First-trimester, three-dimensional transvaginal ultrasound volumetry in normal pregnancies and spontaneous miscarriages

First trimester volumetric measurements: relation with hormone levels and fetal heart rate

PURPOSE

This study aimed to examine two-dimensional ultrasound (2D US) volumetric measurements of 1st trimester structures and their relationship with β-hCG, progesterone, and fetal heart rate (FHR) in 6-10 weeks healthy pregnant women.

METHODS

Using conventional 2D transvaginal ultrasound imaging, the crown rump length (CRL), yolk sac (YS) and gestational sac (GS) were measured in 80 women. Volumetric measurements were done in 32 cases that were selected among 80 women, using a simplified formula for the volume of a prolate ellipsoid: V = 0.523 × length × height × width. The β-hCG and progesterone levels were recorded. The heart rate was determined from M-mode tracings using electronic calipers.

RESULTS

Moderately positive correlation was found between FHR versus CRL, embryo volume and GS volume. FHR increased linearly with CRL value, till CRL became 15 mm, after which it formed a plateau. β-hCG increased linearly till CRL was 15 mm, and then it formed a plateau. Progesterone level was stable till CRL became 20 mm, embryo volume 2 cm(3), after which it increased linearly.

CONCLUSION

Various ranges of relations are observed between FHR, obstetric, and hormonal measurements. The relationship between these parameters might be used for determination of abnormal growth and adverse outcomes in early pregnancy.

Transvaginal ultrasonography in first trimester of pregnancy and its comparison with transabdominal ultrasonography

OBJECTIVES

Examination of pregnant women in the first trimester with transvaginal ultrasonography with the aim to study various fetal development markers, e.g., gestation sac, yolk sac, fetal heart motion, CRL length, and fetal anatomy in both normal and abnormal pregnancies. Comparative evaluation of transvaginal ultrasonography vis-à-vis transabdominal scanning in the study of first trimester of pregnancy and its complications. To assess the relative merits and demerits of transvaginal ultrasonography in comparison with the transabdominal technique.

MATERIALS AND METHODS

The study will be conducted on 50 females patients during the first trimester of pregnancy. The study population will consist of both normal and abnormal pregnancies. These patients will be included on the basis of suspicion of or proven pregnancy of duration up to 12 weeks from LMP. The evaluation of the patients will include the following: Record of patients obstetrical history and clinical examination, record of pregnancy test and relevant investigations, ultrasonic examination of pregnancy. (a) Transabdominal ultrasound scanning will be done with moderately distended bladder by using real time scanners with low frequency probe (3/3.5 MHz); (b) transvaginal sonography will be done with the real-time sector scanner using high-frequency endovaginal probe (5/7.5 MHz), after the patient voids urine. Relevant images will be taken by using the multiformat automatic camera.

RESULTS AND CONCLUSIONS

In the study of 46 normal intrauterine pregnancies, TVS showed additional information in 36 patients (78.3%) as compared to TAS, in detection of gestation sac, yolk sac, double bleb sign, or better visualization of embryonic anatomy. In the abnormal pregnancy (n=17), TVS provided more information in 11 cases (64.9%), which included detection of embryonic demise, yolk sac, double bleb sign, or subchorionic hemorrhage. Regarding ectopic gestations (n=7), TVS gave additional information in 5 cases (71.4%) which included detection of ectopic fetal pole, yolk sac, decidual cast, adnexal mass, and fluid in cul de sac. In two cases, both TAS and TVS gave equal information. However, in 2 cases TAS demonstrated the extent of intraabdominal fluid better than TVS. The other advantages of TVS over TAS are that there is no need for the patient to have uncomfortably full bladder and time is saved from having to wait for bladder to fill. Thus, the potential preoperative patient can be kept fasting. TVS is also superior in obese patients, in patients with retroverted uterus and it also bypasses obstacles such as bone, gas filled bowel, and extensive pelvic adhesions. The limitations encountered with TVS were limited manoveuribility of probe and because of the unorthodox position and angle of the transducer, correct orientation was difficult initially.

Three and four-dimensional ultrasound in obstetrics and gynecology

PURPOSE OF REVIEW

Developments in ultrasound in general, but even more so in three-dimensional ultrasound, parallel the growth in computing power and speed of computer technology. It is not surprising, therefore, that three-dimensional ultrasound technology is constantly evolving at a fast pace. The purpose of this article is to provide enhanced diagnostic capabilities for the obstetrical and gynecologic provider.

RECENT FINDINGS

The most recent advances in three-dimensional ultrasound have to do with two main features. First, an increasingly fast acquisition speed, enabling quick sequences of fast moving organs such as the heart to be captured. Second, the increasing number of different display modalities, making understanding and analysis of normal anatomy and pathology easier for clinicians.

SUMMARY

This article highlights a selected number of clinical situations in which three-dimensional ultrasound meaningfully enhances the contribution of this fast evolving diagnostic imaging tool.

