Diane M. Twickler

Color flow mapping for myometrial invasion in women with a prior cesarean delivery.

OBJECTIVES Our aim was to evaluate the utility of color flow mapping in the prediction of placental myometrial invasion in women with Cesarean delivery. METHODS Ultrasound color flow mapping was performed on placental implantations in potential proximity to the hysterotomy scar. The smallest myometrial thickness was measured under the placenta to evaluate the degree of myometrial attenuation in this area and note was made of unusual vascular lakes. RESULTS Two hundred fifteen women with placentas in proximity to the prior hysterotomy scar underwent color Doppler mapping. Of 20 women with placenta previa and Cesarean delivery, 15 had Cesarean hysterectomy for bleeding complications and nine had the pathological diagnosis of placental invasion. The measurement of <1 mm for the smallest myometrial thickness or presence of large intraplacental lakes was predictive of myometrial invasion (sensitivity 100%, specificity 72%, PPPV 72%, and NPV 100%). CONCLUSIONS Color flow mapping predicted myometrial invasion when the smallest myometrial thickness was <1 mm and large intraplacental lakes were demonstrated.

Effect of Maternal Obesity on the Ultrasound Detection of Anomalous Fetuses

OBJECTIVE: To estimate the effect of maternal habitus on detection of fetuses with major structural anomalies during second-trimester standard and targeted ultrasound examinations. METHODS: This was a retrospective cohort study of pregnancies 18 to 24 weeks that underwent ultrasonography over a 5-year period. An anomalous fetus was considered detected if a major abnormality of the relevant organ system was identified, regardless of the anticipated ultrasound detection. Anomalies were verified using a prospectively maintained database. Body mass index (BMI) was based on weight at first prenatal visit. RESULTS: There were 10,112 standard examinations in low-risk pregnancies and 1,098 targeted examinations in pregnancies with either high-risk indications or with an abnormality detected during standard ultrasonography. Detection of anomalous fetuses decreased with increasing BMI. For normal BMI, overweight, and class I, II, and III obesity, detection with standard ultrasonography was 66%, 49%, 48%, 42%, and 25%, respectively, and with targeted ultrasonography, 97%, 91%, 75%, 88%, and 75%, respectively, both P≤.03. Residual anomaly risk after a normal ultrasound examination increased with increasing BMI, from 0.4% among women of normal BMI to 1.0% among obese women, P=.001. Anomaly detection was lower among women with pregestational diabetes than in those with other high-risk indications, 38% compared with 88% respectively, P<.001. CONCLUSION: With increasing maternal BMI, we found decreased detection of anomalous fetuses with either standard or targeted ultrasonography, a difference of at least 20% when women of normal BMI were compared with obese women. Anomaly detection was even less in pregnancies complicated by pregestational diabetes. Counseling may need to be modified to reflect the limitations of ultrasonography in obese women. LEVEL OF EVIDENCE: II

Persistence of placenta Previa according to Gestational age at ultrasound detection

OBJECTIVE To evaluate gestational age at ultrasound detection of placenta previa as a predictor of previa persistence until delivery, and to estimate the effects of previa type, parity, and prior cesarean delivery on previa persistence. METHODS This was a retrospective cohort study of pregnancies with placenta previa detected during transabdominal or endovaginal ultrasound examination. Previa was categorized as complete if the placenta completely covered the internal cervical os or incomplete if the inferior placental edge partially covered or reached the margin of the os. Gestational age was grouped into 4‐week intervals from 15 to 36 weeks. The outcome was cesarean delivery for persistent previa. RESULTS Previa was detected during 940 ultrasound examinations in 714 pregnancies. Of those with placenta previa at 15–19 weeks, 20–23 weeks, 24–27 weeks, 28–31 weeks, and 32–35 weeks, previa persisted until delivery in 12%, 34%, 49%, 62%, and 73%, respectively. At each interval, complete previa was more likely to persist than incomplete previa, all P < .001. Prior cesarean delivery was an independent risk factor for persistent previa among women diagnosed with previa in the second trimester, P < .05. However, parity was not an independent risk factor for persistence at any gestational age interval after adjusting for prior cesarean delivery. CONCLUSION Gestational age at ultrasound detection of placenta previa may be used to predict likelihood of previa persistence. After midpregnancy, risk of persistence appears to be higher than previously reported. Type of placentation and prior cesarean delivery are important factors that modify the risk that previa will complicate delivery.

