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Early pregnancy diagnostics

Early pregnancy is diagnosed by a combination of signs, data of gyne­cologic examination, instrument and laboratory methods of investi­gation.

Pregnancy signs are divided into three groups.

1. Doubtful signs are various subjective sensations and objec­
tively detected changes in the organism except for the changes in the
internal genital organs:

a) subjective phenomena — nausea, vomiting, loss or increase oi appetite, gustatory caprices (addiction to salty or sour food, chalk, etc.), changes of olfactory sensations (aversion to the smell of meat products, tobacco smoke, etc.), slight fatigability, sleepiness;

b) objective phenomena — pigmentation of the face skin, white line, external genital organs, increased pigmentation of the nipples and the skin around them.

2. Probable signs are objective signs detected in the genital or­
gans, mammary glands, and also with the help of immune response to
pregnancy. These are characteristic of pregnancy, though sometimes
may arise because of other reasons. The signs include cessation of
menstruation at the childbearing age, mammary glands enlargement,
and nipple discharge of milk or colostrum.

Probable signs also include gynecological examination data: in­spection of the external genital organs, examination of the neck of uterus with the help of specula, bimanual gynecological examination. Softening and cyanosis of the vestibule of vagina, vagina itself, and the neck of uterus may be observed; enlargement and softening of the uterus, change in its form; increase of the contractile capacity of uter­us (short-term hardening of the softened uterus).

During the examination of the gravid uterus the most important signs are the following:

a) the Genter's sign: vaginal examination during early pregnancy shows a cristate protuberance on the anterior surface of uterus, directly on its midline; the protuberance does not spread either to the fundus, or its posterior surface, or the neck;

b) the Hegar's sign: vaginal examination shows softening in the region of isthmus, as a result the fingers of the external and internal hands easily meet in this place. The neck is felt as a more dense body ;

c) the Piskachek's sign: vaginal examination shows that the con­tours of the fundus of uterus and the regions of its angles appear to be irregular. The angle corresponding to the place of egg implantation protrudes much more than the opposite one. The whole uterus ap­pears to be asymmetric

d) the Snegirev's sign: during vaginal examination the gravid uter­us begins contracting under the fingers and becomes denser as a result of mechanical irritation.

Probable signs include immune responses to pregnancy, which are based on HCG detection in the urine or blood plasma. HCG is pro­duced by the trophoblast, then by the chorion, placenta. This hor­mone consists of alpha- and beta-subunits. Production begins from the 7th—8th day after fertilization, therefore laboratory diagnostics is possible after this term. Since the method has a threshold of sensitivi­ty, one should take morning urine for the investigation — it has the highest concentration of the hormone. Detection of beta-HCG in the plasma is more reliable. It should be emphasized that though HCG is produced by trophoblast, the reaction is referred to probable signs, because at such pathological state as chorioepithelioma positive reac­tions to HCG are also observed. Besides, after abortion reactions re­main positive during 7—10 days, and at pathological states (tropho­blast diseases) — during 2—4 months. The lower threshold of sensi­tivity of the method is 5 IU/L.



3. True signs of pregnancy are conclusive proofs of pregnancy in the examined woman. All the signs of this group are objective and originate from the fetus. They include the signs shown by intravagi-nal ultrasound investigation. Other true signs reveal beginning from the 20th week of pregnancy and do not belong to the signs of early pregnancy; they are: fetal movement detected manually or during auscultation (not the movement felt by the pregnant woman); aus­cultation of fetal heart tones; palpation of fetal parts (the head, legs, buttocks, arms); detecting fetal heartbeats by means of cardiotoco-graphy. It should be noted that application of the color impulsive Doppler is forbidden till the end of the crucial period of organogene­sis. This is connected with the fact that the usage of modern Doppler technologies at transvaginal echographies if pregnancy term is less than 10 weeks has a potential threat of teratogenic thermal effect as a result of embryo heating.

Currently the standard of early pregnancy diagnostics is the com­bination of two methods:

a). detecting beta-HCG in the urine or blood plasma;

b). transvaginal ultrasound investigation.

The uterus dimensions during the first 3 months of pregnancy, when it is still in the small pelvis cavity, are detected by means of bi­manual gynecological examination, further at abdominal palpation — by the height of uterine fundus standing.

The accuracy of pregnancy term determination depends on the early visit of the woman to the antenatal clinic. It is recommended to conduct the primary examination of the woman by two specialists-obstetricians. Taking into account the difficulty of detecting the term of fertilization, pregnancy is diagnosed with a week interval (for ex­ample: pregnancy of 8—9 weeks). Pregnancy term is detected more reliably on the basis of measuring the parameters of the embryo and fetus by the method of ultrasound investigation.

Late pregnancy diagnostics

The methods of late pregnancy investigation include: general exami­nation of the pregnant or parturient woman, external measuring of the uterus and pelvis of the woman, external and internal obstetric examination; auscultation of fetal heartbeats, auxiliary instrument and apparatus methods of investigating the fetal condition (see the chapter Fetal Condition Imaging and Assessment).

Anamnestic data — pregnancy term calculation in weeks with the help of the pregnancy table from the date of the last menstruation and from the date of the first fetal movement (in para I the first fetal movement is usually felt beginning from 20 weeks of pregnancy, in para II — from 18 weeks). To calculate the term of delivery by the date of the last menstruation one has to count 3 months off it and add 7 days to the obtained date.

