Myometrial Arteries Research Articles

Elastin distribution in the myometrial and vascular smooth muscle of the human uterus.

Magnetic resonance imaging and transvaginal ultrasonography in women of reproductive age suggest that the myometrium consists of inner and outer layers. It was hypothesized that these structural and functional differences in the myometrium might be associated with a variation in elastin distribution. Fifty-one hysterectomy specimens representing all phases of the normal menstrual cycle were studied by immunocytochemistry, orcein staining and image analysis. Elastin was present within the outer myometrial smooth muscle, but was less widely distributed in the inner smooth muscle. Immunoreactivity and staining were observed in the myometrial arteries and arterioles and within the basal portions of endometrial arterioles. Elastin was also present in perivascular tissue, particularly near the large vessels. More extravascular (i.e. perivascular and smooth muscle) elastin was present in the outer myometrium in all cases, although no distinct layering was observed. Semi-quantitative analysis of the elastin distribution in 11 full thickness specimens demonstrated a decreasing gradient from outer to inner myometrium rather than distinct layering. Contrary to previous reports, these data suggest that the external region of the myometrium is more elastic than the inner region and that elastin is found throughout the arteriolar tree of the human uterus.

Uteroplacental circulation during the first trimester of normal and abnormal pregnancy

The aim of this study was to evaluate the uteroplacental vascular characteristics during the first trimester of normal and failed pregnancies. A clinical descriptive study was conducted using colour Doppler ultrasound in 45 women with normal pregnancies (group A) and 44 with non-embryonic sac or missed abortions (group B). The mean gestational age in these two groups was 9.3 and 7.6 weeks respectively ( P < 0.01). The number of myometrial blood vessels (arteries and veins identified by power Doppler mapping), the quantity of intervillous flow, the resistance index (RI) for the arterial system, and the pulsatility index (PI) of the myometrial arteries were evaluated. The number of myometrial blood vessels in group A was lower than that in group B. The intervillous flow was observed in some cases from early pregnancy and more often after 10 weeks. This characteristic was observed significantly more frequently in group B than in group A. The RI and PI in the uterine arteries were significantly higher in group A than in group B. The RI and the PI of the uterine arteries decreased with the advance of gestational age in both groups. Colour Doppler ultrasound provides information about uteroplacental circulation during the first trimester and indicates early development of intervillous circulation. Although a greater uteroplacental blood circulation was observed in failed pregnancies, the overlapping between groups severely limits the application of this characteristic in clinical practice.

Endothelial function in myometrial resistance arteries of normal pregnant women perfused with syncytiotrophoblast microvillous membranes.

To investigate the effects of syncytiotrophoblast microvillous membranes (STBM) in concentrations, found in vivo in women with pre-eclampsia, on endothelial function in isolated resistance arteries. Department of Obstetrics and Gynaecology, Huddinge University Hospital, Stockholm. Twenty-nine myometrial resistance arteries isolated from biopsies of healthy term pregnant women, obtained during caesarean section. The myometrial arteries were mounted in a pressure arteriograph and perfused intraluminally for three hours with STBM (20 to 2000ng/mL) or with erythrocyte membranes or physiological salt solution as controls, all substituted with 0.5% bovine serum albumin. Bradykinin concentration-response curves were performed before and after perfusion. The bradykinin concentrationresponse curves were fitted to the Hill equation and maximal dilation and the pEC50 values were determined from these fits. Differences within groups were analysed with a paired Student's t test. Electron microscopic evaluation of the endothelium was performed. Neither STBM nor erythrocyte membrane perfusion affected maximal dilation or the pEC50 values of the bradykinin concentration-response curves at any concentration. Examination by electron microscopy showed no obvious damage to the endothelium after perfusion with STBM or erythrocyte membranes. Perfusion with STBM in concentrations up to 100 times those reported in pre-eclampsia has no significant effect on bradykinin-mediated dilation in isolated myometrial arteries.

