Academic Division of Reproductive Medicine, School of Human Development, University of Nottingham, UK
1 To whom correspondence should be addressed at: Academic Division of Reproductive Medicine, D Floor, East Block, Queens Medical Centre, Nottingham NG7 2UH, UK. e-mail: nick.fenning{at}nottingham.ac.uk
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: endometrium/menstrual cycle/power Doppler/subendometrial vascularity/three-dimensional ultrasound
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Ultrasound has been used to record endometrial development non-invasively and, whilst the characteristic architectural variations in appearance and thickness have been well described (Randall et al., 1989; Bakos et al., 1993
, 1994
), there is much less information available on how endometrial blood flow changes during the menstrual cycle. Of the studies examining uterine perfusion during the menstrual cycle, the majority have applied pulsed wave Doppler and subsequent waveform analysis of gated signals returning from specific sections of the uterine vessels (Steer et al., 1990
; Kupesic and Kurjak, 1993
; Sladkevicius et al., 1993
; Achiron et al., 1995
; Bourne et al., 1996
). These studies differ quite considerably in design both in terms of their patient populations and with respect to the vessels assessed, with most concentrating on the uterine artery rather than its downstream branches. Those studies that have reported upon blood flow within subendometrial vessels (Kupesic and Kurjak, 1993
; Sladkevicius et al., 1993
; Achiron et al., 1995
; Tan et al., 1996
) are limited by their selection of individual vessels and the assumption that they are representative of the subendometrium as a whole (Hoskins, 1990
). This has to be questioned in the light of recent work during controlled ovarian stimulation treatment that has demonstrated differential flow rates with greater impedance to flow in spiral arteries located in the posterior aspect of the uterus (Hsieh et al., 2000
). In addition, accurate and reliable measurement of blood flow velocities within any vessel requires angle correction and the generation of a well-defined, measurable waveform, both of which are difficult in spiral arteries due to their inherently low flow rates and tortuous nature (Nelson and Pretorius, 1988
; Vieli, 1990
).
Power Doppler is better suited to the study of the subendometrial vasculature as it is more sensitive to these lower velocities and is essentially angle independent (Rubin et al., 1994). Blood flow and vessel patterns are demonstrated by encoding the power in the Doppler signal rather than its mean frequency shift (Rubin, 1999
). In combination with three-dimensional ultrasound, power Doppler provides a unique tool with which to examine the uterine blood supply as a whole as opposed to analysis of individual vessels or two-dimensional planes (Downey et al., 2000
). Following data acquisition, the power Doppler signal can be quantified within any three-dimensional area, thereby permitting investigation of regional uterine blood flow. This technique has been used in the clinical setting to predict the response to controlled ovarian stimulation and subsequent outcome of assisted reproduction treatment (Schild et al., 2000
; Kupesic et al., 2001
; Kupesic and Kurjak, 2002
; Wu et al., 2003
).
Having demonstrated our own inter-observer reliability and validity of data acquisition and measurement with this technique (Raine-Fenning et al., 2002a), the aim of this study was to use three-dimensional power Doppler angiography to quantify the changes in endometrial blood flow that occur throughout the menstrual cycle.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Patient selection
The inclusion criteria were aimed at selecting a control population of women without menstrual dysfunction or obvious subfertility. Thirty women of reproductive age were recruited. The exclusion criteria were: (i) an irregular menstrual cycle; (ii) current hormonal contraception; (iii) intrauterine contraceptive device in situ; (iv) tubal sterilization; (v) a menstrual disorder necessitating any form of treatment; and (vi) history of endometriosis, infertility, pelvic inflammatory disease, recurrent miscarriage or polycystic ovarian disease
We did not specify an upper or lower age limit and did not limit the study to parous women because we wanted to investigate the effects of age and parity. In view of the evidence of a circadian rhythm in uterine blood flow (Zaidi et al., 1995), we attempted to keep the time of assessment similar in each woman whenever possible, and data acquisition was largely undertaken between 07.00 and 13.00 hours.
Approval was given by the local ethical committee, and subsequent recruitment was facilitated through local and regional advertisements. Patients were not financially rewarded for their participation in the study but did receive a small remuneration to cover travel and parking costs. Patients were interviewed by a clinician (N.J.R.F.) to determine their eligibility, outline the study and obtain written consent before enrolment.
