Umbilical waveform variations in the acutely distressed fetus: an experimental model in the fetal sheep.

In previous experimental studies on the pregnant ewe, umbilical arterial and venous waveform variations, produced by maternal aortic and umbilical cord occlusions of different degrees, were investigated in healthy fetuses (pH > 7.30). In our study, the fetal pH in 10 pregnant ewes was first brought down to below 7.20 with a preliminary series of maternal aortic and umbilical cord occlusions; then the 10 ewes were again submitted to a similar series of maternal aortic and umbilical cord occlusion. There were 24 experimental sessions with series of umbilical occlusions and 27 sessions with maternal aorta occlusions. The differences in waveform responses between these two types of fetuses are characteristic. The acidotic fetus produces more protracted drops in S, D, and venous velocity and, at the end of occlusion, the return to normal is slower with no reactive overflow waveform. In addition, there is a typical venous undulating pattern and no reappearance of blood flow velocity during the umbilical cord occlusion (always observed in healthy fetuses). Another important observation is that the fetal heart rate responses (bradycardia or tachycardia or no fetal heart rate variations) are more erratic in the acidotic fetus and do not relate to the intensity of the occlusion or to the fetal pH. The possible clinical implications of these experimental findings are discussed.

Vaginal birth after cesarean section: the patient's point of view.

Advocacy of vaginal birth after cesarean section (VBAC) is the current standard of care. We interviewed patients in our program about their attitudes toward VBAC and cesarean section. The success rate in our VBAC program is similar to rates reported in the literature (65 percent). However, interviews with our patients revealed that 40 percent had no desire to participate in the VBAC program, although they fulfilled the criteria for eligibility. The main reasons given for declining a trial of VBAC were the convenience of an elective cesarean section and fear of another prolonged, painful and potentially dangerous labor. Thirty-two percent of patients in whom VBAC was successful were dissatisfied with the experience and would have preferred an elective cesarean section. The reasons patients gave for attempting VBAC were different from the medical reasons proposed to them. The main reasons given were a desire to deliver "naturally," a fear of surgery and the concern that cesarean section might harm them or their baby.

Use of an indwelling Doppler probe to study acute changes in umbilical vein waveforms in the fetal sheep.

A chronic sheep model for Doppler umbilical vascular analysis with indwelling probes was used for the investigation of umbilical vein velocity waveforms. Maternal aortic occlusions produced a delayed drop but never eliminated umbilical vein velocity. With umbilical cord occlusion, there was immediate umbilical vein waveform response. Sudden cord occlusion and release showed reactive venous overflow velocity at the beginning and end of occlusion. Total cord occlusion produced zero velocity, but within seconds, the flow velocity was seen despite persistent occlusion in 65% of the cases. A characteristic undulating venous waveform pattern synchronous with fetal heart rate in over half of the cases was often observed. Reduction of blood flow by uteroplacental insufficiency may be differentiated from umbilical cord occlusion.

Intrauterine resuscitation in the severely distressed fetal dog.

Severe fetal distress was produced in 16 fetal dogs by successive and/or prolonged occlusion of the maternal abdominal aorta in an acute surgical preparation, and was characterized in fetal arterial blood of 7.06 for pH, 10 mm Hg for O2, 127 mm Hg for CO2, and fetal heart rate decelerations. Five fetuses recovered spontaneously in utero and delivered normally; 3 needed maternal oxygenation before delivery; 3 suddenly died in utero; 5 fetuses were delivered while still alive in utero when the tpH reached 6.85, and eventually expired. Intrauterine recovery and resuscitation was effective in some fetuses.

Pleural effusion in aneuploidy.

Three consecutive cases of isolated pleural effusion in aneuploid fetuses are reported. The presence of pleural effusion in trisomy 13 had not been described in the literature previously. Early development of pleural effusion is usually associated with fetal hydrops and carries a poor prognosis. Late development of pleural effusion can be treated in utero. A karyotype should be performed in all cases of pleural effusion prior to in utero pleuroamniotic shunting.

Amniotic fluid index: an appropriate predictor of perinatal outcome.

Qualitative amniotic fluid volume determination is a routine part of the fetal biophysical profile score. Quantitative amniotic fluid volume measurement, however, is not a factor in the determination of the standard biophysical profile score. This study is a retrospective analysis of antepartum assessment of amniotic fluid volumes and their relationship to neonatal outcomes. The amniotic fluid index was calculated for all patients examined and perinatal outcome was studied for all patients assessed. Patients with reduced or increased amniotic fluid volume had a significant increase in meconium-stained amniotic fluid, Apgar scores less than 7 at 1 and 5 minutes, major congenital anomalies, admission to the neonatal intensive care unit, and were more likely to require delivery by cesarean section for fetal distress. This study suggests that a quantitative ultrasound measurement of amniotic fluid volume represents an effective discriminatory test to be used in pregnancy evaluation.

The use of an indwelling Doppler probe to study acute changes in umbilical artery waveforms in the fetal sheep.

