Multiple pregnancy: diagnosis
Last reviewed: 23.04.2024
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Before the introduction of ultrasound in obstetric practice, the diagnosis of multiple pregnancy was often established in later periods or even during labor.
It is possible to presume the presence of multiple pregnancies in patients whose uterine size exceeds the gestational norm in both vaginal examination (in the early period) and in external obstetric research (in later terms). In the second half of pregnancy, it is sometimes possible to palpate many small parts of the fetus and two (or more) large balloting parts (fruit heads). The auscultative signs of a multi-fruition are the heart tones of the fetuses heard in different parts of the uterus with a difference in the heart rate of at least 10 per minute. Cardiovascular activity of fetuses during multiple pregnancy can be recorded simultaneously by using special cardio monitors for twins (equipped with two sensors).
The basis for the diagnosis of multiple pregnancies in modern obstetrics is considered to be ultrasound. Ultrasound diagnosis of multiple pregnancy is possible, beginning with the early pregnancy (4-5 weeks), and is based on visualization in the uterine cavity of several fetal eggs and embryos.
To develop the correct tactics for managing pregnancy and childbirth in multiple pregnancies, the early (in the first trimester) determination of choriality (placenta number) is crucial.
It is chorality (and not zygote) that determines the course of pregnancy, its outcomes, perinatal morbidity and mortality. The most unfavorable with respect to perinatal complications is a monochorionic multiple pregnancy, observed in 65% of the monogamous twins. Perinatal mortality in monochorionic twins, regardless of zygote, is 3-4 times higher than in bichorial.
The presence of two separately located placenta, a thick interstitial septum (more than 2 mm) is a reliable criterion of bichorial twins. When you identify a single "placental mass" you need to differentiate the "single placenta" (monochorionic twins) from the two merged (bichorial twins). The presence of specific ultrasound criteria - Ti λ-signs, formed at the base of the fetal septum, with a high degree of reliability makes it possible to diagnose mono- or bihorial twins. The detection of the λ-sign at ultrasound examination at any gestation period indicates a bichorial type of placentation, the T-sign indicates monochority. It should be borne in mind that after 16 weeks of pregnancy λ - the symptom becomes less accessible for research.
In later terms of pregnancy (II-III trimesters), an accurate diagnosis of choriality is possible only if there are two separately located placentas. In the presence of a single placental mass (one placenta or fused placenta), echography often involves a hyperdiagnosis of the monochorionic type of placentation.
It is also necessary, starting from early terms, to perform comparative ultrasonic fetometry to predict intrauterine growth retardation of fetus / fetus later in pregnancy. According to the data of ultrasonic fetometry in case of multiple pregnancy, the physiological development of both fetuses is distinguished; dissociated (discordant) development of fetuses (difference in mass of body 20% or more); delay in the growth of both fruits.
In addition to fetometry, as with singleton pregnancy, attention should be paid to the evaluation of the structure and degree of maturity of the placenta / placenta, the amount of amniotic fluid in both amnions. Taking into account that in case of multiple pregnancy, the umbilical cord is often attached to the cord and other abnormalities of its development, it is necessary to investigate the places of umbilical cord retraction from the placental placental surface / placenta.
Particular attention should be paid to assessing the anatomy of the fetus to exclude congenital anomalies, and for monoamnotic twins, to eliminate fused twins.
Given the ineffectiveness of biochemical prenatal screening in multiple pregnancies (higher indices of a-fetoprotein, (3-hCG, placental lactogen, estriol compared to single-pregnancy), the detection of ultrasound markers of congenital developmental anomalies, including the study of collar space in fruit, Edema in one of the fetuses with identical twins should not be considered as an absolute indicator of high risk of chromosomal pathology, since it may be Xia one of the earliest sonographic signs of severe twin-twin transfusion fetal (SFFG).
One of the important points for choosing the optimal tactics for delivery in multiple pregnancies is the determination of the position and presentation of the fruit by the end of pregnancy. Most often, both fetuses are in the longitudinal position (80%): head-head, pelvic-pelvic, head-pelvic, pelvic-head. Less common are the following variants of the position of the fruit: one - in the longitudinal position, the second - in the transverse position; both in the transverse position.
To assess the condition of the fetuses in multiplicity, the commonly used methods of functional diagnostics are used: cardiotocography, dopplerometry of the blood flow in the vessels of the mother-placenta-fetus system.
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