Shraga Rottem

Changes in uterine blood flow during human pregnancy.

A transvaginal duplex Doppler ultrasonography system was used to measure blood flow characteristics in the ascending uterine artery before and during pregnancy. The system uses a 5 MHz Doppler transducer coupled to a 6.5 MHz imaging probe. There was a steady increase in volume flow rate in the left ascending uterine artery from a mean of 94.5 ml/min before pregnancy to a mean of 342 ml/min in late gestation (reflecting a 3.5-fold increase). With the assumption of equal flow on both uterine arteries, the fraction of the cardiac output that is distributed to these vessels was calculated to be 3.5% in early pregnancy and to reach 12% near term. The mean diameter of this vessel in the nonpregnant state was 1.6 mm, increasing to 3.7 mm toward term. The resistance to flow, expressed as the peak systolic to end-diastolic flow velocity ratio, declined from a mean of 5.3 in the nonpregnant state to a mean of 2.3 near term. These changes reflect the perpetual growth and development of the uteroplacental circulation, which provides the metabolic demands of the growing fetus throughout gestation.

First-trimester and early second-trimester diagnosis of nuchal cystic hygroma by transvaginal sonography: Diverse prognosis of the septated from the nonseptated lesion

Fetal cystic hygroma is a congenital malformation of the lymphatic system appearing as a single or multiloculated fluid-filled cavity, most often in the nuchal region. The malformation is believed to arise from failure of the lymphatic system to communicate with the venous nuchal system. Sometimes the lesion progresses to fetal hydrops, causing fetal death. To further delineate the cause and natural history of this disorder, we have prospectively studied eight cases of cystic hygroma of the neck, detected at gestational ages of 9 to 15 weeks by transvaginal sonography. Three of the eight fetuses survived (37.5%) and were normal at birth. Either hydrops fetalis or intrauterine fetal death occurred in the other five fetuses. In one of these five, therapeutic abortion was induced because of trisomy 21. In another fetus of these five, trisomy 18 was diagnosed by amniocentesis. This pregnancy ended in intrauterine fetal death. The ultrasonic evaluation of the cystic hygromas revealed that those that were reabsorbed in the three ultimately normal viable fetuses were nonseptated cysts, whereas all the four cystic hygromas ending in fetal death or associated with aneuploidy were septated, multilocular hygromas. In another fetus with nonseptated hygroma, nonimmune hydrops developed, which resulted in premature delivery and early neonatal death.

The technique of transvaginal sonography with the use of a 6.5 MHz probe.

Ultrasonography has become an important tool in infertility and obstetric practice. Its use in gynecology, while effective, has been less. This article describes the use of a high-frequency 6.5 MHz probe specially designed for intravaginal use. The technique is presented, along with a description of its uses and findings by organ. Patient acceptance has been universal. Its high resolution makes this technique more useful in general gynecologic practice.

Uterine artery flow velocity waveforms and color flow imaging in women with perimenopausal and postmenopausal bleeding. Correlation to endometrial histopathology.

We performed Doppler studies of the uterine artery in 85 women with postmenopausal and perimenopausal bleeding. Sixty‐six women had non‐malignant changes and 19 women had malignant changes on histologic examination of the endometrium. Uterine fibroids were detected in 30 women. When malignant changes were detected in the endometrium, uterine artery resistance index was always below 0.83. The mean uterine artery resistance index was significantly lower in the group of women with pathologic changes of the endometrium (RI = 0.77±0.03) compared to the group with non pathologic changes (RI=0.85±0.08 p<0.01), excluding the women with uterine fibroids. The lowest mean resistance index in the uterine artery was observed in the group of women with uterine fibroids (RI = 0.60 ± 0.09 p< 0.001). In five of six patients with endometrial carcinoma blood vessels were detected around the myometrium by using color flow imaging. Their RI was always less than 0.5. In five patients, blood vessels were detected in uterine fibroids but their RI was always more than 0.5. All six women with endometrial carcinoma but only seven of 13 women with endometrial hyperplasia, had endometrial thickness greater than 5 mm. Doppler velocimetry of the uterine artery carries a high sensitivity (100%) in detecting pathological changes of the endometrium in patients presenting with postmenopausal or perimenopausal bleeding. The presence of high resistance in this vessel, may allow a more conservative approach in this group of patients.

Basic principles and clinical applications of the transvaginal Doppler duplex system in reproductive medicine

ConclusionNew technological advances in the field of ultrasound imaging and in Doppler signal acquisition and analysis help to open new fields of investigation in reproductive medicine. One such example is the recent introduction of the transvaginal Doppler duplex system, which can be applied as a sensitive, noninvasive “flow probe” to evaluate hemodynamic changes in pregnant and nonpregnant patients. Another important development is the application of Doppler color flow mappping, which facilitates vessel recognition and localization. Such instruments are expensive at present and are mostly limited for research purposes. Further developments are likely to emerge once new instruments and new methods of data analysis become available. Further increases in image resolution and improved Doppler signal generation and processing will enable more accurate flow measurements. Another important field is invasive flow measurement, which could be developed for intraoperative and intravascular investigations, based on specialized probes and catheter-mounted transducers. At present further investigations are required for defining the normal ranges in the population and for establishing abnormal patterns. Once causative mechanisms are defined, various treatments may be offered, while monitoring the changes using the techniques described here.