Placenta Praevia: Significance in the Second Trimester

Ca, Mittelstaedt; Cl, Partain; Il, Boyce; Eb, Daniel

doi:10.1148/131.2.465

Cited by 12 publications

(3 citation statements)

References 1 publication

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“…Diagnosis of placenta accreta, increta, or percreta during the pregnancy prior to labor helps prevent an unexpected emergency situation during delivery and thereby decreases the risk to the mother. US, including color Doppler sonography, can establish the diagnosis in most cases, with MR imaging When two-dimensional static US was introduced, it became the method of choice for assessing placental location and for diagnosing placenta previa (115) and monitoring placental migration during pregnancy (116,117). Migration away from the cervix is common except when the previa is central (117).…”

Section: Fetal Anomaly Detection and Assessmentmentioning

confidence: 99%

The History of Imaging in Obstetrics

Benson¹,

Doubilet²

2014

Radiology

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During the past century, imaging of the pregnant patient has been performed with radiography, scintigraphy, computed tomography, magnetic resonance imaging, and ultrasonography (US). US imaging has emerged as the primary imaging modality, because it provides real-time images at relatively low cost without the use of ionizing radiation. This review begins with a discussion of the history and current status of imaging modalities other than US for the pregnant patient. The discussion then turns to an in-depth description of how US technology advanced to become such a valuable diagnostic tool in the obstetric patient. Finally, the broad range of diagnostic uses of US in these patients is presented, including its uses for distinguishing an intrauterine pregnancy from a failed or ectopic pregnancy in the first trimester; assigning gestational age and assessing fetal weight; evaluating the fetus for anomalies and aneuploidy; examining the uterus, cervix, placenta, and amniotic fluid; and guiding obstetric interventional procedures.

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Section: Fetal Anomaly Detection and Assessmentmentioning

confidence: 99%

The History of Imaging in Obstetrics

Benson¹,

Doubilet²

2014

Radiology

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“…Placental migration has been proposed as a possible mechanism for the resolving of placenta previa. Placental migration is generally attributed to uterine growth: during the second trimester, the cervix incorporates into the lower uterine segment; in the third trimester, effacement of the cervix causes the elongation of the lower uterine segment, which results in the enlargement of the uterus in an opposite direction from the cervical os; finally, the low‐lying placenta is seen to move away from the cervical os . In other previous studies, the development of placenta is linked with dynamic vascular changes .…”

Section: Discussionmentioning

confidence: 98%

Uterine artery Doppler velocimetry at mid‐term gestation as a potential predictive factor for the resolution of placenta previa at the end of third trimester of pregnancy

Yang

et al. 2020

J of Obstet and Gynaecol

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Aim: The incidence of placenta previa before the third trimester is high. But many cases resolve as pregnancy progresses. Our study was to evaluate the efficacy of uterine artery Doppler velocimetry at mid-term gestation for predicting placenta previa resolution in third trimester. Methods: A single-center retrospective study was done. A study cohort of 504 subjects with placenta-cervix os distance measured both at 22-24 weeks and after 36 weeks of gestation and uterine artery Doppler velocimetry measured at 22-24 weeks of gestation were selected. The subjects were assigned to control group (n = 351), resolving group (n = 89) and placenta previa group (n = 64) according to their diagnosis of placenta previa at mid-term and the end of the third trimester. The averages of the bilateral ratio of uterine artery systolic to end-diastolic maximum blood flow velocity (S/D ratio), pulsatility index (PI) and resistance index (RI) were used for analysis. Results: The means of S/D ratio, PI and RI of uterine arteries in the placenta previa group were significantly lower than that in either control group or resolving group. No differences were observed between control group and resolving group. The areas under the receiver operating characteristic curve were 0.7632, 0.7579 and 0.7644 for the means of S/D ratio, PI and RI, respectively (P < 0.0001). Conclusion: The means of S/D ratio, PI and RI of the uterine arteries at mid-term gestation are reduced in patients with persistent placenta previa, indicating unique pathogenic changes at mid-term gestation, and have the potential to be a predictive factor on placenta previa resolution.

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“…The incidence of placenta previa described in the literature is extremely variable and oscillates in accordance with gestational age at the time of examination and method of diagnosis. In the second trimester it varies from 1.1% when a transvaginal approach is used to 31.3% with transabdominal ultrasound 15 . In the third trimester the incidence varies from 0.8% to 2.7% by transvaginal ultrasound scan [15][16][17] and at term these values reach between 0.2% and 1.2% 5,18 .…”

Section: Discussionmentioning

confidence: 99%