Endothelial function in myometrial resistance arteries of normal pregnant women perfused with syncytiotrophoblast microvillous membranes

Objective To investigate the effects of syncytiotrophoblast microvillous membranes (STBM) in concentrations, found in vivo in women with pre-eclampsia, on endothelial function in isolated resistance arteries. Setting Department of Obstetrics and Gynaecology, Huddinge University Hospital, Stockholm. Sample Twenty-nine myometrial resistance arteries isolated from biopsies of healthy term pregnant women, obtained during caesarean section. Methods The myometrial arteries were mounted in a pressure arteriograph and perfused intraluminally for three hours with STBM (20 to 2000ng/mL) or with erythrocyte membranes or physiological salt solution as controls, all substituted with 0.5% bovine serum albumin. Bradykinin concentration-response curves were performed before and after perfusion. Main outcome measures The bradykinin concentrationresponse curves were fitted to the Hill equation and maximal dilation and the pEC 50 values were determined from these fits. Differences within groups were analysed with a paired Student's t test. Electron microscopic evaluation of the endothelium was performed. Results Neither STBM nor erythrocyte membrane perfusion affected maximal dilation or the pEC 50 values of the bradykinin concentration-response curves at any concentration. Examination by electron microscopy showed no obvious damage to the endothelium after perfusion with STBM or erythrocyte membranes. Conclusion Perfusion with STBM in concentrations up to 100 times those reported in pre-eclampsia has no significant effect on bradykinin-mediated dilation in isolated myometrial arteries.

Angiopathies in the equine endometrial biopsy – a marker for extrauterine vascular lesions?

Endometrial, myometrial and extrauterine vessels of 13 juvenile mares, 53 adult non-pregnant mares, 11 adult pregnant mares (two of which had a rupture of the uterine artery), and 4 post-parturient mares were investigated by means of histology and immunohistochemistry. The vessels of juvenile mares did not show any alterations. The endometrial vessels of the adult non-pregnant mares, on the other hand, were characterized by mild to moderate panelastofibrosis or panfibroelastosis. The myometrial vessels revealed lesions of the same quality, but to a higher degree in one third of the mares. In the extrauterine vessels (arteria and vena uterina, ramus cranialis of the arteria and vena uterina, arteria and vena ovarica of each side) mild to moderate fibrosis and fibroelastosis of the vascular wall predominated. There was a distinct correlation between the degree of arteriosis in the uterine (endometrial and myometrial) and the extrauterine vessels. Based on these findings, the endometrial biopsy is a reliable indicator for extrauterine arterial alterations. The vascular lesions of the pregnant mares in the first half of the pregnancy resembled those of the adult non-pregnant mares. By contrast, the endometrial, myometrial and extrauterine arteries of mares in the second half of pregnancy and post-parturient mares were characterized by a pronounced hypertrophy of the myocytes within the media.

Preeclampsia: Evidence for impaired shear stress–mediated nitric oxide release in uterine circulation

Objective: We sought to compare flow-mediated dilatation and myogenic and norepinephrine-induced tone in myometrial resistance arteries from women with preeclampsia and healthy pregnant women and to evaluate the role that nitric oxide may play in these responses. Study Design: Arteries (approximately 200μm, at 50 mm Hg) were dissected from myometrial biopsy specimens from women undergoing emergency cesarean delivery because of preeclampsia (n = 6) and from healthy control subjects undergoing planned cesarean delivery (n = 9). Responses to intraluminal flow, pressure, and a constrictor agonist (norepinephrine, 10–6 mol/L) were studied in the absence and presence of the nitric oxide synthase inhibitor N ωnitro-L -arginine (10–4 mol/L). Myogenic and norepinephrine-induced tone were calculated after the determination of artery diameter in the absence of extracellular calcium and in the presence of papaverine (10–4 mol/L). Results: An increase in intraluminal flow led to dilatation of isolated myometrial arteries from healthy gravid women, whereas flow-mediated dilatation was absent in arteries from gravid patients with preeclampsia (increase in diameter at maximum flow rate of 204 μL/min, 28% ± 5% in healthy gravid patients vs –15% ± 6% in gravid women with preeclampsia; analysis of variance, P <.05). Addition of N ω-nitro-L -arginine had no significant effect on flow-mediated responses in arteries from women with preeclampsia, whereas flow-mediated dilatation was abolished after addition of N ω-nitro-L -arginine in arteries from healthy gravid women (increase in diameter at a maximum flow rate of 204 μL/min, 28% ± 5% control vs –9% ± 5% N ω-nitro-L -arginine; analysis of variance, P <.05). Arteries from women with preeclampsia developed pressure-induced myogenic and norepinephrine-induced tone, similar to that obtained in arteries from healthy gravid women. In arteries from gravid women with preeclampsia, inhibition of nitric oxide synthase enhanced myogenic-induced tone (25% ± 4% control vs 35% ± 5% N ω-nitro-L -arginine; P <.05) and norepinephrine-induced tone (36% ± 4% control vs 46% ± 6% N ω-nitro-L -arginine; P <.05), as in arteries from healthy gravid women. Conclusions: Nitric oxide may participate in modulation of pressure- and norepinephrine-induced tone even in preeclampsia, but the shear stress–mediated release of nitric oxide is absent. Failure of shear stress–mediated dilation in myometrial arteries from gravid women with preeclampsia might contribute to the impaired uteroplacental blood flow in this disease. (Am J Obstet Gynecol 2000;183:160-6.)

