Time-averaged Maximum Velocity Research Articles

Intraobserver variation in transvaginal Doppler blood flow measurements in benign ovarian tumors.

Intraobserver variation in transvaginal color Doppler ultrasound measurements in ovarian tumors was evaluated in 20 women selected from a group of patients undergoing surgical exploration for an ovarian lesion. Only those cases who were suspected of having a benign ovarian tumor other than a unilocular simple cyst were recruited. Pulsatility index (PI), resistance index (RI), peak systolic velocity (PSV) and time-averaged maximum velocity (TAMXV) were measured from intratumoral arteries in two repeat ultrasound sessions by the same observer. In each session, only two vessels with optimum Doppler signals were investigated. The repeatability of the measurements was studied by calculation of the within-subjects standard deviation (SD), the value below which the difference between the repeat measurements will lie with a probability of 0.95, the coefficient of variation (CV) and the intraclass correlation coefficient (intra-CC). The CV was 15% for the PI, 13% for the RI, 17% for the PSV and 23% for the TAMXV when the average value from two vessels was used. The corresponding intra-CC values were 0.86, 0.83, 0.96 and 0.90, respectively. In contrast, when a lowest (PI or RI) or a highest (PSV or TAMXV) value was preferred, the CV increased to 25% for the PI, to 18% for the RI, to 28% for the PSV and to 33% for the TAMXV. Similarly, the intra-CC values decreased. All in all, the averaged PI and RI measurements in intratumoral arteries were considered to be reliable. Averaged PSV and TAMXV measurements had high CV figures, raising some doubt as to the consistency of these variables. Averaged index values were more consistent than the extreme (lowest or highest) values.

Blood flow changes in the ovarian and uterine arteries during the normal menstrual cycle

OBJECTIVE: Our purpose was to study the hemodynamic changes in the uterine and intraovarian vessels during the normal menstrual cycle and to relate the vascular changes to hormonal index values. STUDY DESIGN: Seven women who had bilateral tubal patency, a normal pelvis on laparoscopy, and regular ovulatory cycles underwent serial transvaginal ultrasonography on menstrual cycle day 2, daily from estimated day of ovulation –6, hourly from estimated day of ovulation –2, or when the mean follicular diameter was >16 mm (whichever was earlier) until 6 hours after follicular rupture and once 7 days after follicular rupture. At each scan uterine and intraovarian blood flow was assessed with transvaginal color Doppler ultrasonography and serum concentrations of follicle-stimulating hormone, luteinizing hormone, estradiol, and progesterone assessed by fluoroimmunoassay. RESULTS: In one case there was evidence of a luteinized unruptured follicle and the patient was therefore excluded from analysis. In the other six women there was spontaneous ovulation at a mean of 39 hours after the onset of the luteinizing hormone surge. On the side with the dominant follicle, follicular and ovarian stromal peak systolic blood flow velocity rose significantly during the menstrual cycle with no significant change in pulsatility index. The changes in blood flow velocity correlated significantly with changes in serum follicle-stimulating hormone, luteinizing hormone and progesterone concentrations. There were no significant changes in either blood flow velocity or pulsatility index in the contralateral ovary. Uterine artery time-averaged maximum velocity on the side of the developing ovarian follicle increased during the menstrual cycle with no significant change in the contralateral vessel. Uterine artery pulsatility index on the side of the developing follicle declined during the midluteal phase and was significantly lower than on the contralateral side. The changes in time-averaged maximum velocity correlated with the changes in serum estradiol and progesterone concentrations. CONCLUSION: The vascular changes in the wall of the dominant ovarian follicle and ovarian stroma during the menstrual cycle are consistent with activity of angiogenic-like factors. The decline in uterine artery resistance during the midluteal phase may reflect optimal vascularity for implantation of the blastocyst. (Am J Obstet Gynecol 1996;175:625-31.)

Mode of delivery and perinatal cerebral blood flow.