Data acquisition
All data were acquired with a Voluson 530DTM machine (GE Kretz, Zipf, Austria) and a 7.5 MHz transvaginal probe. The ultrasound scans were conducted by one of two observers (N.J.R.F. and J.S.C.) whose inter-observer reliability of data acquisition had been established in preliminary work (Raine-Fenning et al., 2002a). Each patient was scanned in a supine position with knees flexed and hips abducted. The pelvis was examined in detail to exclude obvious ovarian or uterine pathology. Power Doppler ultrasound was then applied using pre-determined settings derived from preliminary work, and these were kept constant for every patient: pulse repetition frequency 1.0, power 4.0, colour gain 38.4, wall motion filter 75, rise 0.2, persistence 0.8, reject 82 and with the central frequency set to mid. These settings were found to offer the best compromise between small vessel detection and Doppler artefact (Raine-Fenning et al., 2002b
). A longitudinal view of the uterus and endometrial cavity was obtained and the volume mode entered. The resultant truncated sector defining the area of interest was then moved and adjusted, and the sweep angle set to 90° to ensure that a complete uterine volume encompassing the entire subendometrium was obtained. The patient was asked to remain as still as possible and every effort was made by the ultrasonographer to limit inappropriate movements of the transducer. A three-dimensional data set was then acquired using the medium speed sweep mode. The resultant multiplanar display was examined to ensure that the area of interest had been captured in its entirety. Particular attention was given to the coronal image in the C plane, specific to three-dimensional ultrasound, which provides more spatial information than the transverse or longitudinal image. If the volume was complete with no power Doppler artefact, the data set was stored to a magnetic optical disk. If there was apparent artefact, such as typical flash artefacts seen with bowel movements or the patient coughing, the data set was reacquired until a satisfactory image was obtained.
Standardization of the ultrasound settings was ensured by using the same pre-defined probe programme without adjustment once the programme had been loaded. Prior to each acquisition, the power Doppler settings were checked to ensure they had not changed during manipulation of the volume sector, which can lead to an automatic increase or decrease in the settings with larger and smaller volumes, respectively. At the end of the scan session, the acquired volumes were reloaded from the magnetic optical disk and sent to a personal computer via a dedicated DICOM link (Digital Imaging and Communications in Medicine) (Mildenberger et al., 2002). 3D ViewTM software (GE Kretz) was used by the personal computer to receive and store the volume data sets and for the subsequent analysis of the endometrial data.
Data analysis
Data assessment was undertaken by one observer (J.S.C.) to limit bias. Three-dimensional endometrial volumetric and vascular measurements were undertaken with the virtual organ computer-aided analysis imaging program (VOCALTM) within 3D ViewTM. VOCAL allows the user to define the volume of interest manually with a standard computer mouse as the data set is rotated about a central axis, and we have previously described the application of this technique for endometrial volume measurements (Raine-Fenning et al., 2002c). For the purpose of this study, all measurements were conducted manually in plane C (coronal image) as this plane was rotated about plane A (longitudinal image) using the 9° rotation step (see Figure 1). Because the data set is rotated through 180°, the 9° rotation step makes 20 planes available to calculate each individual volume and represents the best compromise between reliability, validity and time to define the initial volume (Raine-Fenning et al., 2003
). Once the endometrium had been defined, the power Doppler signal within it was quantified through the histogram facility, which employs specific mathematical algorithms to generate three indices of vascularity (Pairleitner et al., 1999
). These indices are representative of either the percentage of power Doppler data within the defined volume (the VI; vascularization index), the signal intensity of the power Doppler information (the FI; flow index) or a combination of both factors (the VFI; vascular flow index) (see Table I for a full definition of each index) and have been suggested as representative of vascularity and flow intensity (Jarvela et al., 2003
).
|
|
Having confirmed our own inter-observer reliability of both acquisition and quantification of three-dimensional power Doppler data from the endometrium (Raine-Fenning et al., 2002a), we acquired a single data set from each patient at every visit, and a single observer subsequently conducted two serial measurements of all resultant data sets. The mean of these two measurements is shown in the Results.
Hormonal analysis
Blood was centrifuged, and plasma was separated and stored at 20 °C until assayed. Steroid hormone measurements were made by radioimmunoassay as previously described, with minor modifications. Plasma estradiol concentrations were determined following extraction with diethyl ether (Glasier et al., 1989) and utilized estradiol-6-O-carboxymethyloximino-2-[125I]histamine as tracer (IM135, Amersham Pharmacia Biotech UK Ltd, Bucks, UK) with an antibody raised against estradiol-6-carboxymethyloximino-bovine serum albumin (BSA) (UCB A901 Biogenesis Ltd, Poole, UK) (Campbell et al., 1994
). The sensitivity, and intra- and inter-assay coefficients of variation were 50 pmol/l, 10.6% and 13.5%, respectively. Plasma progesterone concentrations were determined by direct immunoassay using [125I]11-progesterone glucuronide (Amersham Pharmacia Biotech) (Yong et al., 1992
) as label, and rabbit antiprogesterone 11-hemisuccinate BSA antiserum (SAPU R7044X) (Souza et al., 1997
). The sensitivity, and intra- and inter-assay coefficients of variation were 175 pmol/l, 8.6% and 14.5%, respectively. Human LH was determined using reagents supplied by the National Institute of Diabetes and Digestive and Kidney diseases (NIDDK). NIDDK-hLH-I-SIAFP-1 (Potency 4500 IU/mg) was labelled with 125I using the chloramine-T method as previously described (Campbell et al., 1990
). The antiserum used was NIDDK-anti-hLH-3, which was used according to the suppliers instructions at a final dilution of 1:600 000. The reference preparation was LER 907, which had a potency of 277 IU/mg. The sensitivity, and intra- and inter-assay coefficients of variation were 1.3 IU/l, 6.6% and 12.8% respectively.
