Uterine Artery Blood Flow Research Articles

1050: Cross-modality, in-vivo validation of 4D-Flow MRI evaluation of uterine artery blood flow in human pregnancy

1050: Cross-modality, in-vivo validation of 4D-Flow MRI evaluation of uterine artery blood flow in human pregnancy

Evaluation of Placental Perfusion Based on Intravoxel Incoherent Motion Diffusion Weighted Imaging (IVIM-DWI) and Its Predictive Value for Late-Onset Fetal Growth Restriction.

Objective The aim of this study was to investigate placental blood perfusion in middle and late pregnancy and explore its predictive value for fetal growth restriction (FGR). Methods All pregnant women included in the study were examined using placental intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI). Three IVIM parameters (D, f, D*) were obtained for each pregnant woman and analyzed using Image J software. Perfusion fraction f is a radiological marker of placental perfusion. The pulsatility index (PI) of the uterine artery is used to indirectly evaluate placental function. Results f-values were significantly lower in the late-onset FGR group compared to the normal late pregnancy group (19.07 vs. 27.78%). In addition, uterine artery PI values were markedly increased in the late-onset FGR group compared to the normal late pregnancy group (1.96 vs. 1.03), and neonatal weight was significantly lower in the late-onset FGR group (2.75 vs. 3.18 kg). There was a significant positive correlation between f-value, uterine artery PI and neonatal weight (r = 0.968, p < 0.01; r = 0.959, p < 0.01). There was a significant negative correlation between f-value and age of gestation (r = − 0.534, p < 0.01). Conclusion Perfusion fraction f was strongly correlated with uterine artery blood flow resistance as measured by color Doppler and had a certain predictive value for late-onset FGR.

Uterine Artery Sparing Robotic-Assisted Radical Trachelectomy. Is Maintaining Uterine Arterial Blood Flow Overrated?

Uterine Artery Sparing Robotic-Assisted Radical Trachelectomy. Is Maintaining Uterine Arterial Blood Flow Overrated?

Standartization of ultrasound examination of the pelvic organs in women

Introduction. In Russia, there has been no research comparing data obtained by ultrasound scanners of different firms, with a comprehensive assessment of pelvic organs in women.Purpose of the study. Compare the results of the study of the internal genitalia of healthy women, obtained on devices from Philips and GE Healthcare. Materials and methods. A comparison of the results of pelvic ultrasound examination in healthy patients of reproductive age (18–45 years), conducted on the expert level devices of GE Healthcare (Austria) and Philips (Netherlands) by the same doctor. Each group consisted of 30 people (15 women in the first and second phase of the cycle). Age did not have significant differences (p &gt; 0.05). Organometry (uterine volume, endometrial thickness, ovarian volume), dopplerometric parameters of blood flow in uterine arteries, such as maximum systolic and average blood flow rate (Vmax, Vmean), uterine artery diameter, arterial perfusion index (API) was calculated, vascularization index (VI), flow index (FI) and vascularization-flow index (VFI) of the uterus and endometrium were obtained in 3D Doppler.Summary. When implementing new techniques should study the information about this method and rely on the regulatory parameters obtained on the devices of similar firms.

Resistance of uterine radial artery blood flow was correlated with peripheral blood NK cell fraction and improved with low molecular weight heparin therapy in women with unexplained recurrent pregnancy loss

Female reproductive mucosa must allow allogenic sperm survival whereas at the same time, avoid pathogen infection. To preserve sperm from neutrophil attack, neutrophils disappear from the vagina during the ovulatory phase (high estradiol); although the mechanisms that regulate neutrophil influx to the vagina during insemination remain controversial.We investigated the sex hormone regulation of the neutrophil migration through the cervix during insemination and revealed that ovulatory estradiol dose fades the CXCL1 epithelial expression in the ectocervix and fornix; hence, retarding neutrophil migration and retaining them in the epithelium. These mechanisms spare sperm from neutrophil attack to preserve reproduction, but might compromise immunity. However, luteal progesterone dose promotes the CXCL1 gradient expression to restore neutrophil migration, to eliminate sperm and prevent sperm associated pathogen dissemination. Surprisingly, these mechanisms are hormone dependent and independent of the insemination. Thus, sex hormones orchestrate tolerance and immunity in the vaginal lumen by regulating neutrophil transepithelial migration in the fornix and ectocervix.

