The role of ultrasound imaging in diagnosing and investigating early pregnancy failure

Patterns and predictors of vaginal bleeding in the first trimester of pregnancy

PURPOSE

Although first-trimester vaginal bleeding is an alarming symptom, few studies have investigated the prevalence and predictors of early bleeding. This study characterizes first trimester bleeding, setting aside bleeding that occurs at time of miscarriage.

METHODS

Participants (n = 4539) were women ages 18 to 45 enrolled in Right From the Start, a community-based pregnancy study (2000-2008). Bleeding information included timing, heaviness, duration, color, and associated pain. Life table analyses were used to describe gestational timing of bleeding. Factors associated with bleeding were investigated by the use of multiple logistic regression with multiple imputation for missing data.

RESULTS

Approximately one fourth of participants (n = 1207) reported bleeding (n = 1656 episodes), but only 8% of women with bleeding reported heavy bleeding. Of the spotting and light bleeding episodes (n = 1555), 28% were associated with pain. Among heavy episodes (n = 100), 54% were associated with pain. Most episodes lasted less than 3 days, and most occurred between gestational weeks 5 to 8. Twelve percent of women with bleeding and 13% of those without experienced miscarriage. Maternal characteristics associated with bleeding included fibroids and prior miscarriage.

CONCLUSIONS

Consistent with the hypothesis that bleeding is a marker for placental dysfunction, bleeding is most likely to be observed around the time of the luteal-placental shift.

Ultrasound studies

This article focuses on the clinical use of ultrasound with the obstetric, gynecologic, and trauma patient by reviewing recent case studies of the use of ultrasound for diagnostic purposes. The article also summarizes the American Institute of Ultrasound in Medicine (AIUM) guidelines for use in several types of patients. The AIUM is a multidisciplinary association whose purpose is to "advance the art and science of ultrasound in medicine and research through educational, scientific, literary, and professional activities." The organization provides guidelines in conjunction with many professional organizations, such as the American College of Cardiology and the American College of Obstetrics and Gynecology. AIUM also serves as an accrediting body for ultrasound practices.

Anormalidades do primeiro trimestre da gravidez: ensaio iconográfico

As anormalidades do primeiro trimestre da gravidez são detectadas pela ultrassonografia transvaginal em exame de rotina ou em caso de sangramento vaginal anormal. A ameaça de abortamento é uma afecção comum no primeiro trimestre da gestação, ocorrendo em mais de um terço dos casos. O advento de sondas vaginais de alta resolução vem revolucionando nossa compreensão da fisiopatologia e o manejo da gestação inicial. Trata-se de ferramenta essencial para determinar a viabilidade da gestação nos casos de ameaça de abortamento. Uma conduta expectante no abortamento poderia reduzir significativamente o número de esvaziamentos desnecessários de produtos retidos, dependendo dos critérios utilizados.

Association between first-trimester vaginal bleeding and miscarriage

OBJECTIVE

To estimate the strength of association between first-trimester bleeding and miscarriage, setting aside bleeding at time of loss.

METHODS

Women enrolled in a community-based pregnancy cohort study before or during early pregnancy. Detailed first-trimester bleeding data were collected by telephone interview. Bleeding episodes proximal to miscarriage (within 4 days) were excluded. We used discrete-time hazard models to evaluate the association between bleeding and miscarriage. Models were adjusted for maternal age, prior miscarriage, and smoking. Exploratory regression tree analysis was used to evaluate the relative importance of other bleeding characteristics (duration, associated pain, color, timing).

RESULTS

Of the 4,510 participants, 1,204 (27%) reported some first-trimester vaginal bleeding or spotting, and 517 miscarriages were observed. Eight percent of those with bleeding reported heavy bleeding episodes. When we evaluated any bleeding, including episodes of only spotting, the unadjusted relative odds ratio (OR) of miscarriage for women with bleeding (n=1,204) was 1.1 (95% confidence interval [CI] 0.9-1.3). However, women who reported heavy bleeding (n=97) had nearly three times the risk of miscarriage compared with women without bleeding during the first trimester (OR 3.0, 95% CI 1.9-4.6). Adjustment for covariates had little effect on estimates. Further analyses suggested that women with heavy bleeding accompanied by pain were the group accounting for most of the elevated risk.

CONCLUSION

Heavy bleeding in the first trimester, particularly when accompanied by pain, is associated with higher risk of miscarriage. Spotting and light episodes are not, especially if lasting only 1-2 days.

LEVEL OF EVIDENCE

II.

