Normal Labor and Delivery



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Managing Early Labor


If the patient is in early labor, with a normal pregnancy, and intact membranes, she may feel like ambulating and this is very acceptable.

Not all women in early labor feel like walking and she need not be forced out of bed. Some patients, particularly those with ruptured membranes and those with certain risk factors are probably better off staying in bed, even during early labor.

While in bed, it is preferable, in women without continuous electronic fetal monitoring, to have them lie on one side or the other, but to avoid being on their back. Such lateral positioning maximizes uterine blood flow and provides a greater margin of safety for the baby.

Women with continuous electronic fetal monitoring may choose whatever position is most comfortable. If there is a problem with uterine blood flow, it will be demonstrated on the fetal monitoring strip and appropriate position changes can be undertaken.

Recheck the maternal vital signs every 4 hours. Elevation of blood pressure may indicate the onset of pre-eclampsia. Elevation of temperature >100.4 may indicate the development of infection.

Because of the risk of vomiting and aspirating later in labor, it is best to avoid oral intake other than small sips of clear liquids or ice chips. If labor is lengthy or dehydration becomes an issue, IV fluids are administered. Lactated Ringer's or Lactated Ringer's with 5% Dextrose at 125 cc/hour (6-hours for 1 L) are good choices.

Periodic pelvic exams are performed using sterile gloves and a water-soluble lubricant. The frequency of such exams is determined by individual circumstances, but for a normal patient in active labor, an exam every 2-4 hours is common. In active labor, progress of at least 1 cm per hour is the expected pattern. If the patient feels rectal pressure, an exam is appropriate to see if she is completely dilated.

Some women experience difficulty emptying their bladder during labor. Avoiding overdistension of the bladder during labor will help prevent postpartum urinary retention. If the patient is uncomfortable with bladder pressure and unable to void spontaneously, catheterization will be welcomed.


Monitor the Fetal Heart


Prior to active labor, the fetal heart rate for low risk patients is usually evaluated every hour or two.

Once active labor begins for these women (4 cm dilated, with regular, frequent contractions), the fetal heart rate is evaluated every 30 minutes. This can be done by looking at the electronic fetal monitor (if used), or by measuring the fetal heart rate following a contraction. Fetal jeopardy is likely if the auscultated fetal heart rate is less than 100 BPM, even if it later rises back to the normal range of 120-160. Persistent fetal tachycardia (greater than 160 BPM) is also of concern.

For women with significantly increased risks, it is better to evaluate the fetal heart rate every 15 minutes during the active phase of labor.

Women in the second stage of labor (completely dilated but not yet delivered) usually have their fetal heart rate evaluated every 5 minutes until delivery.


Electronic Fetal Heart Monitoring


Electronic fetal monitors continuously record the instantaneous fetal heart rate on the upper channel and uterine contractions on the lower channel. They do this by attaching, either externally (and non-invasively) or internally, to detect the fetal heart and each uterine contraction.

Labor is an inherently dangerous life event for a fetus and its mother. In the majority of cases, everything goes smoothly enough and ends happily. In a minority of cases, there are some problems. Electronic fetal monitoring is used to provide:



  1. Minute-by-minute information on the status of the fetus

  2. Accurate historical information on fetal status and the frequency/duration of contractions from earlier in labor.

  3. Insight into the stresses on the fetus and its ability to tolerate those stresses.

Originally, electronic fetal monitoring was thought to be able to prevent such newborn problems as stillbirth, brain damage, seizure disorders, and cerebral palsy. This hope proved to be overly optimistic. Unfortunately, and contrary to earlier thinking, most of the problems that lead to stillbirth, brain damage, seizure disorders and cerebral palsy are not intrapartum problems, but have already occurred by the time a patient comes in to labor and delivery. Nonetheless, electronic fetal monitoring has proved so useful in so many ways that it has become a prominent feature of intrapartum care, and indispensable for high risk patients.

