Lawrence Oppenheimer

The relationship between cervical dilatation at initial presentation in labour and subsequent intervention

Objective To examine the relationship between the cervical dilatation at which women present in labour and the subsequent likelihood of caesarean section.

Association of caesarean delivery for first birth with placenta praevia and placental abruption in second pregnancy

Objective  To quantify the risk of placenta praevia and placental abruption in singleton, second pregnancies after a caesarean delivery of the first pregnancy.

Adverse events detected by clinical surveillance on an obstetric service.

OBJECTIVE: Adverse events are adverse patient outcomes resulting from medical care. We performed this study to estimate the rate of adverse events and potential adverse events—errors that have a high likelihood of causing patient harm—occurring during obstetric care. METHODS: This was a prospective cohort study of an obstetric unit in a teaching hospital. We included patients admitted consecutively to the hospital. A trained observer monitored patients for 72 triggers, which were predefined occurrences deemed likely to indicate an actual or potential adverse event. When a trigger occurred, the observer captured information describing it. A five-person multidisciplinary team, including the observer, three physicians, and a hospital risk manager, judged whether the trigger represented an adverse event or potential adverse event. Adverse events were further characterized as preventable. RESULTS: The cohort included 425 patients; 47% were in active labor. We identified 110 triggers. Nine were considered adverse events (risk 2%, 95% confidence interval [CI] 1–4%, rate 0.8 events per 100 patient days), and six were preventable (risk 1%, 95% CI 0–3%, rate 0.5 events per 100 patient days). The remaining triggers included 14 potential adverse events (risk 3%, 95% CI 2–5%, rate 1.3 events per 100 patient days). No adverse event resulted in permanent disability or death. Adverse events and potential adverse events were most commonly “system” problems, such as unavailable staff or operating rooms, or poor fetal outcomes, such as trauma to the newborn. CONCLUSION: Serious adverse events occur infrequently on an obstetric service. However, important quality problems are common and should be targeted for improvement. LEVEL OF EVIDENCE: II-2

What is a low-lying placenta?

Transvaginal ultrasonography was performed in 127 women thought to have placenta previa. In all cases of complete previa, placental location was confirmed at cesarean section. Where the placenta was situated in the lower segment of the uterus but did not cover the cervical os the distance from the placental edge to the internal cervical os was measured. This distance was analyzed in relation to the route of delivery. No patient with a placental edge greater than 2 cm from the internal cervical os required cesarean section for the indication of placenta previa, whereas seven of eight patients with a distance of less than or equal to 2 cm underwent cesarean section because of bleeding characteristic of a placenta previa. These preliminary results suggest that transvaginal ultrasonography measurement may indicate the optimal delivery route and make the traditional classification of placenta previa obsolete.

Occurrence and predictors of cesarean delivery for the second twin after vaginal delivery of the first twin.

OBJECTIVE: To estimate the occurrence and to assess clinical predictors of emergent cesarean delivery in the second twin after vaginal delivery of the first twin. METHODS: We conducted a population-based cohort study, using the 1995–1997 linked mother/infant twin data from the United States. The adjusted risk ratios and population attributable risks of clinical predictors of emergent cesarean delivery in second twins were estimated for the overall study sample and for those born at less than 36 or 36 weeks or more of gestation. RESULTS: Among the 61,845 second twin births with the first twin delivered vaginally, 5,842 (9.45%) were delivered by cesarean. The cesarean delivery rate was increased in infants born to mothers with medical or labor and delivery complications. Breech and other malpresentations were the most important predictors of emergent cesarean delivery for the second twin (population attributable risk 33.2%; 95% confidence interval 31.8%, 34.6%). Operative vaginal delivery of the first twin was associated with a decreased risk of cesarean delivery for the second twin. Prediction of emergent cesarean for the second twin by clinical factors was stronger in term births than preterm births. CONCLUSION: In the general population, the cesarean delivery rate for the second twin after vaginal delivery of the first twin is approximately 9.5%. With the presence of breech and other malpresentations, the need for emergent cesarean delivery of the second twin after vaginal delivery of the first twin is increased by 4-fold. LEVEL OF EVIDENCE: II-2

