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Quantitative assessment of gestational sac shape: the gestational sac shape score.

ABSTRACT: OBJECTIVE:To develop a quantitative method for characterizing gestational sac shape. METHODS:Twenty first-trimester gestational sacs in normal pregnancies were studied with three-dimensional (3D) ultrasonography. The 3D coordinates of surface-point sets were obtained for each sac using 30-, 15- and six-slice sampling. Cubic spline interpolation was used with the 15- and six-slice surface-point samples to generate coordinates for those 30-slice surface points not measured. Interpolated and measured values, the latter from the 30-slice sample, were compared and the percent error calculated. Cubic spline interpolation was used to determine the coordinates of a standard surface-point sample (3660) for each sac in each slice sample. These coordinate data were used to give each sac a standard configuration by moving its center of gravity to the origin, aligning its inertial axes along the coordinate axes and converting its volume to 1.0 mL. In this form, a volume shape descriptor could be generated for each sac that was then transformed into a vector containing only shape information. The 20 shape vectors of each slice sample were subjected to principal components analysis, and principal component scores (PCSs) calculated. The first four PCSs were used to define a gestational sac shape score (GSSS-30, GSSS-15 or GSSS-6) for each sac in a given slice sample. The characteristics of each set of GSSSs were determined and those for the GSSS-15 and GSSS-6 were compared with the GSSS-30 characteristics. RESULTS:Cubic spline interpolations were very accurate in most cases, with means close to 0%, and approximately 95% of the errors being less than 10%. GSSS-30 accounted for 67.6% of the shape variance, had a mean of zero and an SD of 1.1, was normally distributed and was not related to menstrual age (R=-0.16, P=0.51). GSSS-15 and GSSS-6 had essentially the same characteristics. No significant differences between individual GSSS-30 values and those for GSSS-15 or GSSS-6 were found, indicating the absence of a slice sample effect. CONCLUSION:Using sophisticated mathematical methods, the gestational sac shape, initially represented by the 3D coordinates of 3660 surface points, was converted to a single number, the GSSS. This score had the appropriate properties for quantitatively characterizing normal, first-trimester gestational sac shapes. As it can be obtained from as few as six slices, it should be useful in many clinical situations. This novel approach has the potential for providing quantitative shape information about a variety of biological shapes and how they change over time.

SUBMITTER: Deter RL

PROVIDER: S-EPMC3516405 | biostudies-literature | 2007 May

REPOSITORIES: biostudies-literature

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Quantitative assessment of gestational sac shape: the gestational sac shape score.

Deter R L RL Li J J Lee W W Liu S S Romero R R

Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology 20070501 5

<h4>Objective</h4>To develop a quantitative method for characterizing gestational sac shape.<h4>Methods</h4>Twenty first-trimester gestational sacs in normal pregnancies were studied with three-dimensional (3D) ultrasonography. The 3D coordinates of surface-point sets were obtained for each sac using 30-, 15- and six-slice sampling. Cubic spline interpolation was used with the 15- and six-slice surface-point samples to generate coordinates for those 30-slice surface points not measured. Interpol ...[more]

PMID: 17444551

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Project description:BackgroundWe investigated the feasibility of aneurysm sac embolization using a novel self-expanding porous shape memory polymer (SMP) device during endovascular aortic abdominal or thoracic aneurysm repair (EVAR).MethodsRetrospective analysis of consecutive patients treated at 2 centers in Germany. Patients were treated from January 2019 to July 2021 with follow-up at 7 days and 3, 6, and 12 months. Aneurysm sacs were implanted with SMP devices immediately following endograft placement during the same procedure. Primary endpoint was technically successful SMP-device deployment into the aneurysm sac outside the endograft. Secondary endpoints were changes in aneurysm volume and associated complications (e.g., endoleaks).ResultsWe included 18 patients (16 males), aged 72 ± 9 years, achieving 100% technical success. Mean preprocedure aortic aneurysm sac volume was 195 ± 117 mL with a perfused aneurysm volume of 97 ± 60 mL. A mean of 24 ± 12 SMP devices per patient were used (range 5-45, corresponding to 6.25-56.25 mL expanded embolic material volume). All evaluable patients exhibited sac regression except 2 patients yet to reach 3-month follow-up. At mean 11 ± 7 months (range 3-24), change in aneurysm volume from baseline was -30 ± 21 mL (p < 0.001). In 8 patients, aneurysm regression was observed despite type 2 endoleaks in 6 and type 1A endoleaks in 2, none of them requiring further intervention to date. No morbidity or mortality related to this treatment occurred.ConclusionsSMP devices for aortic aneurysm sac embolization during endovascular repair appear feasible and safe in this small case series. Prospective studies are needed.Key points• Shape memory polymer is a novel, self-expanding, porous, and radiolucent embolic device material. • Aortic aneurysm sacs were treated with polymer devices immediately following endograft placement. • Aortic aneurysm sac regression was observed in all patients with over 3-month follow-up. • Aortic aneurysm sac regression was observed even in the presence of endoleaks.

Project description:Early pregnancy ultrasound must satisfy objective criteria to make a safe diagnosis of miscarriage. The differential diagnosis of low-lying gestational sac includes cervical stage of miscarriage and cervical and caesarean scar ectopic pregnancies. Misdiagnosis can lead to significant maternal morbidity. We describe a pregnancy in a 36-year-old primiparous woman where ultrasound findings of a low-lying gestation sac satisfied criteria for miscarriage; however, dilatation and curettage of pregnancy contents resulted in brisk cervical bleeding. Ultrasound at 6 weeks 6 days of gestation showed an intra-uterine pregnancy of uncertain viability. Repeat scan after 11 days confirmed miscarriage based on an absence of interval progression between scans and no embryonic heartbeat. The collapsed gestational sac (GS) was seen at the level of the internal os with decidual reaction and peri-trophoblastic blood flow. Inferior to the sac, minimally vascular trophoblastic appearing tissue was beginning to distend the upper cervical canal: the sliding sign was positive for the GS and negative for the upper cervical contents. Cervical stroma was clearly seen circumferential to the distending tissue. The patient underwent dilatation and curettage of the uterus complicated by 2000 ml haemorrhage requiring blood transfusion and medical and surgical management with intra-cavitary placement of a Foley catheter. Histopathology confirmed pregnancy tissue with the disruption of cervical epithelium but no true invasion. The patient was counselled to attend a specialist obstetric imaging facility for an early dating ultrasound in future pregnancies. The current body of literature does not describe cases of low-lying gestation sac miscarriage with high-risk features of trophoblastic extension into the cervical canal. We suggest maintaining a high index of suspicion and excluding differential diagnoses as the majority of women have no risk factors for ectopic pregnancy. These cases should be recommended for surgical management.

Dataset Information

Quantitative assessment of gestational sac shape: the gestational sac shape score.

Publications

Quantitative assessment of gestational sac shape: the gestational sac shape score.

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