Maternal and fetal outcomes of spontaneous preterm premature rupture of membranes

The authors retrospectively evaluated maternal and fetal outcomes of 73 consecutive singleton pregnancies complicated by preterm premature rupture of amniotic membranes. When preterm labor occurred and fetuses were at a viable gestational age, pregnant patients were managed aggressively with tocolytic therapy, antenatal corticosteroid injections, and antenatal fetal testing. The mean gestational age at the onset of membrane rupture and delivery was 22.1 weeks and 23.8 weeks, respectively. The latency from membrane rupture to delivery ranged from 0 to 83 days with a mean of 8.6 days. Among the 73 pregnant patients, there were 22 (30.1%) stillbirths and 13 (17.8%) neonatal deaths, resulting in a perinatal death rate of 47.9%. The perinatal survival rate based on gestational age at the onset of fetal membrane rupture was 12.1% at less than 23 weeks of gestation, 60% at 23 weeks, and 100% at 24 to 26 weeks. Maternal morbidity was minimal with puerperal endomyometritis in 5 (6.8%) cases, one of which became septic; however, there was no long-term sequela. Eight (15.7%) liveborn infants had pulmonary hypoplasia, 5 (62.5%) of which resulted in neonatal death. In 33 (45.2%) patients, amniotic membranes ruptured before 23 weeks of gestation. At previable gestational age, the risk of neonatal pulmonary hypoplasia appears to be primarily dependent on gestational age at the onset of premature rupture of membrane rather than gestational age at delivery. Pregnancy outcomes remain dismal when the fetal membrane ruptures before 23 weeks of gestation.     

Anesthesia for fetal surgery

Fetal therapy is an exciting and growing field of medicine. Advances in prenatal imaging and continued innovations in surgical and anesthetic techniques have resulted in a wide range of fetal interventions including minimally invasive, open mid‐gestation, and ex‐utero intrapartum treatment procedures. The potential for maternal morbidity is significant and must be carefully weighed against claimed benefits to the fetus. Appropriate patient selection is critical, and a multidisciplinary team‐based approach is strongly recommended. The anesthetic management should focus on maintaining uteroplacental circulation, achieving profound uterine relaxation, optimizing surgical conditions, monitoring fetal hemodynamics, and minimizing maternal and fetal risk.     

Diagnosing appendicitis during pregnancy

In a 10 year period, 29 of 36 pregnant patients (81 percent) thought preoperatively to have appendicitis had the diagnosis confirmed at operation. Postoperative fetal complications included one intrauterine death and five premature births. There were no maternal deaths and morbidity was limited to atelectasis in five patients. Prompt surgical intervention in 90 percent of our patients did not prevent fetal complications.     

Uptake and distribution of bupivacaine in fetal lambs

Direct continual measurement of placental drug transfer was introduced to evaluate more precisely the fetal uptake of a commonly used local anesthetic in obstetrics. Bupivacaine, 2.7 mg X kg-1 (base), was infused at a constant rate over 1 h into a maternal jugular vein of five chronically prepared pregnant ewes. Blood was sampled simultaneously from the umbilical vein (UV), fetal aorta (FA), and a maternal artery (MA). Fetal uptake rate was determined from the product of the bupivacaine UV-FA blood concentration difference and the umbilical flow rate (Qu). Total fetal accumulation was determined by integrating uptake rate over 5 h. Correlation of total fetal uptake and the infused mean maternal dose (r = 0.993, P less than 0.001) indicated that during the infusion, mean fetal uptake was a constant fraction (0.16) of the maternal infused dose. Total fetal uptake was linear despite wide individual changes in Qu, suggesting that within limits fetal accumulation is not Qu-dependent. Mean ovine protein binding of bupivacaine by maternal and fetal whole blood was 85.49% +/- 2.61 (SD) and by fetal blood, 40.43% +/- 9.60 (SD). Back-transfer of bupivacaine to the mother proceeded against a higher total bupivacaine concentration because unbound unionized drug concentrations in maternal blood were less than in fetal blood. At maternal-fetal equilibrium when UV and FA total blood concentrations were equal, the calculated fetal/maternal concentration ratio (f/m) (0.36) determined from the maternal and fetal protein binding and pH closely approximated the observed (0.35). The f/m increased during both fetal uptake and back-transfer and cannot be considered a good index of placental transfer.(ABSTRACT TRUNCATED AT 250 WORDS)     

