Measurement Of Uterine Volume Research Articles

Value of basal luteinizing hormone level combined with uterine volume measurement in the early diagnosis of central precocious puberty in girls with different Tanner stages

To study the value of basal luteinizing hormone (LH) level combined with uterine volume measurement in the early diagnosis of central precocious puberty (CPP) in girls with different Tanner stages. A retrospective analysis was performed on the girls who presented with breast development before the age of 8 years and attended the Third Affiliated Hospital of Zhengzhou University from January 2017 to September 2022. According to the results of gonadotropin-releasing hormone (GnRH) agonist test, the girls with peak LH ≥5.0 IU/L and peak LH/follicle stimulating hormone ≥0.6 were enrolled as the positive group, and the other girls were enrolled as the negative group. The two groups were compared in terms of the basal LH level and uterine volume. The receiver operating characteristic (ROC) curve was used to analyze their value in the early diagnosis of CPP. For the girls with Tanner B2 and B3 stages, the positive group had significantly higher basal LH level and uterine volume than the negative group (P<0.05). The basal LH level had an optimal cut-off value of 0.325 IU/L and 0.505 IU/L respectively in the diagnosis of Tanner stage B2/B3 CPP, while uterine volume had an optimal cut-off value of 1.639 mL and 2.158 mL respectively. Basal LH level combined with uterine volume measurement had a significantly larger area under the ROC curve than uterine volume measurement alone (P<0.001), but with no significant difference compared with that of basal LH level measurement alone (P>0.05). Basal LH level combined with uterine volume measurement is valuable in the early diagnosis of CPP in girls with different Tanner stages, which provides a basis and guiding significance for clinical diagnosis of CPP.

Reduced uterine volume after induction of puberty in women with hypogonadism.

Adequate uterine growth is an essential component of pubertal induction with exogenous oestradiol in those with hypogonadism. Poor uterine development will render the individual vulnerable in the context of fertility. We assessed uterine size using ultrasound in those who had undergone pubertal induction treatment compared with a reference group who had experienced spontaneous puberty. This is a single-centre, retrospective, cross-sectional study of women who underwent pubertal induction compared with a reference group. Ninety-five women with hypogonadism who had previously undergone pubertal induction and were receiving maintenance oestrogen replacement as adults were recruited: 48 women with Turner syndrome, 32 with premature ovarian insufficiency and 15 with gonadotrophin deficiency. The reference group consisted of 35 nulliparous women attending with male factor subfertility with a normal pelvis on ultrasonography. Pelvic ultrasound was performed by a single observer. Uterine dimensions (total length, anterior-posterior (AP), transverse, uterine volume and fundal cervical AP ratio (FCR) measurements) were recorded. Clinical details were also recorded. Those with hypogonadism had significantly reduced uterine dimensions compared with the reference group (uterine length 64mm vs 71mm P=<.05, uterine volume 28.9mL vs 43.9mL P=<.05). All women in the reference group attained a mature uterine configuration with a FCR >1, compared with 84% of those with hypogonadism (P=.01). A total of 24% and 48% of the diagnostic group had total uterine length and uterine volume measurements less than the 5th percentile of the reference group, respectively. In a subgroup of 22 women in whom serum oestradiol concentrations could be analysed, there was a positive correlation between this parameter and uterine volume. Despite standard oestrogen therapy, uterine growth is often compromised in those with hypogonadism. Uterine health has historically been overlooked in pubertal induction protocols; however, with increasing options for fertility treatment, adequate uterine development is crucial. Given the variation in uterine size witnessed, a more tailored approach to treatment with regular monitoring of uterine dimensions should be advocated.

