Transvaginal Transducer Research Articles

Pseudoprognathism—an auxiliary ultrasonographic sign for transvaginal ultrasonographic diagnosis of cleft lip and palate in the early second trimester

Cleft lip and palate have been diagnosed antenatally only in the late midtrimester or at later gestational ages, when it is too late for pregnancy termination. The diagnosis of fetal cleft lip was made in three low-risk nulligravid women at 14 to 16 weeks of gestation by systematic screening with a 6.5 MHz transvaginal transducer and was confirmed by postabortal examination.

Pseudoprognathism—An auxiliary ultrasonographic sign for transvaginal ultrasonographic diagnosis of cleft lip and palate in the early second trimester

Cleft lip and palate have been diagnosed antenatally only in the late midtrimester or at later gestational ages, when it is too late for pregnancy termination. The diagnosis of fetal cleft lip was made in three low-risk nulligravid women at 14 to 16 weeks of gestation by systematic screening with a 6.5 MHz transvaginal transducer and was confirmed by postabortal examination. Cleft lip and palate have been diagnosed antenatally only in the late midtrimester or at later gestational ages, when it is too late for pregnancy termination. The diagnosis of fetal cleft lip was made in three low-risk nulligravid women at 14 to 16 weeks of gestation by systematic screening with a 6.5 MHz transvaginal transducer and was confirmed by postabortal examination.

Transvaginal ultrasonic assessment of the early fetal brain.

The introduction of high resolution transvaginal transducers has expanded our knowledge of the first and early second-trimester fetus. This article describes transvaginal assessment of normal brain development. The feasibility of early detection of various fetal central nervous anomalies, such as anencephalus, exencephalus, hydrocephalus, Dandy Walker syndrome and myelomeningocele is described.

Comparison of implantation and early development of human embryos fertilized in vitro versus in vivo using transvaginal ultrasound.

Several reports in the literature suggest delayed implantation of in vitro-fertilized human embryos compared to in vivo-fertilized eggs. The use of high-frequency transvaginal transducers for early detection of pregnancy has allowed the identification of the gestational sac with very low serum human chorionic gonadotropin (beta-hCG) levels. Thus, the present study evaluated whether retarded implantation can be identified using this novel technology. We studied 13 single pregnancies after in vitro fertilization (IVF) and 14 pregnancies after artificial insemination either by husband (n = 6) or donor (n = 8). In the IVF patients, oocytes were retrieved 35 hours after hCG administration. Embryo transfer occurred approximately 48 hours after retrieval. Artificial insemination was performed 24 and 48 hours after hCG administration. Transvaginal ultrasound scans and serum beta-hCG levels were evaluated every 3 days starting day 12 post-hCG administration. Serum beta-hCG levels rose in parallel when in vitro- and in vivo-fertilized embryos were compared. Similarly, there was no difference between groups in the mean time needed to detect early embryonic structures, such as the embryonic sac, yolk sac, and heartbeats, or the growth rate of the gestational sac. In conclusion, there was no difference in detecting implantation and early embryonic development of human embryos fertilized in vivo versus in vitro as ascertained by ultrasound scans and serum beta-hCG levels. An embryonic sac is detected 23-24 days after hCG administration in pregnancies achieved by assisted reproductive techniques.

Embryonic Heart Rate and Age

This study used linear regression analysis to show that embryonic heart rate (EHR) can be used in the clinical setting to provide an estimate of embryonic age that correlates well with the fetal crown-rump length age (CRL; r = 0.856). A regression was performed on data from 275 examinations in which an embryonic heart rate was recorded before the ninth menstrual week from a cross-sectional population of 1,136 examinations throughout pregnancy. In this analysis, EHR was used as the independent variable and CRL as the dependent variable to yield the following formula for CRL age in menstrual days: CRL Age (menstrual days) = 8.18 + 0.285 EHR. Based on this result, a rounded version of the formula was sought that would provide essentially the same estimated fetal age as the regression formula for the range of EHR that occurred in the sample (84-193 beats/min) yet allow for a simpler computation. Within that range of EHR, the following clinical versions of the regression formula were found to produce results that did not differ significantly from the original formula: Days of Gestation = 0.3 EHR -8 and Menstrual Days Age = 0.3 EHR + 6. Both the original regression and the clinical versions yielded 95% prediction intervals of approximately ± 8 days across the range of EHR that occurred in the sample. While fetal age based on this method is only an approximation of the CRL age, the heart rate can be obtained using time/motion mode sonography when only the less accurate gestational sac diameters are available. The EHR is useful to corroborate early age estimates, especially when using transvaginal transducers and may provide useful information concerning cardiac development.

Probe Covers and Disinfectants for Transvaginal Transducers

There are a variety of probe covers and disinfectants available to minimize the risk of transferring infections to patients during transvaginal sonography (TVS). This article describes the methodology for preventing transmission of pathogenic microorganisms to patients and personnel.