Statistical analysis
Statistical analysis was undertaken using SPSS version 10.1.4 using the repeated measures general linear model to determine differences with time.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Assessment of blood flow
The majority of studies examining uterine perfusion during the normal menstrual cycle have used two-dimensional ultrasound and pulsed wave Doppler to determine blood flow velocity and impedance to flow within the uterine artery (Goswamy and Steptoe, 1988; Scholtes et al., 1989
; Battaglia et al., 1990
; Steer et al., 1990
; Santolaya-Forgas, 1992
; Sladkevicius et al., 1993
; Bourne et al., 1996
; Tan et al., 1996
; Zaidi, 2000
). Almost all report a gradual yet continuous increase in blood flow velocity in association with a reduction in the resistance to flow from the early follicular phase maximal at the time of implantation. Several groups also noted a temporary increase in resistance to flow in association with a concomitant reduction in velocity during the peri-ovulatory period (Scholtes et al., 1989
; Steer et al., 1990
; Collins et al., 1991
; Sladkevicius et al., 1993
) that has been attributed to a physical vascular obstruction induced by a transient increase in myometrial basal tone and uterine contractility (Lyons et al., 1991
; de Ziegler et al., 2001
). Myometrial contractions, however, are intermittent and occur less frequently with time from ovulation (Bulletti et al., 2000
; de Ziegler et al., 2001
), and are unlikely to explain the sustained fall in endometrial blood flow seen in this study.
The majority of these studies assume that blood flow within the uterine arteries is representative of regional uterine and endometrial perfusion. This is supported by studies that have looked at blood flow characteristics within vessels at the subendometrial level and report similar patterns of flow to those seen in the uterine arteries (Sladkevicius et al., 1993, 1994
; Achiron et al., 1995
; Bourne et al., 1996
). Nevertheless, analysis is still generally restricted to a single vessel and complicated by the tortuous nature of the vessels and low velocity flow profiles. Power Doppler is more sensitive to these lower velocities and, in combination with three-dimensional ultrasound, provides information from the endometrium or subendometrial region as a whole, thereby giving an impression of perfusion. Indeed, our findings are much more in keeping with studies that have been designed specifically to examine perfusion within the human endometrium during the menstrual cycle.
Fraser et al. (1987) measured endometrial blood flow across the menstrual cycle by observing the clearance of radiolabelled xenon133 following its instillation into the uterine cavity. They demonstrated a similar pattern to that observed in this study, with a significant elevation in the middle to late follicular phase (days 1012), followed by a substantial fall and a subsequent slow rise during the luteal phase (days 2126) that was maintained until menstruation. More recently, Gannon et al. (1997
) used an intrauterine laser Doppler technique to assess the weekly variation in red blood cell flux within the subendometrium during the menstrual cycle. They found that the mean endometrial microvascular perfusion varied throughout the cycle, with two distinct and significantly increased episodes of perfusion during the follicular and luteal phases of the cycle. Whilst they also noted the highest flow during the proliferative phase, contrary to our findings and those of Fraser et al. (1987
), this peak (days 69) and the second luteal peak (days 1722) both occurred at an earlier stage of the menstrual cycle. The discrepancies most probably reflect measurement technique, with both three-dimensional power Doppler ultrasound and xenon clearance being more representative of overall uterine and endometrial flow. Laser Doppler fluxmetry provides more information about small segments of the endometrium, as it measures the passage of red blood cells through a sphere of 1 mm diameter (Johansson et al., 1991
; Mayrovitz, 1992
). It may not, therefore, be truly representative of the entire endometrium, although Gannon et al. (1997
) did show minimal regional variation throughout the uterus.
Not all data relating to changes in uterine blood flow are derived from work in humans. Animal studies also suggest that a decrease in uterine flow may occur following ovulation in cows (Ford et al., 1979; Waite et al., 1990
), ewes (Greiss and Anderson, 1969
) and sows (Ford and Christenson, 1979
). Waite et al. (1990
) demonstrated an increased uterine arterial smooth muscle tone and lower uterine artery flow rate in association with the reversal in estrogen to progesterone ratio that occurs during the luteal phase of the cycle following oestrus in the cow. Ford et al. (1979
) reported the same relationship between uterine blood flow and the ratio of estradiol to progesterone during the oestrous cycle of non-pregnant cows. More recently, Zhang et al. (1995
) used a hydrogen gas clearance technique to demonstrate that myometrial blood flow was significantly greater than endometrial flow in ovariectomized rats and that uterine blood flow increased in response to boluses of 17
-estradiol.