Preeclampsia: Evidence for impaired shear stress–mediated nitric oxide release in uterine circulation

Objective: We sought to compare flow-mediated dilatation and myogenic and norepinephrine-induced tone in myometrial resistance arteries from women with preeclampsia and healthy pregnant women and to evaluate the role that nitric oxide may play in these responses. Study Design: Arteries (approximately 200μm, at 50 mm Hg) were dissected from myometrial biopsy specimens from women undergoing emergency cesarean delivery because of preeclampsia (n = 6) and from healthy control subjects undergoing planned cesarean delivery (n = 9). Responses to intraluminal flow, pressure, and a constrictor agonist (norepinephrine, 10–6 mol/L) were studied in the absence and presence of the nitric oxide synthase inhibitor N ωnitro-L -arginine (10–4 mol/L). Myogenic and norepinephrine-induced tone were calculated after the determination of artery diameter in the absence of extracellular calcium and in the presence of papaverine (10–4 mol/L). Results: An increase in intraluminal flow led to dilatation of isolated myometrial arteries from healthy gravid women, whereas flow-mediated dilatation was absent in arteries from gravid patients with preeclampsia (increase in diameter at maximum flow rate of 204 μL/min, 28% ± 5% in healthy gravid patients vs –15% ± 6% in gravid women with preeclampsia; analysis of variance, P <.05). Addition of N ω-nitro-L -arginine had no significant effect on flow-mediated responses in arteries from women with preeclampsia, whereas flow-mediated dilatation was abolished after addition of N ω-nitro-L -arginine in arteries from healthy gravid women (increase in diameter at a maximum flow rate of 204 μL/min, 28% ± 5% control vs –9% ± 5% N ω-nitro-L -arginine; analysis of variance, P <.05). Arteries from women with preeclampsia developed pressure-induced myogenic and norepinephrine-induced tone, similar to that obtained in arteries from healthy gravid women. In arteries from gravid women with preeclampsia, inhibition of nitric oxide synthase enhanced myogenic-induced tone (25% ± 4% control vs 35% ± 5% N ω-nitro-L -arginine; P <.05) and norepinephrine-induced tone (36% ± 4% control vs 46% ± 6% N ω-nitro-L -arginine; P <.05), as in arteries from healthy gravid women. Conclusions: Nitric oxide may participate in modulation of pressure- and norepinephrine-induced tone even in preeclampsia, but the shear stress–mediated release of nitric oxide is absent. Failure of shear stress–mediated dilation in myometrial arteries from gravid women with preeclampsia might contribute to the impaired uteroplacental blood flow in this disease. (Am J Obstet Gynecol 2000;183:160-6.)

