Characterization of ovine utero-placental interface tensile failure.

Data on the strength of the utero-placental interface (UPI) would help improve understanding of the mechanisms of placental abruption (premature separation of the placenta from the uterus) during motor-vehicle crashes involving pregnant occupants. An ovine model was selected for study because like the human, its placenta has a villous attachment structure. Uteri with intact placentas were obtained from three sheep as by-products of another research study. The samples were harvested between 102 and 119 days of the 145-day gestational period. Rectangular specimens with areas measuring 15 mm × 5 mm were cut through the thickness of the placenta and uterus. Each subject provided eight samples, of which four were tested at a nominal strain rate of 0.10 strains/sec and the remainder was tested at a nominal strain rate of 1.0 strains/sec. Sutures were used to secure the uterine side of the specimens to the test fixture, while mechanical clamps were used to attach the placenta side. A FARO arm scanner recorded the initial geometry of the tissue, and a random dot pattern applied to the placenta and uterus tissue allowed visualization of displacement. For the structure of the UPI, mean tensile failure strain and standard deviations are 0.37 (0.11) and 0.37 (0.18) for the 0.10 and 1.0 strain rates, respectively (p-value = 0.970) while the associated failure stresses are 6.5 (1.37) and 15.0 (5.08) kPa, (p-value = 0.064). The results from sheep UPI testing provide the first estimate of the human UPI structural failure tolerance.

Frequency of antibiotic resistance among group B Streptococcus isolated from healthy college students.

We report resistant rates to erythromycin and clindamycin among Streptococcus agalactiae (group B Streptococcus) isolated from a random sample of healthy male and nonpregnant female college students. Observed resistance rates were twice as high as those reported among pregnant women from the same geographic area 2 years prior.

Maternal and transplacental pharmacokinetics of cefazolin.

OBJECTIVE: To evaluate the intrapartum pharmacokinetics of cefazolin, including delivery to amniotic fluid (AF) and fetal compartments, and to ascertain that adequate cefazolin concentrations are attained to exceed the mean concentration inhibiting 90% (MIC(90)) of group B streptococcus strains. METHODS: Cefazolin (1 g) was administered intravenously at five separate time intervals (0.5, 1, 2, 4, and 6 hours) before elective cesarean at term to 26 women with intact membranes and with no significant infections or cardiovascular, liver, or renal disease. Samples of maternal blood, cord blood, and AF were obtained at the time of delivery. Exact collection times relative to cefazolin infusion were noted. Amniotic fluid contaminated with blood or meconium was excluded. Cefazolin concentration was measured by high-pressure liquid chromatography. RESULTS: All maternal and cord plasma cefazolin levels, except one, were above the MIC(90) for Streptococcus agalactiae (group B streptococcus). For AF, all cefazolin levels, except two, were above the MIC(90). CONCLUSIONS: Cefazolin concentrations greater than or equal to the MIC(90) for group B streptococcus were attained in nearly all maternal, fetal, and AF samples. This information, together with the knowledge that there is rare resistance of group B streptococcus to cefazolin, supports the use of cefazolin as a better alternative than clindamycin or erythromycin for group B streptococcus prophylaxis in patients with a nonanaphylactic penicillin allergy.

Development and Testing of a Prototype Pregnant Abdomen for the Small-Female Hybrid III ATD.