Correlation of Maternal Stress Because of Positive Aneuploidy Screening Serum Analytes and Uterine Arteries' Doppler Ultrasound Index: A Prospective Cohort Study.

BackgroundAntenatal anxiety or maternal stress is a prevalent chronic mental disorder in pregnant women. We have assessed the effect of maternal stress from positive aneuploidy screening results on the changes in uterine artery blood flow.Materials and MethodsWe performed a prospective cohort (one sample) pilot study at a hospital in Tehran, Iran. A total of 60 pregnant women who were candidates for amniocentesis due to abnormal sequential screening test results entered the study. We conducted 2 standard psychological tests, the Spielberger’s State-Trait Anxiety Inventory and the Beck Anxiety Inventory, to determine anxiety levels in the participants before amniocentesis and two weeks after amniocentesis. The uterine artery resistance index was also measured before and two weeks after amniocentesis. The level of maternal stress was compared with the uterine artery resistance index.ResultsPatients had a mean State Trait Anxiety Inventory score before amniocentesis of greater than 40, which meant that the mothers experienced high anxiety. There were no correlations between both inventories’ anxiety scores and uterine artery blood flow before amniocentesis. However, two weeks after amniocentesis, we observed significant negative correlations between the State Anxiety (P=0.0041) and Trait Anxiety (P=0.010) Inventory scores and the uterine artery resistance indexes. Also, there was an association between the decreased right uterine artery resistance index and State Anxiety scores (P=0.036). There were significant correlations between State and Trait Anxiety scores and second trimester analytes of β-human chorionic gonadotropin (β-hCG, P<0.001), α-fetoprotein (P<0.001), and unconjugated estriol (P=0.048).ConclusionMaternal anxiety because of positive aneuploidy screening serum analytes and amniocentesis can af- fect perinatal outcomes via mood-based alterations in blood flow of the uterine arteries and the screening markers β-hCG,unconjugated estriol, and α-fetoprotein.

Uterine Artery Doppler Velocimetry During Individually Prescribed Exercise in Pregnancy.

To evaluate uterine artery blood flow in response to typical exercise sessions performed in pregnancy in accordance with the current recommendations from the American College of Obstetricians and Gynecologists and the U.S. Department of Health and Human Services. This prospective cross-sectional study measured uterine artery Doppler velocimetry in healthy pregnant women after individually prescribed exercise, including 1) moderate-intensity exercise (40-59% of heart rate reserve) in both nonexercisers and regular exercisers and 2) vigorous-intensity exercise (60-84% of heart rate reserve) in women who regularly engage in exercise. Resting uterine artery Doppler measures were obtained after a 20-minute fetal heart tracing; then the exercise session was performed. Immediately after the exercise session ended, the participants returned to the semirecumbent, leftward tilt position for ultrasound examination. Uterine artery measures were obtained 3.4±0.9 minutes (mean±SD) postexercise. Forty-five healthy pregnant women participated in the study: 30 regular exercisers and 15 nonexercisers. For the moderate-intensity session, mean gestational age was 31.1 and 31.7 weeks for the exercisers and nonexercisers, respectively. Mean uterine artery Doppler indices (pulsatility index, resistance index, systolic/diastolic ratio) did not significantly change with exercise. For the vigorous-intensity session, the average gestational age was 31.5 weeks. After vigorous activity, all mean uterine artery Doppler indices showed reductions postexercise, for example, pulsatility index decreased from 0.63±0.12 to 0.58±0.12 (P=.04). Individually prescribed exercise according to guidelines for pregnant women does not adversely alter uterine artery Doppler values, suggesting that uterine blood flow is not reduced as a result of exercise.

