Development of fetal organs and adaptation to extrauterine life

Under unsatisfactory environmental conditions, such as the mother's illness, placental insufficiency, PROM, etc., the fetus must make the transition to extrauterine life from an unfortunate intrauterine existence. The adaptation process of the fetus to extrauterine environment in these cases is extreme importance. In our present investigation, we studied the developmental pattern of the functions of each fetal organ and the specific aspects of fetal metabolism. Using the brush border technique, we clarified that the fetal absorptional function of intestine developed from the 24th week of gestation and reached adult level in 32nd gestational weeks. The fetal renal reabsorption function developed from the 30th week of gestation and reached adult level in 36 gestational weeks. The liver function (enzymatic activity, etc.) remained low during the entire fetal life and developed gradually after birth. Taurine plays an important metabolical role and has a specific transport system during fetal life. The coagulation of vitamin K-dependent factors and activity remained low level at 27-31st gestational week, reaching full term level after 30 days. The switching of HbF to HbA was delayed more significantly in premature infants than in full term infants, but this delay of switching is effectively corrected by the increase of 2.3 DPG in premature infants. Immune response remained immature even in the full term fetus, but the non-specific immune response (NK activity, LAK activity, etc.) developed in the early fetal period and showed characteristic activity. The steroids which originated from the fetal-placental unit related intimately to the continuity of pregnancy and fetal development.     

The influence of thermal environment on pulmonary hemodynamic acclimation to extrauterine life in normal full-term neonates

Objective: To assess chronological changes of pulmonary blood flow in response to ambient temperature load in normal full-term neonates. Methods: Group I (n=8) neonates were maintained at 25-26 degrees C for the first 24 h after birth, with Group II (n=7) at 32-33 degrees C. Left pulmonary artery flow volume (Vp) and ductus arteriosus diameter were measured at 2, 4, 6, 12, and 24 h using Doppler ultrasound. Core and peripheral temperatures, as a marker for cold stress, were also evaluated over the same time frame. Results: For Group I, Vp was steady for the first 6 h after birth before gradually decreasing. In contrast, Vp for Group II significantly decreased from 2-6 h, without later changes. At 6 h after birth in Group II, mean values of both Vp and ductus arteriosus diameter were significantly lower, whereas mean value of peripheral temperature was significantly higher than values in Group I (P<0.05). Conclusion: Pulmonary blood flow in neonates placed at neutral ambient temperature stabilizes earlier than that of neonates placed at room temperatures. Changes of peripheral flow in response to ambient temperature load may be associated with decreased pulmonary blood flow through a left-to-right ductal shunt.     

Spectral analysis of heart rate variability: an emerging tool for assessing stability during transition to extrauterine life

Transition from fetal to neonatal life is likely the most physiologically demanding time of life. Complex changes in major organ system functioning and reorganization of metabolic processes must occur rapidly to achieve postnatal homeostasis. Identifying the neonate with subtle signs of unsuccessful transition is a challenge to the perinatal health care provider. Alterations in fetal or neonatal heart rate and heart rate variability may serve as an indicator of the neural control influencing cardiac function and a sensitive indicator of compromised health. Evaluation of the neural control of the heart can be done noninvasively and provides a discriminating measure of the level of stress vulnerability the fetus or newborn may be experiencing. This article reviews the origins of physiological variability of the fetal and neonatal heart rate in the transition to extrauterine life. The technique of spectral analysis as a new tool for surveillance of the at-risk fetus and neonate is then introduced, and implications for clinical practice and future research avenues are discussed.     

Developmental characteristics of fetal arrhythmias during the period from intrauterine to early extrauterine life assessed using dual echocardiography

To evaluate the outcome of fetal arrhythmias, serial echocardiographic examinations were made on 29 fetuses between 18 and 41 weeks gestation, including 23 with premature contractions (PCs) and 6 with complete atrioventricular block (AVB). Of the cases of PCs 43.5% (10/23) disappeared spontaneously during the antenatal period. 39.1% (9/23) converted to a normal sinus rhythm in early neonatal life, while 17.4% (4/23) had complications of either atrial or ventricular tachycardia. All with AVB (6/6) remained, regardless of advance in gestational age and continued through to the postnatal period. PCs and AVB indicate functional error and an impairment during development of the conduction system, respectively.     