Ultrasonography in the Diagnosis and Management of Abnormal Early Pregnancy

The demand for ultrasound in early pregnancy has been increasing steadily, and is now a routine investigation for most women within the first trimester of their pregnancy. It is a safe investigation which provides reassurance, charts normal development, and identifies women with abnormal or high risk pregnancies. Transvaginal ultrasound has revolutionized the diagnosis of early pregnancy as it can detect a pregnancy at an earlier stage, whether it is normal and therefore reassuring, or abnormal and require intervention. Ultrasound is also a useful tool to aid decisions regarding management of abnormal pregnancy, such as ectopic pregnancy or miscarriage. This chapter looks at the important role ultrasound plays in the diagnosis and management of abnormal pregnancy.

Quantitative and morphological assessment of early gestational sacs using three-dimensional ultrasonography

OBJECTIVE

Our main objective was to determine the value of three-dimensional ultrasonography (3DUS) and Virtual Organ Computer-aided AnaLysis (VOCAL) in the evaluation of gestational sac volume and morphology during early pregnancy.

METHODS

Twenty-eight normal early pregnancies were scanned approximately every 2 weeks using transabdominal (TAS) and transvaginal (TVS) sonography. The VOCAL technique was used to create computerized surface models to classify gestational sac shapes as discoid or ellipsoid. Serial sac volume changes were analyzed using repeated measures ANOVA. Bland-Altman plots determined examiner bias and limits of agreement (LOA) for sac volume measurements. Gestational sac volumes were compared between the two-dimensional (2D) ellipsoid and VOCAL techniques. Differences between volume measurements were tested using the two-tailed paired t-test with statistical significance at the P < 0.05 level.

RESULTS

Each subject was examined at a mean +/- SD menstrual age of 7.9 +/- 0.6 weeks (Scan 1), 9.9 +/- 0.6 weeks (Scan 2), and 11.9 +/- 0.6 weeks (Scan 3). Sac volumes significantly increased over time from 22 +/- 11 mL at Scan 1, to 57 +/- 21 mL at Scan 2 and 116 +/- 35 mL at Scan 3 (P < 0.001). Predominant sac shapes were classified as ellipsoid (76.2%) or discoid (23.8%). Additional descriptors included: concave (60.7%), irregular (53.6%), or smooth (7.1%), with 19% of the overall group having more than one additional shape attribute. Clinically acceptable volume measurement bias and agreement were found for the following comparisons: (1) TAS versus TVS; (2) interobserver volume measurements; and (3) intraobserver volume measurements. The VOCAL technique yielded slightly greater sac volumes (64 +/- 45.4 mL) when compared to the 2D ellipsoid model (48.6 +/- 36.8 mL) (28.9 +/- 24.3% (95% limit of agreement range, - 18.7 to 76.5%), P < 0.001).

CONCLUSIONS

Reproducible sac volume measurements can be obtained using VOCAL with either TAS or TVS. Early gestational sacs variably appear as discoid or ellipsoid structures with a concave indentation from the placenta. Sac volumes can be underestimated if an ellipsoid shape is assumed. Morphological and quantitative analysis of the gestational sac may provide baseline parameters for studying patients at risk for early pregnancy failure.

Amniotic fluid volumetry by three-dimensional ultrasonography during the first trimester of pregnancy

In a longitudinal prospective study, we quantitated the amniotic fluid volume (AFV) of 25 normal fetuses by endovaginal 3-D ultrasonography (3D-US) from the 8th to the 11th week of pregnancy. AFV by 3D-US was obtained by subtracting the volumetric measurement of the embryo (EV) from the amniotic sac volume (ASV). EV and ASV were obtained by virtual organ computer-aided analysis (VOCAL), using 6 degrees of rotation. AFV increased from 5.75 to 42.96 cm(3) from the 8th to the 11th week (ANOVA, p < 0.05), with a correlation between gestational age and AFV (p < 0.001, r(2) = 98.1%). We conclude that there was an increase in AFV assessed by 3D-US. The AFV values for normal fetuses can be used for comparison with those detected in pregnancies with risk of fetal loss.

Three- and 4-dimensional ultrasound in obstetric practice: does it help?

OBJECTIVE

The purpose of this article was to review the published literature on 3-dimensional ultrasound (3DUS) and 4-dimensional ultrasound (4DUS) in obstetrics and determine whether 3DUS adds diagnostic information to what is currently provided by 2-dimensional ultrasound (2DUS) and, if so, in what areas.

METHODS

A PubMed search was conducted for articles reporting on the use of 3DUS or 4DUS in obstetrics. Seven-hundred six articles were identified, and among those, 525 were actually related to the subject of this review. Articles describing technical developments, clinical studies, reviews, editorials, and studies on fetal behavior or maternal-fetal bonding were reviewed.