Histologic evaluation of fetal brains following maternal pneumoperitoneum

Background: The purpose of this study was to determine if maternal pneumoperitoneum with carbon dioxide (CO2) produces evidence of central nervous system (CNS) injury in preterm fetal guinea pigs. Methods: Thirty pregnant guinea pigs at gestational day (GD) 45 were assigned at random to one of three treatment groups: anesthesia only, CO2 pneumoperitoneum (5 mmHg), or laparotomy. Dams were killed 3 or 5 days postprocedure and fetal brains (83 total) harvested and fixed for subsequent histopathologic evaluation. For comparative purposes, histologic features of fetal guinea pig brain injury were defined from examination of fetal brains harvested from an additional dam that underwent laparotomy with 20 min of uterine arterial occlusion. Results: Carbon dioxide pneumoperitoneum did not increase maternal/fetal morbidity. No evidence of brain injury was found in fetuses from any of the treatment groups. Conclusion: Carbon dioxide pneumoperitoneum at 5 mmHg for 40 min in the pregnant guinea pig does not produce evidence of fetal brain injury.     

The effect of maternal hypothermic cardiopulmonary bypass on fetal lamb temperature, hemodynamics, oxygenation, and acid-base balance

OBJECTIVE: To evaluate fetal-maternal temperature relationship and fetal cardiovascular and metabolic response during maternal hypothermic cardiopulmonary bypass in pregnant ewes. METHODS: Cardiopulmonary bypass was instituted in 9 pregnant ewes, reaching 2 different levels of maternal hypothermia: 24 degrees C to 20 degrees C (deep hypothermia) in group A (5 cases) and less than 20 degrees C (very deep hypothermia) in group B (4 cases). Hypothermic levels were maintained for 20 minutes, then the rewarming phase was started. Fetal and maternal temperature, blood pressure, heart rate, electrocardiogram, blood gases, and acid-base balance were evaluated at different levels of hypothermia and during recovery. RESULTS: Fetal survival was related to maternal hypothermia: all group A fetuses survived, while 2 of 4 fetuses of group B in which maternal temperature was lowered below 18 degrees C died in a very deep acidotic and hypoxic status. Maternal temperature was always lower than fetal temperature during cooling; during rewarming the gradient was inverted. The start of cardiopulmonary bypass and cooling was associated with transient fetal tachycardia and hypertension; then, both fetal heart rate and blood pressure progressively decreased. The reduction of fetal heart rate was of 7 beats per minute for each degree of fetal cooling. Deep maternal hypothermia was associated with fetal alkalosis and reduction of Po(2). Very deep hypothermia, in particular below 18 degrees C, caused irreversible fetal acidosis and hypoxia. CONCLUSIONS: Deep maternal hypothermic cardiopulmonary bypass was associated with reversible modifications in fetal cardiovascular parameters, blood gases, and acid-base balance and therefore with fetal survival. On the contrary, fetuses did not survive to a very deep hypothermia below 18 degrees C.     

Percutaneous fetal access and uterine closure for fetoscopic surgery

Background: Maternal morbidity and preterm labor from fetal surgery might be minimized by a percutaneous technique for fetal access and uterine closure. Methods: In each of 16 ewes, we inserted three trocars percutaneously into the amniotic cavity using ultrasound and fetoscopic guidance. In six ewes, percutaneous uterine closure after the procedure was attempted. We assessed feasibility and acute complications of our technique during surgery and at autopsy. Results: We achieved percutaneous fetal access in 14 ewes and closed the uterus percutaneously in all six ewes attempted. Fetal injury was related to amnioinfusion or fixation of chorioamniotic membranes. Other complications were trocar dislodgment and damage to uterine wall and chorioamniotic membranes. The latter complication was prevented using balloon-tipped trocars. Conclusions: Percutaneous intraamniotic access and uterine closure for fetoscopic surgery can be achieved reliably with little maternal and fetal morbidity in sheep. Minor modifications are desired to apply this approach in humans. Received: 18 September 1996/Accepted: 12 December 1996     