7 Power spectral analysis of fetal heart rate

Summary This chapter examines the role of power spectral analysis (PSA) in elucidation of the physiological control mechanisms of fetal heart rate and as a potential indicator of fetal well-being. The importance of fetal heart rate variability (FHRV) as an indicator of fetal oxygenation is discussed, and the limitations in the current methods of measurement of FHRV are highlighted. Evidence is presented for the paramount influence of the autonomic nervous system in the control of heart rate variability. The basic proposition underlying spectral analysis is that the two autonomic branches influence heart rate in a frequency-dependent way, and their differential effects can be determined by PSA which breaks down the heart rate trace into its component frequencies. The application of PSA to heart rate variability data is an established tool in cardiology, and the published literature related to its use in the adult, neonate and fetus is reviewed. The power spectrum is sensitive to the activity state of the fetus, particularly fetal breathing movements, which have a variable effect on short- and long-term FHRV. There are a variety of mathematical approaches to the construction of power spectra, and a particular method of data acquisition and analysis is presented together with some theoretical background. Recent experimental evidence indicates a role for PSA as an indicator of fetal activity state, and the effect of hypoxia on the spectrum of the fetus in labour is discussed. There are some problems with the technique of PSA, particularly in regard to accepted definitions and methods of analysis. It is a powerful non-invasive tool in the elucidation of fetal cardiac control, but its value in the detection of the compromised fetus has yet to be tested in a clinical trial.

INFLUENCE OF AN EDUCATIONAL PROGRAM ON MEDICAL STUDENTS' ATTITUDES TO SUBSTANCE USE DISORDERS IN PREGNANCY

Substance use disorders (SUDs) in pregnancy are becoming increasingly prevalent. Our study aimed to measure the effect of a teaching module on alcohol, tobacco, and drug use on the attitude of second year medical students toward pregnant women with SUDs. A questionnaire was administered to 84 medical students before a 5-week systems block on human reproduction, which included specific learning events related to SUDs. The questionnaire was readministered at the completion of the block. Pre- and postintervention scores were compared. Students showed significant improvement (p <. 05, reliability coefficient 0.90) in their level of comfort in dealing with women with SUD in pregnancy. Other positive trends relating to attitudes toward drug- and alcohol-dependent women during pregnancy were also identified. SUD teaching interventions among medical students can improve their comfort level and attitude toward pregnant women with SUDs. This supports the current initiative of Project CREATE (Curriculum Renewal and Evaluation of Addiction Training and Education) to implement a comprehensive undergraduate SUD teaching program in Canadian medical schools.

Comparison of maternal risk factors between placental abruption and placenta previa.

The purpose of this study was to compare risk factors between placental abruption and placenta previa among primiparous and multiparous singleton pregnancies. We analyzed data from a population-based retrospective cohort with singleton pregnancies in the United States for 1995 to 2000. Maternal risk factors for placenta previa and placental abruption were examined using multiple logistic regressions. A total of 5,630,854 primiparous and 11,026,768 multiparous singleton pregnancies were available for final analyses after excluding subjects with missing information on outcomes or important exposures. Placental abruption was recorded in 4.8 per 1000 primiparous singleton births and 5.9 per 1000 multiparous singleton pregnancies. The occurrence of placenta previa was 1.9 per 1000 primiparous singleton pregnancies and 3.9 per 1000 multiparous singleton pregnancies. The effects of maternal age, race, parity, and previous cesarean section were stronger on placenta previa than on placental abruption, and the effects of cigarette smoking, alcohol drinking, and prenatal care were stronger on placental abruption than on placenta previa. A composite outcome of selected medical and pregnancy complications was related with placental abruption but not with placental previa. Placental abruption is more likely to be affected by conditions occurring during pregnancy, and placenta previa is more likely to be affected by conditions existing prior to pregnancy.

A Multidisciplinary Checklist for Management of Suspected Placenta Accreta

Rates of abnormally invasive placentation have been escalating. The condition requires meticulous planning to ensure safety at delivery. Although placenta accreta remains the most common reason for Caesarean hysterectomy in developed nations, medical and surgical therapies have allowed fertility preservation. Most planning strategies start with risk factor assessment and diagnostic imaging. Early planning of arrangements for antepartum and intrapartum management is preferable to late planning, when emergency situations are more likely to occur. Based on maternal and fetal morbidities, and published evidence of factors that may diminish these risks, we have developed a checklist to aid the antepartum and intrapartum management of potentially challenging cases of invasive placentation or to aid in considering tertiary care consultation and transfer. The proposed checklist may best benefit physicians working in primary and secondary levels of care in Canada. Ideally, this checklist would be available in electronic form, with alerts as needed; a copy of the checklist should be kept in the patients medical chart, with periodic updates.

Delayed clamping of the umbilical cord after delivery and implications for public cord blood banking

Public banking of umbilical cord blood units (CBUs) containing higher numbers of cells ensures timely engraftment after transplantation for increasing numbers of patients. Delayed clamping of the umbilical cord after birth may benefit some infants by preventing iron deficiency. Implications of delayed cord clamping for public cord blood banking remains unclear.