Histological changes in uterine vascularity
The highest rate of endometrial cell proliferation does occur during the early proliferative phase of endometrial growth and is maximal around days 810 in the upper one-third of the functionalis layer (Ferenczy et al., 1979). Significant dilatation of the vessels within the subepithelial capillary plexus occurs during the post-ovulatory phase, leading to oedema appearing in the stroma at the time of the expected implantation (Peek et al., 1992
). It is possible therefore that the power Doppler signal falls at this time as a result of an increase in the distance between individual vessels and a resultant decrease in microvessel spatial density (Gannon et al., 1997
). However, whilst there is evidence of a reduction in endometrial capillary spatial density following ovulation, it tends to occur during the latter part of the luteal phase as the endometrium becomes progressively oedematous (Johannisson et al., 1987
; Hourihan et al., 1991
). Nevertheless, implantation itself is characterized by an inflammatory-like response associated with increased vascular permeability and vasodilatation, and these processes could theoretically affect the power Doppler signal. Similarly, during the late luteal phase, we may have seen an increase in the power Doppler signal due to an increase in endometrial vascular density associated with the progressive coiling of the spiral arteries or endometrial compaction characteristic of the late luteal phase (Shaw and Roche, 1980
).
Relationship to sex steroids
Our three vascular indices closely paralleled the changes seen in serum estradiol and progesterone throughout the menstrual cycle (see Figure 3). Both endometrial and subendometrial vascularity demonstrated a significant elevation in the middle to late follicular phase as the estrogen to progesterone ratio increased. Animal work has shown that the increase in uterine blood flow during this phase is due to a vasodilatatory response that is reproduced by exogenous 17-estradiol administration via a nitric oxide-mediated mechanism (Vagnoni et al., 1998
). This relationship was maintained thereafter, with all three indices of vascularity reaching maximum values around the time of the estradiol peak before falling in parallel with the reduction in the circulating estradiol to progesterone ratio to reach a nadir in the early post-ovulatory period. Goswamy and Steptoe (1988
) described a similar pattern but in terms of an increase in the resistance to flow in association with this post-ovulatory fall in estradiol. Whilst other groups have described the subsequent loss of the relationship with estradiol at this point (Fraser et al., 1987
), the indices of vascularity then began to rise again, closely following, although lagging behind, the post-ovulatory increase in progesterone. The vascular indices, however, continued to rise even as the progesterone levels fell during the late luteal phase, reaching some of the highest values throughout the whole menstrual cycle just prior to menstruation. This may simply reflect tissue density and the increased coiling of spiral arteries as discussed above, but may also relate to the increasing role of the reninangiotensin system in menstrual regulation (Johnson, 1980
).
Subgroup analysis
Whilst cigarette smoking is associated with endothelial dysfunction (Neunteufl et al., 2000) and an increase arterial wall stiffness (Caro et al., 1987
), its effect on uterine blood flow is less clear. Different groups have suggested that smoking is associated with either an increase (Nordenvall et al., 1991
) or a decrease (Castro et al., 1993
) in the systolic to diastolic ratio of the uterine artery, whilst most report no effect at all (Morrow et al., 1988
; Newnham et al., 1990
; Bruner and Forouzan, 1991
; Kimya et al., 1998
). In this study, smoking was specifically associated with a reduction in the VI and VFI, but not the FI.
Contrary to this were the isolated findings of a lower FI in the group of women aged 31 or more and a higher FI in parous patients. Seventy-two percent of parous women (13 of 18) were actually aged 31 or more, suggesting that the effect of age outweighs the positive effect of parity. Whilst both findings may have been expected and can be explained physiologically, there is a surprising paucity of work addressing either issue. A reduction in uterine blood flow with age has been described, but only during the post-menopausal period where there is a clear correlation between years since the menopause and the resistance to flow within the uterine, radial and spiral arteries (Kurjak and Kupesic, 1995). Three-dimensional power Doppler angiography has been used to demonstrate a reduction in ovarian stromal vascularity with age in both women of reproductive age (Kupesic et al., 2003
) and older peri-menopausal women (Pan et al., 2002
), but there are no data on uterine vascularity addressing the effect of age or parity. The numbers involved, however, are small, and larger studies dedicated to factors that may influence endometrial blood flow are warranted.
Arguably one of the most important findings from our subgroup analysis was that these differences were observed within the subendometrium only and not within the endometrium. This serves to remind us that the myometrium and endometrium have separate and discrete vascular beds and should therefore be considered independently (Ramsey, 1977; Rogers and Gannon, 1981
). Shell-imaging permits such discriminatory analysis and provides a novel technique with which to examine regional blood flow within any given organ or tissue.