Operative techniques in the fetal rabbit

The development of fetal surgical techniques has made the antenatal correction of congenital defects possible. These techniques have evolved from trials with animal models, permitting increasingly sophisticated operations with low morbidity and mortality. Experimental models range from large animals offering longer gestations but with single pregnancies and high cost, to smaller animals offering multiple pregnancies at reduced cost but with shorter gestations. This paper describes operative techniques in the fetal rabbit and its advantages as a fetal surgical model. Experience with the pregnant rabbit has shown it to be a suitable surgical model for several reasons. Pregnancies are multiple, increasing cost effectiveness and permitting operation on up to eight fetuses per litter without fetal loss. Techniques that promote fetal survival include local housing of does several days prior to operation and preoperative sedation. Spontaneous mask ventilation provides ease of anesthetic administration and titration. Overall surgery is well tolerated with a low incidence of intraoperative complications. Rabbit models have been used in the study of transamniotic fetal feeding, abdominal wall defects, and wound healing. These techniques have resulted in postoperative fetal viability approaching 90%, with negligible maternal mortality in over 4000 fetal operations, thereby making the rabbit a manageable cost-effective model of fetal surgery.     

Maternal and fetal plasma atrial natriuretic peptide concentrations during elective caesarean section

Atrial natriuretic peptide (ANP) is stored in the atrial cardiocyte and is capable of exerting potent, selective, and transient effects on fluid and electrolyte balance and on blood pressure. Because fluid shifts and hemodynamic adjustments occur during parturition, ANP might play a homeostatic role in the parturient and fetoplacental unit. We measured maternal and fetal plasma ANP concentrations in 19 parturients during elective caesarean section. Plasma ANP levels were also measured in seven nonpregnant women of the same age group. The baseline ANP concentration in parturients was significantly higher (29.77 +/- 6.06 pg/ml vs 7.37 +/- 2.1 pg/ml; mean +/- s.e.mean) than in their nonpregnant counterparts. The umbilical artery (UA) ANP concentration was significantly higher than the umbilical vein concentration (91.91 +/- 14.91 pg/ml vs. 40.04 +/- 9.71 pg/ml). Factors under the anaesthesiologist's control may influence maternal and fetal plasma ANP levels. There was a significant correlation between the volume of maternal Ringer's lactate infusion received and maternal ANP concentration. A significant correlation was seen between the total dose of ephedrine administered acutely prior to delivery and the UA ANP concentration. These data suggest that: 1) increased blood volume during pregnancy is associated with increased maternal plasma ANP levels, and 2) the fetus can produce its own ANP, and is thereby capable of responding to ANP stimulating factors.     

Adverse effects of maternally administered lidocaine on the asphyxiated preterm fetal lamb

Lidocaine was infused at a constant rate of 0.1 mg.kg-1.min-1 for 180 min into 12 chronically prepared pregnant sheep while asphyxia, induced by partial umbilical cord occlusion, was maintained in the premature fetus (80% of gestation). In five similar preparations saline instead of lidocaine was infused into the mother for 180 min. Maternal and fetal arterial blood pressure, heart rate, pHa, PaCO2, and PaO2 were monitored, and fetal cardiac output and the distribution of blood flow to fetal organs were measured, using labeled microspheres, before and after asphyxia and again after maternal infusion of lidocaine or saline. Maternal and fetal arterial blood and maternal urine were obtained at intervals for determination of lidocaine concentrations and urinary drug clearance. At the end of infusion, these animals were killed and tissues dissected for determination of lidocaine concentrations and organ blood flow. Maternal and fetal lidocaine plasma concentrations at steady state were 2.32 +/- 0.12 and 1.23 +/- 0.17 microgram/ml, respectively, similar to those seen during human epidural anesthesia. Asphyxia resulted in a significant drop in fetal heart rate and increased blood flow to the brain, heart, and adrenals. Asphyxia and saline did not produce additional deterioration of the fetus, but asphyxia and lidocaine led to a significant increase in PaCO2 and decreases in pHa, mean arterial pressure, and blood flows to the brain, heart, and adrenals. It is concluded that the immature fetus loses its cardiovascular adaptation to asphyxia when exposed to clinically acceptable plasma concentrations of lidocaine obtained transplacentally from the mother.     