Hemodynamics of the uterine and umbilical arteries during the perinatal period in ewes

Examining feto-maternal blood flow is extremely important for accurate prenatal control and predicting adverse conditions during puerperium. We aimed to analyze blood flow of uterine artery (UA) and umbilical artery (UMA) from and subsequent to mid-gestation, lambing and postpartum of 15 ewes, subjected to lambing induction with aglepristone. Hemodynamic variables, diameter and blood flow of UA and UMA were determined by Doppler and B-mode ultrasonography at 60, 90 and 120 days of pregnancy, at 12 h before, 12 h after first aglepristone injection and 12 h after induction and days 1, 3, 5, 7, 15 and 30 after lambing. The UMA peak systolic:diastolic velocity (S/D), resistance index (RI) and pulsatility index (PI) decreased from mid-pregnancy until 120 d, whereas peak systolic velocity (PSV), end diastolic velocity (EDV) and time average maximum velocity (TAMAX) increased towards 120 d. The UMA RI additionally decreased at 12 h after lambing induction. The UMA diameter and volume increased from mid-gestation until 12 h before lambing induction. UA PSV and TAMAX increased from 60 until 90 days of pregnancy, while EDV, PSV and TAMAX decreased soon after parturition, with a further reduction at 7 days. The UA diameter and volume decreased during postpartum, stabilizing by 15 days after parturition. In conclusion, pregnancy is marked by progressive increase in uterine and umbilical blood flow, while lambing acutely diminishes umbilical vascular resistance, suggesting lack of progesterone influence on vasodilation. Conversely, puerperium is characterized by reduction in uterine blood supply mostly within the first 2 weeks of postpartum in sheep.

153. Spiral arterial blood flow during pregnancy; a systematic review and meta-analysis

Objectives To evaluate the physiological adaptation of blood flow in human uterine spiral arteries throughout the course of normotensive and hypertensive pregnancies based on existing literature. Methods A systematic literature review and meta-analysis on the change of arterial uterine spiral arteries, measured by Doppler ultrasonography, was conducted. Literature search was performed in Pubmed, EMBASE and Cochrane Library. The search was limited to papers published in English. Both first and second selection were performed by two independent researchers. Weighted means of the Doppler indices were calculated for the three pregnancy trimesters. Results Seven longitudinal prospective and four cross-sectional studies were included with publication dates ranging from 1995 to 2015. Ultrasound measurements were performed at certain gestational ages using transvaginal or transabdominal transducers. In normotensive pregnancies, pulsatility index (PI) decreased from 0.76 (95% CI: 0.65–0.86) in the first trimester to 0.51 (95% CI: 0.45–0.57) (p Conclusions PI and RI in uterine spiral arteries both decreased with advancing gestational age with the largest decrease between the first and second trimester. This is in concordance with previous histological hypertrophic decidual vasculopathy- and Doppler uterine artery findings. Longitudinal studies examining comprehensively the predictive value of spiral artery Doppler for hypertensive pregnancies are yet to be determined.