This study has demonstrated distinct changes in vascularity during the normal menstrual cycle, as assessed by three-dimensional power Doppler, characterized by a pre-ovulatory peak and a post-ovulatory fall that reaches a nadir at the time of implantation. The changes parallel those seen in serum estradiol during the follicular phase and serum progesterone during the luteal phase. Indices of subendometrial vascularity are significantly lower in smokers and women aged 31 or more, but are increased in parous women. Three-dimensional power Doppler angiography offers a new tool with which to investigate endometrial perfusion and could potentially be used to define pathophysiological change associated with certain disease processes and to quantify the effect of various treatment modalities on these.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Achiron R, Levran D, Sivan E, Lipitz S, Dor J and Mashiach S (1995) Endometrial blood flow response to hormone replacement therapy in women with premature ovarian failure: a transvaginal Doppler study. Fertil Steril 63,550554.[ISI][Medline]
Bakos O, Lundkvist O and Bergh T (1993) Transvaginal sonographic evaluation of endometrial growth and texture in spontaneous ovulatory cyclesa descriptive study. Hum Reprod 8,799806.[Abstract]
Bakos O, Lundkvist O, Wide L and Bergh T (1994) Ultrasonographical and hormonal description of the normal ovulatory menstrual cycle. Acta Obstet Gynecol Scand 73,790796.[ISI][Medline]
Battaglia C, Larocca E, Lanzani A, Valentini M and Genazzani AR (1990) Doppler ultrasound studies of the uterine arteries in spontaneous and IVF stimulated ovarian cycles. Gynecol Endocrinol 4,245250.[ISI][Medline]
Bourne TH, Hagstrom HG, Granberg S et al. (1996) Ultrasound studies of vascular and morphological changes in the human uterus after a positive self-test for the urinary luteinizing hormone surge. Hum Reprod 11,369375.[Abstract]
Bruner JP and Forouzan I (1991) Smoking and buccally administered nicotine. Acute effect on uterine and umbilical artery Doppler flow velocity waveforms. J Reprod Med 36,435440.[ISI][Medline]
Bulletti C, Jasonni VM, Tabanelli S, Ciotti P, Vignudelli A and Flamigni C (1985) Changes in the uterine vasculature during the menstrual cycle. Acta Eur Fertil 16,367371.[Medline]
Bulletti C, de Ziegler D, Polli V, Diotallevi L, Del Ferro E and Flamigni C (2000) Uterine contractility during the menstrual cycle. Hum Reprod 15 Suppl 1,8189.[Medline]
Campbell BK, Scaramuzzi RJ, Downing JA and Evans G (1990) Steroid secretion rates and plasma binding activity in androstenedione-immune ewes with an autotransplanted ovary. J Reprod Fertil 89,485496.[Abstract]
Campbell BK, Gordon BM and Scaramuzzi RJ (1994) The effect of ovarian arterial infusion of transforming growth factor alpha on ovarian follicle populations and ovarian hormone secretion in ewes with an autotransplanted ovary. J Endocrinol 143,1324.[Abstract]
Carbillon L, Challier JC, Alouini S, Uzan M and Uzan S (2001a) Uteroplacental circulation development: Doppler assessment and clinical importance. Placenta 22,795799.[CrossRef][ISI][Medline]
Carbillon L, Perrot N, Uzan M and Uzan S (2001b) Doppler ultrasonography and implantation: a critical review. Fetal Diagn Ther 16,327332.[CrossRef][ISI][Medline]
Caro CG, Lever MJ, Parker KH and Fish PJ (1987) Effect of cigarette smoking on the pattern of arterial blood flow: possible insight into mechanisms underlying the development of arteriosclerosis. Lancet 2,1113.[Medline]
Castro LC, Allen R, Ogunyemi D, Roll K and Platt LD (1993) Cigarette smoking during pregnancy: acute effects on uterine flow velocity waveforms. Obstet Gynecol 81,551555.[Abstract]
Collins W, Jurkovic D, Bourne T, Kurjak A and Campbell S (1991) Ovarian morphology endocrine function and intra-follicular blood flow during the peri-ovulatory period. Hum Reprod 6,319324.[Abstract]
de Ziegler D, Bulletti C, Fanchin R, Epiney M and Brioschi PA (2001) Contractility of the nonpregnant uterus: the follicular phase. Ann NY Acad Sci 943,172184.
Downey DB, Fenster A and Williams JC (2000) Clinical utility of three-dimensional US. Radiographics 20,559571.
Ferenczy A, Bertrand G and Gelfand MM (1979) Proliferation kinetics of human endometrium during the normal menstrual cycle. Am J Obstet Gynecol 133,859867.[ISI][Medline]
Ford SP and Christenson RK (1979) Blood flow to uteri of sows during the estrous cycle and early pregnancy: local effect of the conceptus on the uterine blood supply. Biol Reprod 21,617624.[ISI][Medline]
Ford SP, Chenault JR and Echternkamp SE (1979) Uterine blood flow of cows during the oestrous cycle and early pregnancy: effect of the conceptus on the uterine blood supply. J Reprod Fertil 56,5362.[Abstract]
Fraser IS, McCarron G, Hutton B and Macey D (1987) Endometrial blood flow measured by xenon 133 clearance in women with normal menstrual cycles and dysfunctional uterine bleeding. Am J Obstet Gynecol 156,158166.[ISI][Medline]
Friedler S, Schenker JG, Herman A and Lewin A (1996) The role of ultrasonography in the evaluation of endometrial receptivity following assisted reproductive treatments: a critical review. Hum Reprod Update 2,323335.