A new prototype pregnant abdomen for the Hybrid III small-female ATD is being developed and has been evaluated in a series of component and whole-dummy tests. The new abdomen uses a fluid-filled silicone-rubber bladder to represent the human uterus at 30-weeks gestation, and incorporates anthropometry based on measurements of pregnant women in an automotive driving posture. The response of the new pregnant abdomen to rigid-bar, belt, and close-proximity airbag loading closely matches the human cadaver response, which is thought to be representative to the response of the pregnant abdomen. In the current prototype, known as MAMA-2B (Maternal Anthropomorphic Measurement Apparatus, version 2B), the risk of adverse fetal outcome is determined by measuring the peak anterior pressure within the fluid-filled bladder. Peak internal bladder pressures measured in a series of sled-test simulations of frontal crashes of different severities and occupant-restraint conditions have been correlated to the likelihood of adverse fetal outcome based on risk curves developed from in-depth investigations of real-world crashes involving pregnant occupants. Compared to the original pregnant abdomen, the new prototype has improved geometry and improved impact response to a range of potential in-vehicle loading conditions, However, additional instrumentation development and more rigorous testing are needed before the MAMA-2B can be confidently used to assess restraint system performance with regard to reducing the likelihood of adverse fetal outcome in motor-vehicle crashes.

Myometrial contractile strain at uteroplacental separation during parturition.

OBJECTIVE: A simplified geometric model of the uterine wall during the second and third stages of labor was created to estimate the magnitude of myometrial strain associated with the initiation of placental separation. STUDY DESIGN: The uterine wall was modeled as an isovolumetric, incompressible spherical shell whose overall radius decreased and mural thickness increased on uterine muscle contraction after delivery of the fetus. Either a 3.5-MHz or a 5-MHz ultrasonography probe was used to measure the change in uterine mural thickness of 14 healthy patients from just before delivery to the time of initial separation of the placenta. The measured change in uterine wall thickness was then used to calculate its average radial and circumferential strain with a simple mathematic model. RESULTS: Placental separation occurred at radial and circumferential strains (mean +/- SD) of 450% +/- 182% and -75% +/- 11%, respectively. These strains are consistent with the known maximal contractile strains achievable by smooth muscle. CONCLUSION: Placental separation is likely associated with maximal myometrial contractile strain. Before birth the presence of the fetal and amniotic fluid volumes usually renders such contractile strains unachievable, thereby helping to guard against premature placental separation.

A comprehensive program to improve safety for pregnant women and fetuses in motor vehicle crashes: a preliminary report.

OBJECTIVE: A program was developed to study the mechanisms of abruptio placentae and pregnancy loss caused by motor vehicle crashes. The results were intended to be used to develop strategies to improve protection of the fetus in this setting. STUDY DESIGN: Four integrated projects were conducted: (1) seated anthropometric measurements and belt fit determination during pregnancy, (2) development of new models of traumatic abruptio placentae, (3) investigations of crashes involving pregnant women, and (4) the development of the second-generation pregnant crash dummy from these data and others. RESULTS: Twenty-two different pregnant subjects in five different height groups underwent serial measurements of abdominal surface contours, seat belt fit, and distances between the subjects and various landmarks in the automobile interior with a laboratory-designed "automobile seat" (seating buck). The abdomen was significantly closer to the steering wheel in the shorter stature group than among the taller women. Beginning at approximately 20 weeks' gestation the fundus of the uterus was above the lower rim of the steering wheel. Lap belts fit properly over the anterior superior iliac spine throughout gestation, but the lap belt overlapped the uterus in the midsagittal plane. Two separate mechanisms for traumatic abruptio placentae were tested: shear failure and tensile failure. In the shear failure model large circumferential strains in the uterine wall induce a shear strain across the uteroplacental interface, and the model predicts placental separation at a mean circumferential strain of -58% +/- 8%. By means of finite-element modeling, it was demonstrated that tensile failure might also be a mechanism that causes abruptio placentae during rapid deceleration of the uterus. Crash investigations were performed in 43 cases involving pregnant women beyond 20 weeks' gestation. There were a total of 8 fetal losses and 8 major complications (fetal survival with abruptio placentae, direct fetal injury, or preterm delivery before 34 weeks' as a result of the accident). The best predictors of fetal loss or adverse outcome were impact severity and proper seat belt use. With these newly acquired data a second-generation crash dummy, known as the Maternal Anthropomorphic Measurement Apparatus version 2b (MAMA-2b), is being developed. It incorporates strain gauges in the fundal region of the fluid-filled uterus plus pressure transducers in both the anterior and posterior uterus. Criteria are being developed to associate the likelihood of abruptio placentae with measurements from these instruments that correspond to the two major hypothesized mechanisms of abruptio placentae. CONCLUSION: An improved understanding of the elements of automobile crashes that cause fetal loss and other major pregnancy complications has been gained through this series of investigations.