Measurement of uterine volume in patients with endometriosis and its clinical significance

Objective: To measure the uterine volume by ultrasonic imaging in nullipara patients with endometriosis and analyze its clinical significance. Methods: From July 1st, 2016 to August 1st, 2017, 107 cases of nullipara patients with endometriosis hospitalized in Peking University First Hospital were selected as endometriosis group. Among 107 cases, 59 cases were in proliferative phase of menstrual cycle, 48 cases were in secretory phase; and 10 cases had an abortion history.Totally 101 cases of patients without endometriosis operated for other benign disease during the same period were chosen as the control group. All patients underwent laparoscopic surgery, and the diagnosis was confirmed by pathology. The uterine size was measured by transvaginal or transrectal color Doppler ultrasound, and the uterine volume was calculated according to the known formula. Results: The uterine volume of the endometriosis group [(69±26) cm(3)] was larger than that of the control group [(54±18) cm(3), P<0.01]. In the endometriosis group, the uterine volume of patients with pregnant history [(78±34) cm(3)] was larger than that of patients without pregnant history [(68±25) cm(3)]. The endometrial thickness in endometriosis group was higher than that of the control group [(9.1±3.5) versus (7.8±2.9) mm, P<0.05], and positively correlated with the uterine volume (r=0.39, P<0.05). The hemoglobin in endometriosis group was lower than that in the control group [(124±12) versus (131±10) g/L, P<0.01], and was negatively correlated with the uterine volume in the two groups (r(endometriosis)=-0.12, r(control)=-0.21; both P<0.05).The uterine volume of dysmenorrhea patients in the endometriosis group [(73±28) cm(3)] was greater than that of patients without dysmenorrhea [(62±19) cm(3), P<0.01]; both uterine volumes of patients with and without dysmenorrhea in endometriosis group were larger than those of patients with or without dysmenorrhea in the control group (P<0.05). The degree of dysmenorrhea in endometriosis group was positively correlated with the uterine volume (r=0.20, P=0.042). The uterine volume of stage Ⅳendometriosis patients [(79±30) cm(3)] was greater than that of stage Ⅲ patients in endometriosis group [(58±14) cm(3), P<0.01]. Conclusion: Patients with endometriosis are of increased uterine volume, which may be related to dysmenorrhea, menorrhagia and infertility.

2D/3D ultrasonography for endometrial evaluation in a cohort of 118 postmenopausal women with abnormal uterine bleedings.

2D/3D transvaginal ultrasonography in evaluation of endometrium in postmenopausal women with abnormal uterine bleedings (AUB). 2D/3D transvaginal ultrasonography (TVU) was performed in 118 menopausal women with AUB. Endometrial volume and thickness, uterine volume and endometrial vascularity were evaluated. Complete histologic evaluation of the endometrium was obtained through dilatation & curettage (D&C) and/or hysteroscopy. Accordingly, patients were divided into 3 groups: controls (no endometrial pathology, n = 49), GI (benign endometrial pathology, n = 37), GII (endometrial carcinoma, n = 32). GII had greater thickness and volume of the endometrium, compared to GI and controls. The presence of arterial vascular flow was identified only in GI and GII (51.35% and 93.75%, respectively). Endometrial volume merged together with uterine volume measurements (TVU-3D) showed a strong, statistical significance between GI and GII, allowing differentiation of begin and malignant endometrial pathologies in postmenopausal women. In TVU diagnostics of postmenopausal women with AUB the following play the most significant role: 1) endometrial thickness (TVU-2D); 2) endometrial volume (TVU-3D); 3) uterine plus endometrial volume (TVU-3D); 4) vascularization within the endometrium, allowing to differentiate between pathological and normal endometrium (TVU-2/3D). Evaluation of the endometrial vascularity, both in TVU-2D and TVU-3D technique, does not allow for reliable differentiation between benign lesions and endometrial cancer.