Gannon BJ, Carati CJ and Verco CJ (1997) Endometrial perfusion across the normal human menstrual cycle assessed by laser Doppler fluxmetry. Hum Reprod 12,132139.[CrossRef][ISI][Medline]
Glasier AF, Irvine DS, Wickings EJ, Hillier SG and Baird DT (1989) A comparison of the effects on follicular development between clomiphene citrate, its two separate isomers and spontaneous cycles. Hum Reprod 4,252256.[Abstract]
Goswamy RK and Steptoe PC (1988) Doppler ultrasound studies of the uterine artery in spontaneous ovarian cycles. Hum Reprod 3,721726.[Abstract]
Goswamy RK, Williams G and Steptoe PC (1988) Decreased uterine perfusiona cause of infertility. Hum Reprod 3,955959.[Abstract]
Greiss FC Jr and Anderson SG (1969) Uterine vascular changes during the ovarian cycle. Am J Obstet Gynecol 103,629640.[ISI][Medline]
Habara T, Nakatsuka M, Konishi H, Asagiri K, Noguchi S and Kudo T (2002) Elevated blood flow resistance in uterine arteries of women with unexplained recurrent pregnancy loss. Hum Reprod 17,190194.
Hoskins PR (1990) Measurement of arterial blood flow by Doppler ultrasound. Clin Phys Physiol Meas 11,126.[CrossRef][ISI][Medline]
Hourihan HM, Sheppard BL, Belsey EM and Brosens IA (1991) Endometrial vascular features prior to and following exposure to levonorgestrel. Contraception 43,375385.[ISI][Medline]
Hsieh YY, Chang FC and Tsai HD (2000) Doppler evaluation of the uterine and spiral arteries from different sampling sites and phases of the menstrual cycle during controlled ovarian hyperstimulation. Ultrasound Obstet Gynecol 16,192196.[CrossRef][ISI][Medline]
Jaffe RB (2000) Importance of angiogenesis in reproductive physiology. Semin Perinatol 24,7981.[ISI][Medline]
Jarvela IY, Sladkevicius P, Tekay AH, Campbell S and Nargund G (2003) Intraobserver and interobserver variability of ovarian volume gray-scale and color flow indices obtained using transvaginal three-dimensional power Doppler ultrasonography. Ultrasound Obstet Gynecol 21,277282.[CrossRef][ISI][Medline]
Jirous J, Diejomaoh M, Al-Othman S, Al-Abdulhadi F, Al-Marzouk N and Sugathan T (2001) A correlation of the uterine and ovarian blood flows with parity of nonpregnant women having a history of recurrent spontaneous abortions. Gynecol Obstet Invest 52,5154.[CrossRef][ISI][Medline]
Johannisson E, Landgren BM, Rohr HP and Diczfalusy E (1987) Endometrial morphology and peripheral hormone levels in women with regular menstrual cycles. Fertil Steril 48,401408.[ISI][Medline]
Johansson K, Jakobsson A, Lindahl K, Lindhagen J, Lundgren O and Nilsson GE (1991) Influence of fibre diameter and probe geometry on the measuring depth of laser Doppler flowmetry in the gastrointestinal application. Int J Microcirc Clin Exp 10,219229.[ISI][Medline]
Johnson IR (1980) Renin substrate active and acid-activatable renin concentrations in human plasma and endometrium during the normal menstrual cycle. Br J Obstet Gynecol 87,875882.[ISI][Medline]
Kimya Y, Cengiz C, Ozan H and Kolsal N (1998) Acute effects of maternal smoking on the uterine and umbilical artery blood velocity waveforms. J Maternal-Fetal Invest 8 7981.
Kupesic S and Kurjak A (1993) Uterine and ovarian perfusion during the periovulatory period assessed by transvaginal color Doppler. Fertil Steril 60,439443.[ISI][Medline]
Kupesic S and Kurjak A (2002) Predictors of IVF outcome by three-dimensional ultrasound. Hum Reprod 17,950955.
Kupesic S, Bekavac I, Bjelos D and Kurjak A (2001) Assessment of endometrial receptivity by transvaginal color Doppler and three-dimensional power Doppler ultrasonography in patients undergoing in vitro fertilization procedures. J Ultrasound Med 20,125134.