RESULTS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, especially facial clefts. There is also evidence that 3DUS provides additional diagnostic information in neural tube defects and skeletal malformations. Large studies comparing 2DUS and 3DUS for the diagnosis of congenital anomalies have not provided conclusive results. Preliminary evidence suggests that sonographic tomography may decrease the examination time of the obstetric ultrasound examination, with minimal impact on the visualization rates of anatomic structures.

CONCLUSIONS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical role of 3DUS and 4DUS for the diagnosis of congenital heart disease and central nervous system anomalies. Future studies should determine whether the information contained in the volume data set, by itself, is sufficient to evaluate fetal biometric measurements and diagnose congenital anomalies.

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

The advent of high-resolution transvaginal ultrasound (TVS) has revolutionized our understanding of the pathophysiology and the management of early pregnancy failure. Knowledge of the ultrasound appearances of normal early pregnancy development and a good understanding of its pitfalls are essential for the diagnosis and management of early pregnancy failure. Ultrasound imaging has rapidly replaced all other techniques used to study normal human development in the first trimester, and ultrasound features of the early gestational sac have corroborated anatomical studies showing that the first structures to appear are the celomic cavity and the secondary yolk sac. No single ultrasound measurement of the different anatomical features in the first trimester has been shown to have a high predictive value for determining early pregnancy outcome. Similarly, Doppler studies have failed to demonstrate abnormal blood flow indices in the first-trimester uteroplacental circulation of pregnancies that subsequently end in miscarriage. Ultrasound parameters combined with maternal serum hormone levels, maternal age, smoking habits, obstetric history and the occurrence of vaginal bleeding have all been combined in multivariate analyses, with mixed results. Combined ultrasound and in-vitro experiments have demonstrated that the maternal circulation inside the placenta starts at the periphery at around 9 weeks of gestation and that this is associated with a physiological oxidative stress which could be the trigger for the formation of the placental membranes. Abnormal development of these membranes can result in subchorionic hemorrhage and threatened miscarriage with subsequent long-term consequences such as preterm rupture of the membranes and preterm labor, irrespective of the finding of a hematoma on ultrasound. In both euploid and aneuploid missed miscarriages there is clear ultrasound evidence for excessive entry of maternal blood at a very early stage inside the developing placenta resulting in oxidative stress and subsequent degeneration of villous tissue. The finding of blood flow in the intervillous space in cases of first-trimester miscarriage using color Doppler also appears to be useful in the prediction of success of expectant management. Miscarriages with blood flow within the intervillous space are up to four times more likely to complete with expectant management. TVS is considered the gold standard in the diagnosis and management of incomplete miscarriage. Expectant management of miscarriage, using ultrasound parameters to determine eligibility, could significantly reduce the number of unnecessary evacuations of the retained products of conception, depending on the criteria used.

Medical abortion at 9–13 weeks' gestation: a review of 1076 consecutive cases

OBJECTIVE

The aim of the study was to assess the use, efficacy and factors influencing the outcome of medical abortion at 9-13 weeks' gestation.

METHODS

Retrospective chart review of consecutive women undergoing medical abortion at 9-13 weeks' gestation was done.

RESULTS

A total of 1927 abortions were carried out at 9-13 weeks' gestation, of which 1076 (55.8%) were undertaken medically. Efficacy decreased with increasing gestation (p=.02). Surgical evacuation was carried out in 45 (4.2%) women including 10 (2.7%) at 64-70 days, 11 (3.3%) at 71-77 days, 10 (5.1%) at 78-84 days and 14 (8.0%) at 85-91 days of gestation (p=.02). Indications for surgery included continuing pregnancy [16 (1.5%) women], retained sac [5 (0.5%)], incomplete abortion [20 (1.9%)] and emergency curettage for bleeding [4 (0.4%)]. The number of misoprostol doses used and the induction-to-abortion interval both significantly increased with gestation (p<.001), while analgesia requirements did not vary with increasing gestation (p=.18).

CONCLUSIONS

Medical abortion at 9-13 weeks' gestation is an effective alternative to surgery. Medical methods should be offered routinely at these gestations, thus increasing women's choice.

Three-dimensional first trimester fetal volumetry: comparison with crown rump length

BACKGROUND

Ultrasonographic volumetry measurements of human fetus have become possible using three-dimensional ultrasound systems.

OBJECTIVE

To evaluate the weekly increase of fetal volume during the first trimester of normal pregnancies compared to the crown rump length and creating a first trimester fetal volume nomogram.

METHODS

Crown rump length and three-dimensional ultrasonographic volumetry measurements performed on 72 first trimester fetuses using virtual organ computer aided analysis (VOCAL).

RESULTS

A significant direct correlation (r = 0.939) was found between the calculated fetal volumes and crown rump lengths. A 6-12 weeks gestation fetal volume nomogram was proposed.

CONCLUSION

Fetal volume database in the first trimester may serve as a reference table for diagnosis of early pregnancy failure.