Dating and growth in the first trimester

Measurement of embryonic or foetal size using the greatest length of the embryo or foetal crown rump length can be used to accurately determine the gestational age of a normal first trimester pregnancy to within three to five days. Transvaginal ultrasound scan can be used to measure the size of an embryo and gestation sac earlier than transabdominal ultrasound. The original Robinson curve used for dating pregnancies is still valid in most cases. Ultrasound dating in the first trimester is now recommended for all women with spontaneous pregnancies, even those with certain menstrual dates. First trimester growth in normal pregnancy is not uniform and is influenced by both maternal and foetal factors. Early foetal growth restriction is demonstrated in many pregnancies that subsequently end in first trimester miscarriage and is also demonstrated in fetuses with triploidy, trisomy 18 and possibly trisomy 13. Pregnancies which are small at the 11-14 week ultrasound scan appear to be at risk of later intrauterine growth restriction, preeclampsia and preterm delivery. Cross-sectional and serial measurement of foetal growth in the first trimester may be helpful in predicting both miscarriage and adverse late pregnancy outcomes.

Intervillous and uteroplacental circulation in normal early pregnancy and early pregnancy loss assessed by 3-dimensional power Doppler angiography

OBJECTIVE

To assess intervillous and uteroplacental circulation in early normal pregnancies and miscarriages.

STUDY DESIGN

One hundred normal pregnancies and 46 delayed miscarriages were evaluated by 3-dimensional vaginal ultrasound and power Doppler angiography. Volumes of the early placenta and the subplacental area were obtained between 5 and 12.6 weeks' gestation. The placental volume, vascularization index, flow index, and vascularization flow index was calculated.

RESULTS

Intraclass correlation coefficients ranged from 0.961 for placental volume to 0.885 for intervillous flow index. Intervillous power Doppler signals were not detected before the sixth week. Placental volume (R(2) = 0.68), intervillous vascularization index (R(2) = 0.30), flow index (R(2) = 0.33) and vascularization flow index (R(2) = 0.35), uteroplacental flow index (R(2) = 0.34), and vascularization flow index (R(2) = 0.17) increase significantly (P < .001) throughout the first trimester of normal pregnancies. Uteroplacental vascularization index was not significantly related to gestational age. Intervillous vasculariztion index, flow index, and vascularization flow index were significantly raised in miscarriages, but there were no significant differences for uteroplacental vascularization index, flow index, or vascularization flow index.

CONCLUSION

Intervillous and uteroplacental blood flow increases throughout the first trimester of normal pregnancies. Intervillous circulation is abnormally increased when a miscarriage is diagnosed.

Fetal thermal effects of diagnostic ultrasound

Processes that can produce a biological effect with some degree of heating (ie, about 1 degrees C above the physiologic temperature) act via a thermal mechanism. Investigations with laboratory animals have documented that pulsed ultrasound can produce elevations of temperature and damage in biological tissues in vivo, particularly in the presence of bone (intracranial temperature elevation). Acoustic outputs used to induce these adverse bioeffects are within the diagnostic range, although exposure times are usually considerably longer than in clinical practice. Conditions present in early pregnancy, such as lack of perfusion, may favor bioeffects. Thermally induced teratogenesis has been shown in many animal studies, as well as several controlled human studies; however, human studies have not shown a causal relationship between diagnostic ultrasound exposure during pregnancy and adverse biological effects to the fetus. All human epidemiologic studies, however, were conducted with commercially available devices predating 1992, that is, with acoustic outputs not exceeding a spatial-peak temporal-average intensity of 94 mW/cm2. Current limits in the United States allow a spatial-peak temporal-average intensity of 720 mW/cm2 for fetal applications. The synergistic effect of a raised body temperature (febrile status) and ultrasound insonation has not been examined in depth. Available evidence, experimental or epidemiologic, is insufficient to conclude that there is a causal relationship between obstetric diagnostic ultrasound exposure and obvious adverse thermal effects to the fetus. However, very subtle effects cannot be ruled out and indicate a need for further research, although research in humans may be extremely difficult to realize.

Angiogenesis in implantation

PROBLEM

Implantation failure and early pregnancy loss are common following natural conceptions and they are particularly important clinical hurdles to overcome following assisted reproduction attempts. The importance of adequate vascular development and maintenance during implantation has recently become a major focus of investigation.

MATERIALS AND METHODS

Review of current published literature was undertaken to summerize the cells and cell products that regulate tissue vascularity during implantation.

RESULTS

Vascular development at the maternal fetal interface can be regulated by a number of different cell types; two principal candidates are trophoblast and natural killer cells. A wide range of soluble factors, some with well established angiogenic functions as well as other more novel factors, can contribute to vascular development and maintenance at the maternal-fetal interface.