Avoiding Morcellation of Laparoscopic Hysterectomy Specimens with Preoperative Measurement of Uterine Volume

Abstract Background: Hysterectomy is the second most common surgery among women, with ∼600,000 performed each year in the United States. Objective: The aim of this research was to identify preoperative factors associated with the ability to remove an intact uterine specimen transvaginally and avoid morcellation during laparoscopic hysterectomy. Materials and Methods: Patients were identified who underwent robotic-assisted total laparoscopic hysterectomy from January 9, 2008, to November 15, 2012. Charts were reviewed retrospectively for demographics. Preoperative uterine dimensions were used to calculate uterine volume. Subjects without preoperative uterine dimensions based on imaging were excluded. Demographics, indication for hysterectomy, need for uterine morcellation, histology, and actual uterine weight were noted. Statistical analysis was performed, using recursive partitioning and logistical regression analyses. Results: Four hundred and thirty-six patients were identified, with 136 excluded becaus...

SEGMENTATION OF UTERINE USING NEIGHBORHOOD INFORMATION AFFECTED POSSIBILISTIC FCM AND GAUSSIAN MIXTURE MODEL IN UTERINE FIBROID PATIENTS MRI

Uterine fibroids are common tumors of female pelvis. Uterine volume measurement before and after surgery has an important role in predicting the outcome and later on in comparing with the result of the uterine fibroid shrinkage surgery. Because of inhomogeneity and different shapes and sizes of uterus and fibroids, segmentation of uterus is a difficult task. In this paper, using T1 and Enhanced-T1 MR images uterine is initially segmented using a new clustering algorithm named neighborhood information affected possibilistic fuzzy C-means (NIAPFCM). NIAPFCM uses membership, typicality and spatial neighborhood information to cluster each voxel. Finally, the redundant parts are removed by superimposing the segmented region of the T1-enhanced image over the registered T1 image. Gaussian mixture model (GMM) is applied to the extracted region histogram as a model for accurate tresholding. The results obtained using the proposed method are evaluated by comparing with manual segmentations using volume-based and distance-based metric methods. Also, the result of NIAPFCM is compared with fuzzy C-means (FCM) and possibilistic fuzzy C-means (PFCM) algorithms. We found this algorithm efficient, which provides good and reliable results.

Abstract No. 256 - Uterine and dominant fibroid volume and particle volume as predictors of pain and post embolization syndrome following uterine fibroid embolization

Purpose Uterine fibroid embolization (UFE) is now a common procedure performed for treatment of symptomatic leiomyomata. Immediate post procedure pelvic pain and cramping is the most common reported complaint following treatment. Post embolization syndrome consisting of nausea, vomiting, and/or low grade fever also commonly affects the post procedure recovery. The purpose of this study is to evaluate if the total uterine volume, dominant fibroid volume, or volume of particles administered can be used as a predictor for pain and post embolization syndrome in the immediate post procedural recovery. Previous studies have demonstrated that post procedure pain is not easily predicted by uterine or fibroid volume. Materials and Methods This is a single center trial consisting of 82 patients who underwent UFE in a standard manner from March 2010 - March 2011. Measurement of uterine volume and dominant fibroid volume was obtained prior to procedure. 500-700 micrometer (um) and/or 700-900 um trisacryl gelatin microspheres (Embospheres) were utilized to achieve stasis or near stasis of blood flow. During a 23-hour observation period, patients and nurses completed a Data Collection Form at 1 hr, 2 hr, 4 hr, 8 hr, and 16 hr (+/- 15min each). Post procedural pain was defined by the total dose of fentanyl received and standardized relative to each patient’s body mass index (micrograms fentanyl/bmi). Results Regression analysis were utilized to independently compare the fentanyl dose per body mass index with the total volume of embospheres used, the total uterine volume, and the dominant fibroid volume as predictors of post procedural pain. These analysis demonstrate no correlation between the fentanyl dose/bmi relative to the total volume of embospheres utilized, the total uterine volume, or the dominant fibroid volume. Conclusion Post procedural pain following UFE is a complex process which has proven difficult to predict. This study demonstrates no statistical correlation between post UFE pain and the volume of embospheres utilized, the total uterine volume, or the dominant fibroid volume. These findings reinforce similar results from previously published data.