Scopolamine for uterine involution of dairy cows

The objective of this study was to evaluate the effect of administration of scopolamine (a parasympatholytic drug) immediately after delivery, on uterine involution in dairy cows. The cows were divided into two groups: group T (treated with scopolamine butylbromide 40 mg/100 kg P.V., within 24 h of delivery) and group C (treated with 2 ml/q of saline solution). The cows were monitored at T0, within 24 h of delivery, T7, T14, T28 and T40 respectively 7th, 14th, 28th and 40th day postpartum, by measuring the levels of hydroxyproline (HYP), an important marker of uterine involution; by ultrasound examination for the measurement of the diameter of uterine horns and of blood flow in the middle uterine artery; and by evaluation of reproductive indices. HYP showed higher concentrations in the T group than in the C group at all times, but the difference was significant at T7 and T40. Uterine diameters were reduced from T7 to T40, with lower values in the T group, as compared to the C group; the pulsatility index (PI) of the middle uterine artery increased in the T group compared to the C group, with a statistically significant difference at T7. There was a better conception-delivery interval and higher pregnancy rate in the T group compared to the C group. It is likely that scopolamine blocked the uterine contractions in postpartum, for the duration of its half-life. After cessation of its pharmacological effect, the uterus may have started to contract more effectively. These results suggested that scopolamine could be useful as a pharmacological approach to postpartum management.

Maternal nutrient restriction alters uterine artery hemodynamics and placentome vascular density in Bos indicus and Bos taurus.

The objective was to examine uterine artery blood flow (UBF) as well as macroscopic and microscopic placentome vascular density in nutrient-restricted Angus and Brahman heifers. Angus (n = 6) and Brahman (n = 6) heifers were bred to a single sire and pregnancy confirmed at 30-d postbreeding. Heifers were randomly assigned to 1 of 2 dietary treatments consisting of 100% (control-fed; CON; n = 6) or 60% (total nutrient-restricted; RES; n = 6) based from net energy requirements for gestating heifers. Nutritional treatments were imposed from days 50 to 180 of gestation. On day 175 of gestation, UBF was collected ipsilateral and contralateral to the conceptus via Doppler ultrasonography. Heifers underwent Cesarean sections for collection of 2 adjacent placentomes on day 180 of gestation. The primary cotyledonary artery of 1 placentome was perfused with Alexa Fluor 647 Con A conjugate to examine macroscopic cotyledonary vascular density via an in vivo imaging system. The second placentome was fixed for microscopic immunofluorescence labeling of capillaries and separated into maternal (caruncle) and fetal (cotyledon) components for determination of angiogenic factor mRNA expression. Main effects of nutritional treatment and breed are reported in the absence of a significant nutritional treatment by breed interaction. Ipsilateral UBF was decreased (P < 0.05) by 48% in RES vs. CON, whereas breed did not influence ipsilateral UBF. Contralateral UBF was not different between nutritional treatments; however, contralateral UBF was decreased (P < 0.05) by 63% in Brahman vs. Angus cattle. Macroscopic cotyledonary vascular density was increased (P < 0.05) by 36% in RES vs. CON and 82% in Brahman vs. Angus heifers. Percent capillary area and capillary perimeter were increased (P < 0.05) in RES vs. CON and increased (P < 0.05) in Brahman vs. Angus heifers. Dietary treatments did not alter angiogenic factor expression; however, transcript abundance of caruncle and cotyledon ANGP1, FLT1, and KDR was increased (P < 0.05) in Brahman vs. Angus heifers. In summary, these data indicate compensatory responses in macroscopic and microscopic placentome blood vessel density during maternal nutrient restriction-induced reductions in UBF. Moreover, a greater macroscopic density of cotyledonary blood vessels was observed in Brahman vs. Angus heifers.

Uterine artery flow velocity waveform (FVW) type and subednometrial vascularity in recurrent pregnancy loss

Purpose: To assess the subendometrial and uterine artery blood flow and pattern of the waveform of the uterine artery in cases of recurrent pregnancy loss compared with normal controls.Subjects and methods: Fifty women with a history of two or more successive pregnancy losses were investigated by Doppler transvaginal ultrasound to assess the subendometrial blood flow resistance index (RI), type of Doppler waveform of the uterine artery, and uterine artery pulsatility index (PI) in the mid-luteal phase. Fifty normal women acted as controls.Results: Subendometrial blood flow RI and uterine artery PI were higher in cases than controls. The majority of cases of recurrent pregnancy loss had a waveform pattern of A, or loss of diastolic flow, whereas the controls were mainly C wave.Conclusions: Some sort of endometrial and subendometrial ischemia can be suggested in cases of recurrent pregnancy loss, waveform pattern of uterine artery changes may be used to monitor changes in vascularity of endometrium if vascular enhancers are given in such cases.

