Auscultation of heartbeats

CTG structure and analysis:

1. Basal fetal HR is a mean of instantaneous values of fetal HR nonregistering accelerations and decelerations. BHR is calculated in intervals in 10 min. Normal fetal BHR (normocardia) is the frequency from 110tol70bpm.

2. HR variability is a complex parameter of fetal cardiac function. It can be assessed by the width of CTG record (HR amplitude) and by oscillations frequency.

Record width (amplitude) is measured between the absolute maxi­mum and minimum of all oscillations nonregistering accelerations and decelerations, i.e. the amount of deflection from the basal rhythm (Fig. 32).

In the given example the amplitude will make 150-135 = = 15(bpm).

There are differentiated 4 variants of amplitude:

— monotonic — with deflections from the basal rhythm up to 5 bpm;

— flattened (extremely wave-like, with deflections from 5 to 9 bpm);

— wave-like — from 10 to 25 bpm;

— pulsating (saltatory rhythm) — more than 25 bpm.
Oscillations frequency is their quantity per minute.

By frequency there are differentiated low (less than 3 per min), medium (3—6 per min), and high frequency (more than 6 per min) oscillations.

By the character of origination accelerations and decelerations may be sporadic, periodical, and regular, by duration — typical and prolonged.

Sporadic— appear in response to fetal movements, are not regular.

Regular— are registered in approximately equal intervals of time and are connected with fetal movements.

Periodical— are connected with fetal vital activity, e.g. accelera­tions and decelerations arising after a labor pain or caused by umbili­cal cord compression.

Typicalaccelerations and decelerations last more than 15 sec, but not longer than 2 min.

Accelerations and decelerations are prolongedif basal rhythm change lasts more than 2 min.

3. Accelerations are temporary BHR changes characterised by BHR increase during more than 15 sec (weak HR changes from 10 to 30 bpm, medium — 30—60 bpm, considerable — more than 60 bpm; Fig. 34).

4. Decelerations — temporary BHR changes characterised by BHR decrease.

4.1. Spontaneous decelerations (dip 0). Short-term decelera­tions, last not more than 30 sec, the amplitude of 30—40 beats from the basal level. These changes have no practical meaning. De­celerations of this type may be sporadic, regular, and periodical.

4.2. Early decelerations (dip I) are periodical, i.e. are detected only if the uterus is active. Deceleration duration and amplitude correspond to the duration and intensity of parodynia.

4.3. Late decelerations (dip II) are periodical, i.e. also con­nected with parodynia, but arise later (up to 30 sec after begin­ning) and reach their high after the maximum uterine tension.

4.4. Variable decelerations (dip III) are also referred to periodical. This is a stable form of HR reduction, a combination of dip I and dip II. They are characterised by unsteady time of emer­gence relative to labor pains, different duration and form. During delivery fetal condition is assessed by the W. Fisher's scale (1976).

At normal fetal condition CTG is characterized by: BHR within 110—170 bpm (normocardia), variability (record width) — 10— 25 bpm with oscillation frequency of 3—6 cycles per min (undulating type), presence of HR accelerations and no decelerations.

Non-stress test (NST) is assessment of fetal cardiac function re­activity with the help of CTG during pregnancy in response to spon­taneous movements. The pregnant woman is in comfortable position during CTG.

NST may be reactive (norm) when during 20 min there are 2 or more accelerations of fetal heartbeats by. more than 15 bpm and last­ing not less than 15 sec connected with fetal movements. The test is areactive if there are less than 2 accelerations of fetal heartbeats by less than 15 bpm, lasting less than 15 sec, connected with fetal move­ments during 40 min of monitoring.

Stress test is assessment of fetal cardiac function reactivity by means of CTG during pregnancy in response to functional tests: oxy­tocin introduction, breath-holding, physical load of the mother, nip­ples stimulation, thermal irritation of the belly skin, or acoustic stimu­lation. This method has low predictive value concerning the fetus and a very high frequency of error-positive results.

Biophysical fetal profile (BFP) is a change of biophysical indices controlled by the central nervous system at fetal hypoxia.

Biophysical indices include: frequency of fetal respiratory move­ments, fetal motion activity, fetal tone, fetal cardiac function reacti­vity and NST, amniotic fluid volume, placenta maturity (Table 3).

Modified BFP combines NST with amniotic fluid index.

Amniotic fluid index is a total of maximal recesses with fluid in 4 quadrants of the uterine cavity: 0—5 cm — evident oligohydram­nios, 5.1—8 cm — moderate oligohydramnios, 8.1 — 18 cm — normal index, more than 18 cm — hydramnion.

Each index is assessed in points from 0 (pathology) to 2 (norm), then the total of points of all biophysical parameters is analyzed. Thus, BFP is found.

BFP is detected beginning from 30 weeks of pregnancy.

Indications to BFP:

1. Areactive NST of the fetus at CTG recording.

2. Syndrome of fetal development delay.

3. Chronic fetoplacental insufficiency.

4. A high degree of risk in the pregnant woman at some extra­genital pathology.

V. Organizational structure of lesson:

Organizational moments-2%;

Topic motivation -3%;

Checking the initial level of knowledge -20%;

Independent work of students under supervision of a lecturer -35%;

Checking the final level of knowledge -20%;

The rating of students` knowledge -15%;

Lecturer`s summary/conclusion, home task-5%.

VI. Methodical support:

The place of practical training: department of pathology pregnant, gynecology department, intensive care department, low operating, classroom.

Visual aids: tables, slides, results of laboratory examinations, case histories of pregnant women with early and late gestosis, a set of tools for abortion.

Checking questions for the assessment of the final level of knowledge

1. The structure of female pelvis, its changes before delivery.

2. The names of (four) bones that constitute the female pelvis.

3. The boundaries and planes of the small pelvis, their form and dimensions.

4. The main external and internal female pelvis dimensions.

5. Additional measurements of the pelvis.

6. Methods of true conjugate determination.

7. Muscles of superficial (external) layer of the pelvic floor.

8. Muscles of middle layer of the pelvic floor.

9. Muscles of internal layer of the pelvic floor.

10. Function of urogenical diaphragm.

11. Osteocranum structure of the newborn.

12. Configuration of sutures and fontanels of fetus head, notion of head configuration.

13. Dimensions of a head, shoulders, buttocks of a full-term newborn.

14. Mass and length of a full-term newborn.

15. Parameters of a full-term and mature fetus.

Case studies for the assessment of the final level of knowledge

On pelvimetry there is noted that the diagonal conjugate equals 12.5 cm and carpus circumference is 15 cm.