RU2621270C1 - Method for amniotic fluid volume determination - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: ultrasound survey of pregnant women in trimester II and III is performed to measure the amniotic fluid index. In this case, the estimated weight of the fetus is determined according to the Hadlock formula and the volume of amniotic fluid V is calculated according to the formula:

where GP is the gestation period (weeks), AFI is the amniotic fluid index (mm), and M is the estimated fetal mass (g).

EFFECT: method allows to increase the accuracy of amniotic fluid volume determination by determining the amniotic fluid index, fetal body mass and gestation period using a mathematical formula.

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Description

The invention relates to medicine, namely to obstetrics, and can be used to determine the amount of amniotic fluid.

The choice of the optimal tactics of pregnancy and childbirth depends on the exact determination of the volume of amniotic fluid [1]. The amount of amniotic fluid reflects the condition of the fetus and changes with pathological conditions of both the fetus and the uterine-placental complex. Polyhydramnios often accompanies abnormalities in the development of the gastrointestinal tract, intrauterine infection, and oligohydramnios - malformations of the urinary system. The combination of oligohydramnios with fetal malnutrition and polyhydramnios are unfavorable for perinatal outcomes. In pregnant women with low and polyhydramnios, the frequency of obstetric benefits and surgical interventions during pregnancy and childbirth is 21.5-57.7% [2].

A known method for determining the volume of amniotic fluid [3, 4], which is based on measuring the vertical size of the largest water pocket between the wall of the uterus and the surface of the body of the fetus after a general examination of the contents of the uterus. With a normal amount of amniotic fluid, this size is in the range of 2 to 8 cm, with a size of 1 to 2 cm, they speak of the boundary amount of water, with a decrease in size less than 1 cm - low water, more than 8 cm - high water. The method has the following disadvantages: lack of accuracy due to the fact that the method involves a qualitative determination of the volume of amniotic fluid, there is no estimate of the amount of amniotic fluid, the measurement is approximate in nature [3].

A known method for determining the volume of amniotic fluid [3, 5], taken as a prototype, which is based on ultrasound and includes the calculation of the index of amniotic fluid. To determine the amniotic fluid index, the uterine cavity is divided into four quadrants. The white line of the abdomen divides the uterus into the right and left halves, the line at the level of the navel - into the upper and lower parts. Then determine the depth (vertical size) of the largest pocket of amniotic fluid in each quadrant. The sum of the four values is the amniotic fluid index. The amniotic fluid volume index changes during pregnancy, but in the III trimester it should be within 10-25 cm, values below 10 cm indicate a decrease in amniotic fluid volume, below 5 cm - low water; values greater than 25 cm indicate polyhydramnios [1].

However, the method has the following disadvantages: lack of accuracy due to the fact that the method involves a qualitative determination of the volume of amniotic fluid, there is no estimate of the amount of amniotic fluid, the measurement is approximate [3 |.

To increase the accuracy of determining the volume of amniotic fluid in pregnant women, an ultrasound scan is performed, the amniotic fluid index is measured [3, 5], the estimated fetal mass is determined by the Hadlock formula [6], and the amniotic fluid volume V is calculated by the formula:

, где CГ - срок гестации (недели), ИАЖ - индекс амниотической жидкости (мм), Μ - предполагаемая масса плода (г).

, where CG is the gestation period (weeks), IAG is the amniotic fluid index (mm), Μ is the estimated fetal mass (g).

The selection of criteria was carried out on the basis of assessing the dependence of amniotic fluid volume on the total number of certain ultrasound parameters according to the construction of a mathematical model based on regression analysis methods [7].

The method is as follows: in pregnant women in the II and III trimester of gestation, an ultrasound scan is performed, the index of amniotic fluid is measured, the estimated fetal mass is determined by the formula

, где СГ - срок гестации (недели), ИАЖ - индекс амниотической жидкости (мм), Μ - предполагаемая масса плода (г).Hadlock and calculate the volume of amniotic fluid V according to the formula:

where SG is the gestation period (weeks), IAI is the amniotic fluid index (mm), Μ is the estimated fetal mass (g).

Example 1. Pregnant Α., Multiparous, 34 years old, was admitted on 12.02.16 to the Department of Pregnancy Pathology with a diagnosis of Pregnancy 31-32 weeks.

Chronic placental insufficiency, subcompensated form. Fetal growth retardation, II degree. Chronic fetal hypoxia. Low water. Mild gestational anemia. Chronic obstructive pulmonary disease, mixed variant, moderate course, remission. DN I. 02.15.16, a pregnant woman performed an ultrasound examination: amniotic fluid index = 32 mm, estimated fetal mass = 1200 g. Amniotic fluid volume V was calculated by the formula:

According to the results of additional research methods (cardiotocography, Doppler ultrasound), February 15, 2016, pronounced signs of a violation of the reactivity of the fetal cardiovascular system were revealed. Given the decompensated form of chronic placental insufficiency, it was decided to deliver the woman on 02.15.16 by cesarean section on an emergency basis.