A chronic sheep model for Doppler umbilical vascular analysis was developed, in which indwelling Doppler probes were used. These were designed with a fixed angle of insonation and implanted directly on the umbilical cord to register umbilical artery velocity waveforms. The fetuses in eight pregnant ewes underwent maternal aortic and umbilical cord constrictions producing serial blood flow reductions. Occlusion of the umbilical cord and maternal aorta caused distinctly different waveforms. Cord occlusion produced an immediate response with an elevated systolic/diastolic ratio and disappearance of diastolic velocity. Maternal aortic occlusion produced a delayed response with drops in both systolic and diastolic velocity; diastolic velocity never reached zero. Although systolic/diastolic ratios are believed to reflect placental resistance, the maintenance of the systolic/diastolic ratio with diminution of systolic velocity suggests declining fetal cardiac output as an additional factor. It is possible to differentiate uteroplacental from umbilicoplacental insufficiency by Doppler methods. With technologic improvements Doppler ultrasonography may allow better analysis of acute stressful conditions during human labor.

Fetal heart rate and transcutaneous monitoring during experimentally induced hypoxia in the fetal dog.

A model of impaired oxygen delivery, using an acute surgical preparation in the fetal dog, is described. Fetal heart rate, transcutaneous pO2 and pCO2, and tissue pH were simultaneously recorded during hypoxic episodes produced by a series of successive occlusions of the maternal abdominal aorta. Corresponding values were also determined in the arterial blood of the fetus. The following pathophysiologic sequence of events was observed: 1) a latency period with no changes; 2) a drop in pO2 which stabilized later at a lower pressure; 3) late fetal heart rate deceleration, the pattern of which was not related to the progressively deteriorating fetal condition; 4) a progressive increase in pCO2; 5) a progressive decrease in pH. Abnormal tissue values consistently preceded and were more adversely affected than corresponding blood values. This experimental model demonstrates first that late decelerations of the fetal heart rate are an early sign of fetal hypoxia and second that a fall in fetal blood pH, beyond that level normally seen during labor, occurs relatively late in this pathophysiologic sequence. Between these two, there are intermediary stages that could be continuously monitored in order to identify worsening fetal condition. Continuous tissue pH and transcutaneous pO2 and pCO2 recording may potentially be of significant clinical value.

The use of a rapid in situ technique for third-trimester diagnosis of trisomy 18.

A rapid in situ coverslip technique was used to diagnose trisomy 18 within 1 week of amniocentesis in the third trimester. Two cases are presented. The clinical significance and advantages over umbilical vein aspiration are discussed.

Nonstress test and maternal position.

Antepartum evaluation of 225 low-risk primipara and 262 high-risk primipara and multipara using nonstress testing revealed 53 to be nonreactive when the test was performed in the supine position. When the test was repeated in the lateral decubitus position, it became reactive nonstress testing in 21 of these patients. This group of patients with a supine nonreactive nonstress test and a lateral reactive nonstress test demonstrated an associated compression of the abdominal aorta by the pregnant uterus in the supine, but not the lateral position. This study distinguishes three types of nonreactive nonstress tests: those due to placental insufficiency, those resulting from compression of the abdominal aorta by the pregnant uterus, and the falsely nonreactive. The percentage of false nonreactive nonstress tests results will be reduced by performing the test in the lateral decubitus position.

Arterial PO2, PCO2, and pH versus transcutaneous PO2 and PCO2 and tissue pH in the fetal dog.

In the fetal dog, simultaneous recording by transcutaneous PO2 and PCO2 and tissue pH electrodes were compared to corresponding arterial values during hypoxic episodes produced by occlusion of the maternal abdominal aorta. Before occlusion, the differences between the paired values were minimal. Under anoxic conditions, expected changes in the peripheral circulation were observed. However, the transcutaneous PO2 was lower, the transcutaneous PCO2 much higher, and the tissue pH much lower than in blood. Continuous electrodes demonstrate changes resulting from gas and hydrogen ion coming from cells more readily than blood because they are closer to the former. Additionally, carbon dioxide and hydrogen ion are buffered to a greater degree in blood than in cells. Consequently, under conditions of stress and active metabolism, PCO2 is higher while PO2 and pH are lower in cells than in blood. When compared with monitoring of gases and acid-base balance through blood sampling, continuous transcutaneous and intracutaneous monitoring would seem to be more representative of the environment at the cellular level.

Failure of ibuprofen in treatment of herpes genitalis.

Motrin (ibuprofen), a potent inhibitor of prostaglandin synthetase, was tested in women and men for treatment of recurrences of genital herpes. In a double-blind trial, no statistically significant differences were observed between treated and placebo groups in any of the measured parameters.

Intravenous gammaglobulin therapy in the management of a patient with idiopathic thrombocytopenic purpura and a warm autoimmune erythrocyte panagglutinin during pregnancy.