CONCLUSIONS

Robust vascular development occurs during implantation and early placentation of normal pregnancies. Studies to define the extent and mechanisms by which defects in vascularity contribute to human implantation failure and early miscarriage need to be undertaken.

Pregnancy outcome of a patient with atypical polypoid adenomyoma

OBJECTIVE

Detailed description and follow-up of a patient with atypical polypoid adenomyoma and infertility, from investigation until delivery of a healthy baby.

DESIGN

Case report.

SETTING

Tertiary infertility center.

PATIENT(S)

A patient suffering from persistent APA and infertility.

INTERVENTION(S)

Danggui (Angelica sinensis) and low-dose aspirin.

MAIN OUTCOME MEASURE(S)

Pregnancy and live birth.

RESULT(S)

Conception after Danggui but intrauterine death at 25 weeks. Successful live birth after Danggui plus low-dose aspirin.

CONCLUSION(S)

Danggui corrected atypical polypoid adenomyoma and led to pregnancy twice in the same patient. Low-dose aspirin may improve the circulation in the placental bed and lead to live birth.

Doppler examination of uteroplacental circulation in early pregnancy: can it predict adverse outcome?

PURPOSE

To determine whether spectral Doppler measurements obtained from bilateral uterine, arcuate, radial, and spiral arteries in early gestation correlate with adverse pregnancy outcome.

METHODS

One hundred five pregnant women underwent transvaginal Doppler sonographic examination of uteroplacental circulation at 6-12 weeks' gestation. Resistance index (RI) and pulsatility index (PI) of bilateral uterine, arcuate, radial, and spiral arteries were measured. Diameters of gestational sac (GS) and yolk sac, crown-rump length (CRL), GS-CRL difference, and GS/CRL ratio were also recorded. Correlation was made with pregnancy outcome.

RESULTS

Sixteen women developed adverse pregnancy outcome. In these women, right uterine artery PI and RI were significantly higher than in women with normal obstetrical outcome. Spiral artery PI and RI values were also higher, but the difference was not statistically significant. GS-CRL difference, GS/CRL ratio, and yolk sac diameters were significantly lower in this group.

CONCLUSION

Transvaginal Doppler examination can detect hemodynamic changes in uteroplacental circulation associated with subsequent adverse pregnancy outcome.

In utero imaging of the placenta: importance for diseases of pregnancy

Maurice Panigel demonstrated by X-rays, almost 40 years ago, placental maternal blood jets in non-human primates. Although to researchers the importance of the placenta is evident, in clinical obstetrical imaging, the fetus takes precedence. The placenta is imaged almost as an after thought and mostly to determine its location in the uterus. In animal species, the placenta was imaged with techniques which would be considered too invasive (or too costly for routine use) in humans, many pioneered by Panigel: radioangiography, radioisotopes scintigraphy, thermography, magnetic resonance imaging (MRI) and spectroscopy, positive emission tomography (PET) and single photon emission computed tomography (SPECT). Ultrasound allows for detailed, and, as far as is known, safe analyses of not only placental structure in the human but also its function. Earlier, only 2-dimensional grey-scale was available and more than 20 years ago, placental grading was popular. Later, colour imaging and spectral Doppler analysis of blood velocity both in the umbilical artery and within the placenta as well as the uterus and fetal vessels became essential and, more recently, the use of ultrasound contrast agents has been described, albeit not yet in a clinical setting. Three-dimensional ultrasound permits evaluation of the placenta in several planes, more precise depiction of internal vasculature as well as more accurate volume assessment. Several medical disorders of the pregnant woman or her fetus begin or end in the placenta, and ultrasound is the optimal investigation method. Obvious examples include pre-eclampsia and other forms of hypertension in pregnancy, less than optimal fetal growth (i.e. intrauterine growth restriction), triploidy (and its placental manifestation: partial mole), non-immune hydrops as well as several infectious processes. Ultrasound is also particularly suited to evaluate specific placental conditions, such as abnormal placentation (placenta previa and accrete for instance), gestational trophoblastic disease and placental tumors (e.g. chorioangioma).

Low endometrial volume may predict early pregnancy loss in women undergoing in vitro fertilization

PURPOSE

To evaluate the role of 3-D US measurement of the endometrium during early IVF-pregnancy and before the appearance of gestational sac in the prediction of pregnancies outcome.

METHODS

60 pregnant women following IVF treatment were included in the study. The women underwent transvaginal 3D US measurements of endometrial volume and thickness on day 15-17 post ET. Patients were followed and classified according to pregnancy outcome into 2 further groups. The group with early pregnancy loss and the group with ongoing pregnancy.