A comparative study of vascular responsiveness of myometrial and omental small resistance arteries in late-gestation sheep

Objective: We determined whether local regulation by vasoactive agents differs in the myometrial and omental vascular beds in the pregnant sheep. Specifically, we hypothesized that there would be blunting of in vitro responses to constrictor agonists, enhancement of sensitivity to dilator agonists, or both in myometrial compared with omental resistance arteries. Study Design: We compared in vitro responsiveness of small resistance intramyometrial and omental arteries from near-term pregnant ewes to the vasoconstrictor agents norepinephrine, U46619 (a thromboxane sympathomimetic), and potassium and the vasodilator agents acetylcholine and bradykinin. Results: The vascular sensitivity and the maximum response of intramyometrial small arteries to U46619 was attenuated compared with that of omental arteries. There were no significant differences between the intramyometrial and omental arteries in response to norepinephrine, potassium, acetylcholine, or bradykinin. Conclusions: These results support regional heterogeneity of regulation of function in different maternal vascular beds during pregnancy. The relative insensitivity of the myometrial arteries to the thromboxane mimetic indicates the existence of decreased constrictor function that may facilitate preservation of uterine blood flow in vivo. (Am J Obstet Gynecol 1999;181:663-8.)

Relationship of cell adhesion molecule expression to endothelium-dependent relaxation in normal pregnancy and pregnancies complicated with preeclampsia or fetal growth restriction.

To determine the degree of endothelium-dependent relaxation in myometrial and omental resistance arteries from normal pregnancies and pregnancies complicated with preeclampsia or fetal growth restriction (FGR) (compromised pregnancy group), and to correlate the results with the endothelial surface expression of cell adhesion molecules (CAMs) in the same vessels. Parallel wire myography was used to assess the relaxation of omentum or myometrial vessels obtained from nonpregnant women (n = 3), women with normal pregnancies (n = 11), and women with pregnancies complicated by preeclampsia or fetal growth restriction (n = 10). These resistance vessels were constricted with incremental concentrations of vasopressin (10(-10) mol/L to 3.3 x 10(-8) mol/L) prior to the addition of incremental concentrations of bradykinin (10(-10) mol/L to 3.3 x 10(-6) mol/L). Immunohistochemistry was used to assess the endothelial expression of the CAMs E-selectin, ICAM-1, VCAM-1, and PECAM. A significant reduction in endothelium-dependent relaxation of myometrial vessels was found in the compromised pregnancy group when compared with both the normotensive pregnant group and the nonpregnant group. This reduction was not noted with omental vessels. All vessels in the nonpregnant group, normal pregnant group, and compromised pregnancy group expressed PECAM and ICAM-1 on the endothelium. There was no difference in intensity of immunostaining between the groups. None of the vessels in any of the groups expressed VCAM-1 or E-selectin. We found no evidence that impaired relaxation responses to bradykinin are linked to altered expression of CAMs in preeclampsia and FGR. These results suggest that increased CAM expression occurs in a vascular bed separate from those investigated in the present study. Possible sites for this would be in the microcirculation of organs such as the kidney.

Endometrial Morphology and Ultrasound Vascular Findings

Luteal-phase supplementation has proved necessary in Gn-RH analog and human gonadotropin-stimulated cycles. We studied the effects of vaginally and intramuscularly delivered progesterone on the endometrium. Thirty patients enrolled in an IVF program without embryo transfer due to absence of fertilization were included in the study. Patients were randomly allocated to two treatment groups. Group A (n = 15) was administered 200 mg progesterone b.i.d. by the vaginal route (Esolut, Angelini) starting on the day of oocyte pick up and group B (n = 15) was given 100 mg intramuscular progesterone once daily (Prontogest, Amsa). Six days after HCG administration, biopsies were obtained for endometrial histological maturation and estrogen (ER) and progesterone (PR) receptor analyses. In addition, ultrasound measurements of endometrial thickness were made and uterine and myometrial artery flow was determined. Serum concentrations of estriol and progesterone were measured on the day of HCG, at oocyte pick up and at endometrial biopsy. The two treatment groups were similar in terms of follicular phase parameters during superovulation with Gn-RH analog and gonadotropin. Histologic, receptor and ultrasonographic analyses showed no significant differences between the two treatment groups. Our results indicate that both intramuscular and vaginal progesterone are equally effective on the endometrium.