Two forms of continuous electronic fetal heart monitoring are used, internal and external. Internal monitoring provides the most accurate information, but requires a scalp electrode be attached to the fetus, and a pressure-sensing catheter to be inserted inside the uterine cavity. Both of these require membranes be ruptured and both have small, but not inconsequential risks. For that reason, they are usually used only when the clinical circumstances justify the small increased risk of complication.

External monitoring usually provides very good information about the timing of contractions and the fetal response. External monitoring consists of belts worn by the mother during labor that record the abdominal tension (indirectly recording a contraction), and the instantaneous fetal heart rate. External monitoring has the advantages of simplicity, safety, availability, and reasonable reliability under most general obstetrical circumstances. However, it is subject to more artifact than internal monitoring, may not detect subtle changes, and may not accurately record the information, particularly if the mother is overweight or active.





Uterine Blood Flow


Maternal blood flows to the uterus primarily through the uterine arteries. The arteries branch out, once they enter the uterus, and supply blood to the muscle cells of the myometrium, and through the wall to the intervillous space (IVS). Once the maternal blood reaches the IVS, it simply dumped into the space, where it drifts about until some is drained off through the maternal venous system. Unlike the highly controlled capillary circulation, there is little control over this process. It is similar to a swimming pool (the IVS), where fresh water is dumped in through a faucet (the maternal arterioles), while the drains in the bottom of the pool (maternal venous system) sucks up any available water that happens to be nearby.

The placenta floats on top of the IVS, with its chorionic villi dipping down into the pool. Across the villous membrane pass oxygen, carbon dioxide, nutrients and waste products. Some of this passage is active transport (eg, glucose), some facilitated (eg, because of pH gradient), and some is passive.

Many factors influence uterine blood flow delivery to the IVS, including:


  • Maternal position (lateral, recumbant improves flow)

  • Maternal exercise (decreases flow)

  • Surface area of the placenta (placental abruption decreases flow)

  • Hypotension or hypertension (both decrease flow)

  • Uterine contractions (contractions reduce flow)

Once the maternal blood reaches the IVS, oxygen and nutrients must still must traverse the villous membrane. If thickened (as with edema or infection), then transvillous transport of materials will be impaired, at least to some degree.

Baseline Fetal Heart Rate
The baseline fetal heart rate is normally between 120 and 160 beats per minute (110 to 160 at full term). This seems to be the range that the normal, healthy fetus prefers to keep itself well-supplied with oxygen and nutrients. The heart can be faster, but only at a cost of increased energy utilization that is normally not justified. The heart can beat slower, but if the bradycardia is prolonged, it can lead to progressive tissue oxygen debt.

Tachycardia
Tachycardia is the sustained elevation of fetal heart rate baseline above a 160 BPM. Tachycardia can be a normal response to some increased need for oxygen, for example:

  • Increased fetal activity (everyone's heart rate goes up when we exercise)

  • Maternal fever (with an elevated body temperature, all enzyme systems speed up, increasing the need for oxygen on a metabolic basis)

It can also increase in the presence of more worrisome problems, including:

  • Chorioamnionitis

  • Maternal hypothyroidism

  • Drugs (Tocolytic drugs, Vistaril, etc.)

  • Fetal hypoxia

  • Fetal anemia

  • Fetal heart failure

  • Fetal arrhythmias

Most tachycardias are not indicative of fetal jeopardy, particularly in the absence of any other FHR abnormalities.

Bradycardia
Bradycardia is the sustained depression of fetal heart rate baseline below 120 BPM (110 at full term). Most of these are caused by increased vagal tone, although congenital cardiac abnormalities can also be responsible.

Mild bradycardia (to 80 or 90 BPM) with retention of beat-to-beat variability is common during the second stage of labor and not of great concern so long as delivery occurs relatively soon. Moderate to severe bradycardia (below 80 BPM) with loss of beat-to-beat variability, particularly in association with late decelerations, is more troubling and may indicate fetal distress, requiring prompt resolution.