To ascertain whether the perinatal cerebral blood flow velocity differed between vaginally delivered appropriate for gestational age (vag. AGA) term babies, AGA babies delivered by Caesarean section (C.s. AGA), and small for gestational age (C.s. SGA) babies also delivered by Caesarean section. Forty-five babies were examined by Doppler ultrasound of the middle cerebral artery prior to and immediately after delivery, and at 1 h and 24 h after birth. The pulsatility index (PI) and time-averaged maximum velocity (TAMXV) were calculated. No differences in TAMXV were found between the vag. AGA and C.s. AGA groups at any of the four recordings. A significantly higher PI value was found in the C.s. AGA group 1 h after birth. The C.s. SGA group had lower PI values before and just after birth, but did not differ significantly from the C.s. AGA group at 1 h or 24 h after birth. The results suggest mode of delivery to have a transitory effect on cerebral vascular resistance in healthy term AGA babies. The C.s. SGA group differed in the initial recording just after birth, but later manifested similar blood flow velocities in middle cerebral artery as the C.s. AGA group.

Transvaginal Doppler examination of uteri with myomas.

The uterine arteries and arteries in the wall and core of myomas were examined with transvaginal color and spectral Doppler ultrasound in 28 premenopausal and 17 postmenopausal women with uterine myomas. Eighteen premenopausal women and 100 postmenopausal women without myomas served as the controls for uterine artery Doppler measurements. The respective median time-averaged maximum velocity and pulsatility index (PI) values for the left uterine artery were 36.1 cm/s and 1.36 in premenopausal women with myomas vs. 17.6 cm/s and 2.58 in controls; p = 0.0001. The corresponding values in postmenopausal women were 13.9 cm/s and 1.93 vs. 11.0 cm/s and 2.33; p < 0.05. PI values < 1.0 were recorded from 92% (24/26) of the myomas in premenopausal women and from 69% (11/16) of those in postmenopausal women. We conclude that uterine myomas substantially affect blood flow velocity in the uterine arteries, and that PI values < 1.0 are common in uterine myomas and do not indicate malignancy.

Ultrasound studies of vascular and morphological changes in the human uterus after a positive self-test for the urinary luteinizing hormone surge.

The aim of the study reported here was to establish complementary data for changes in uterine size, echogenicity and vascularity during the menstrual cycle relative to a positive self-test for urinary luteinizing hormone (LH) and day 1 of next menses. Thirteen volunteers (aged 23-32 years) with apparently regular menstrual cycles were recruited from the nursing staff. The plan was to examine all women by transvaginal ultrasonography with colour Doppler imaging on day 11 of the menstrual cycle. A urinary LH self-test was to be used daily until a positive result was obtained and the women were to be re-scanned daily until the dominant follicle had ruptured. All women were then to be scanned at least every 48 h (within +/- 2 h of the same time of day) until day 6 of the next menstrual cycle. Matched samples of peripheral blood were taken at the time of each scan for hormone analysis. The main outcome measures were the times of follicular rupture, a positive test result for urinary LH and the start of menses, uterine volume, cavity length, endometrial thickness and grade, pulsatility index (PI), and time-averaged and peak systolic maximum velocities in uterine and radial arteries and in subendometrial vessels. Nine women fulfilled the criteria for an ovulatory cycle, and seven provided data over the complete study. The principal changes relative to a positive urinary LH test were (i) a continued rise in endometrial thickness to days 3 and 4 (this index then remained relatively constant, but the layered appearance was lost) and (ii) a gradual decrease in the uterine arterial PI. There was a significant rise in uterine volume, cavity length and uterine arterial PI around the time of the next menses, and a fall in endometrial thickness and blood velocity in the uterine and radial arteries and subendometrial vessels. The data may have implications for the assessment of reproductive status and the design of future studies on disorders of implantation or menstruation.