Placental transfer of local anaesthetics in the premature sheep fetus

This study was designed to test whether there is any difference in the placental transfer of bupivacaine or lidocaine in the early compared to the late preterm maternal/fetal sheep preparation; and whether the premature lamb fetus reacts to a steady state local anaesthetic infusion differently from the same lamb near term. Eleven ewes were studied in two groups receiving bupivacaine (group A) or lidocaine (group B). Hysterotomy and insertion of fetal and maternal lines were performed at 110 days gestation, and studies were repeated weekly using the same local anaesthetic until delivery. We found no difference in maternal or fetal cardiovascular responses to bupivacaine or lidocaine in the early (mean 119 days) compared to the late (mean 132 days) preparations. The levels of bupivacaine and lidocaine in the fetal blood were similar in early and late fetuses, as were the fetal/maternal ratios of both drugs.     

Thermal injury in pregnancy--the neglected tragedy

Thermal injury sustained during pregnancy presents special management problems for the gravid woman and her unborn child. Because of the reported high morbidity and mortality and lack of available data in South Africa, a multicentre retrospective review was undertaken by five burn centres. Thirty-three patients (average age 25,7 years) with mean 30% (range 1-80%) total body surface area burn were assessed. A review of the clinical material led to the following observations and conclusions. Pregnancy does not influence maternal outcome after thermal injury and maternal survival is usually accompanied by fetal survival in the absence of significant maternal complications. Maternal survival is less likely if the burn wound exceeds 50% total body surface area. Thermal injury does increase the risk of spontaneous abortion and premature labour, and fetal survival depends on fetal maturity. Early obstetric intervention is only indicated in the gravely ill patient where complications (hypoxia, hypotension, sepsis) jeopardize the life of a viable fetus. The mode of delivery should be determined by obstetric considerations.     

Intrauterine fetal resuscitation

The delivery of oxygen to the fetus is dependent on adequate maternal blood oxygen concentration, uterine blood supply, placental transfer and fetal gas transport. Any disturbance in these factors, singly or in combination, can result in progressive fetal hypoxia and acidosis. The term fetal distress is non-specific but is usually applied to certain characteristic features on electronic fetal monitoring, confirmed if possible by fetal blood sampling. The aim of intrauterine fetal resuscitation (IUFR) measures is to increase oxygen delivery to the placenta and umbilical blood flow in an attempt to reverse fetal hypoxia and acidosis, so that labour may continue safely or to improve the fetal condition whilst arranging urgent delivery. IUFR measures include maternal re-positioning into left lateral (or alternatives, i.e. right lateral or knee-elbow if necessary), maternal oxygen administration at 15 litres/minute via non-rebreathing mask, rapid infusion of 1000 ml crystalloid (except in fluid restricted or pre-eclamptic patients), decreasing uterine contractions by stopping oxytocics and administering acute tocolytics (terbutaline 250 μg subcutaneously or intravenously (IV), glyceryl trinitrate 60–180 μg IV or sublingual spray, two puffs). A vasopressor (i.e. ephedrine) may be required in cases of maternal hypotension.     

Alterations in maternal-fetal cellular trafficking after fetal surgery

Background/PurposeBidirectional trafficking of cells between the mother and the fetus is routine in pregnancy and a component of maternal-fetal tolerance. Changes in fetal-to-maternal cellular trafficking have been reported in prenatal complications, but maternal-to-fetal trafficking has never been studied in the context of fetal intervention. We hypothesized that patients undergoing open fetal surgery would have altered maternal-fetal cellular trafficking.MethodsCellular trafficking was analyzed in patients with myelomeningocele (MMC) who underwent open fetal surgical repair (n = 5), patients with MMC who had routine postnatal repair (n = 6), and healthy control healthy patients (n = 9). As an additional control for the fetal operation, trafficking was also analyzed in patients who were delivered by an ex utero intrapartum treatment procedure (n = 6). Microchimerism in maternal and cord blood was determined using quantitative real-time polymerase chain reaction for nonshared alleles.ResultsMaternal-to-fetal trafficking was significantly increased in patients who underwent open fetal surgery for MMC compared with healthy controls, patients who underwent postnatal MMC repair, and patients who underwent ex utero intrapartum treatment. There were no differences in fetal-to-maternal cell trafficking among groups.ConclusionPatients undergoing open fetal surgery for MMC have elevated levels of maternal microchimerism. These results suggest altered trafficking and/or increased proliferation of maternal cells in fetal blood and may have important implications for preterm labor.     