Kupesic S, Kurjak A, Bjelos D and Vujisic S (2003) Three-dimensional ultrasonographic ovarian measurements and in vitro fertilization outcome are related to age. Fertil Steril 79,190197.[CrossRef][ISI][Medline]
Kurdi W, Campbell S, Aquilina J, England P and Harrington K (1998) The role of color Doppler imaging of the uterine arteries at 20 weeks gestation in stratifying antenatal care. Ultrasound Obstet Gynecol 12,339345.[CrossRef][ISI][Medline]
Kurjak A and Kupesic S (1995) Ovarian senescence and its significance on uterine and ovarian perfusion. Fertil Steril 64,532537.[ISI][Medline]
Kurjak A, Kupesic-Urek S, Schulman H and Zalud I (1991) Transvaginal color flow Doppler in the assessment of ovarian and uterine blood flow in infertile women. Fertil Steril 56,870873.[ISI][Medline]
Lyons EA, Taylor PJ, Zheng XH, Ballard G, Levi CS and Kredentser JV (1991) Characterization of subendometrial myometrial contractions throughout the menstrual cycle in normal fertile women. Fertil Steril 55,771774.[ISI][Medline]
Mayrovitz HN (1992) Age and site variability of skin blood perfusion in the hairless mouse ear determined by laser Doppler flowmetry. Int J Microcirc Clin Exp 11,297306.[ISI][Medline]
Mildenberger P, Eichelberg M and Martin E (2002) Introduction to the DICOM standard. Eur Radiol 12,920927.[CrossRef][ISI][Medline]
Morrow RJ, Ritchie JW and Bull B (1988) Maternal cigarette smoking: the effects on umbilical and uterine blood flow velocity. Am J Obstet Gynecol 159,10691071.[ISI][Medline]
Nelson TR and Pretorius DH (1988) The Doppler signal: where does it come from and what does it mean? Am J Roentgenol 151,439447.[ISI][Medline]
Neunteufl T, Priglinger U, Heher S et al. (2000) Effects of vitamin E on chronic and acute endothelial dysfunction in smokers. J Am Coll Cardiol 35,277283.[CrossRef][ISI][Medline]
Newnham JP, Patterson L, James I and Reid SE (1990) Effects of maternal cigarette smoking on ultrasonic measurements of fetal growth and on Doppler flow velocity waveforms. Early Hum Dev 24,2336.[ISI][Medline]
Nordenvall M, Ullberg U, Laurin J, Lingman G, Sandstedt B and Ulmsten U (1991) Placental morphology in relation to umbilical artery blood velocity waveforms. Eur J Obstet Gynecol Reprod Biol 40,179190.[ISI][Medline]
Pairleitner H, Steiner H, Hasenoehrl G and Staudach A (1999) Three-dimensional power Doppler sonography: imaging and quantifying blood flow and vascularization. Ultrasound Obstet Gynecol 14 139143.[CrossRef][ISI][Medline]
Pan HA, Cheng YC, Li CH, Wu MH and Chang FM (2002) Ovarian stroma flow intensity decreases by age: a three-dimensional power Doppler ultrasonographic study. Ultrasound Med Biol 28,425430.[CrossRef][ISI][Medline]
Peek M, Landgren BM and Johannisson E (1992) The endometrial capillaries during the normal menstrual cycle: a morphometric study. Hum Reprod 7,906911.[Abstract]
Raine-Fenning NJ, Campbell BC and Johnson IR (2002a) The reproducibility of volume acquistion and the repeatability of measurements of endometrial vascularity with three-dimensional power Doppler angiography. Abstracts from the British Medical Ultrasound Society 33rd Annual Scientific Meeting, Edinburgh, December 2001. Eur J Ultrasound 15 Suppl 1,S32S33.
Raine-Fenning NJ, Campbell BC and Johnson IR (2002b) The semi-quantification of three-dimensional power Doppler angiography of the endometrium: preliminary experience. Abstracts from the 13th Euroson Congress/33rd British Medical Ultrasound Society Annual Scientific Meeting, Edinburgh, December 2001. Eur J Ultrasound 15 Suppl 1,S32.
Raine-Fenning NJ, Campbell BK, Collier J, Brincat MB and Johnson IR (2002c) The reproducibility of endometrial volume acquisition and measurement with the VOCAL-imaging program. Ultrasound Obstet Gynecol 19,6975.[CrossRef][ISI][Medline]
Raine-Fenning NJ, Clewes JS, Kendall NR, Bunkheila AK, Campbell BK and Johnson IR (2003) The interobserver reliability and validity of volume calculation from three-dimensional ultrasound datasets in the in vitro setting. Ultrasound Obstet Gynecol 21,283291.[CrossRef][ISI][Medline]
Ramsey EM (ed) (1977) Vascular Anatomy. Plenum Press, New York.