Regulation of maternal placental blood flow: A review

Summary We do not know for certain that the maternal placental circulation is under physiological control. The human placenta is hemochorial and lacks arterioles, the principal determinants of resistance and flow in other organs. Innervation of the uterine arteries does not extend to the spiral arteries and work on isolated vessels suggests that sympathetic nerves are unimportant in the control of placental blood flow. Vasodilator fibers supply the larger vessels and may use nitric oxide and substance P as neurotransmitters. Hormones such as arginine vasopressin and angiotensin II have no effect on myometrial vessels in the physiological range of plasma concentrations. Angiotensin II may be important in disease states like pre-eclampsia, however, as might the endothelium derived autacoid, endothelin-1. There may be an endothelium-derived relaxing factor in uterine arteries. It is not necessarily nitric oxide; it might be prostacyclin. Clinical studies on the effect of nitric oxide donors on umbilical artery flow velocity have yielded conflicting results. Further work is required to resolve these differences and define criteria for determining the effects of autacoids and drugs in a clinical context. There is still ample room for work on isolated vessels. We need to know if vascular reactivity to endothelin-1, atrial natriuretic peptide and other autacoids is altered in pre-eclampsia. Since such studies likely will be made on myometrial arteries taken from the lower uterine segment, it needs also to be shown that they react to autacoids in the same way as arteries from the placental site. It should be possible to obtain placental vessels at Cesarean section in cases of placenta previa. Because reduced placental perfusion is a feature of pre-eclampsia, and often is associated with fetal growth restriction, research on the control of maternal placental blood flow is of great potential benefit.

Myogenic and Endothelial Properties of Myometrial Resistance Arteries from Women with Preeclampsia

Objecrive: To compare myometrial resistance arteries from women with preeclampsia and normal pregnant women with respect to myogenic behavior, acetylcholine-mediated dilatation, and distensibility.Study Design: Arteries from women with preeclampsia (n = 14) and healthy term pregnant women (n = 17) were studied in a pressurized arteriograph system. Myogenic tone was evaluated during increments in intraluminal pressure from 20 to 120 mm Hg, as well as distensibility index at the same pressure steps in Ca2+-free solution substituted with papaverine. Endotheliumdependent relaxation was assessed by evaluating the response to acetylcholine (10−6 M) in the absence and presence of Nω-nitro-L-arginine in arteries pressurized at a constant intraluminal pressure of 70 mm Hg.Results: Overall myogenic tone did not differ between the arteries from the two patient groups studied, but the slope of the pressure-myogenic tone relationship in arteries from women with preeclampsia was significantly different (positive). Relaxation to acetylcholine was impaired in arteries from women with preeclampsia (6 ω 1% versus 18 t 4%, p < 0.05), whereas inhibition of nitric oxide synthase with Nω-nitro-L-arginine abolished this response in both patients groups. The distensibility index (Ca2+-free solution plus papaverine) of arteries from women with preeclampsia was increased as compared to arteries from normal pregnant women (p <0.05).Conclusions: Pressure-induced myogenic tone and impaired acetylcholine-mediated vasodilatation in myometrial resistance arteries from women with preeclampsia might contribute to the increased vascular resistance in the uterine circulation seen in preeclampsia. The increased distensibility of the myornetrial arteries from women with preeclampsia might represent a compen-satory mechanism to preserve the blood flow in the uteroplacental vascular bed.

A relationship between myometrial resistance artery behaviour and circulating lipid composition?

A relationship between myometrial resistance artery behaviour and circulating lipid composition?

Plasma from women with pre-eclampsia causes a loss of endothelium dependent relaxation in myometrial resistance arteries

Plasma from women with pre-eclampsia causes a loss of endothelium dependent relaxation in myometrial resistance arteries

The extent of trophoblast invasion in the preplacental vasculature of the guinea-pig