Variability
The normal fetal heart rate baseline is from 120 to 160 BPM and has both short and long-term "variability." Short term variability means that from one moment to the next, the fetal heart speeds up slightly and then slows down slightly, usually with a range of 3-5 BPM from the baseline.

Variability is normally controlled by the fetal brain through sympathetic and parasympathetic influences. Reduced variability occurs normally during fetal sleep and usually returns after 20 to 40 minutes.

Reduced variability may also occur:


  • Following narcotic administration

  • With fetal anomalies or injury

  • With hypoxia and acidosis in combination with such FHR abnormalities as late decelerations, tachycardia, bradycardia, and severe variable decelerations.

Persistent or progressively reduced variability is not, by itself, a sign of fetal jeopardy. But in combination with other abnormalities may indicate fetal intolerance of labor.

Long-term variability
Long-term variability represents broad-based swings in fetal heart rate, or "waviness," occurring up to several times a minute. One form of long-term variability of particular significance is a fetal heart "acceleration." These usually occur in response to fetal movement, and are 15 BPM above the baseline or more, lasting 10-20 seconds or longer. They can often be provoked by stimulating the fetal scalp during a pelvic examination, or by acoustically stimulating the fetus with a loud, obnoxious noise. The presence of fetal accelerations is reassuring that the fetus is healthy and tolerating the intrauterine environment well.

During labor, no significance is attached to the absence of fetal accelerations.



Effect of Contractions
During a uterine contraction, blood flow through the uterus slows. If the contraction is strong enough, all blood flow through it will stop.

This decreased flow occurs because of the pressure gradients in the system.

Maternal mean arterial pressure (MAP) is around 85 mm Hg.  The pressure on the inside of the uterus (at rest) is around 10 mm Hg. The pressure within the uterine muscle (intramyometrial pressure or IMP) is usually about 2-3 times that of the intra-amniotic pressure. Because of these pressures, blood flows from the high pressure uterine arteries, through the intramyometrial spiral arteries (and past the medium pressure intramyometrial zone) and into the low pressure intravillous space. From the IVS, blood is drained out through the even lower pressure venous system and returned to the mother's circulation.

During a contraction, the intramyometrial pressures rise with the increased muscle tone. As the compressive pressure rises, blood flow through the spiral arteries diminishes (less pressure gradient to drive the blood through them), and then stops when the IMP equals the MAP. The IMP usually equals the MAP when the amniotic fluid pressure is around 40 mm Hg. (Remember that the intramyometrial pressure is 2-3 time that of the amniotic fluid pressure). As the contraction eases up, blood flow through the spiral arteries resumes and by the end of the contraction, blood flow is back to normal.

Thus, with each contraction of any significance, there is initially reduced blood flow to the intervillous space, then a cessastion of blood flow, followed by a gradual resumption of blood flow.

On one level, you could imagine the danger of the fetal oxygen supply being interrupted by each uterine contraction. On another level is the realization that for a normal fetus, this interruption is nearly trivial (similar to holding your breath for 5 seconds). But if the contractions are coming too frequently (with very little time between contractions for the fetus to resupply), or if the fetus already has a significant problem, then contractions can pose a threat.



Contraction Patterns
During latent phase labor (prior to 4 cm), contractions may occur every 3-5 minutes and may or may not be painful.

A normal contraction pattern in active labor shows contractions occurring about every 2-3 minutes and lasting about 60 seconds.



  • If contractions are less often than every 2-3 minutes in the active phase, labor may progress more slowly, if at all. While less frequent contractions are the rule in latent phase labor (prior to 4 cm), they are the exception in active labor.

Coupling
Coupling means that two contractions occur one right after the other rather than the normal pattern. Usually, coupling is followed by a longer contraction-free interval. Tripling can also be seen where three contraction occur without any significant recovery time.