Hydramnios: Anomaly prevalence and sonographic detection

OBJECTIVE To characterize the prevalence and ultrasound detection of fetal anomalies in pregnancies with hydramnios, and to estimate anomaly and aneuploidy risks when no sonographic abnormality is noted. METHODS This was a retrospective cohort study of singleton pregnancies with hydramnios. Hydramnios was categorized as mild, moderate, or severe based on greatest amniotic fluid index of 25.0–29.9 cm, 30.0–34.9 cm, or 35.0 cm or more, respectively. Antenatal anomaly detection was compared with assessment in the immediate neonatal period. Aneuploidy and fetal deaths were analyzed separately. RESULTS Hydramnios was diagnosed in 672 pregnancies, and 77 (11%) of neonates had one or more anomalies. Though more severe hydramnios was associated with higher likelihood of anomaly (P < .001), sonographic anomaly detection (79%) did not differ according to degree of hydramnios (P = .4). Of anomalies which eluded sonographic diagnosis, cardiac septal defects, cleft palate, imperforate anus, and tracheoesophageal fistula were the most frequent. If sonographic evaluation was normal, the risk of a major anomaly was 1% with mild hydramnios, 2% with moderate hydramnios, and 11% with severe hydramnios (P < .001). Aneuploidy was present in 10% of fetuses with sonographic anomalies and 1% without apparent sonographic anomalies. The fetal death rate was 4% in the setting of hydramnios; 60% of these cases had anomalies. CONCLUSION The anomaly detection rate in pregnancies with hydramnios was nearly 80%, irrespective of the degree of amniotic fluid increase. Residual anomaly risk after normal sonographic evaluation was 2% or less if hydramnios was mild or moderate and 11% if severe.

Puerperal septic pelvic thrombophlebitis: Incidence and response to heparin therapy

OBJECTIVE Before the availability of modern imaging studies the diagnosis of septic pelvic thrombophlebitis causing prolonged puerperal fever was difficult to confirm without surgical exploration. With the use of computed tomography infection-related pelvic phlebitis can now be confirmed, and this study was designed to determine its incidence after delivery. We also designed a randomized clinical trial to evaluate the efficacy of heparin added to antimicrobial therapy for treatment of women with septic phlebitis. STUDY DESIGN We studied women who had pelvic infection and fever that persisted after 5 days despite adequate antimicrobial therapy with clindamycin, gentamicin, and ampicillin. After giving consent study participants underwent abdominopelvic computed tomographic imaging. Women with pelvic thrombophlebitis were randomly assigned to 1 of 2 management schemes that included continuation of antimicrobial therapy, either alone or with the addition of heparin, until the temperature was </=37.5 degrees C for 48 hours. RESULTS During the 3-year study period 44,922 women were delivered at Parkland Hospital; among these 8535 (19%) were delivered by the cesarean route. There were 69 women who met criteria for prolonged infection, and 15 (22%) of these were found to have septic pelvic thrombophlebitis. Four had infection after vaginal delivery and 11 had been delivered by the cesarean route. Of 14 women randomly assigned to therapy, 8 were assigned to receive continued antimicrobial therapy without the addition of heparin and the other 6 were assigned to receive heparin therapy in addition to the antimicrobial agents. According to an intent-to-treat analysis there was no significant difference between the responses of women with pelvic infection who were and were not given heparin therapy. Specifically, women not given heparin were febrile for 140 +/- 39 hours compared with 134 +/- 65 hours for women who received heparin (P =.83). Duration of hospitalization was also similar between the 2 groups at 10.6 +/- 1.9 days for those with thrombosis who were given antimicrobial agents alone and 11.3 +/- 1.2 days for women who also received heparin (P >.5). The 54 women with persistent fever but without computed tomographic evidence of septic pelvic thrombophlebitis were hospitalized for a mean of 12.0 +/- 4.1 days, compared with 10.9 +/- 2.9 days for women in whom thrombosis was diagnosed (P =.14). These women were followed up for >/=3 months post partum and none showed evidence of reinfection, embolic episodes, or postphlebitic syndrome. CONCLUSIONS The overall incidence of septic pelvic thrombophlebitis was 1:3000 deliveries. The incidence was about 1:9000 after vaginal delivery and 1:800 after cesarean section. Women given heparin in addition to antimicrobial therapy for septic thrombophlebitis did not have better outcomes than did those for whom antimicrobial therapy alone was continued. These results also do not support the common empiric practice of heparin treatment for women with persistent postpartum infection.