Sonographic measurement of uterus and ovaries in premenarcheal healthy girls between 6 and 13 years old: Correlation with age and pubertal status

To provide normal references of sonographic uterine and ovarian size in premenarcheal healthy girls aged 6-13 years in different stages of puberty. Two hundred forty girls were enrolled into the study (mean age ± SD, 9.5 ± 1.7 years [range, 6-13.5 years]). Pubertal status was classified according to Tanner staging. All subjects underwent pelvic sonographic examination for the measurement of uterine volume, body and cervical length, anteroposterior diameter of fundus, body, and cervix, ovarian volume, and both right and left prominent follicular diameter. A gradual increase with age was observed in all uterine and ovarian measurements. Both uterine and ovarian parameters were significantly correlated to age, height and weight, and stages of puberty. Uterine volume was <3.5 cm(3) in 98% of prepubertal girls, and in stage 2 it was significantly more than in stage 1 (3 ± 3.2 versus 1.7 ± 1.7, respectively) (p < 0.001). Uterine body length was also significantly greater in stage 2 than stage 1 (17.5 ± 4.5 versus 14.6 ± 3.3, respectively) (p < 0.001). The reference values for uterus and ovaries were determined in healthy girls. There is a progressive increase in size of internal female genitalia in relation to age, height, weight, and puberty. Uterine volume and body length presented the best correlation with age and stage of puberty.

MR Volumetric Measurements of the Myomatous Uterus: Improved Reliability of Stereology Over Linear Measurements

Stereology is a simple, fast method for object segmentation that involves counting the number of intersections of a randomly positioned grid over an object. The objectives of this study were to determine observer reliability in making stereologic- and ellipsoid-based measurements of uterine and leiomyoma volumes and to test the agreement between these two methods of measurement. Two observers made uterine and dominant leiomyoma volume measurements on MR images in 30 patients using stereology and the popular ellipsoid-based technique. Stereologic volume measurements were made from high-resolution T2 images in two perpendicular planes (axial and sagittal). Ellipsoid volume was calculated by multiplying the maximal sagittal, anteroposterior, and transverse dimensions by pi/6. For these measurements, interobserver reliability was tested with paired t-tests and percent differences were determined. A mean stereologic volume and a mean ellipsoid volume were determined and tested for agreement with a paired t-test. Percent differences were also calculated. Stereologic measurements demonstrated excellent interobserver reliability with 0.3% difference in mean uterine volumes (P = .69) and 0.3% difference (P = .81) in mean leiomyoma volumes. The ellipsoid method resulted in poorer interobserver reliability with 7% difference (P = .01) in mean uterine volumes and 4% difference (p = .24) in mean leiomyoma volumes. The ellipsoid method also significantly overestimated uterine volumes by 14% (P < .01) compared with stereology. Stereology provided high interobserver reliability for leiomyoma and overall uterine volume measurements and was more reliable than the ellipsoid method, which uses linear measurements. Stereology appears well suited when precise volume measurements are desired for assessing response to uterine arterial embolization treatments.

Rapid Reduction of Leiomyoma Volume During Treatment With the GnRH Antagonist Ganirelix

