Labor. This is the process by which products of conception (fetus, placenta, cord and membranes) are expelled from the uterus. It is defined as the progressive effacement and dilatation of the uterine cervix, resulting from rhytmic contarctions of the uterine musculature.
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This is the process by which products of conception (fetus, placenta, cord and membranes) are expelled from the uterus. It is defined as the progressive effacement and dilatation of the uterine cervix, resulting from rhytmic contarctions of the uterine musculature
Uterine contractions without effacement and dilatation of the cervix occur normally in the third trimester of pregnancy and are termed Braxton-Hicks contractions. Their number and intensity becomes greater as the patient approaches term. Sometimes they result in the patient’s perception of discomfort and cause so called „false labor” which doesn’t change the status of the cervix (its length and dilatation)
Lightening - (2-3 weeks before labor) It is the result of fetal head descending into the pelvis. The patient reports a change in the shape of her abdomen and the sensation that the baby has gotten less heavy. As the bladder is compressed by the fetal head there may be more frequent urination. The patient may also notice an easier time breathing, because there is less pressure on the diaphragm.
Bloody show - (1-2 days before labor) this is the passage of blood-tinged (pink) mucus from vagina which is the result of begining of the cervical effacement and extrusion of mucus from the endocervical glands.
In longitudinal lie, the presenting part is either cephalic (96%) or breech (3%)
The pelvis is formed by five bones: the ilium, the ischium, the pubis, the sacrum, the coccyx and the ligaments connecting them.The ilium, the ischium and the pubis form the lateral and anterior boundaries of the pelvis. The sacrum and coccyx form the posterior wall of the pelvis.
The pelvis may be divided into:1.The false pelvis - the upper part - which is seldom involved in the problems of labor2.The true pelvis - the lower part - which formes the bony canal through which the baby must pass during deliveryThe pelvis inlet divides the false pelvis from the true pelvis
2.The second Leopold maneuverdetermines location of small parts
(it is used to determine the position)
Using one hand to steady the fetus, the fingers of the other hand are used to palpate either the firm, long fetal spine or the various shapes and movements indicating fetal small parts (hands and feet)
3.The third Leopold maneuver identifies descent of presenting partSuprapubic palpation identifies the presenting part as the fetal head which is relatively mobile, or a breech which moves the entire body
4.The fourth Leopold maneuveridentifies the cephalic prominence
As long as the cephalic prominence is easily palpable, the vertex is not likely to have descended to 0 station (linea interspinalis, level of ischial spines)
!!! In every case of vaginal bleeding the vaginal examination should be done with extreme care, only by use of speculum, because of the risk of disrupting a placenta previa !!!
The clinical significance of the fetal head presenting at 0 station is that the biparietal diameter of the fetal head (9,5-10 cm - the greatest transverse diameter of the fetal skull), has negotiated the pelvic inlet
effacement and early cervical dilatation (to 3-4 cm) - the accelerated phase (from 5 to 7 cm) - the transition phase (from 8 to 10 cm)
The second stage(the period of expulsion)lasts from complete cervical dilatation till the delivery of the infant
The third stage(the placental stage) begins immediately after delivery of the infant and ends with the delivery of the placenta
The fourth stage is defined as the early postpartum period of approximately 2 hours after delivery of the placenta. During this period the patient undergoes significant physiologic adjustment and must be under close medical control
During the first stage of labor frequency of contractions rises from 1/10 min. to 5/10 min.The contractions gradually become more frequent and regular. They also become longer (60 s) and stronger
As the contractions continue through the first stage of labor, a pull is exerted on the cervix. The pressure of the baby’s presenting part (head) against the cervix stimulates the release of the hormone oxytocin, which in turn stimulates further contractions. As the upper portion of the uterus contracts, the lower portion relaxes, allowing the baby to descend further toward the vagina.
If the fetal membranes don’t rupture spontaneously, sometimes (often) in the active phase of labor (dilatation > 4-5 cm) we perform amniocentesis :
Sometimes sponatneous (and rarely artificial rupture of membranes) may cause some risk:- umbilical cord prolapsemay occur if rupture of the membranes takes place before engagement of the presenting fetal part (fetal heart tones should be assesed after rupture of membranes in any case)- icidence of infection may be increased if labor is prolonged, because there is an entry for bacteria- in some cases abruption of the placenta occurs
Mechanism of labor refers to the changes of the position of the fetus and movements of its head during the passage through the birth canal.These movements are accomplished by the forceful contractions of the uterus.The long diameter of the inlet of the pelvis is side to side. The long diameter of the outlet is from front to back. Therefore, the baby’s head must turn 90 degrees to emerge from the outlet. During normal cephalic labor the occipital portion of the fetal head is the lower-most part in maternal pelvis and rotates toward symphysis pubis.