If labor is progressing normally, coupling can be ignored. Often, however, coupling is associated with dysfunctional progress in labor. In these cases, coupling can be treated with:



  • Rest

  • Hydration

  • Narcotics

  • Epidural Anesthesia

  • Oxytocin

Tachysystole
If contractions are persistently more often than 5 contractions in 10 minutes, this is called "tachysystole." Tachysystole poses a problem for the fetus because it allows very little time for resupply of the fetus with oxygen and removal of waste products. For a normal fetus, tachysystole can usually be tolerated for a while, but if it goes on long enough, the fetus can be expected to become increasingly hypoxic and acidotic.

Tachysystole is most often caused by too much oxytocin stimulation. In these cases, the simplest solution is to reduce or stop the oxytocin to achieve a more normal and better tolerated labor pattern. Other causes of tachysystole include:



  • Dehydration

  • Placental abruption

  • Pre-eclampsia

  • Chorioamnionitis

In cases of spontaneous tachysystole, increasing maternal hydration and placement in the lateral decubitus position may slow the contractions.

Periodic Heart Rate Changes
These heart rate changes are recurring throughout labor. They are typically associated in some way with uterine contractions. There are three basic recognized types:

  • Early Decelerations

  • Late Decelerations

  • Variable Decelerations

Each has its own features and clinical significance. In addition, a fetus may demonstrate combined decelerations (for example, a severe variable deceleration with a late deceleration component.)

Early Decelerations
Early decelerations are periodic slowing of the fetal heartbeat, synchronized exactly with the contractions. These dips are rarely more than 20 or 30 BPM below the baseline.

These innocent changes are thought to be due, in many cases, to fetal head compression within the birth canal.

Sometimes, patients demonstrating early decelerations will later develop variable decelerations (see below).

Late decelerations
Late decelerations are repetitive, gradual slowings of the fetal heartbeat toward the end of the contraction cycle. They are felt to represent some degree of utero-placental insufficiency.

All blood flow in and out of the IVS stops briefly during a contraction. A normal fetus with normal reserve (oxygen in its bloodstream, in the blood of the placenta, and in the intravillous space) will probably not notice the tiny drop in total oxygen availability during these contractions. But a fetus who has used up its reserve, or cannot maintain its reserve will, over the course of the contraction, develop some degree of hypoxia, hypercarbia and acidosis. This otherwise normal fetus will respond by slowing its heart rate, to conserve energy. The fetal heart is the largest consumer of oxygen in the fetus and if the rate can be slowed, the fetus will survive longer on less oxygen. After the contraction passes and fresh blood resupplies the intervillous space, the hypoxia, hypercarbia and acidosis is eased and the fetal heart rate returns to normal.

Clinically, the development of late decelerations is a worrisome sign that the fetus has very little reserve. Techniques that may be used to correct this problem include:


  • Changing maternal position to improve uterine blood flow

  • IV hydration to increase maternal blood volume, presumably leading to increased uterine blood flow

  • Administering oxygen to the mother to try to get some additional oxygen through to the fetus. Of the three standard treatments, oxygen administration is the least useful, since the maternal hemoglobin oxygen saturation is likely already 99%. The effect of breathing additional oxygen will probably have minimal effect on the oxygen saturation.

  • Decreasing or discontinuing oxytocin infusion to slow down or stop contractions that are provoking the decelerations.

  • Tocolytic drugs to slow down or stop contractions that are provoking the decelerations.

If the late decelerations are persistent and non-remediable, this is considered "fetal distress," "fetal intolerance of labor," or a "non-reassuring fetal heart rate pattern." Such patients should be delivered promptly to avoid fetal injury or death. Sometimes cesarean section is required to achieve prompt delivery.

If persistent and not correctable, they represent a threat to fetal well-being.



Variable Decelerations
Variable decelerations are variable in onset, duration and depth. They may occur with contractions or between contractions.