Intravenous gammaglobulin (IVIgG) was recently introduced for the treatment of idiopathic thrombocytopenic purpura (ITP). Reported is a previously splenectomized patient who had a severe exacerbation of her ITP during pregnancy and was managed with large doses of IVIgG throughout the second half of her pregnancy. She also had an autoimmune IgG erythrocyte panagglutinin on her red blood cells and in her serum, but only minimal evidence of hemolysis. There was little or no transplacental passage of her autoimmune antibodies since she delivered a normal fetus after 34 weeks of gestation who had a normal platelet count and no evidence of an antierythrocyte antibody. Interestingly, at the time of delivery the mother's serum IgG was dramatically elevated, but the cord serum IgG was normal for the length of gestation, indicating the presence of a dramatic and abnormal difference in IgG between maternal and fetal blood. This raises the possibility that the IVIgG therapy may have actually prevented transplacental passage of the pathological antibodies.

Use of male and female professional patient teams in teaching physical examination of the genitalia.

The use of the gynecologic teaching associate, or professional patient, for teaching pelvic examination to medical students is well established in the United States. The genitorectal examination of the man, however, has received scant attention. Most U.S. medical schools continue to use either male medical students or real patients for this part of the physical diagnosis course. We offer a course that uses male and female professional patient teams. All the students rated the course highly. Male students appreciated the teaching of the examination on women more than did their female colleagues. Female students rated the male patients higher than the female patients in all the categories. The female students found the male patients to be more helpful in discussing their anxieties than did the male students. Examination of the female pelvis and the genitorectal examination of the male may be threatening to both student and patient. The use of male and female professional patient teams built confidence in the examination technique and alleviated student anxiety. The use of a professional patient was particularly appreciated by students of the opposite sex. In this era of gender equality in medical school and in society at large, equal attention to the genital examinations of both men and women is clearly mandated.

Lymphocyte subsets in women on low dose oral contraceptives.

Oral contraceptive users have been reported to have a higher incidence of viral, bacterial and fungal infections. This study was undertaken to try to elucidate some of the mechanisms responsible for this increased susceptibility to infection. Peripheral blood lymphocytes were labelled with murine monoclonal antibodies directed against T cells and the various lymphocyte subsets: helper cells, suppressor/cytotoxic cells, or natural killer cells. The lymphocytes were then analyzed on a Coulter Electronics Epics V fluorescent activated cell sorter (FACS). A total of 27 control and 33 oral contraceptive users were studied. In comparison to the control group, there was no significant difference between the two groups in percentage or absolute numbers of total T cells, helper cells, suppressor/cytotoxic cells or natural killer cells. This study suggests that the increase in herpes virus, C. trachomonas, candida, and other infections in women taking oral contraceptives is not related to alterations in the numbers of T lymphocyte subsets or in levels of NK cells.

Maternal and fetal cardiovascular effects of nicotine infusion in pregnant sheep.

The effects of nicotine on uterine and umbilical hemodynamics were studied in seven pregnant ewes equipped with electromagnetic flow probes around the main uterine and common umbilical arteries, and with polyvinyl catheters inserted into the fetal aorta and maternal femoral vessels. Maternal systemic infusions of 1.0 to 1.5 mg/min significantly decreased uterine blood flow by 42% (p less than 0.001) and 32% (p less than 0.05), respectively. However, nicotine infusion rates of 0.5 mg/min, resulting in mean peak maternal nicotine concentrations of 130 +/- 5.0 ng/ml (SE), a value substantially higher than that reported in smoking humans, did not significantly alter uterine or umbilical vascular hemodynamics. Furthermore, at this lower nicotine dose, no alterations were observed in maternal or fetal plasma norepinephrine and epinephrine. The findings suggest either a species difference between sheep and humans in the threshold of catecholamine release to nicotine exposure or the need for repetitive nicotine infusions throughout the day to stimulate the human smoking experience.

Corticosteroid suppression of estrogen-induced uterine blood flow in nonpregnant sheep.

Estrogenic stimulation of uterine hyperemia and water imbibition are well-described endocrine events. Uterine blood flow responses to estrogen appear to have a similar mechanism of action. Although corticosteroids inhibit the uterine hyperemic and water imbibition effects, their influence on estrogen-induced uterine blood flow has not been clarified. Accordingly, the effects of hydrocortisone on estrogen-induced uterine blood flow were studied in seven nonpregnant castrate ewes equipped with electromagnetic flow probes around the main uterine arteries and with polyvinyl catheters inserted into postbifurcational branches of the uterine arteries. Inferior vena cava infusions of hydrocortisone, 0.50 to 9.25 mg/kg of body weight, administered 1 hour before estrogenic stimulation suppressed uterine blood flow increases by 10% to 35%. Direct uterine intra-arterial infusions of hydrocortisone also inhibited estrogen-induced uterine blood flow at calculated concentrations as low as 5.65 microM in uterine arterial blood. These findings support the conclusion that estrogen-induced uterine blood flow and water imbibition are correlative events and further serve to elucidate the mechanisms by which steroid hormones interact to modify uterine blood flow.