Uteroplacental and luteal circulation in normal first-trimester pregnancies: Doppler ultrasonographic and morphologic study

OBJECTIVE: Our purpose was to establish reference data representative of normal findings at transvaginal color and spectral Doppler ultrasonographic examination of the uteroplacental and luteal circulation in the first trimester and to relate the Doppler findings to morphologic data. STUDY DESIGN: A cross-sectional study was performed of 64 uncomplicated pregnancies of 5 to 11 completed gestational weeks terminated by legal abortion for psychosocial reasons. Doppler examinations of the main uterine arteries, subchorionic arteries, intrachorionic area, and corpus luteum were performed. Abortion material was examined morphologically. RESULTS: In the uterine and subchorionic arteries blood flow velocity increased and pulsatility index values decreased with advancing gestation. Arterial or venous Doppler shift spectra were recorded from the intrachorionic area in 91% (58/64) of the pregnancies. Intrachorionic arterial blood flow velocities and pulsatility index values were low and did not change with advancing gestation; the mean time-averaged maximum velocity, peak systolic velocity, and pulsatility index values were 4.6 cm/sec, 6.0 cm/sec, and 0.47, respectively. Morphologic examination showed trophoblast plugs in the spiral arteries to consistently manifest multiple spaces containing red blood cells at the choriodecidual junction. CONCLUSION: Blood flow velocity in the uteroplacental arteries increases and pulsatility index values decrease with advancing gestation, indicating a steady increase in uterine perfusion during the first trimester. Our findings suggest intervillous flow to be present as early as the first trimester. (A M J O BSTET G YNECOL 1996;174:768-75.)

A comparison of intratumoural indices of blood flow velocity and impedance for the diagnosis of ovarian cancer

The aim was to assess the value of blood flow velocity indices in an ultrasound-based test to discriminate between malignant and benign adnexal tumours. Fifty-one women (35 premenopausal and 16 postmenopausal) with persistent adnexal masses were scanned prior to surgery using transvaginal sonography with colour Doppler imaging. Intratumoural flow velocity waveforms obtained by pulsed Doppler sonography were used to determine the time averaged maximum velocity (TAMXV), peak systolic velocity (PSV), pulsatility index (PI) and resistance index (RI). The tumours were classified by histologic criteria (42 benign, 1 borderline and 8 malignant tumours). Two of the malignant and the single borderline tumour were stage I, five were stage III and one was stage IV. Detectable blood flow signals were found in all malignant and borderline tumours and in 33 of 42 (78.6%) of the benign tumours. TAMXV was the best parameter for discrimination of benign and malignant adnexal pathology and at a cut-off value of TAMXV ≥12 cm/s to indicate malignancy, the sensitivity and specificity were 88.9% and 81.0%, respectively. At the same sensitivity level, this gave a better specificity than the PI ≤0.90 (specificity 61.9%, P = 0.036), RI ≤ 0.60 (specificity 54.8%, P = 0.010) and PSV ≥ 16 cm/s (specificity 71.4%, P = 0.121). Discrimination between benign and malignant tumours was improved further by using two criteria rather than one. When the two criteria of a TAMXV of ≥12 cm/s and a PI ≤ 1.0 were applied simultaneously, the tumours could be characterised with a sensitivity of 88.9% and a specificity of 88.1%. Therefore, intratumoural PSV and TAMXV could be used to discriminate between benign and malignant adnexal tumours better than values for PI and RI. The best discrimination was achieved by using a combination of cut-off values for velocity and impedance parameters as two criteria to define malignancy.