Through cesarean section surgery, a lively premature baby girl was born without injuries and deformities, weighing 1150 g, growing 37 cm, with an Apgar score of 3 and 4 points. Amniotic fluid volume was 110 ml.

Example 2. Pregnant S., nulliparous, 22 years old, was admitted on 10/6/15 to the Department of Pregnancy Pathology with a diagnosis of Pregnancy 40 weeks. Chronic pyelonephritis, in the stage of latent inflammation. CKD ₀ . Mild myopia.

10/07/15, a pregnant woman performed an ultrasound examination: amniotic fluid index = 143 mm, estimated fetal mass = 3500 g. Amniotic fluid volume V was calculated by the formula:

10/08/15, through a natural birth canal was born a live full-term boy without injuries and deformities, weighing 3450 g, height 51 cm, with an Apgar score of 9 and 9 points. Amniotic fluid volume was 950 ml.

Example 3. Pregnant S., primiparous, 29 years old, was admitted on March 17, 16 to the Department of Pregnancy Pathology with a diagnosis of Pregnancy 34 weeks. Burdened obstetric history. Isosensitization by Rh - factor with an antibody titer of 1: 512. Chronic placental insufficiency, subcompensated form. Chronic fetal hypoxia. Polyhydramnios. Syndrome of connective tissue dysplasia. Mitral valve prolapse of 1 degree, mitral insufficiency of I degree.

03/18/16, the pregnant woman performed an ultrasound examination: amniotic fluid index = 298 mm, estimated fetal mass = 2450 g. Amniotic fluid volume V was calculated by the formula:

According to the results of instrumental research methods (cardiotocography, Doppler ultrasound), the presence of chronic fetal hypoxia was confirmed. Given the hemolytic disease of the fetus, it was decided to deliver the woman on March 18, 16, by cesarean section in an emergency. Through cesarean section surgery, a lively premature baby boy was born without injuries and deformities, weighing 2490 g, height 46 cm, with an Apgar score of 2 and 4 points. Amniotic fluid volume was 2000 ml.

This method was used to determine the volume of amniotic fluid in the II and III trimester of pregnancy in 300 pregnant women. The error determined by measuring in the measured capacity the volume of amniotic fluid obtained during operative delivery was 5.8% (± 60 ml at full term gestation). The results are presented in the table.

The accuracy of the proposed method for determining the mass of the fetus is 93-97%. Polyhydramnios is characterized by an increase in the numerical values of the amniotic fluid volume of more than 97.5 percentile, and low water content - less than 2.5 percentile.

Bibliography

1. Obstetrics from ten teachers: Per. from English / Ed. S. Campbell, C. Lisa. - 17th ed. - M.: Medical News Agency, 2004. - 464 p.

2. Guide to practical exercises in obstetrics: a training manual / ed. V.E. Radzinsky - M .: GEOTAR-Media, 2011 .-- 656 p.

3. Prenatal sonography / Ed. M.V. Medvedev - 1st ed. - M .: Realnoe Vremya, 2005 .-- 560 s.

4. Chamberlain P.F., Manning F.A., Morrison I. et al. Ultrasound evaluation of amniotic fluid volume. II. The relationship of increased amniotic fluid volume to perinatal outcome // Am. J. Obstet. Gynecol. 1984. V. 150. No. 3. P. 250-254.

5. Phelan J.R., Ahn M.O., Smith C.V. Amniotic fluid index measurements during pregnancy // J. Reprod. Med. 1987. V. 32. P. 601.

6. Merz Eberhard. Ultrasound diagnostics in obstetrics and gynecology: trans. from English In 2 t. / Eberhard Merz; under the editorship of A.I. Gus // T. 1. Obstetrics. - M.: MEDpress-inform, 2011 .-- 720 p.

7. Methodology and practice of data analysis in medicine: monograph / I.A. Levin [et al.] // T. 1. Introduction to data analysis. - M. - Tel Aviv: APLIT, 2010 .-- 168 p.

Claims (1)

A method for determining the volume of amniotic fluid, including measuring the amniotic fluid index by ultrasound, characterized in that the fetus mass is determined by the Hadlock formula and amniotic fluid volume is calculated by the formula:

where SG is the gestation period (weeks), IAI is the amniotic fluid index (mm), M is the estimated fetal mass (g).