Fetal syphilis: clinical and laboratory characteristics.

Objective To examine the pathophysiology of fetal syphilis and correlate hematologic, immunologic, and sonographic findings. Methods Twenty-four women with untreated syphilis during pregnancy were prospectively identified. Sonography with amniocentesis and percutaneous umbilical blood sampling were performed. Darkfield examination, rabbit infectivity testing, and polymerase chain reaction for detection of Treponema pallidum were performed on amniotic fluid. Hematologic and chemical testing of fetal blood was performed using standard techniques. Fetal antitreponemal IgM was detected by Western blot assay. Maternal syphilis was treated with 2.4 to 4.8 million units of benzathine penicillin G intramuscularly. Neonatal outcomes and signs of congenital syphilis were recorded. Results Six women had primary, 12 had secondary, and six had early latent syphilis. Sixty-six percent of fetuses (95% confidence interval [CI] 47%, 82%) had either congenital syphilis or detection of Treponema pallidum in amniotic fluid. Sixty-six percent had hepatomegaly, including three fetuses (12.5%, 95% CI 4%, 31%) with ascites. Fetal antitreponemal IgM was detected in three cases. Abnormal liver transaminases were found in 88% (CI 69%, 96%), anemia in 26% (CI 13%, 47%), and thrombocytopenia in 35% (CI 19%, 55%). Maternal treatment was successful in 83% (CI 64%, 93%). Risk of treatment failure was significantly increased when hepatomegaly and ascites were present (P = .01). Conclusion Findings with fetal syphilis are similar to those of neonatal syphilis. We hypothesize that fetal transaminase elevation occurs early in the course of infection; hematologic abnormalities and hydrops occur later. Severity of disease may be associated with risk of treatment failure.

Cerebral blood flow and cranial magnetic resonance imaging in eclampsia and severe preeclampsia

Objective To measure cerebral blood flow in women with eclampsia and severe preeclampsia using phase-contrast magnetic resonance imaging (MRI). Methods Women with eclampsia and severe preeclampsia were studied and compared with normotensive cohorts. Magnetic resonance imaging studies were performed initially in hypertensive women after seizure treatment or prophylaxis was given. Magnetic resonance imaging flow measurements were made using a phase contrast velocity imaging technique in each middle and posterior cerebral artery. Conventional brain MRI and magnetic resonance angiography of the circle of Willis were performed at the time of flow measurement. Women with preeclampsia and eclampsia served as their own controls and were matched with normotensive cohorts. All of the hypertensive women were studied again 4–5 weeks postpartum. Paired t test analysis and an analysis of variance were performed. Considering a 20% minimum detectable difference in flow, the power was 0.80, 0.92, 0.86, and 0.96 for the left and right middle cerebral arteries and the left and right posterior cerebral arteries, respectively. Results All 28 women enrolled were studied initially within 24 hours of delivery or of their most recent seizure. There were no significant differences in blood flow in either the posterior or middle cerebral arteries in women with eclampsia or severe preeclampsia between the initial studies and those 4–5 weeks postpartum, or compared with their normal counterparts. No findings of vasospasm were seen. T2-weighted brain images were markedly abnormal in all eight women with eclampsia, mildly abnormal in two of ten with severe preeclampsia, and normal in all ten controls. Conclusions No flow changes were seen in the posterior or middle cerebral arteries of women with eclampsia and severe preeclampsia despite the presence of remarkable brain lesions in all women with eclampsia. These findings question the role of vasospasm and cerebral hypoperfusion, although a vasodilatory effect of magnesium could not be excluded.