Results of objective examination — the height of uterine fundus standing over the womb at measuring with a measuring tape in rela­tion to a standard gravidogram, external obstetric examination (the Leopold's maneuver), auscultation of fetal heartbeats (beginning from 20 weeks), the data of ultrasound fetometry.

Fetus Attitude in the Uterine Cavity (fetus position, the type of position, presentation)

Attitude of fetus is the relation of small fetal parts and head to the body. At normal attitude the spine is bent to the abdominal surface, the head is pulled to the chest, the arms are bent in the elbow joints and folded on the chest, the legs are bent in the knee and hip joints, pulled to the stomach.

Fetal lie is the relation of the longitudinal axis of fetus to the longi­tudinal axis of uterus. There are differentiated the following fetal lies:

--- longitudinal — the longitudinal axis of fetus and the longitudi­nal axis of uterus coincide;

--- transversal — the longitudinal axis of fetus crosses the longitu­dinal axis of uterus;

oblique — the longitudinal axis of fetus crosses the longitudi­nal axis of uterus at a sharp angle.

Fetus position is the relation of the fetal back to the right and left sides of uterus. Two positions are differentiated:

the first — the fetal back is turned to the left;

the second — the fetal back is turned to the right.

At transversal and oblique lie the position is detected by head lo­cation: the head is on the left of the maternal stomach midline — the first position, on the right — the second.

The type of position relation of the fetal back to the anterior or posterior uterine wall. There are two types:

--- anterior — the fetal back is turned to the front;

--- posterior — the fetal back is turned backwards.
Presentation is the relation of a big fetal part (the head or pelvis) to the inlet of small pelvis. There are differentiated cephalic and pel­vic presentations.

A presenting part is the part of fetus, which is located closer to the inlet and is the first to go through the maternal passages. At the bent fetal head the most low located part is the occiput. Such presentation is called vertex and is observed most often.

Considerably less frequently the head is unbent. Depending on the level of unbending the presenting part may be the crown (sincipi­tal presentation), forehead (brow presentation), or face (face presen­tation).

At pelvic presentation the most low located part might be the but­tocks (breech presentation) or feet (foot presentation).

The major segment of fetal head is understood as the largest cir­cumference of the head, with which it goes through the planes of small pelvis depending on its fitting. At vertex presentation, when the head is fitted into the pelvis in bent position, the largest circumfer­ence is the one corresponding to the circumference of the small oblique size. At extended fitting of the head the major segment will be different (depending on the degree of deflexion).

The minor segment of fetal head is considered by convention the part of the head smaller than the major segment, with which the head goes through the smaller pelvis planes.

 

EXTERNAL OBSTETRIC EXAMINATION MANEUVERS (THE LEOPOLD'S MANEUVERS)

The first maneuver. The purpose is to detect the standing of the fundus of uterus and the part of fetus located close to the fundus of uterus. To do this, the doctor stands on the right of the pregnant woman, facing her, puts both palms on the fundus of uterus, detects the height of its standing over the womb and the part of fetus located close to the fundus of uterus.

The second maneuver. The purpose is to detect the position and position type of the fetus. Both palms are removed from the fundus of uterus and in turn palpate the parts of fetus directed to the lateral uterine walls. The back and small parts of fetus are found. At irregular position the head is adjacent to one of the lateral uterine walls.

The third maneuver. The purpose is to detect the character of the presenting part of fetus (presentation). With one hand, usually the right one, which is lying slightly above the pubis, the presenting part of fetus is covered, after what cautious movements are made with this hand to the right and to the left. At cephalic presentation a dense, spheric part is detected, which has well-defined contours. If the fetal head is not yet fitted into the area of brim, it easily moves between the thumb and the rest of fingers. At pelvic presentation a volumi­nous soft part is detected, it is not spheric and can not move.

The fourth maneuver. The purpose is to detect the level of pre­senting part standing (of the head in particular) relative to the area of brim and to the degree of its fitting. The doctor stands on the left, with the face to the lower extremities of the pregnant woman, puts both hands with palms down on the lateral parts of the lower uterine segment and palpates accessible parts of the presenting part of fetus, trying to get with the fingertips between the pre­senting part and lateral parts of the area of brim.

 

MEASURING THE ABDOMEN CIRCUMFERENCE AND THE HEIGHT OF UTERINE FUNDUS STANDING

Abdomen circumference (AC) is measured with ameasuring tape, which goes through the navel in front and through the middle of lum­bar area from behind.

The height of uterine fundus standing (HUFS) is measured with a measuring tape from the upper margin of symphysis to the most pro­truding point of the fundus of uterus. The results of HUFS measuring are compared with a standard gravidogram (normally by the 30lh week of pregnancy HUFS increase makes 0.7—1.9 cm a week; at 30—36 weeks — 0.6—1.2 cm a week; at 36 and more — 0.1—0.4 cm. If case monitoring shows lagging of dimensions by 2 cm or absence of increase during 2—3 weeks, it gives ground to suspect fetal growth inhibition).

 

CALCULATING THE FORESEEABLE FETAL BODY WEIGHT

The foreseeable fetal body weight (FBW) is approximately calcu­lated by the following formula:

FBW = AC x HUFS. More reliably fetal body weight is estimated by ultrasonic fetometry.

 


Date: 2014-12-28; view: 1209


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