Twenty premenopausal women with symptomatic fibroids, who were scheduled for surgery, participated in a prospective, open-label study evaluating the rapidity and maximum reduction of leiomyomata volume possible using daily treatments with 2 mg of the GnRH antagonist ganirelix. Before starting and after completing treatment, and at weekly intervals during treatment, the size and location of leiomyomas were evaluated using an ultrasound scan (USS), and blood samples were taken for a serum hormone analysis. In addition, magnetic resonance imaging (MRI) was performed before treatment and after maximum reduction. Maximum reduction was considered to have occurred when four consecutive USS measurements found less than a 10% decrease. Treatment consisted of daily subcutaneous injections of 2 mg ganirelix given in the upper leg by the study subjects themselves. Treatment continued until maximum reduction in leiomyomata and uterine volume was achieved, but for no more than 12 weeks. Nineteen women completed the treatment regimen. Initial USS assessment found leiomyoma volumes ranging from 2.9 to 1085.2 mL, and baseline MRI measurements ranged from 3.6 to 1015.5 mL. Corresponding uterine volume measurements were 50.3 to 1085.2 mL with USS and 64.3 to 1612.7 mL with MRI. There were 7 submucosal, 10 intramural, 1 transmural, and 9 subserosal leiomyomas identified in the 19 women. Six were located on the anterior wall, 12 on the posterior wall, and 9 in the fundus. USS assessments found a median decrease of -42.7% (range, -77.0% to 14.1%) in leiomyoma volume and a decrease of -46.6% (range, -78.6% to -6.1%) in uterine volume. Baseline and end point MRI measurements showed a median decrease in leiomyoma volume of -29.2% (range, -62.2% to 35.6%) and a median decrease in uterine volume of -25.2% (range, -63.6% to 28.9%). The median length of treatment was 19 days (range, 1-65 days) to achieve maximum leiomyoma reduction and 17 days (range, 8-52 days) for maximum reduction in uterine size. In the serum hormone analyses, serum LH and E 2 were undetectable at the first weekly assessment and remained too low to measure throughout the trial. Median FSH values dropped to below 2 IU/L by the third weekly assessment and stayed there. Progesterone concentrations were low throughout the study. Reported side effects included hot flushes, which were experienced by 75% of patients, and headaches, which occurred in 45% of study subjects. Eight women reported symptoms in the first week but most appeared in the third week. Only two of the 19 women had no adverse events.

The reliability and validity of three dimensional ultrasound volumetric measurements using an in vitro balloon and in vivo uterine model.

To evaluate the reliability and validity of two and three dimensional ultrasound volumetric measurements using balloon and uterine models. Prospetive observational study. Obstetric ultrasound department at a university teaching hospital. Two and three dimensional ultrasound volumetric measurements (with 5, 10 and 15 ultrasonic slices) were performed on 30 different sets of ultrasound images obtained from 15 water filled balloons with volumes ranging from 19 to 697mL. The measurements were performed independently by two observers who were blinded to the true volumes of the balloons. For the uterine model, only three dimensional ultrasonic volume measurements were performed independently on 16 uteri by two observers who were again unaware of the definitive uterine volumes. For the assessment of intra-and inter-rater reliability, the intraclass correlation coefficient was used. The index of concordance between the ultrasonic volumes and those obtained by the reference standard (validity) was assessed with the conventional Pearson's correlation coefficient, limits of agreement method and the intra-class correlation coefficient. High levels of reliability and validity were obtained for both two and three dimensional ultrasound balloon volume measurements. For two dimensional ultrasonic volume measurements, the intra-class correlation coefficient ranged from 0.992 to 0.998 for reliability and validity whereas the Pearson's correlation coefficient for validity was 0.996. With three dimensional ultrasonic volume measurements, the intra-class correlation coefficient ranged from 0.991 to 0.999 for reliability and validity whereas the Pearson's correlation coefficient for validity was 0.999. Both two and three dimensional ultrasonic measurements tended to underestimate the true balloon volume with the largest observed mean difference obtained with three dimensional ultrasound measurements using five ultrasonic slices and the smallest value obtained with three dimensional ultrasound measurements employing 15 ultrasonic slices. The mean difference in volume measurement for two dimensional ultrasound was intermediate between these two values. However, two dimensional ultrasound volume measurement generated the largest range between the limits of agreement whereas the smallest range was obtained with three dimensional ultrasound using 10 ultrasonic slices. The intra-class correlation coefficient for reliability and validity with three dimensional ultrasonic uterine volume estimation ranged from 0.956 to 0.996 whereas the Pearson's correlation coefficient for validity ranged from 0.993 to 0.999). The use of three dimensional ultrasound also consistently under-estimated the actual uterine volumes. The larger the number of ultrasonic slices employed for three dimensional ultrasound, the smaller was the mean difference between the ultrasonic and true uterine volume measurements and the smaller the limits of agreement. The reliability and validity of balloon and uterine volume measurement by three dimensional ultrasound is high. This allows further research on three dimensional ultrasound for measuring pelvic organ volumes in the prediction of pelvic pathology.