Engagementis defined as descent of the biparietal diameter of the head to the level of the pelvic inlet. Clinically it is diagnosed by palpation of the leading point of the presenting part in the level of ischial spines (0 station). In multiparas engagement sometimes does not occur until dilatation of the cervix begin. In primiparas it often occurs in the last days of pregnancy causing the feel of lightening (2-3 weeks)
Descent of the presenting partis a necessary for the successful completion of passage through the birth canal.It is the continous progress of the fetus as it passes through the birth canal. It is brought about by the downward pressure of uterine contractions.The greatest rate of descent occurs during the latter portions of the first stage of labor and during the second stage of labor
Flexion of the fetal headallows for the smallest diameters of the fetal head (suboccipito-bregmatic plane 32 cm of circumference)to present to the maternal pelvis. Flexion occurs when fetus descends and the head encounters resistance. During flexion the head of the fetus is bent forward causing its chin to rest on its sternum (breastbone). Flexion is important because the narrowest part of the head must enter the pelvic outlet.
Internal rotationfacilities presentation of the optimal diameters of the fetal head to the bony pelvis. It is the rotating of the head of the fetus 90 degrees from the transverse to the long diameter of the pelvis.In normal labor the head rotates with its occiput toward symphysis pubis.This movement takes place mainly during the second stage of labor.
Extension of the fetal headoccurs as it reaches the introitus and is stopped under the pubic arch. To accomodate to the upward curve of the birth canal, the flexed head now extendsExternal rotationoccurs after delivery of the head as the head rotates back 90 degrees from the long to the transverse diameter of the pelvis relative to its shouldersExpulsion is the final delivery of the fetus from the birth canal. It is delivery of the shoulders and the rest of the body
- the patient shouldn’t be left without care for any significant length of time
- supporting person may be allowed to remain with the patient throughout the labor and delivery process in most cases
In the second stage of labor patients report the need of push which accompanies the contractions. During the contraction voluntary maternal effort (pushing) can be added to the involuntary contractile forces of the uterus to facilitate delivery of the fetus.At the pik of each contraction, the mother is encouraged to take a deep breath, hold it and push (perform extended Valsalva maneuver) so that abdominal muscules contract and help to expell the fetus. This increase in intra-abdominal pressure aids in fetal descent through the birth canal and this is the indispensable condition of deliveryThe second stage of labor shouldn’t last longer than two hours !!
The position of the patient for delivery most preferred by physicians is the dorsal lithotomy position (on the patient’s back). This allows the physician to have better control of the delivery and facilitates subsequent surgical repair after deliveryIn every succesive contraction, the maternal force correlated with uterine contractions cause more of the fetal scalp to be visiable at the introitus.
andafter local injection of anesthetic substance
(1% xylocaine)episiotomy (an incision of the perineum) is performed (in our Clinic mediolateral)- obligatory in primiparas - in some cases in multiparas
The main role of episiotomy is to enlarge the vaginal outlet and to facility delivery(especially indicated in cases of instrumental delivery)
Then the physician performs a modified Ritgen maneuver. One hand is placed over the vertex while the other exerts pressure through the perineum onto the fetal chin. The chin can then be delivered slowly, with control applied by the hand. A sterile towel is used to avoid contamination of this hand by contact with the anus.
After delivery of the head the neck should be evaluated for the possible presence of a umbilical cord, which should be reduced over the fetal head if possible. If the cord is tight, it may be doubly clumped and cut.After delivery of the head , the shoulders descend and rotate from transverse to the anteposterior diameter of the pelvis.The attendant’s hands are placed on the occiput and vertex, applying gentle downword pressure, thus delivering the anterior shoulder.The posterior shoulder is then delivered by upward traction on the fetal head. The rest of the fetal body deliveries easily.
After delivery nasal and oral suction is performed.It is especially important in case of presence meconium in amniotic fluid because of the possibility of MAS (meconium aspiration syndrom).After clumping the umbilical cord the newborn is attended to the neonatologist.
Immediately after delivery of the infant, the uterus significantly decreases in size. This is the cause of separation of the placenta in the third stage of labor.The classic signs of placental separation are:- rise of the uterus in abdomen and its globular configuration- a gush of blood- lengthening of the umbilical cord
1.Waiting for spontaneous extrusion of the placenta, even up to 30 minutes
2. Giving immediately after the delivery of the fetal head a bolus of Oxytocin for making a strong contraction of the uterus
If spontaneous placental separation does not occur it is necessery to to remove the placenta manually.This is accomplished by passing a hand into the uterine cavity and using the palm of the hand to separate the placenta from the uterine wall.
After delivery of the placenta the evaluation of its surface must be performed. If there are any lacks the revision of the uterine cavity by excochleation must be done.
Then, inspection of the birth canal should be accomplished. It includes control of:- lacerations of the introitus, vulvar area and periurethral area- lacerations of vagina and extensions of the episiotomy- lacerations of the cervixRepair of these lacerations and the episiotomy is accomplished with an absorbable suture in local block.
For the first (especially two) hours aftere delivery there is the graetest risk of postpartum complications.
Postpartum uterine hemorrhage occurs in 1% of deliveries. It is more likely to occur in cases of:
- rapid labor
- protracted labor
uterine enlargement (large fetus, polihydramnios,
- prolonged use of betamimetic agent
In the fourth stage of labor the uterine palpation by abdominal wall must be repeated in frequent intervals to accertain uterine tone. The amount of blood loss must be observed.It is also necessary to observe the pulse and blood pressure.