Pregnancy-induced structural changes in spiral arteries seem to be a prerequisite for successful fetal outcome in humans. It is unknown whether these changes also occur in other preplacental vessels (radial and arcuate arteries) in normal pregnancies. Since the radial and arcuate arteries need to dilate in order to accommodate the increase in placental blood flow during pregnancy, it is expected that they are also invaded by trophoblast and respond with structural changes. The objective of the present study was to evaluate the extent of trophoblast invasion in the guinea-pig preplacental vasculature and its effect on the vascular structure of mesometrial, myometrial and arcade arteries. Under general anaesthesia the vascular system of non- ( n=4), mid- ( n=4) and late- ( n=8) pregnant guinea-pigs was fixed by immersion or perfusion. Cross-sections of immersion-fixed mesometrial and arcade arteries were stained with toluidine blue. Cross-sections of perfusion-fixed mesometrial, myometrial and arcade arteries were stained with haematoxylin-eosin, Elastica van Gieson staining and antibodies against α-smooth-muscle-actin (ASMA), cytokeratin and factor VIII, to detect vascular smooth muscle, trophoblastic, and endothelial cells, respectively. In addition, the external and internal vascular circumference of sections from perfusion-fixed tissue was determined. All cross-sections were evaluated by light microscopy. In the course of pregnancy, progressive endothelial swelling, disappearance of the elastic lamina interna and disarrangement of the tunica media were observed in the myometrial and throughout the mesometrial arteries up to the junction with the arcade arteries. These changes coincided the migration of keratin-positive staining giant cells. It is concluded that in normal guinea-pig pregnancy, structural changes occur in the entire mesometrial artery and at least a part of the myometrial artery, although such changes were not seen in the arcade artery.

Role of nitric oxide in the regulation of vascular tone in pressurized and perfused resistance myometrial arteries from term pregnant women

Objective: Our purpose was to evaluate flow-induced responses, myogenic tone, and norepinephrine-induced constriction in myometrial resistance arteries from normal term pregnant women and the role that nitric oxide and prostanoids may play in these responses. Study Design: Arteries (approximately 200 μm, n = 14, at 40 mm Hg) were dissected from myometrial biopsy specimens from women undergoing cesarean section and then were mounted in a pressure arteriograph. Responses to intraluminal flow, pressure, and a constrictor agonist (norepinephrine 10 −6 mol/L) were studied in the absence and presence of Nω-nitro- l-arginine methyl ester ( n = 7) or indomethacin ( n = 5). Myogenic and norepinephrine-induced tone were calculated after the determination of artery diameter in the absence of extracellular calcium. Results: Arteries developed myogenic tone (80 mm Hg) that was not modulated by nitric oxide or prostanoid release, whereas norepinephrine-induced tone was significantly enhanced by the nitric oxide inhibitor. An increase in intraluminal flow led to dilatation in physiologic salt solution and indomethacin, but to constriction in the presence of Nω-nitro- l-arginine methyl ester (percent increase in diameter at flow rate of 184.6 μl/min, 24% ± 8% in physiologic salt solution and 20% ± 4% in the presence of indomethacin versus –27% ± 12% in Nω-nitro- l-arginine methyl ester alone and –21% ± 10% in indomethacin and Nω-nitro- l-arginine methyl ester, respectively, analysis of variance, p < 0.05). Conclusions: Flow-induced shear stress is a physiologic modulator of vascular tone in myometrial arteries from pregnant women. Nitric oxide, but not prostanoids, mediates this response and also blunts norepinephrine constriction. Nitric oxide may play a fundamental role in the maintenance of adequate blood supply to the fetus during human pregnancy.

Loss of endothelium-dependent relaxation in myometrial resistance arteries in pre-eclampsia.

To measure endothelium-dependent relaxation in myometrial resistance arteries and to compare this parameter in nonpregnant and normotensive pregnant women and those with pregnancies complicated by pre-eclampsia. A prospective study. Nottingham City Hospital. Thirty-seven nonpregnant women undergoing hysterectomy and 51 pregnant women undergoing caesarean section, of whom there were 39 normotensive and 12 with pre-eclampsia. Resistance arteries, dissected from myometrial biopsies, were mounted on a wire myograph and preconstricted with vasopressin then subjected to incremental doses of bradykinin. Endothelium-dependent relaxation to bradykinin was seen in the vessels of nonpregnant and normotensive pregnant women. Markedly reduced endothelium-dependent relaxation was found in the myometrial arteries from women with pre-eclampsia when compared with both nonpregnant (P < 0.0001) and normotensive pregnant (P < 0.0001) women. A significant loss of endothelium-dependent relaxation in myometrial resistance arteries in pre-eclampsia may contribute to the altered vasoreactivity seen in pre-eclampsia, and particularly to the decreased placental perfusion and fetal growth retardation commonly associated with this condition.