Abruptio placentae after auto accidents. A case-control study.

OBJECTIVE: To compare accident and injury characteristics in pregnant women with and without abruptio placentae involved in auto accidents (AAs). STUDY DESIGN: A retrospective, case-control study involving 12 pregnant women (16-39 weeks) with a diagnosis of abruptio placentae after AAs and 12 control subjects matched for gestational age (+/- 2 weeks) involved in AAs without abruptio placentae from 1988 through 1997. Numerous variables were compared, including restraint system use, estimated speed of the collision, injury severity score (ISS), clinical findings and patient position in the vehicle. Patient complaints and physical examination on admission were also recorded, and obstetric and neonatal outcomes were compared. Statistical analysis was performed using the independent sample t, Mann-Whitney and Fisher's exact tests, when appropriate. RESULTS: There was no significant difference in the frequency of unrestrained subjects or position in the vehicle between cases and controls. Estimated speed of the vehicle at the time of collision was significantly higher in the abruptio placentae group (> 30 mph, 92% vs. 50%, P = .03), as was the mean ISS code (20 [SD 12.71] vs. 4 [SD 5.13], P < .001). Abdominal pain and vaginal bleeding were seen more frequently in women with abruptio placentae as compared to controls (58% vs. 25% and 33% vs. 0, respectively). Patients with abruptio placentae had a higher incidence of preterm delivery (mean gestational age at delivery = 29 weeks [SD 7.99] vs. 36 weeks [SD 7.21], P = .008) and stillbirth (57% vs. 0%, P = .002) and lower mean birth weight (1,924 g [SD 931] vs. 3,069 g [SD 450], P = .003). There was no significant difference in cesarean section rates between the groups (58% vs. 30%, P = .23). There was no difference in the two groups in placental location on ultrasonography. CONCLUSION: Pregnant women who were involved in severe accidents (i.e., higher speed or ISS) were more likely to suffer abruptio placentae. In severe accidents, proper restraints were frequently not used. Because of the severity of these accidents, current restraint systems may not be sufficient to prevent abruptio placentae even with proper restraint use. Efforts toward designing new restraint systems for pregnant women should be encouraged.

Investigations of crashes involving pregnant occupants.

Case reports of 16 crashes involving pregnant occupants are presented that illustrate the main conclusions of a crash-investigation program that includes 42 crashes investigated to date. Some unusual cases that are exceptions to the overall trends are also described. The study indicates a strong association between adverse fetal outcome and both crash severity and maternal injury. Proper restraint use, with and without airbag deployment, generally leads to acceptable fetal outcomes in lower severity crashes, while it does not affect fetal outcome in high-severity crashes. Compared to properly restrained pregnant occupants, improperly restrained occupants have a higher risk of adverse fetal outcome in lower severity crashes, which comprise the majority of all motor-vehicle collisions.

Lichen sclerosus in pregnancy: presentation of two cases.

Numerous skin diseases occurring in the pregnant patient have been reported. Some of these diseases are unique to pregnancy and some, including vulvar varicosities, vulvar edema, postpartum labial adhesions, and hematomas, are a result of physiological changes of pregnancy or the birth process. In addition, a variety of viral and bacterial infectious diseases of the vulva may occur during pregnancy. Vulvar neoplasms may also be found in pregnancy. In two patients, ages 27 and 31, lichen sclerosus first was diagnosed during their initial prenatal visits. Only one of the patients was symptomatic. The symptomatic patient used topical steroids for relief of vulvar itching. Two patients with lichen sclerosus of the vulva in pregnancy are reported, with emphasis on the diagnosis and treatment of this condition.

