup analysis of the population of women who gave birth while epidural analgesia was available on request demonstrated that nulliparous parturient women who requested epidural analgesia were almost twice as likely to require operative vaginal or cesarean delivery as women who did not request epidural analgesia, a finding suggesting that women who request labor epidural analgesia have an inherent propensity toward operative delivery. CONCLUSION The introduction of an on-demand labor epidural analgesia service does not increase the rate of cesarean delivery or operative vaginal delivery.

Risk factors for early cytologic abnormalities after loop electrosurgical excision procedure

OBJECTIVE To evaluate risk factors for early cytologic abnormalities and recurrent cervical dysplasia after loop electrosurgical excision procedure (LEEP). METHODS A retrospective analysis was performed of all pathology records for LEEPs performed at our institution from January 1996 through July 1998. Follow‐up cytology from 2 through 12 months after LEEP was reviewed. Patients with abnormal cytology were referred for further colposcopic evaluation. Statistical analysis using χ2 test for trend, proportional hazards model test, Fisher exact tests, and life table analysis were performed to identify risk factors for early cytologic abnormalities after LEEP and to determine relative risk of recurrent dysplasia. RESULTS A total of 298 women underwent LEEP during the study period, and 29% of these had cytologic abnormalities after LEEP. Grade of dysplasia, ectocervical marginal status, endocervical marginal status, and glandular involvement with dysplasia were not found to be independent risk factors for early cytologic abnormalities. However, when risk factors were analyzed cumulatively, the abnormal cytology rate increased from 24% with no risk factors to 67% with three risk factors present (P = .037). Of patients with abnormal cytology after LEEP, 40% developed subsequent dysplasia, and the mean time to diagnosis was approximately 6 months. The relative risk of subsequent dysplasia ranged from a 20% increase to twice the risk if post‐LEEP cytology was low‐grade squamous intra‐epithelial lesion or high‐grade squamous intraepithelial lesion, respectively. CONCLUSION Based on these results, consideration should be given for early colposcopic examination of patients who have evidence of marginal involvement or endocervical glandular involvement with dysplasia. These patients are at increased risk for abnormal cytology and recurrent dysplasia. This initial visit should occur at 6 months, as the mean time to recurrence of dysplasia was 6.5 months.

Comparison of probe sheaths for endovaginal sonography

Objective To compare the effectiveness of commercially available probe covers with less expensive condoms. Methods During a 10-month period, sonographers performed endovaginal ultrasound examinations on patients by randomly testing either commercially available probe covers or condoms on the vaginal probe. After use, the sheaths were tested for damage by filling them with water to observe for leakage and thereby determine the breakage rate. Results Perforations were noted in 15 of 180 probe covers and three of 180 condoms (8.3 versus 1.7%, P < .05; relative risk [RR] 5.4, 95% confidence interval [CI] 1.4-18.5). Potential contamination of the endovaginal probe occured during nine of 174 examinations and one of 178 examinations in which probe covers and condoms, respectively, were used (P < .05; RR 9.7, 95% CI 1.2–67.7). Conclusion Condoms are less expensive and superior to commercially available probe covers for covering the ultrasound probe during endovaginal examinations.

The frequency of glove contamination during cesarean delivery.

Objective: To determine the frequency of glove contamination associated with fetal extraction during cesarean delivery. Methods: The study was performed in 25 women having scheduled or unscheduled cesarean delivery. Surgeons double‐gloved for all procedures. Immediately before and after delivery of the fetus, the dorsal aspect of the fingers and hand of the surgeons outer glove was swabbed with cottontip applicators and cultured for aerobic and anaerobic organisms. Only the glove from the hand that was used to deliver the infant was cultured. Results: Nine of 25 cultures (36%, 95% confidence interval [CI] 17‐55) performed immediately before fetal extraction were positive for staphylococci. No other organisms were isolated. Cultures performed following fetal extraction showed non‐staphylococcal bacteria in 11 of 14 (79%, 95% CI 58‐100) laboring women and one of 11 (9%, 95% CI 0‐26) nonlaboring women, a statistically significant difference (P < .01). In the laboring patients, non‐staphylococcal bacteria were isolated with similar frequency from the dorsal aspect of the hand (seven of 14, 50%, 95% CI 24‐76) and the fingers (ten of 14, 71%, 95% CI 47‐95). These cultures yielded mostly bacterial species from the Enterobacteriaceae family. Conclusion: In laboring patients with ruptured membranes, delivery of the fetal head frequently results in contamination of the surgeons glove with pathogenic bacteria. This finding may partially explain the increased frequency of post‐cesarean endometritis associated with manual extraction of the placenta. (Obstet Gynecol 1994;83:538‐42)

Epidural analgesia and fetal head malposition at vaginal delivery

Objective To determine if nulliparas who delivered with on-demand epidural analgesia are more likely to have malpositioning of the fetal vertex at delivery than women delivered during a period of restricted epidural use. Methods A retrospective cohort of nulliparous women with spontaneous labor delivered during a 12-month period immediately before the availability of on-demand labor epidural analgesia was compared with a similar group of nulliparas delivered after labor epidural analgesia was available on request. The primary outcome variable was a non-occiput anterior position or malpositioned fetal head at vaginal delivery. Results The frequency of epidural use increased from 0.9% before epidural analgesia became available on demand to 82.9% afterward. Fetal head malpositioning at vaginal delivery occurred in 26 of 434 (6.0%) women delivered in the before period compared with 29 of 511 (5.7%) in the after period (relative risk 0.95, 95% confidence interval 0.6, 1.6). No statistically significant difference in the incidence of fetal head malpositioning was present after patients were stratified by mode of delivery (Mantel–Haenszel weighted relative risk 0.94, 95% confidence interval 0.6, 1.4). The study sample size provided 85% power to detect a two-fold increase in the incidence of fetal malpositioning from a baseline rate of 6% associated with on-demand epidural use. Conclusion Providing on-request labor epidural analgesia to nulliparas in spontaneous labor did not result in a clinically significant increase in the frequency of fetal head malpositioning at vaginal delivery.