Intrauterine fetal resuscitation

The delivery of oxygen to the fetus is dependent on adequate maternal blood oxygen concentration, uterine blood supply, placental transfer and fetal gas transport. Any disturbance in these factors, singly or in combination, can result in progressive fetal hypoxia and acidosis. The term fetal distress is non-specific but is usually applied to certain characteristic features on electronic fetal monitoring, confirmed if possible by fetal blood sampling. The aim of intrauterine fetal resuscitation (IUFR) measures is to increase oxygen delivery to the placenta and umbilical blood flow in an attempt to reverse fetal hypoxia and acidosis, so that labour may continue safely or to improve the fetal condition while arranging urgent delivery. IUFR measures include maternal re-positioning into left lateral or alternatives (i.e. right lateral or knee–elbow if necessary), rapid infusion of 1000 ml crystalloid (except in fluid-restricted or pre-eclamptic patients), decreasing uterine contractions by stopping oxytocics and administering acute tocolytics (terbutaline 250 μg SC or IV, glyceryl trinitrate 60–180 μg IV or sublingual spray, two puffs). A vasopressor (i.e. ephedrine) may be required in cases of maternal hypotension.     

胎兔皮肤伤口中糖胺多糖及透明质酸含量分析

目的探讨胎兔皮肤伤口无瘢痕愈合机理。方法 取胎兔,孕兔,成年兔切口及其周围组织,用阿利新蓝比色法,醋酸纤维素膜电脉分离法测定糖胺多糖（GAG）和透明质酸（HA）含量。结果 （1）胎兔正常皮肤（GAG及HA的含量均明显高于孕兔及成年兔（P＜0．01）,手术区,胎兔,孕兔,成年兔在术后3天时GAG及HA均升高（P＜0．05）。但术后第7天,胎兔GAG含量仍维持在高水平,而孕兔及成年兔其含量下降到接近正常水平,。结论 高浓度的HA在胎兔伤口间质的持续存在对胎兔伤口无瘢痕愈合起很重要的作用。     

Growth curves of the fetal prostate based on three-dimensional reconstructions: a correlation with gestational age and maternal testosterone levels

OBJECTIVE: To create a nomogram of the fetal growth of the human prostate corresponding to gestational age, and to investigate the relationship between the expansive growth of the fetal prostate and the maternal testosterone surge during pregnancy. MATERIALS AND METHODS: In all, 27 fetal prostates at 11-40 weeks of gestation, and seven neonatal specimens at 1-20 weeks after birth, were analysed. Serial sections of prostates were immunostained and examined using light microscopy. After modular image acquisition the volumes were calculated using three-dimensional reconstruction. The prostate volumes were correlated with gestational age, and related to reference testosterone levels during pregnancy. RESULTS: There was exponential growth of the fetal prostate with gestational age. The increasing volume of the prostate during the fetal period corresponded with maternal testosterone levels. In the second trimester there was a significant increase in prostate volume in relation to the bladder. In infants, macroscopically there was an inverse proportion between bladder size and prostate volume. CONCLUSIONS: Starting from the second trimester there is distinct growth of the fetal prostate, obviously triggered by the maternal testosterone surge. In neonates there is an inversion of the dimensions between bladder and prostate. These results indicating exponential growth of the fetal prostate provide evidence of a gender-related transient infravesical obstruction in human fetuses.     

Obstetric hemorrhage during an exit procedure for severe fetal airway obstruction

Purpose

To report a case of massive obstetric hemorrhage occurring during Cesarean delivery for an ex utero intrapartum treatment (EXIT) procedure. Methods to optimize the anesthetic, obstetric, and perinatal management are discussed.