Quantitative differences in arterial morphometry define the placental bed in preeclampsia

The purpose of this study was to quantitatively analyze normal and preeclamptic uteroplacental vasculature. Myometrial arteries from eight placental bed biopsies from uncomplicated term deliveries and 12 from proteinuric preeclampsia were characterized as uteroplacental, spiral, or basal arteries. Basal lumens within 0.2 mm radius and spiral/uteroplacental lumens within 0.4 mm radius were considered as the same artery. The biopsy area, lumen density, and arterial density (after correction for multiple lumens), lumen area, lumen perimeter, mean wall thickness, inflated diameter, and a slant factor, measuring the obliqueness of arterial transection, and ratios of lumen characteristics to mean wall thickness were analyzed. In preeclamptic cases, there were more basal lumens/mm 2 and basal arteries/nun 2 ( P = .003, P = .03), and more spiral lumens/mm 2 and spiral arteries/ mm 2 ( P = .01, P = .03). Basal lumen area ( P = .0003) and wall thickness ( P = .007), and basal and spiral artery lumen perimeters and inflated diameters (for each, P = .0001, P = .048, respectively) and inflated diameter/wall ratios ( P = .04, P = .05) were reduced compared with normal cases. Preeclamptic spiral and basal arteries are more tortuous or densely distributed than normal placental bed arteries, with smaller-caliber lumens and thicker walls. Failure of proper placentation may result in abnormal spatial anatomy in the placental bed. Alternatively, an anatomic variant of spiral and basal arteries may be more susceptible to hemodynamic stresses and endothelial damage and may predispose to preeclampsia.

Giant cell arteritis of the uterus: case report and review

We here report a rare case of giant cell arteritis (GCA) of the myometrium found incidentally in a 68-year-old Caucasian woman presenting with uterovaginal prolapse and a known past history of temporal arteritis/polymyalgia rheumatica. Histology revealed a segmental arteritis of small, medium and some quite large myometrial arteries with extensive destruction of both internal and external elastic laminae. Multinucleate giant cells, lymphocytes and histiocytes were most prominent in the inflammatory infiltrate. The findings in this case are compared with previous reports. In a review of the literature it was found that almost one third of cases presented with generalised symptoms such as fever, anemia, fatigue and weight loss. The symptoms were not immediately recognised as temporal arteritis or polymyalgia rheumatica. On routine physical examination or radiological investigation, benign gynecological pathology such as a simple ovarian cyst or uterine leiomyoma were found. The subsequent unexpected discovery of GCA on histological examination was the critical event in alerting clinicians to the diagnosis of temporal arteritis/polymyalgia rheumatica. Without exception steroid therapy was successful in achieving relief of generalised symptoms.

A comparison of endothelium-dependent relaxation in omental and myometrial resistance arteries in pregnant and nonpregnant women

OBJECTIVES: The study aimed to compare endothelium-dependent relaxation in the resistance arteries of the uterine vascular bed by use of a systemic comparison and to investigate the role of the endothelium in adaptation to pregnancy in these vascular beds. STUDY DESIGN: Myometrial and omental resistance arteries were collected from 22 normotensive pregnant women and 27 nonpregnant women of reproductive age. On a wire myograph and preconstricted with vasopressin, the arteries were relaxed with the endothelium-dependent vasodilator bradykinin. RESULTS: The omental arteries showed a consistently greater endothelium-dependent relaxation than the myometrial arteries, both in the nonpregnant state ( p < 0.0001) and in pregnancy ( p = 0.008); pregnancy did not significantly alter this relaxation in arteries from either the myometrial ( p = 0.2075) or omental ( p = 0.372) vascular beds. CONCLUSIONS: The endothelium-dependent relaxation to bradykinin is less in myometrial resistance arteries than in omental resistance arteries. There appears to be no intrinsic difference between vessels from nonpregnant and pregnant women in endothelium-dependent response to bradykinin. (Am J Obstet Gynecol 1996;175:1307-12.)