Development of quantitative Doppler indices for uteroplacental and fetal blood flow during the third trimester

The aim of our study was to describe the development of uteroplacental and fetal blood flow during the third trimester. Doppler examination was carried out on 393 uncomplicated pregnancies with uncomplicated term delivery. Using a pulsed color Doppler, we calculated the maximum systolic, mean and maximum end-diastolic velocity after correcting the angle of insonation. Patients under tocolysis or other medication influencing blood flow parameters were excluded from this cross-sectional study. Summarizing the results gained by Doppler ultrasound investigation of the uteroplacental and fetal blood vessels, we created quantiles as quantitative Doppler indices for the maximum systolic, mean (TAMX = time averaged maximum velocity) and maximum end-diastolic velocity. The following conclusions could be drawn: (1) resistance to the blood flow in the maternal portion of the placenta does not change during the third trimester; (2) resistance to the blood flow on the fetal side of the placenta decreases up to week 42 of gestation; (3) cerebral vascular resistance decreases constantly up to gestational week 42; and (4) vascular resistance to the blood flow of the kidney decreases only slightly during the third trimester. This study offers clinically important values for quantitative Doppler flow velocimetry for the first time. We hope that our findings improve the usefulness of Doppler ultrasound as a diagnostic tool in obstetrical management.

Interobserver agreement in the results of Doppler examinations of extrauterine pelvic tumors

The aim of this study was to evaluate interobserver agreement in the results of Doppler measurements of peak systolic velocity (PSV), time-averaged maximum velocity (TAMXV) and the color content of tumor scans in extrauterine pelvic tumors. The results of transvaginal color and spectral Doppler examinations of 66 extrauterine pelvic masses obtained by two observers experienced in ultrasonography were compared. Each observer aimed to obtain the highest possible Doppler shift from arteries in the wall, septa and solid parts of each tumor. Tumor vascularization was assessed in terms of the 'tumor color score', i.e. the color content of the Doppler scan as rated for the tumor as a whole by each observer on a visual analog scale. The tumors were classified according to arbitrarily chosen cut-off limits for the tumor color score, the highest tumor TAMXV and the highest tumor PSV. Inter-class correlation coefficient values for TAMXV and PSV were < or = 0.75, whereas that for tumor color score was 0.89. Interobserver agreement was complete for the detection of color in tumors (Kappa value 1.0), excellent for the recording of arterial Doppler shift spectra from tumors (Kappa value 0.82), and moderate or good for classifying tumors based on cut-off limits for TAMXV, PSV (Kappa values ranging from 0.44 to 0.67) and tumor color score (Kappa values ranging from 0.59 to 0.66).(ABSTRACT TRUNCATED AT 250 WORDS)

Transvaginal gray-scale and Doppler ultrasound examinations of the uterus and ovaries in healthy postmenopausal women.

The aim of this study was to elicit reference data representative of normal findings at transvaginal gray-scale and Doppler ultrasound examination of the uterus and ovaries in postmenopausal women. A total of 144 asymptomatic postmenopausal women with normal findings at clinical gynecological examination were included in the study. They underwent transvaginal sonography including Doppler measurements of blood flow velocity in the uterine and ovarian arteries. Ninety-eight (68%) women had a normal uterus and normal or non-visible ovaries at ultrasound examination, 23 (16%) had small uterine myomas but normal or non-visible adnexa, 19 (13%) had small adnexal cysts but a normal uterus, and four (3%) had both small myomas and small adnexal cysts. The median time-averaged maximum velocity (TAMXV) and pulsatility index (PI) values for the right and left uterine artery of normal uteri (n = 117) were 10.4 cm/s (range 2.2-43.0) and 10.6 cm/s (2.9-30.8), and 2.33 (0.97-5.13) and 2.35 (0.98-4.58), respectively. Median volumes of the normal right (n = 93) and left ovaries (n = 90) were 1.3 cm3 (0.4-3.7) and 1.2 cm3 (0.4-3.0), respectively, and median TAMXV and PI values for the stromal arteries in the normal right (n = 53) and left ovaries (n = 54) were 2.1 cm/s (1.3-4.6) and 2.3 cm/s (1.1-7.3), and 1.31 (0.65-2.61) and 1.26 (0.63-1.85), respectively. Our results provide a basis for gray-scale and Doppler ultrasound studies of pathological conditions in the female pelvis after the menopause.

Ovarian stromal blood flow in women with polycystic ovaries--a possible new marker for diagnosis?