Randall JM, Fisk NM, McTavish A and Templeton AA (1989) Transvaginal ultrasonic assessment of endometrial growth in spontaneous and hyperstimulated menstrual cycles. Br J Obstet Gynecol 96,954959.[ISI][Medline]
Rogers PA and Abberton KM (2003) Endometrial arteriogenesis: vascular smooth muscle cell proliferation and differentiation during the menstrual cycle and changes associated with endometrial bleeding disorders. Microsc Res Tech 60,412419.[CrossRef][ISI][Medline]
Rogers PA and Gannon BJ (1981) The vascular and microvascular anatomy of the rat uterus during the oestrous cycle. Aust J Exp Biol Med Sci 59,667679.[ISI][Medline]
Rubin JM (1999) Power Doppler. Eur Radiol 9,S318S322.[ISI][Medline]
Rubin JM, Bude RO, Carson PL, Bree RL and Adler RS (1994) Power Doppler US: a potentially useful alternative to mean frequency-based color Doppler US. Radiology 190,853856.[Abstract]
Santolaya-Forgas J (1992) Physiology of the menstrual cycle by ultrasonography. J Ultrasound Med 11,139242.[Abstract]
Schild RL, Holthaus S, dAlquen J et al. (2000) Quantitative assessment of subendometrial blood flow by three-dimensional-ultrasound is an important predictive factor of implantation in an in-vitro fertilization programme. Hum Reprod 15,8994.
Scholtes MC, Wladimiroff JW, van Rijen HJ and Hop WC (1989) Uterine and ovarian flow velocity waveforms in the normal menstrual cycle: a transvaginal Doppler study. Fertil Steril 52,981985.[ISI][Medline]
Shaw ST and Roche PC (1980) Menstruation. Oxford Rev Reprod Endocrinol 2,4195.
Sladkevicius P, Valentin L and Marsal K (1993) Blood flow velocity in the uterine and ovarian arteries during the normal menstrual cycle. Ultrasound Obstet Gynecol 3,199208.[CrossRef][ISI][Medline]
Sladkevicius P, Valentin L and Marsal K (1994) Blood flow velocity in the uterine and ovarian arteries during menstruation. Ultrasound Obstet Gynecol 4,421427.[CrossRef][ISI][Medline]
Smith SK (2000) Angiogenesis and implantation. Hum Reprod 15 Suppl 6,5966.
Smith SK (2001) Regulation of angiogenesis in the endometrium. Trends Endocrinol Metab 12,147151.[CrossRef][ISI][Medline]
Souza CJ, Campbell BK, Webb R and Baird DT (1997) Secretion of inhibin A and follicular dynamics throughout the estrous cycle in the sheep with and without the Booroola gene (FecB). Endocrinology 138,53335340.
Steer CV, Campbell S, Pampiglione JS, Kingsland CR, Mason BA and Collins WP (1990) Transvaginal colour flow imaging of the uterine arteries during the ovarian and menstrual cycles. Hum Reprod 5,391395.[Abstract]
Strigini FA, Lencioni G, De Luca G, Lombardo M, Bianchi F and Genazzani AR (1995) Uterine artery velocimetry and spontaneous preterm delivery. Obstet Gynecol 85,374377.
Tan SL, Zaidi J, Campbell S, Doyle P and Collins W (1996) Blood flow changes in the ovarian and uterine arteries during the normal menstrual cycle. Am J Obstet Gynecol 175,625631.[ISI][Medline]
Vagnoni KE, Shaw CE, Phernetton TM, Meglin BM, Bird IM and Magness RR (1998) Endothelial vasodilator production by uterine and systemic arteries. III. Ovarian and estrogen effects on NO synthase. Am J Physiol 275,H1845H1856.[ISI][Medline]
Vieli A (1990) Ultrasonic Doppler and duplex systems: possibilities and limitations. Urol Int 45,251257.[ISI][Medline]
Waite LR, Ford SP, Young DF and Conley AJ (1990) Use of ultrasonic Doppler waveforms to estimate changes in uterine artery blood flow and vessel compliance. J Anim Sci 68,24502458.
Wu HM, Chiang CH, Huang HY, Chao AS, Wang HS and Soong YK (2003) Detection of the subendometrial vascularization flow index by three-dimensional ultrasound may be useful for predicting the pregnancy rate for patients undergoing in vitro fertilization-embryo transfer. Fertil Steril 79,507511.[CrossRef][ISI][Medline]
Yong EL, Glasier A, Hillier H et al. (1992) Effect of cyclofenil on hormonal dynamics, follicular development and cervical mucus in normal and oligomenorrhoeic women. Hum Reprod 7,3943.[Abstract]
Zaidi J (2000) Blood flow changes in the ovarian and uterine arteries in women with normal and polycystic ovaries. Hum Fertil 3,194198.
Zaidi J, Jurkovic D, Campbell S, Okokon E and Tan SL (1995) Circadian variation in uterine artery blood flow indices during the follicular phase of the menstrual cycle. Ultrasound Obstet Gynecol 5,406410.[CrossRef][ISI][Medline]
Zhang RS, Guth PH, Scremin OU and Chaudhuri G (1995) H2 gas clearance technique for separating rat uterine blood flow into endometrial and myometrial components. Am J Physiol 268,R569R575.[ISI][Medline]
Submitted on June 26, 2003; accepted on October 6, 2003.