The use of transvaginal ultrasonography in the diagnosis of ectopic pregnancy

Despite advances in diagnosis made by the introduction of serum beta-subunit of human chorionic gonadotropin determinations and transabdominal ultrasonography, ectopic gestations still present a major diagnostic challenge. The increased resolution of the transvaginally introduced high-frequency ultrasound transducer probes seems to solve this diagnostic problem. In this study 145 patients were referred for ultrasonographic workup because of a suspected ectopic gestation. In 38 patients a diagnosis could be made with classical transabdominal scanning. One hundred seventeen patients required additional transvaginal scanning with a 5.0 and a 6.5 MHz probe. In 98 patients a diagnosis was made during the first transvaginal scan; nine patients were rescanned within 3 days for the final diagnosis. In 56 patients, ectopic pregnancy was successfully ruled out by transvaginal scanning. Thirty-nine ectopic pregnancies were diagnosed. Only one false-positive identification was made. The sensitivity of diagnosing ectopic pregnancy by high-frequency transvaginal sonography was 100%; the specificity was 98.2%. The positive predictive value of this method was 98%, and the negative predictive value was 100%. The rate of the beating fetal heart was seen in the tube (23%). The high number of unruptured tubal pregnancies in this series (66%) suggests the possibility of an early diagnosis that may have therapeutic implications. The use of higher-frequency transvaginal transducer probes improves the diagnosis of the ectopic gestation.

Inability of sonography to detect imminent ovulation.

Sonographic visualization of the cumulus oophorus or of morphologic alterations in the wall of the dominant follicle have been reported to be reliable signs of imminent ovulation when conventional transabdominal sonography is used. To determine if transvaginal sonography could allow a more frequent and confident prediction of imminent ovulation, we prospectively monitored 22 ovulatory menstrual cycles in four women undergoing artificial insemination and in 13 normally menstruating volunteers. Scanning was done on alternate days in the periovulatory period; a 7.5-MHz transvaginal transducer was used. Despite the improved resolution obtained with transvaginal sonography, confident identification of the cumulus oophorus or of mural changes in the follicle was not possible in any of the cycles followed. No other consistent follicular characteristic predicted imminent ovulation. We conclude that confident prediction of imminent ovulation is not possible with sonographic analysis.

Transvaginale gepulste Dopplermessungen von Strömungsgeschwindigkeiten in Beckengefäßen nach Zyklusstimulation

The availability of pulsed Doppler probes has made it possible to sample signals at a chosen depth and thus to detect the flow in any selected deep vessel. Pulsed Doppler signal processing combined with real-time imaging, the so-called "duplex" method, is now also available for transvaginal transducers. The advantage of endosonographic ultrasound investigation is the possibility of using higher frequencies leading to a better resolution of anatomical structures of the small pelvis. Therefore this method allows the precise localisation of a deep vessel and the positioning of the Doppler sample volume within it. The transvaginal approach enables one to position the transducer close to the artery for better measurements. For our study we used a vaginal probe with 7.5 MHz with a pulsed Doppler equipment linked to a Combison 320 (Kretztechnik, Zipf, Austria). The integrated pulsed Doppler is not attached at a fixed angle but can be moved in the whole sector of 240 degrees. We investigated, if during follicle phase of the cycle changes of the pelvic blood flow velocity could be observed. 14 patients undergoing in vitro fertilization for sterility reasons participated in our study. We performed daily measurements of the blood-flow velocity of the ovarian artery and the internal iliac artery from cycle day 8 until the day of induction of ovulation. During cycle stimulation the observed decrease of the A/B ratio was dependent on cycle day and number of follicles. We found a decrease of the A/B ratio in the ovarian artery from 3.85 in cases with 2 follicles to 2.71 in cases with 5 follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

A close look at early embryonic development with the high-frequency transvaginal transducer

Transabdominal sonography has been, for the past two decades, used as an effective diagnostic and research tool in obstetrics. It is predominantly used in the second and third trimesters of gestation. Its use in the first trimester is relatively limited and mostly diagnostic in nature. The introduction of the higher frequency transvaginal transducer probe, with its higher resolution of the images, opens new possibilities to study early gestation. We studied embryonic development in 38 well-dated and normal pregnancies. A well-defined intrauterine gestational sac could be seen at 4 weeks and 1 to 4 days of menstrual age. The beta-subunit of human chorionic gonadotropin level at this time was 450 to 750 mlU/ml. Structures such as the yolk sac, membranes, ventricular system in the brain, musculoskeletal system, and cord were described and illustrated. Textbooks and atlases were used for comparative purposes. High-resolution transvaginal sonography will facilitate first-trimester perinatology.