Maternal Obesity Limits the Ultrasound Evaluation of Fetal Anatomy

Objective. The purpose of this study was to evaluate the effect of maternal habitus on adequate visualization of fetal anatomy during a standard second‐trimester ultrasound examination. Methods. This was a retrospective cohort study of singleton pregnancies at 18 to 24 weeks that underwent sonography over a 5‐year period. Pregnancies complicated by an indication for targeted sonography were excluded. Standard ultrasound examinations were performed according to American Institute of Ultrasound in Medicine criteria. Ten anatomic components were evaluated for adequacy of visualization: atria of the cerebral ventricles, posterior fossa, midline face, 4‐chamber view of the heart, spine, ventral wall, umbilical cord vessels, stomach, kidneys, and bladder. The body mass index (BMI) was based on the patients weight at the first prenatal visit. Results. Of 10,112 women who underwent a standard ultrasound examination, 2% were underweight; 38% were of normal weight; 34% were overweight; and 26% were obese. Visualization of fetal anatomy decreased significantly with increasing maternal BMI for the complete survey as well as for each individual component with the exception of the fetal bladder (all P < .001). Among those with a normal or underweight BMI, an overweight BMI, and class 1, 2, and 3 obesity, all 10 anatomic components were adequately visualized at the initial examination in 72%, 68%, 57%, 41%, and 30% of cases, respectively (P < .001). Conclusions. Increasing maternal BMI limits visualization of fetal anatomy during a standard ultrasound examination at 18 to 24 weeks. In obese women, the fetal anatomy survey could be completed during the initial examination in only 50% of cases. Counseling may need to be modified to reflect the limitations of sonography in obese women.

Pitfalls in ultrasonic cervical length measurement for predicting preterm birth.

OBJECTIVE To describe the anatomic and technical difficulties encountered with transvaginal ultrasound imaging of the cervix in a consecutive series of women at risk for preterm delivery. METHODS Three groups of women had cervical ultrasound examinations: those with histories of preterm birth, those with incompetent cervices, and those admitted for preterm labor that did not progress. Standardized ultrasound examinations of the cervix involved measuring the length of the endocervical canal, funneling length, and internal os dilation with and without fundal pressure. RESULTS Sixty consecutive women had transvaginal ultrasound examinations for assessment of the cervix. Forty-six had histories of preterm birth, five had incompetent cervices, and nine had arrested preterm labor. Six types of problems arose, which can be divided into anatomic or technical considerations, with an overall frequency of 27% (95% confidence interval 16%, 40%). Anatomic pitfalls that hampered identification of the internal os included an undeveloped lower uterine segment (n = 5), a focal myometrial contraction (n = 1), rapid and spontaneous cervical change (n = 1), and an endocervical polyp (n = 1). Technical pitfalls included incorrect interpretation of internal os dilation because of vaginal probe orientation (n = 7) and artificial lengthening of the endocervical canal because of distortion of the cervix by the transducer (n = 1). CONCLUSION We caution those who perform cervical length examinations to be wary of falsely reassuring findings due to potential anatomic and technical pitfalls.

Cerebral edema complicating eclampsia

OBJECTIVE This study was undertaken to describe and correlate clinical findings with computed tomographic and magnetic resonance imaging scan results in 10 women with eclampsia and widespread cerebral edema. STUDY DESIGN This was a clinical descriptive study of 10 women with eclampsia and symptomatic cerebral edema who were encountered at Parkland Hospital from 1986 through 1998. During this 13-year period nearly 175 women had eclampsia from a total of >160, 000 women delivered. The clinical courses of these 10 women with eclampsia and symptomatic cerebral edema are described, along with findings from computed tomographic and magnetic resonance imaging scans. RESULTS In 3 cases symptoms followed an acute and severe elevation of blood pressure while the patient was being treated for eclampsia. All 3 of these women had severe generalized edema with radiographic findings of impending transtentorial herniation. Herniation did occur in 1 of these women, and she died. The other 7 women had central nervous system symptoms that persisted after an initial eclamptic convulsion. Symptoms ranged from lethargy, confusion, and blurred vision to obtundation and blindness. Five of these women had multiple areas of edema mostly apparent at the gray matter-white matter junction. Two women demonstrated extensive unilateral brain involvement; however, their symptoms were similar to those of the women with multifocal areas of cerebral edema. CONCLUSION Symptomatic cerebral edema developed in almost 6% of women with eclampsia. Its genesis probably represents a continuum of central nervous system lesions that result from eclampsia. We postulate that women with symptoms of extensive cerebral edema have a cytotoxic edema caused by ischemia that is intensified by a vasogenic edema associated with sudden or severe hypertension.