Typically, they have an abrupt onset and rapid recovery (in contrast to other types of decelerations which gradually slow and gradually recover.

Variable decelerations are thought to represent a vagal response to some degree of umbilical cord compression. If the umbilical cord is only slightly compressed, this will obstruct the umbilical vein (low pressure system) which returns re-oxygenated blood to the fetal heart. The initial normal fetal response to this is a slight increase in fetal heart rate to compensate for the lack of blood return and the slowly diminishing oxygen supplies. If this slight increase in FHR is followed by a major drop in FHR, this phenomenon is called a "shoulder."


As pressure on the umbilical cord increases, the high-pressure umbilical arteries become occluded. When this happens, there is an immediate rise in fetal blood pressure. 30% of the fetal cardiac output goes to the placenta and if that flow is blocked, the fetus will rapidly develop significant hypertension. The normal fetus will respond to this hypertension by immediately slowing the heart down by sending a signal through the vagus nerve. When the umbilical cord obstruction is released, the vagal response disappears and the fetal heart returns to normal.

If a mild degree of cord compression continues (enough to continue to obstruct the umbilical veins for a while), then another "shoulder" may appear at the end of the deceleration.

If the variable deceleration lasts long enough to cause hypoxia, there may be a more gradual rise back to the baseline and some "overshoot." Overshoot means the heart rate goes higher than the baseline for a while, to compensate for the mild degree of hypoxia and acidosis that has occurred during that deceleration. If you exercise vigorously for a minute, your muscle tissues will acquire some degree of oxygen debt and a mild degree of local acidosis. When you sit down and rest, your heart rate will be higher than before you started exercising, but will return to normal as you resupply your muscles with oxygen and remove the local waste products. The fetus responds in a similar fashion.

Variable decelerations, unlike late decelerations, are not caused by hypoxia, although if severe enough, frequent enough and persistent enough, can ultimately lead to some degree of fetal acidosis.

The interventions to effectively treat variable decelerations may include:



  • Changing maternal position to improve uterine blood flow

  • IV hydration to increase maternal blood volume, presumably leading to increased uterine blood flow

  • Administering oxygen to the mother to try to get some additional oxygen through to the fetus. Of the three standard treatments, oxygen administration is the least useful, since the maternal hemoglobin oxygen saturation is likely already 99%. The effect of breathing additional oxygen will probably have minimal effect on the oxygen saturation.

  • Amnioinfusion to improve oligohydramnios

  • Decreasing or discontinuing oxytocin infusion to slow down or stop contractions that are provoking the decelerations.

  • Tocolytic drugs to slow down or stop contractions that are provoking the decelerations.

  • Digital elevation of the fetal head out of the maternal pelvis to ease pressure on the umbilical cord.

Occasional mild or moderate variable decelerations are common and not considered threatening. They are seen in the majority of laboring patients at some time or other. They are more common in the second stage of labor.

Mild variable decelerations do not dip below 70 BPM and last less than 30 seconds.

Severe variable decelerations dip below 60 BPM for at least 60 seconds ("60 x 60"). If persistent and not correctable by simple means, they can be threatening to fetal well-being. Like persistent, non-remediable late decelerations, fetuses demonstrating persistent, non-remediable severe variable decelerations should be delivered promptly, preferably vaginally, but by cesarean section if necessary.

Prolonged decelerations


Prolonged decelerations last more than 60 seconds and occur in isolation. Causes include maternal supine hypotension, epidural anesthesia, paracervical block, tetanic contractions, and umbilical cord prolapse.

Some of these are largely self-correcting, such as the deceleration following paracervical block, while others (maternal supine hypotension) respond to simple measures such as repositioning.

Other causes (such as umbilical cord prolapse) require prompt intervention to avoid or reduce the risk of fetal injury.