An effect of maternal nifedipine therapy on fetoplacental blood flow: a prospective study.

The aim of this study is to assess the effects of maternal nifedipine administration on placental and fetal blood flow. A total of 29 patients with preterm labor diagnosis admitted to the tertiary care center, Zeynep Kamil Hospital, were evaluated. Before and 24-48h after administration of oral nifedipine, Doppler ultrasound scan was carried out to measure fetal middle cerebral artery, ductus venosus, umbilical artery, and maternal uterine artery blood flow. After 24 and 48h of therapy, there were no changes in mean PI and RI in the umbilical arteries and ductus venosus (p > 0.05). Fetal middle cerebral artery and maternal uterine artery PI and RI values showed a significant reduction 24-48h after oral nifedipine therapy (p < 0.05). Our study showed that 24 and 48h after oral nifedipine therapy, there is a significant increase in fetal MCA and maternal uterine artery blood flow, while fetal umbilical artery and ductus venosus Doppler values do not change.

EFFECT OF VAGINAL SILDENAFIL ON IN VITRO FERTILIZATION SUCCESS RATES IN WOMEN WITH PREVIOUS FAILED IN VITRO FERTILIZATION ATTEMPTS

Objectives: Endometrial thickness of &lt;9 mm is a predictor of in vitro fertilization (IVF) failure, although neither pregnancy rates nor the pregnancy outcomes are dependent on the endometrial thickness alone. The impact that uterine artery blood flow has on endometrial growth is dependent on nitric oxide which concentrations could be altered by halting a cyclic guanosine monophosphate-mediated pathway with a phosphodiesterase type 5 selective inhibitor such as sildenafil.Methods: In this clinical trial, 72 patients aged below 45 years which have had at least two earlier failed IVF attempts were randomly split into two groups each consisting of 36 patients. Both groups were started on a long IVF protocol. The case group was also administered 100 mg vaginal sildenafil suppositories daily, starting on day 3 of menstruation which was continued until human chorionic gonadotropin administration. Endometrial thickness was measured using ultrasonography in both groups plus pregnancy rates were assessed in both groups.Results: The mean age of the patients in Group A who received sildenafil; in this clinical trial, 72 patients aged below 45 years which have had at least two previous failed IVF attempts were randomly split into two groups each consisting of 36 patients was 33.8±4.8 in contrast to Group B (control group) with the mean age of 33.8±4.8. Mean endometrial thickness of 8.6±0.1 mm was recorded in Group B compared to 9.0±0.7 mm in Group A (p=0.03). Of all the 36 participants who received sildenafil citrate during the IVF cycle, 12 (33.3%) patients had successful pregnancies while 24 (66.7%) failed to get pregnant. In the control group, out of the 36 participants, 10 (27.8%) patients got pregnant while 26 (72.2%) failed the cycle (p=0.9).Conclusion: This study showed that although using vaginal sildenafil during the IVF cycle does improve endometrial thickness before implantation, this does not necessarily lead to higher pregnancy rates.

Pregnancy upregulates angiotensin type 2 receptor expression and increases blood flow in uterine arteries of rats.