Clinical features

A healthy parturient underwent an urgent EXIT procedure at 32 weeks gestation for a giant fetal neck mass. During the intraoperative period, severe intraoperative hemorrhage occurred from the site of the uterine incision. No evidence of placental bleeding, premature placental separation, or inadequate uterine relaxation was observed during the perioperative period. Placement of a uterine stapling device was unsuccessful in achieving adequate surgical hemostasis. Initial attempts with laryngoscopy and rigid bronchoscopy to secure the fetal airway on placental support were unsuccessful, and early termination of placental support was deemed necessary due to the severity of maternal blood loss. After full delivery of the neonate and termination of placental support, neonatal ventilation with bag-mask ventilation was achieved and successful endotracheal intubation occurred during repeat bronchoscopy.

Conclusions

The risk of obstetric hemorrhage due to uterine relaxation and inadequate surgical hemostasis in patients undergoing EXIT procedures is poorly reported. To reduce adverse maternal and neonatal outcomes, the premature termination of placental support during EXIT procedures may be required in the setting of severe obstetric hemorrhage.     

产妇血清、脐动、静脉及羊水中瘦素水平与胎儿生长发育关系

目的 :探讨瘦素水平与胎儿宫内生长发育的关系。方法 :采用放射免疫测定法 ,分别检测 65例孕 3 7～ 42周分娩产妇血清及脐动、静脉、羊水中的瘦素水平 ,同时测定产妇血脂水平。根据不同出生体重分为小于胎龄儿 ( SGA)组 ( n=1 0 )、适于胎龄儿 ( AGA)组 ( n=45)及超于胎龄儿 ( L GA)组 ( n=1 0 ) ,对结果进行相关性分析。结果 :( 1 )产妇血清瘦素水平与胎儿出生体重、胎盘重量、脐动、静脉及羊水中的瘦素水平均无明显相关性 ( P均 >0 .0 5) ;产妇的体重指数与胎儿出生体重、身长、脐动、静脉瘦素水平均呈显著正相关( P均 <0 .0 1 ) ;脐动静脉瘦素水平与胎盘重量、胎儿出生体重、身长均呈正相关 ( P均 <0 .0 1 ) ,与高密度脂蛋白呈负相关 ( P<0 .0 1 ) ;羊水瘦素水平与胎儿出生体重、胎盘重量、母体重及血脂水平均无相关性 ;产妇血清及脐动、静脉、羊水瘦素水平均与胎儿性别无相关性。 ( 2 )三组的脐动、静脉瘦素水平及胎盘重量 L GA组 ,高于 AGA及 SAG组 ( P均 <0 .0 5) ;AGA组又比 SAG组高 ( P<0 .0 5) ;三组的产妇血清及羊水瘦素水平无显著差异( P>0 .0 5) ;三组脐动、静脉瘦素水平均低于产妇血清瘦素水平 ( P<0 .0 5)。男、女婴的脐动、静脉、羊水及产妇血清瘦素水平无显著性差异。结论 :( 1 )胎儿的     

Pelvic fractures in pregnancy: factors influencing maternal and fetal outcomes

BACKGROUND: The purpose of this study was to determine factors influencing maternal and fetal outcomes associated with pelvic fractures in pregnancy. METHODS: A literature review of pelvic and acetabular fractures during pregnancy was performed, providing 101 cases for analysis (1 case report was included). Factors influencing maternal and fetal mortality were evaluated. RESULTS: Pelvic and acetabular fractures during pregnancy were associated with a high maternal (9%) and a higher fetal (35%) mortality rate. Automobile-pedestrian collisions had a trend toward a higher maternal mortality rate, and vehicular collisions had a trend toward a higher fetal mortality rate, compared with falls. Injury severity influenced both maternal and fetal outcomes. Fracture classification (simple vs. complex), fracture type (acetabular vs. pelvic), the trimester of pregnancy, and the era of literature reviewed did not influence mortality rates. When considering potential causes of fetal death, direct trauma to the uterus, placenta, or fetus was not associated with a higher fetal mortality rate, compared with maternal hemorrhage. Pelvic and acetabular fracture surgery has rarely been reported in this patient population. CONCLUSION: Pelvic and acetabular fractures in pregnancy continue to be associated with a high fetal mortality rate. Mechanism of injury and injury severity appeared to influence mortality rates, whereas the fracture classification, the fracture type, the trimester of pregnancy, and the era of literature reviewed did not.