Ruptured extrauterine pregnancy

Extrauterine pregnancies contribute substantially to maternal mortality in all parts of the world. The most common cause of these deaths is massive bleeding after rupture of the ectopic pregnancy. The advent of transvaginal ultrasonography in early pregnancy and the use of quantitative measurement of the β-unit of human chorionic gonadotropin have revolutionized the management of this condition. These diagnostic modalities allow its early detection and, in many cases, treatment before rupture occurs. There is an ever increasing body of evidence supporting expectant, medical, and surgical management of ectopic pregnancy according to certain criteria. The indications and criteria for the different management options are described in the literature and in clear guidelines from institutions such as the Royal College of Obstetricians and Gynaecologists. Methotrexate, in a single dose protocol, is widely used in the medical management of ectopic pregnancy. Surgical therapy can be either laparoscopic or via laparotomy. Be that as it may, ruptured ectopic pregnancy will continue to present as a gynecologic emergency requiring prompt and appropriate care. Resuscitation of these patients should be an organized, systematic, and rapid process with the ultimate goal of getting them to the operating theatre in the best possible hemodynamic status. The aim of surgery should be to stop active bleeding by the most expedient method. The use of autotransfusion is well established in cardiac surgery, vascular surgery, orthopedic surgery, and trauma. Using autologous blood should be considered also in the treatment of ruptured extrauterine pregnancy when faced with massive bleeding and a need for transfusion. Advanced abdominal pregnancy is a rare condition with high perinatal and maternal morbidity and mortality. Placental management at delivery remains a dilemma. The risk of massive bleeding upon removal must be balanced against the risk of infection and other complications during the long time needed for resorption of the placenta if left in situ. Despite a reduction in maternal mortality due to ectopic pregnancy in the developed world during the preceding period, it would appear that no further inroads have been made in the last two decades. In developing countries, the problem is far greater, and problems with resources and infrastructure persist. It remains a challenge to all practitioners caring for women to apply available resources and use the published evidence-based guidelines to manage these women effectively and safely.     

Diagnosis of extrauterine pregnancy

In pregnancies, the incidence of ectopic pregnancy varies from 1.2% to 1.4%. Diagnostic management of ectopic pregnancy is made by biochemical and ultrasonographic analysis. The evaluation of symptoms and anamnesis improves both comprehension and evaluation of technical data. This review analyzed the risk factors most commonly reported in women with ectopic pregnancy. According to the literature, the improvement of biochemical knowledge has determined the study of many substances: beta hCG, specific glycoproteins beta 1, creatine kinase, renine, progesterone. Transvaginal ultrasound examination presents different specificity and sensitivity. When ultrasonic imagining is not clear, it is useful to study uterine and adnexal vascularization by color Doppler and pulsed Doppler. The majority of authors consider laparoscopy as a gold standard for diagnosing an ectopic pregnancy. The endoscopic approach has multiple advantages: it could be in the same time diagnostic and therapeutic. The curettage of uterine cavity has been proposed as a diagnostic tool for analyzing by frozen section the presence or not of chorial villi. In personal opinion, an easy and simple diagnostic management should involve the clinical, biochemical and ultrasonographic procedures. Laparoscopy should be the last step in order to confirm a diagnosis and to establish the best therapeutical approach.     

Epidemiology of extrauterine pregnancy

An epidemiological study of ectopic pregnancy shows an increased frequency, a diminution of mortality by ectopic pregnancy. This review of the literature points out the influence of several factors implicated in the increased incidence of ectopic pregnancy: pelvis inflammatory disease (PID), intrauterine device and other contraceptive methods tubal ligation, induced abortions, tubal microsurgery, proximal tubal disease, ovulation induction and in vitro fertilization, diethylstilboestrol (DES) syndrome.     

Simultaneous intrauterine and extrauterine pregnancies

The frequency of such combinations is currently equal or inferior to one for 10,000 pregnancies. The use of ovulation-inducers as well as the increased frequency of ectopic pregnancies are, for a large part, responsible for this increased frequency. Five of the six cases that we did observe in seven years follow a clomiphen citrate-induced ovulation. The clinical diagnosis remains difficult. It is greatly facilitated by echography and laparoscopy. Adjusting the treatment of induction of ovulation in case of sterility should decrease the incidence of these pregnancies.