Blood flow changes in the ovarian stroma of women embarking on in-vitro fertilization treatment were assessed on day 2 or 3 of the menstrual cycle using colour and pulsed Doppler ultrasound. Women were divided into three groups: group 1, 63 women with regular, ovulatory menstrual cycles and normal ovaries on ultrasound scan; group 2, 13 women similar to group 1 but with polycystic ovaries (PCO) on ultrasound scan; and group 3, 12 women with biochemical evidence of previous anovulatory cycles and/or oligomenorrhoea and/or elevated serum luteinizing hormone concentrations (> 10 IU/l) in the early follicular phase together with PCO on ultrasound scan. A subjective assessment of the intensity and quantity of coloured areas in the ovarian stroma appeared to be greater in both groups 2 and 3 compared with group 1. Mean (SEM) ovarian stromal peak systolic blood flow velocity (Vmax) was 16.88 (1.79) and 16.89 (2.36) cm/s in groups 2 and 3 respectively. These velocities were significantly greater than the mean (SEM) ovarian stromal Vmax of group 1; 8.74 (0.68) cm/s (P < 0.001). Mean (SEM) ovarian stromal time averaged maximum velocity (TAMX) was 10.55 (0.91) and 10.89 (1.80) cm/s in groups 2 and 3 respectively, both significantly greater than mean ovarian stromal TAMX of group 1, (P < 0.001). There was no significant difference in pulsatility index (PI) between the three groups. There thus appears to be significantly greater ovarian stromal blood flow velocity in women with polycystic ovaries as detected by colour and pulsed Doppler ultrasound. Increased ovarian stromal blood velocity may be a new parameter to assist in the ultrasound diagnosis of PCO.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiology: Description of circadian rhythm in uterine artery blood flow during the peri-ovulatory period

Uterine artery blood flow was assessed by transvaginal colour and pulsed Doppler ultrasound prospectively in six women during the peri-ovulatory period. All patients had regular ovulatory menstrual cycles and a mid-luteal serum progesterone consistent with spontaneous ovulation in the preceding cycle. Each patient underwent serial transvaginal ultrasound examination and Doppler assessment of blood flow in the uterine arteries. When the mean follicular diameter was > 16 mm or day -2 from the estimated day of ovulation was reached, patients were scanned at 6 hourly intervals at 0600, 1200, 1800 and 2400 h until follicular rupture. The pulsatility index (PI) and time averaged maximum velocity (TAMX) were calculated as Doppler indices of impedance to blood flow and velocity respectively. A venous blood sample was taken at each visit for subsequent hormonal analysis. The mean uterine artery PI showed a marked daily fluctuation with a nadir occurring most commonly at 0600 h. A comparison between the mean PI values at 0600 and 1800 h showed significantly lower results at 0600 h in both dominant (P < 0.05) and nondominant (P < 0.02) uterine arteries. Furthermore, mean uterine artery TAMX showed daily fluctuations with peak values most commonly occurring at 0600 h with the nadir occurring during the afternoon and late evening. There was no temporal relationship between the fluctuations in PI and changes in luteinizing hormone, follicle stimulating hormone, oestradiol or progesterone concentrations. These observations suggest that there is a circadian rhythm in uterine artery blood flow during the peri-ovulatory period which appears to be independent from the hormonal changes.

Circadian variation in uterine artery blood flow indices during the follicular phase of the menstrual cycle.

We investigated for the presence of circadian variation in uterine artery blood flow indices during the late follicular phase of the menstrual cycle. Twenty women with regular menstrual cycles underwent transvaginal color Doppler assessment of blood flow in the uterine arteries on two occasions precisely 12 h apart on the same day in the follicular phase. Ultrasound examinations were performed between 06.00 and 10.00 and repeated between 18.00 and 22.00. Indices of uterine artery blood flow included the pulsatility index (PI) and the time-averaged maximum velocity (TAMX). The changes in PI and TAMX were related to variations in serum concentrations of estradiol and luteinizing hormone (LH). We noted a significantly higher PI and lower TAMX in the evening compared to the morning values, p < 0.001 and p = 0.01, respectively. There was no significant change in estradiol or LH concentrations between morning and evening (p > 0.05). There appears to be a circadian rhythm in uterine artery blood flow occurring independently of these hormonal parameters. The circadian changes in PI and TAMX may be larger than the previously described effects of hormones on these parameters. The accurate interpretation of uterine artery blood flow indices should take these time-related fluctuations into account.