Frequent resistance of clinical group B streptococci isolates to clindamycin and erythromycin.

OBJECTIVE: To determine both the frequency of reported penicillin allergy in parturients and the frequency of resistance in vitro of clinical isolates of group B streptococci to clindamycin and erythromycin. METHODS: One hundred clinical isolates of group B streptococci were tested to determine the frequency of resistance to clindamycin, erythromycin, penicillin G, vancomycin, and cefazolin. The frequency of beta-lactam allergy and reported allergic reaction also were recorded for all consecutive laboring women during the 4-month study. RESULTS: The frequency of group B streptococcal resistance to clindamycin was 15% and to erythromycin was 16%. No isolates were resistant to penicillin G, vancomycin, or cefazolin. Twelve percent of the 963 women who delivered during the study reported a penicillin allergy, but only 30% of those could describe their allergic reaction. CONCLUSION: In vitro resistance of group B streptococci to clindamycin and erythromycin occurred frequently in this population. Whereas the importance of this finding in vivo is uncertain, it raises concern about the possibility of inadequate prophylaxis using currently recommended alternatives in penicillin-allergic patients. Artful questioning of women reporting penicillin allergy may lessen the likelihood of using these less desirable agents in the setting of intrapartum antimicrobial prophylaxis.

Motor vehicle crashes, pregnancy loss and preterm labor.

Trauma during pregnancy is remarkably common, and is greatly underestimated in terms of its contribution to both maternal and perinatal morbidity and mortality. Motor vehicle crashes, falls, assaults, including domestic violence, are all important mechanisms of injury, and clinical algorithms have been developed to manage the injured pregnant women. Focus on recognition and management of the most common injuries seen in pregnant women, namely abruptio placentae and uterine rupture are addressed through hemodynamic stabilization and continuous fetal and uterine contraction monitoring in the women injured beyond 24 weeks' gestation.

Safety belt use during pregnancy.

OBJECTIVE: To evaluate the importance of prenatal education on the proper use of seat belts during pregnancy. METHODS: Three hundred fifty pregnant women were provided surveys at their first prenatal visit and then again at 28-32 weeks' gestation. The surveys assessed the actual use and placement of seat belts before and during pregnancy and knowledge about the use of restraint systems during pregnancy. In addition, the women were surveyed with respect to the information provided to them regarding seat belt use. RESULTS: Two hundred ninety-eight women returned both surveys, 68% of whom reported using seat belt in a manner currently recommended. Nearly 20% stated that they rarely or never used seat belts during their pregnancy. Women who reported receiving information regarding seat belt use from their prenatal provider were significantly more likely both to use their belts (83% versus 65%; P < .001) and to identify proper belt placement (77% versus 57%; P < .001) compared with those who did not receive information, respectively. CONCLUSIONS: Despite current recommendations and laws regarding seat belt use during pregnancy, one-third of women report either not using seat belts or using them improperly during pregnancy. Prenatal care providers can substantially influence the proper use of seat belts by discussing their correct use during pregnancy.

Automobile crash simulation with the first pregnant crash test dummy.

OBJECTIVE: Our goal was to develop a pregnancy insert for the Hybrid III (First Technology, Farmington, Mich.) crash dummy allowing evaluation of the effects of various restraint conditions on energy transmission to both the fetal and maternal compartments. STUDY DESIGN: A pregnancy insert with an elasticized vinyl uterine shell, simulated silicon amniotic fluid, and a 28-week simulated fetus was fitted to a female crash dummy. The fetus was instrumented with accelerometers in the head and thorax and a transducer to measure force transmission through the uterus. Thirty-nine crash tests were run under six different restraint conditions at speeds ranging from 10 to 25 miles/hr. Fetal responses were compared for different restraint conditions. RESULTS: Increasing speed of the crash resulted in greater force transmission through the uterus. Placement of the lap belt over the uterus instead of under the uterus resulted in a threefold to fourfold increase in force transmission through the uterus at all speeds tested. Air bag deployment in the unbelted or out-of-position dummy (laying against air bag) appears to impart significant energy transmission to the fetus. CONCLUSIONS: Energy transmission can be measured in terms of both abdominal force and acceleration within the fetal head and thorax. This new dummy demonstrates substantial transmission of energy, which is accentuated in some restraint conditions commonly used by pregnant women. The use of the 3-point restraint system appears to reduce the likelihood of injury in this model.