Normal pregnancy is associated with decreased uterine vascular contraction and increased blood flow even though angiotensin II (AngII) levels are increased. AngII not only activates the angiotensin type 1 receptor (AT1R) to mediate vasoconstriction but also angiotensin type 2 receptor (AT2R) to cause vasodilation. We hypothesized that upregulation of AT2R expression and function accounts for increased uterine artery blood flow during pregnancy. Virgin, pregnant (at different days of gestation) and post-partum Sprague-Dawley rats were used to determine uterine artery hemodynamics using micro ultrasound and plasma angiotensin II levels by ELISA. Isolated uterine arteries were examined for AT1R and AT2R expression and isometric contraction/relaxation. Plasma AngII levels were steady up to mid-pregnancy, increased as pregnancy advanced, reaching a peak in late pregnancy, and then restored to pre-pregnant levels after delivery. The pattern of increase in AngII levels mirrored a parallel increase in uterine blood flow. AT1R expression did not change, but AT2R expression increased during pregnancy correlating with uterine blood flow increase. Treatment with the AT2R antagonist PD123319 reduced uterine arterial blood flow. Vasoconstriction to angiotensin II was blunted in pregnant rats. Treatment with PD123319 caused greater enhancement of AngII contraction in pregnant than virgin rats. Ex vivo exposure of estradiol to uterine arterial rings dose dependently upregulated AT2R expression, that was inhibited by estrogen receptor antagonist. These results demonstrate that elevated AngII levels during gestation induce an increase in uterine blood flow via heightened AT2R-mediated signaling. Estrogens appear to directly upregulate uterine vascular AT2R independent of any endogenous factors.

P3: Uterine radial artery blood flow resistance at 8‐week gestation indicates pregnancy loss in recurrent pregnancy loss women with inherited thrombophilia

P3: Uterine radial artery blood flow resistance at 8‐week gestation indicates pregnancy loss in recurrent pregnancy loss women with inherited thrombophilia

Correction: Gestational Dietary Protein Is Associated with Sex Specific Decrease in Blood Flow, Fetal Heart Growth and Post-Natal Blood Pressure of Progeny.

[This corrects the article DOI: 10.1371/journal.pone.0125694.].

Uteroplacental secretion of progesterone and estradiol-17β in an ovine model of intrauterine growth restriction

Using a mid to late gestation model of intrauterine growth restriction, uteroplacental secretion of progesterone and estradiol-17β were examined. From day 50 to 130 of gestation, 31 ewe lambs were allocated to receive 100% (ADQ) or 60% (RES) of nutrient requirements. At day 130, umbilical and uterine artery blood flows were determined and blood samples were collected from maternal saphenous artery, gravid uterine vein, umbilical vein, and umbilical artery. Uteroplacental secretion of progesterone was increased in RES compared to ADQ fed dams. There was a net secretion and net metabolism of estradiol-17β in RES, and ADQ fed dams, respectively. In relation to steroid synthesis, cotyledonary abundance of steroidogenic acute regulatory protein was greater in RES compared with ADQ fed dams, while abundance of aromatase was not different between dietary treatments. Caruncular aldo-keto reductase 1C abundance was less in RES compared to ADQ fed dams. The increase in progesterone secretion, therefore, is due in part to an increase in synthesis and a decrease in placental catabolism. Caruncular cytochrome P450 3A, which catalyzes the conversion of estrogens to catechol-estrogens, was in lesser abundance in RES compared to ADQ fed dams. Opposite responses in estradiol-17β uteroplacental secretion compared with metabolism may be mediated through placental estrogen metabolism via cytochrome P450 enzymes.

Pregnancy Enhances Calcium Spark Activity Independent of Altitude in Ovine Uterine Arterial Myocytes