Transvaginal Doppler examination for the differential diagnosis of solid pelvic tumors.

To evaluate the ability of transvaginal Doppler examination to discriminate between different types of solid pelvic tumors, 55 women scheduled for laparotomy because of a solid pelvic mass underwent transvaginal sonographic examination, including color and spectral Doppler techniques. Arteries in the wall and core of each mass were examined. The histological diagnoses were as follows: uterine myoma (n = 28), malignant ovarian tumor (n = 19), and benign ovarian tumor (n = 8). Pulsatility index values tended to be highest in the malignant ovarian tumors, albeit with considerable overlap with respect to the other tumor types. The respective median pulsatility index values for arteries in the wall and core of the malignant ovarian tumors were 0.93 and 0.87, versus 0.65 and 0.51 in the benign ovarian tumors and 0.80 and 0.67 in the myomas. Time-averaged maximum velocity did not differ significantly among the three types of tumor. We conclude that Doppler measurement of blood flow velocity in tumor arteries does not add substantial information to the differential diagnosis between myomas and benign or malignant solid ovarian tumors.

Effect of a prostaglandin E 1 analogue (gemeprost) on uterine and luteal circulation in normal first trimester pregnancies. A Doppler velocimetry study

To evaluate the effects of gemeprost on utero-placental and luteal circulation and on the embryo/fetus in normal first trimester pregnancies. Sixty-seven women with a normal first trimester pregnancy requesting termination of pregnancy for psychosocial reasons were randomly allocated to pre-operative treatment with vaginal suppositories containing placebo or gemeprost. The women underwent transvaginal color and spectral Doppler ultrasound examination before the application of the suppository, 4 h after the application of the suppository but before the abortion, and on the seventh post-operative day. Blood flow velocities in the uterine and subchorionic arteries, the intrachorionic area and arteries in the wall of the corpus luteum and the embryonic/fetal heart rate were measured. The median value for pulsatility index (PI) in the dominant uterine artery was 2.4 before treatment with gemeprost and 8.5 4 h after treatment ( P = 0.0006); the corresponding values for time-averaged maximum velocity (TAMXV) being 27 cm/s and 10 cm/s ( P = 0.0006). Four (14%) of 28 embryos/fetuses in the gemeprost group were dead 4 h after treatment with gemeprost and the median heart rate of those still alive was significantly lower than before treatment (130 vs. 163 bpm; P = 0.003). In the placebo group, the results for the uterine arteries and the embryonic/fetal heart rate did not differ significantly between the first and second ultrasound examinations. The median values for PI and TAMXV in the arteries of the corpus luteum wall at the first ultrasound examination were 0.71 and 18 cm/s, respectively, in the placebo group and 0.71 and 20 cm/s, respectively, in the gemeprost group. These values remained almost unchanged at the second and third ultrasound examinations in both groups. Gemeprost has profound effects on utero-placental circulation in the first trimester and can induce embryonic/fetal bradycardia and sometimes embryonic/fetal demise. It has no unequivocal effect on luteal circulation.