The reliability and validity of three dimensional ultrasound volumetric measurements using an in vitro balloon and in vivo uterine model

Objective To evaluate the reliability and validity of two and three dimensional ultrasound volumetric measurements using balloon and uterine models. Design Prospective observational study. Setting Obstetric ultrasound department at a university teaching hospital. Method Two and three dimensional ultrasound volumetric measurements (with 5, 10 and 15 ultrasonic slices) were performed on 30 different sets of ultrasound images obtained from 15 water filled balloons with volumes ranging from 19 to 697mL. The measurements were performed independently by two observers who were blinded to the true volumes of the balloons. For the uterine model, only three dimensional ultrasonic volume measurements were performed independently on 16 uteri by two observers who were again unaware of the definitive uterine volumes. Outcome measure For the assessment of intra-and inter-rater reliability, the intraclass correlation coefficient was used. The index of concordance between the ultrasonic volumes and those obtained by the reference standard (validity) was assessed with the conventional Pearson's correlation coefficient, limits of agreement method and the intra-class correlation coefficient. Results High levels of reliability and validity were obtained for both two and three dimensional ultrasound balloon volume measurements. For two dimensional ultrasonic volume measurements, the intra-class correlation coefficient ranged from 0.992 to 0.998 for reliability and validity whereas the Pearson's correlation coefficient for validity was 0.996. With three dimensional ultrasonic volume measurements, the intra-class correlation coefficient ranged from 0.991 to 0.999 for reliability and validity whereas the Pearson's correlation coefficient for validity was 0.999. Both two and three dimensional ultrasonic measurements tended to under-estimate the true balloon volume with the largest observed mean difference obtained with three dimensional ultrasound measurements using five ultrasonic slices and the smallest value obtained with three dimensional ultrasound measurements employing 15 ultrasonic slices. The mean difference in volume measurement for two dimensional ultrasound was intermediate between these two values. However, two dimensional ultrasound volume measurement generated the largest range between the limits of agreement whereas the smallest range was obtained with three dimensional ultrasound using 10 ultrasonic slices. The intra-class correlation coefficient for reliability and validity with three dimensional ultrasonic uterine volume estimation ranged from 0.956 to 0.996 whereas the Pearson's correlation coefficient for validity ranged from 0.993 to 0.999). The use of three dimensional ultrasound also consistently under-estimated the actual uterine volumes. The larger the number of ultrasonic slices employed for three dimensional ultrasound, the smaller was the mean difference between the ultrasonic and true uterine volume measurements and the smaller the limits of agreement. Conclusions The reliability and validity of balloon and uterine volume measurement by three dimensional ultrasound is high. This allows further research on three dimensional ultrasound for measuring pelvic organ volumes in the prediction of pelvic pathology.