During pregnancy, uterine artery blood flow increases in order to accommodate the growing fetus. However, the molecular mechanisms by which this change in uterine blood flow occurs remains to be elucidated. The BKCa channel, which is activated in response to ryanodine receptor (RyR) generated increases in intracellular Ca2+ known as Ca2+ sparks, helps regulate uterine artery blood flow. BKCa channel activation leads to vascular smooth muscle relaxation, thus decreasing uterine artery vascular tone and increasing uterine blood flow during pregnancy. Further to this, long term hypoxia due to high altitude exposure diminishes pregnancy – related increases in uterine blood flow. Based on these relationships we hypothesized that both pregnancy and membrane depolarization would increase Ca2+ spark activity, whereas ryanodine and long term hypoxia would inhibit Ca2+ spark activity. Uterine arteries were isolated from near‐term pregnant (n=6) and non‐pregnant sheep (n=6) in normoxia, as well as near‐term pregnant (n=6) and non‐pregnant sheep (n=6) exposed to hypoxic conditions at White Mountain (elevation 3,801 m) for 100 plus days. Isolated uterine arteries were subjected to three distinct ex vivo treatments: (1) control (saline), (2) 30mM potassium (30K), which causes membrane depolarization, and (3) 30K with ryanodine (10 μM), an RyR antagonist. Indeed, Ca2+ spark activity was increased in pregnant uterine arteries as compared to non‐pregnant uterine arteries, whereas hypoxia reduced spark frequency in all the aforementioned groups. Treatment with 30K increased Ca2+ spark activity in all groups. In comparison, 30K + ryanodine treatment decreased Ca2+ spark activity. Pregnancy increased the full width of sparks. However, pregnancy or hypoxia caused only minor changes in the amplitude and temporal aspects of sparks. These findings support the claim that membrane depolarization, due to 30K treatment, causes an increase in Ca2+ spark activity whereas ryanodine inhibits release of Ca2+ from the sarcoplasmic reticulum and thus decreases Ca2+ sparks. Taken together, these findings support the notion that the ryanodine receptors and BKCa channels work in conjunction with each other. This study provides further insight into the mechanisms that regulate uterine artery vascular tone and blood flow, and thus may prove useful in designing treatments for pregnancy complications that arise from increased uterine vascular tone, such as intrauterine growth restriction.Support or Funding InformationThis work is supported by The National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development grant number HD083132, by the National Science Foundation under Grant No. MRI 0923559, and the Loma Linda University School of Medicine. VW was a Walter E Macpherson Medical Student Summer Research Fellow.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effect of clomiphene citrate on uterine hemodynamics in women with unexplained infertility.

PurposeThe aim of the study was to evaluate the effect of clomiphene citrate on uterine artery blood flow using pulsed Doppler and endometrial and subendometrial micro vascularization using 3D power Doppler in unexplained infertility.Patients and methodsIn a prospective observational study at a university teaching hospital, the mid-luteal (peri-implantation) endometrial thickness and volume, uterine artery pulsatility index (PI) and resistance index (RI), endometrial and subendometrial vascularization index (VI), flow index (FI), and vascularization flow index (VFI), and serum estradiol and progesterone levels were compared between natural and clomiphene citrate stimulated cycles in the same group of 50 patients with unexplained infertility. Statistical analysis was done using paired t-test to compare different study variables.ResultsThe primary outcome, which was the endometrial flow index, was significantly lower in the stimulated cycles (mean ± SD: 23.89±7.96 vs 27.49±8.73, mean difference (95% CI): −3.6 (−2, −5.9); P=0.03). The mean ± SD of endometrial thickness (10.92±3.04 vs 12.46±3.08 mm; P=0.01), volume (4.57±1.28 vs 5.26±1.32 cm3; P=0.009), endometrial VI (0.86±0.15 vs 0.95%±0.21%; P=0.02), VFI (0.25±0.08 vs 0.31±0.12; P=0.004), subendometrial VI (1.93±0.68 vs 2.26%±0.75%; P=0.02), FI (26.81±9.16 vs 30.73±9.87; P=0.04), and VFI (0.68±0.18 vs 0.79±0.21; P=0.006) were significantly lower in the stimulated cycles. However, there were no significant differences in the uterine artery PI (P=0.12) and RI (P=0.08) or serum estradiol (P=0.54) and progesterone (P=0.37) levels between natural and stimulated cycles.ConclusionPeri-implantation endometrial perfusion is significantly lower in clomiphene citrate stimulated cycles when compared to natural ones in patients with unexplained infertility.