Reproducibility of Doppler blood flow velocity measurements in the uterine and ovarian arteries of postmenopausal women

Objective: To assess the reproducibility of transvaginal Doppler measurements in the uterine and ovarian arteries of postmenopausal women. Methods: Intra-observer repeatability of Doppler measurements of the pulsatility index (PI) and time-averaged maximum velocity (TAMXV) in the uterine arteries was assessed in examinations of 22 postmenopausal women, three replicate Doppler measurements being made by one observer from one of the uterine arteries. Inter-observer agreement in Doppler measurements of PI and TAMXV in the uterine and ovarian arteries was assessed by comparing the results of Doppler measurements made by two independent investigators in 20 and 15 women, respectively. Results: Intra-observer reproducibility of Doppler measurements was good, intra-class correlation coefficients ranging from 0.79 to 0.96 and coefficients of variation from 7 to 22%. Inter-observer agreement was acceptable for the left uterine artery, the inter-class correlation coefficient being 0.89 for the PI and 0.78 for the TAMXV, and the respective coefficients of variation 10 and 22%. Inter-observer reproducibility of Doppler measurements in arteries in the ovarian stroma was unsatisfactory (inter-class correlation coefficients <0.75; coefficients of variation ≥ 22%). Conclusions: The reproducibility of Doppler measurements in the left uterine artery of postmenopausal women would probably allow the detection of small to moderate differences in PI and TAMXV, but inter-observer reproducibility of Doppler measurements in intra-ovarian arteries is not good enough to allow the detection of small differences in PI or TAMXV.

Reproducibility of Doppler measurements of blood flow velocity in the uterine and ovarian arteries in premenopausal women

Intra- and interobserver reproducibility of Doppler measurements of the pulsatility index (PI) and time-averaged maximum velocity (TAMXV) in the uterine and ovarian arteries were evaluated in examinations of healthy premenopausal women. Each woman underwent reproducibility measurements once in the late follicular phase and once in the midluteal phase. Intraobserver repeatability was assessed in examinations of 12 women, three replicate Doppler measurements being made by one observer in the same vessel. Interobserver agreement was assessed by comparing the results of Doppler measurements made by two investigators in 11 women. The intraclass correlation coefficient (Intra-CC) was 0.78 for the TAMXV in the dominant uterine artery in the follicular phase and 0.82 for the PI in the wall of the dominant follicle. For all other measurements the Intra-CC was <0.75, indicating poor reproducibility. The interclass correlation coefficient (Inter-CC) was >0.75 (0.79 to 0.88) for the PI and TAMXV in the dominant uterine artery in the follicular phase and for the PI of both uterine arteries in the luteal phase. For all other measurements the Inter-CC was <0.75.

Doppler C0&lt;sub&gt;2&lt;/sub&gt; and Diamox Test: Decreased Reliability by Changes of the Vessel Diameter?

Transcranial Doppler sonography measures cerebrovascular reserve capacity by comparing blood flow velocities in basal cerebral arteries before and after vasostimulation by different methods. This presupposes constancy of the vessel diameter insonated. To investigate this assumption 18 subjects underwent a CO₂ (inhalation of 5% CO₂ respectively hyperventilation) and a Diamox test (i.v. injection of 1 g acetazolamide). Since the diameter of the middle cerebral artery in humans cannot be assessed sonographically with sufficient accuracy, we used the diameter of the internal carotid artery as a measure and made a comparison of the flow velocities in both vessels. The relative changes in time-averaged maximum velocity in both vessels showed a close correlation with a regression coefficient of 0.96 in the CO₂ test and 0.87 in the Diamox test. Since, on the other hand, no significant changes in the lumen of the internal carotid artery could be found during the CO₂ test (r = 0.99), our results support the assumption of at least a fairly constant diameter of the middle cerebral artery during moderate hyper- respectively hypocapnia and after intravenous injection of 1 g acetazolamide.

Assessment of fetal compromise by Doppler ultrasound investigation of the fetal circulation. Arterial, intracardiac, and venous blood flow velocity studies.