RESULTS

While no differences were observed between those who miscarried and those who did not in gestational age, endometrial thickness or volume, spontaneous early pregnancy loss was significantly higher in patients with endometrial volume <2 mL as compared to those with endometrial volume >2 mL.

CONCLUSIONS

3-D US measurement of endometrial volume of less than 2 mL during early IVF pregnancy and prior to the appearance of gestational sac is a powerful predictor of pregnancy loss.

Endometrial and subendometrial vascularity is higher in pregnant patients with livebirth following ART than in those who suffer a miscarriage

BACKGROUND

Blood flow towards the peri-implantation endometrium may have effects on miscarriage and live birth following assisted reproduction treatment, in addition to its role in implantation.

METHODS

Three-dimensional ultrasound examination with power Doppler was performed on the day of oocyte retrieval in stimulated IVF cycles and on LH + 1 day in frozen thawed-embryo transfer (FET) cycles to measure endometrial thickness, endometrial pattern, uterine artery Doppler flow indices, endometrial volume, vascularization index (VI), flow index (FI), vascularization flow index (VFI) of endometrial and subendometrial regions.

RESULTS

In stimulated IVF cycles, 45 (28.0%) out of 161 pregnant patients subsequently miscarried. Patients in the live birth group had significantly higher endometrial VI and VFI and subendometrial VI, FI and VFI, when compared with those in the miscarriage group. In a multiple logistic regression analysis, only endometrial VI was significantly associated with the chance of live birth with an odds ratio of 1.384 [95% confidence interval (CI) 1.025-1.869, P = 0.034]. For FET cycles, patients in the live birth group had significantly higher endometrial VFI, subendometrial VI and VFI than those in the miscarriage group.

CONCLUSIONS

Endometrial and subendometrial vascularity was significantly higher in pregnant patients with live birth following stimulated IVF and FET treatment than in those who suffered a miscarriage.

Imaging in gynecology

This chapter summarizes the diagnostic performance (sensitivity, specificity, positive and negative likelihood ratios) of ultrasound, computer tomography, and magnetic resonance imaging in the diagnosis of various gynecological diseases and tumors. Positron emission tomography is not discussed. Imaging in infertility, in the diagnosis of Mullerian duct anomalies and in gynecological oncology (staging of gynecological cancers, diagnosis of recurrence of gynecological cancer, diagnosis of trophoblastic tumors) is not dealt with. Ultrasound is the first-line imaging method for discrimination between viable intrauterine pregnancy, miscarriage and tubal pregnancy in women with bleeding and/or pain in early pregnancy, for discrimination between benign and malignant adnexal masses and for making a specific diagnosis in adnexal tumors (e.g. dermoid cyst, endometrioma, hemorrhagic corpus luteum, etc.), for diagnosing intracavitary uterine pathology in women with bleeding problems, and for confirming or refuting pelvic pathology in women with pelvic pain. Magnetic resonance imaging can have a role as a secondary test in the diagnosis of adenomyosis, 'deep endometriosis' (e.g. endometriosis in the rectovaginal septum or in the uterosacral ligaments), and in the diagnosis of extremely rare types of ectopic pregnancy (e.g. in the spleen, liver or retroperitoneum).

Prognosis of very large first-trimester hematomas

OBJECTIVE

The aim of this study was to evaluate the outcome of pregnancies complicated by very large hematomas in the first trimester.

METHODS

Between January 2001 and January 2006, 8085 patients between 5 and 14 weeks' gestation underwent routine first-trimester ultrasonographic examinations at our practice. Of these, 30 patients had a "very large" (> 50% of the gestational sac) intrauterine hematoma. These 30 patients were further classified according to pregnancy outcome (normal or adverse), maternal age, vaginal bleeding, crown-rump length, gestational age at diagnosis of the hematoma, and position and location of the hematoma. P < .05 was considered statistically significant.

RESULTS

Six patients were excluded (4 were still pregnant, and 2 were lost to follow-up), leaving 24 patients eligible for analysis, of which 11 (46%) had adverse outcomes and 13 (54%) had normal outcomes. The group with adverse outcomes had a significantly lower gestational age at diagnosis than the second group (7 weeks [range, 5.7-8.4 weeks] versus 8.4 weeks [range, 6.2-14 weeks]; P = .0227), but crown-rump length, vaginal bleeding, and position and location of the hematoma were similar.

CONCLUSIONS

Very large hematomas were associated with adverse outcome in 46% of the pregnancies. Vaginal bleeding was not associated with a poor prognosis. Neither position nor location of the placental hematoma was related to the outcome; however, when the hematoma was diagnosed at an early gestational age, the outcomes were worse.