An incremental dosing protocol for women with severe vaginal trichomoniasis and adverse reaction to metronidazole.

OBJECTIVE: Our purpose was to develop and test an incremental dosing protocol for women with adverse reaction to metronidazole and severe symptomatic Trichomonas vaginitis. STUDY DESIGN: Two women with documented Trichomonas infection and presumed metronidazole allergy were initially treated with a number of alternative methods without success. With persistent severe symptoms associated with their infection, these women were admitted to the hospital and underwent an intravenous incremental metronidazole dosing protocol. RESULTS: Both patients were successfully treated without adverse event. They are both symptom-free and apparently cured several months after treatment. CONCLUSION: This protocol offers a new therapeutic option to women with adverse metronidazole reactions and severe symptomatic Trichomonas vaginitis resistant to treatment with nonmetronidazole therapy.

Mycobacterium chelonei breast abscess associated with nipple piercing.

BACKGROUND: Breast abscesses are typically seen in the setting of complicated mastitis in lactating women. Abscesses resulting from foreign bodies are not commonly seen in the breast. Over the past few decades, body piercing has become increasingly common, yet the infectious morbidity resulting from it is not well recognized. A breast abscess associated with nipple piercing is described in this report. CASE: A 19-year-old woman developed a breast abscess approximately 10 weeks after the placement of a nipple ring. Multiple drainage procedures were performed before the infection was controlled. The cultures grew Mycobacterium chelonei, an organism not commonly causing soft-tissue infection. CONCLUSION: Body piercing may be associated with significant infections. The use of sterile equipment and techniques should be used to prevent these uncommon infections.

Antiendotoxin antibody is protective against tubal damage in an Escherichia coli rabbit salpingitis model.

OBJECTIVE: This study was designed to determine whether pretreatment with an endotoxin antibody reduces tubal damage and tumor necrosis factor-alpha production in an Escherichia coli rabbit salpingitis model. STUDY DESIGN: Twenty New Zealand White rabbits underwent laparotomy with direct inoculation of Escherichia coli into the fallopian tube. The animals were given either antibody and antibiotic, antibiotic alone, or no treatment. At 7 days the degree of tubal damage was measured by gross observation, light microscopy, and electron microscopy. Serum tumor necrosis factor-alpha levels were also assayed at 0, 2, 4, and 36 hours. RESULTS: Animals pretreated with antiendotoxin antibody demonstrated significantly less damage on the basis of gross observation and electron microscopy compared with both antibiotic alone and untreated animals. Tumor necrosis factor-alpha levels were also significantly reduced at 2 and 4 hours in the antibody-treated group. CONCLUSIONS: Endotoxin plays a direct role in tubal damage in this Escherichia coli salpingitis model, and damage can be blocked, in part, by pretreatment with antiendotoxin antibody. Tumor necrosis factor-alpha appears to play a significant role in mediating tubal damage resulting from endotoxin.

Pelvic fluid collections following hysterectomy and their relation to febrile morbidity.