Doppler studies of the fetal circulation in intrauterine growth retardation and hypoxia have demonstrated a compensatory redistribution of arterial blood flow with increased flow to the cerebrum and myocardium and decreased flow to the periphery. The aim of this study was to evaluate the significance of changes in fetal venous blood flow waveforms in high-risk pregnancies and to investigate the time relation between alterations in venous and arterial Doppler waveform indices in compromised fetuses. The cross-sectional study consisted of 108 high-risk singleton pregnancies between 23 and 42 weeks' gestation without fetal chromosomal abnormalities or major malformations. Blood flow velocity waveforms were recorded from the umbilical arteries, descending thoracic aorta, middle cerebral artery, tricuspid and mitral ventricular inflow, ductus venosus, inferior vena cava, and the right hepatic vein. The mean velocity and pulsatility index were calculated for arterial vessels, the E/A ratio for atrioventricular blood flow, and peak forward velocities during ventricular systole and early diastole, the lowest forward velocity or peak reverse velocity during arterial contraction, and time-averaged maximum velocity for venous vessels. Two ratios for venous waveforms, one of which is the equivalent of the pulsatility index, were calculated. Fetal biophysical assessment was based on a computerized cardiotocogram and the biophysical profile score. The compromised group consisted of 37 fetuses delivered by cesarean section for an abnormal heart rate trace (n = 21) or severe preeclampsia (n = 9) or which died in utero (n = 7) within 10 days of their last Doppler investigation. This group showed significant alterations in arterial and venous flow velocity waveforms but not in atrioventricular inflow. Additionally, to find out whether venous Doppler investigation may help to detect a worsening of the situation in fetuses already showing arterial blood flow redistribution, we analyzed the data of these fetuses separately. The 41 fetuses that had an aorta/middle cerebral artery pulsatility index ratio > 95th percentile were divided into compromised and non-compromised groups according to their biophysical assessment and whether or not they developed fetal distress (cesarean section for abnormal heart rate trace or intrauterine death). The mean values for Doppler parameters of the compromised groups differed significantly from the noncompromised groups in all venous vessels, whereas differences on the arterial side were much less pronounced. Velocity ratios of venous waveforms were significantly higher, and absent or reverse flow in the ductus venosus with atrial contraction indicated a poor prognosis, with a perinatal mortality of 5 out of 8. Fetal compromise is associated with significant alterations in the fetal arterial and venous circulation. Significant changes in venous Doppler waveforms develop due to increased afterload and perhaps myocardial failure in late deterioration after fetal arterial redistribution is established and seem to be closely related to abnormal biophysical assessment findings. Therefore, Doppler investigation of the fetal venous circulation may play an important role in monitoring the redistributing growth retarded fetus and thereby may help to determine the optimal time for delivery.

Blood flow velocity in the uterine and ovarian arteries during menstruation.

Eleven healthy women with regular menstrual cycles were examined with a combination of two-dimensional real-time ultrasound and color and spectral Doppler techniques on the 7th day after follicular rupture, and on the 1st, 2nd, 3rd and 4th days of menstrual bleeding. Both uterine arteries, arteries in the stroma and hila of both ovaries, in the wall of the largest follicle of the non-dominant ovary and in the wall of the corpus luteum were examined with the Doppler technique. The pulsatility index (PI) and the time-averaged maximum velocity were calculated. In the uterine arteries, the PI was highest on the first day of menstrual bleeding (median PI 3.2 for the dominant and 3.0 for the non-dominant uterine artery), after which it decreased to its lowest values on the second day (median PI 2.1 and 1.8, respectively) and third day (median PI 2.2 and 2.1, respectively). The time-averaged maximum velocity reached its highest value on the second and third days of menstruation. The corpus luteum was still visible on the first day of menstrual bleeding in all women, and on the second day in five. It was indistinguishable on the third and fourth days of menstruation in all women. In the dominant ovary, the time-averaged maximum velocity of flow in the arteries in the ovarian hilum decreased during menstrual bleeding and was lower during menstruation than in the preceding luteal phase. In the non-dominant ovary, neither the PI nor the time-averaged maximum velocity manifested any consistent changes during the period studied. We conclude that substantial changes in PI and time-averaged maximum velocity occur in the uterine arteries and in the arteries of the dominant ovary during menstruation.