Elevated level of basic fibroblast growth factor in leiomyoma-related abnormal uterine bleeding and its reversal by interferon-α

Objectives: To test for the first time the role of basic fibroblast growth factor (b-FGF) in abnormal uterine bleeding from myoma; to test for the first time in the literature the role of interferon-α as a new modality in the treatment of abnormal uterine bleeding by myoma; to test for the first time the role of interferon-α in the treatment (nonsurgical) of the myoma.Methods: Twenty patients with multiple myoma, with abnormal uterine bleeding, and 20 control patients with no abnormal uterine bleeding as a control group were enrolled in the study. Serum levels of EGF were measured in the three groups. Interferon-α treatment was started for 1 week in both groups with abnormal bleeding. Measurement of uterine volume in the myomatous groups before and after treatment was performed.Results: A statistically significant increase in b-FGF is seen in the myomatous bleeding group; P <0.05 in the nonmyomatous bleeding group and the control group. Also, there was a statistically significant decrease in the amount of myomatous blood loss in the nonmyomatous group after 1 week of treatment with interferon-α; (P <0.05). There was also a statistically significant decrease in the uterine volume of the myomatous group after treatment with interferon-α (P <0.001).Conclusions: Patients with Leiomyoma related bleeding had elevated levels of b-FGF in the endometrium. They also had abnormal patterns of b-FGF. Interferon-α can effectively stop the bleeding from a myomatous uterus. A new mechanism of bleeding with myoma and a new line of treatment have been born. Basic fibroblast growth factor is an important in the regulation of human uterine cells, and a new line of treatment for myoma has been born (ie, interferon).

The use of screening ultrasonography in the evaluation of postmenopausal breast cancer patients on tamoxifen: Is endometrial echo thickness enough?

This study addresses the efficacy of endometrial echo thickness and uterine volume in predicting endometrial histology in postmenopausal breast cancer patients on tamoxifen citrate. Sixty-four post-menopausal women with breast cancer using tamoxifen for at least 6 months were entered in the study. All subjects underwent transabdominal and transvaginal ultrasonography by a board-certified radiologist as well as having an office endometrial biopsy performed by a gynecologist. Twenty of the 64 patients were evaluated on two separate occasions at least 6 months apart. Histologic findings ranged from atrophic or inactive endometrium ( N = 29), proliferative endometrium ( N = 6), simple hyperplasia without atypia ( N = 9), and scant tissue insufficient for diagnosis ( N = 20). Endometrial echo averaged 10.6 mm (range: 1.2–25.0 mm), and mean uterine volume was 105 cm 3 (range: 12–600 cm 3). The correlation between histology and endometrial thickness was not significant ( r = 0.12, P = 0.34). However, the correlation between histology and uterine volume was statistically significant ( r = 0.31, P = 0.017). Both uterine volume and endometrial thickness were found to increase with duration of therapy but only uterine volume was found to correlate with the length of treatment. This study suggests that tamoxifen has a universal uterotropic effect stimulating myometrial as well as endometrial growth and, in addition, a uterine volume measurement may be more predictive of endometrial histopathology than endometrial thickness in this patient population.

The inaccuracy of total uterine volume measurements: sources of error and a proposed solution.

Inaccuracies in total intrauterine volumes calculated using the prolate ellipse equation have been reported. No previous study has examined all the sources of error. In this study, a comprehensive approach was undertaken. Measurements were obtained from scans of the pregnant uterus in the prone position using an automated water-path scanner (Octoson) and in the supine position using standard static B-mode scanners. Several conclusions could be drawn: 1) From the Octoson prone scans, uterine volumes obtained using the prolate ellipse formula were markedly different from the true uterine volumes obtained by the summation of stepped areas. This showed that the prolate ellipse formula was inaccurate. 2) From the static supine scans, many observer inconsistencies were found in uterine volumes obtained from the prolate ellipse formula. This made the prolate ellipse formula unreliable. 3) Previously published graphs calculated from the prolate ellipse equation, comparing fetal age with total intrauterine volume, were found to vary accuracy, presumably as a result of 1 and 2. A more accurate approach is proposed. Using the outer uterine wall as the boundary, the stepped area-to-volume values of transverse scans taken at 3-cm intervals were found to closely approximate true volumes, with an average error of only 3.5 per cent. Since these measurements encompass the intrauterine contents and the myometrium, it is suggested that the term "total uterine volume" be used instead of "total intrauterine volume."