OBJECTIVE: To determine the incidence of pelvic fluid collections after hysterectomy, detected by transvaginal sonography and pelvic examination, and to correlate these findings with postoperative febrile morbidity. METHODS: Thirty-eight women, aged 26-65, were studied by pelvic examination and transvaginal sonography 1-5 days after vaginal or abdominal hysterectomy. The sonographer was unaware of the patient's clinical course before the examination and was not involved in clinical decision making. The results of the study were not made available to the treating physician. RESULTS: Transvaginal sonography revealed a sonolucent mass consistent with a fluid collection above the vaginal cuff ranging in size from 3.9-74.7 cm3 in 13 of 38 patients (34.2%). Only one of the 13 fluid collections was evident on pelvic examination performed before ultrasound. Nine of 13 women (69.2%) with fluid collections developed febrile morbidity, compared to three of 25 (12%) who did not have fluid collections (P = .006, Fisher exact test). Cuff cellulitis was clinically diagnosed in seven of the 13 women (53.8%) with fluid collections, compared to none of 25 women without fluid collections (P < .001, Fisher exact test). CONCLUSIONS: Pelvic fluid collections are common after hysterectomy. Women who develop post-hysterectomy fluid collections appear to be at increased risk for the development of febrile morbidity and cuff cellulitis. Transvaginal sonography may facilitate the diagnosis of post-hysterectomy pelvic fluid collections, which are not readily detected by pelvic examination.

Amniotic fluid glucose concentration: a marker for infection in preterm labor and preterm premature rupture of membranes.

UNLABELLED: Amniotic fluid Gram stain and culture have been utilized as laboratory tests of microbial invasion of the amniotic cavity. The Gram stain of amniotic fluid has a low sensitivity in the detection of clinical infection or microbial invasion of the amniotic cavity, and amniotic fluid culture results are not immediately available for management decisions. Glucose concentration is used to diagnose infection in other sites such as cerebrospinal fluid. OBJECTIVE: The purpose of this study was to evaluate the usefulness of amniotic fluid glucose concentration in detecting microbial invasion of the amniotic cavity associated with preterm labor and preterm premature rupture of membranes. METHODS: Amniocentesis was performed in 60 women with preterm labor and/or preterm premature rupture of membranes. Gram stain and culture for Mycoplasma hominis, Ureaplasma urealyticum, aerobic, and anaerobic bacteria were performed. Subjects were studied prospectively for the development of positive amniotic fluid cultures and the development of clinical chorioamnionitis. RESULTS: The diagnosis of clinical chorioamnionitis was made in 25% (15/60) of women entered into the study. Low amniotic fluid glucose concentration Was considered < 15 mg/dl. The sensitivity, specificity, and positive predictive value of low amniotic, fluid glucose concentration to predict clinical chorioamnionitis were 73.3%, 88.1%, and 68.8% respectively, while positive amniotic fluid culture, hada sensitivity of 43.8%, specificity of 79.5%, and positive predictive value of 43.8%. CONCLUSIONS: Amniotic fluid glucose concentration was more sensitive in predicting chorioamnionitis than either Gram stain or culture. Amniotic fluid glucose concentration was better in predicting clinical chorioamnionitis than predicting positive amniotic fluid culture results. Gestational age-dependent normal ranges and pathologic conditions that may alter amniotic fluid glucose concentrations should be considered when interpreting amniotic fluid glucose values to diagnose microbial invasion of the amniotic cavity.

Development of pelvic abscess following water-skiing injury.

Several descriptions of hydrostatic injuries while water-skilng have been described, including lacerations of the perineum, vagina, and cervix. Salpingitis or pelvic abscess resulting from water-skiing injuries are rare but important complications. A case of a pelvic abscess following a fall while water-skiing is described. The abscess was drained laparoscopically, resulting in a good clinical outcome. The mechanism of injury and recommendations for prevention are also presented. Upper genital tract infection may result from water-skiing injuries due to hydrostatic pressure forcing bacteria and water through the vagina and cervix into the endometrium, fallopian tube, and peritoneal cavity. While an uncommon complication, physicians and other practitioners caring for women should be aware of this potential complication from water-skiing.