LECTURE № 7 STRUCTURE OF MATERNAL PASSAGES AND PHYSIOLOGY OF THE BIRTH ACTIVITY. Dr. Nagayeva S. FEMALE GENITALS For clear picture there is short description of anatomy and physiology of reproductive apparatus. Large and small lips of pudendum Vagina Uterus - consists from 3 parts - cervix of the uterus, an isthmus, body of womb. Tubes Ovaries Ligamentous apparatus of the womb and of the ovaries Muscles of a womb settle down in three layers, thus each layer of muscles has its own direction. There is a network of blood vessels develops in thickness of womb's muscles and they are connecting with vessels of a placenta. Because of fast growth the womb and small dimensions of a fetus at the first and second trimesters , the last one freely settles down in a cavity of amniotic sack. The fetus grows in the third trimester more quickly and settles down in the most physiologic position – cranial presentation (in most cases). CRANIAL PRESENTATION At that , movements of a fetus are better felt in the field of a bottom or edges of an uterus. At the first pregnancy the head of a fetus starts to fall to a cavity of a small basin at 38 week. At secundiparas this process occurs at the beginning of the birth activity. WHAT MAY TO HINDER FROM HEAD SINKING: a short umbilical cord or repeated cord entanglement wrong position of a head (overextension) incorrect attitude of the fetus increased tone of the lower segment of the uterus Tumors of the presentation part or of the maternal passages, congenital anomalies of development the fetus the large dimension of a fetus placenta previa narrowed or deformed female basin Fetal head nestles to a small basin and divides amniotic fluid on front and back amniotic fluid . Such division of amniotic fluid promotes soft painless uterine cervix effacement during birth activity. In some cases such division of amniotic fluid hasn't been occur. As a result the capsule of the fluid sack stretches on a head and slows down the process of uterine cervix effacement. That in it turn leads to weariness of the lying-in woman. Such pathology demands medical assistance. From 30 weeks of pregnancy the woman start to feel solitary short-term prenatal contractions (Braxton - Hicks contractions). These contractions appears under influence of a hormone oxytocin on an uterus. The contractions leads to gradual structural maturing of uterine cervix. Besides that they carry out easy gymnastics of your child in a tummy. From 37 weeks these contractions has been appeared more often and as a rule at the evening. These contractions do not cause uterine cervix effacement . Therefore they called false (or harbingers of sorts). Besides they are not periodical and disappear themselves. At this period you can lose the mucus plug . It looks like mid-size mucous piece , colored from light cream to light brown . Such contractions can lead the premature rupture of amniotic fluid sack. You should go to maternity home immediately , if you caught sight of liquid discharge from genital tracts. The long waterless interval increases the risk of intrauterine infection and can entail fetal death. STAGE OF DILATION Labor begins at the certain hormonal background of female organism. Exuded oxytocin causes regular uterine contractions. Normal the center of stimulation appears in the uterine bottom, from which a chain of electric impulses spreading along the whole length of the uterus. That produce contraction at all three layers of an uterine muscles. During contraction the muscle are shortening , displacing about each other, thereof the uterine capacity decreases and the intrauterine pressure increases. These pressure passing by means the aquatic environment and the fetal bladder filling and wedging in the cervical canal of uterus. That promotes tender and painless uterine cervix effacement. STAGE OF EXPULSION When uterine cervix become smooth completely and opens on 10 sm., the fetus will start the forward turning movement. While the cervix of the uterus has been opened , the fetus has been prepared for forthcoming travel too. Under influence of contractions he specialized to the size of the maternal passages. For the beginning it has bent a head to pass by the smaller diameter of a head through the maternal passages. Then soft bones of a skull of a fetus have started to be displaced one for another. In such condition it will move through the maternal passages. STAGE OF EXPULSION He feels greater workload and the expressed oxygen insufficiency during the birth contractions. His heartbeats are up to 160-180 beat per minute. That's why it is important for woman to be able to correctly breathe. In the pause he is resting together with mum, the rhythm of its heart is restored. During labor the fetus passes through wide and narrow parts of a basin. In a narrow part of a basin loading on a fetus is the greatest. THE AFTERBIRTH STAGE The birth process ends with the birth of placenta. There are new series of contractions after birth, occurring within 510 minutes. They are banishing a placenta and an amniotic fluid from the uterus. The uterus contracts and settles down below the navel. EARLY AFTERBIRTH PERIOD This period (2hours) is threatened of complications (bleeding). Recently confined woman spends this time on labor bed under supervision of the medical personnel. After 2 hours, at absence of complications ,she and her baby are moving to "Mother and the Child " department.