Pain Relief


Different cultures approach the pain of labor differently and individuals vary in their responses to labor pains. Some women will need little or no help with pain relief, while others will benefit from it. While no analgesic is 100% safe 100% of the time, pain relief is generally very safe and provides for a much happier experience for the woman and her family.

The following principles may be helpful:



  • A small number of women in labor will have virtually no pain and they do not need any analgesia.

  • The majority of women will have moderate discomfort, particularly toward the end of labor and they will generally appreciate some analgesia.

  • Some women will experience severe pain during labor and they will benefit from your most intensive efforts.

  • Giving analgesics prior to the onset of active labor (before 4 cm dilatation) will usually slow the labor process, although for some (those with a prolonged latent phase), it may actually speed up labor.

Focused breathing (Lamaze techniques) during contractions can be very helpful in reducing or eliminating the need for pharmacologic analgesia. Hypnotherapy can provide similar relief, as can massage therapy.

Continuous lumbar epidural anesthetic is effective and versatile, but requires skilled providers and is only rarely available in advanced military settings..

Among specific labor pain relief strategies are:


  • Narcotic Analgesia

  • Paracervical Block

  • Local infiltration

  • Pudendal block

  • Spinal (Saddle Block)

  • Inhalation Analgesia

  • Epidural

Narcotics


Narcotic analgesics can be highly effective at treating the pain of labor. They are generally safe for the baby, although it is better to avoid large doses toward the end of labor in order to avoid respiratory depression in the newborn.

Good dosages for this purpose include:



  • Dilaudid (butorphanol) 1-2 mg IM Q 3-4 hours

  • Dilaudid (butorphanol) 1 mg IM and 1 mg IV every 3-4 hours

  • Demerol (meperidine) 12-25 mg IV every 60-90 minutes

  • Demerol (meperidine) 50-100 mg IM every 3-4 hours

  • Demerol (meperidine) 50 mg plus Vistaril (promethazine) 50 mg IM every 3-4 hours

  • Morphine 2.5-5 mg IV every 60-90 minutes

  • Morphine 7.5 - 15 mg IM every 3-4 hours

More frequent, smaller doses are better than larger, less-frequent doses. Smaller doses given IV are immediately effective, but wear off quickly. Whether that is an advantage or disadvantage depends on how close the woman is to delivery and her need for immediate pain relief.

The greatest safety with narcotics is achieved when an antagonist (naloxone or Narcan) is available to treat the baby should depression appear.


Paracervical Block



The nerves conducting the pain of labor pass next to the cervix. Blocking nerve conduction at this point blocks labor pain.



Inject a total of 20 cc of 1% Lidocaine into the lateral vaginal fornices, with injection sites of 10, 8, 2, and 4 o'clock (5 cc in each site).

The pain of uterine contractions is conducted through nerves passing close to the cervix. From there, the pain is conducted through multiple fibers to the sympathetic chain at L2-L5.

Labor pain can be effectively blocked by interrupting the transmission of pain sensation as it passes through or close to the cervix. This is called a paracervical block.

Up to 20cc of 1% Lidocaine is used. 10 cc is injected on each side of the cervix, usually in divided doses, at 10 o'clock, 8 o'clock, 2 and 4 o'clock (5 cc in each site). Usually within 5 minutes, the patient becomes completely pain free. The block will last 60-90 minutes and can be repeated.

The block is effective when lidocaine reaches the broad ligament. Injections directly into the cervix may block some pain associated with dilation, it will fail to block the pain of the uterus contracting. In theory, you should be able to have a single injection site on each side of the cervix and the block will be effective. In practice, there is enough anatomic variation from person to person over the precise location of the broad ligament that experienced physicians typically will use divided doses to insure that at least some of the drug will get to where it's supposed to go.

How to Give a Paracervical Block
The essential equipment includes and "Iowa Trumpet," a long, hollow, blunt tube for placing at the injection site, and a matching needle, slightly longer. Pre-packaged kits typically will include both the Iowa Trumpet and the needle. Most kits will also have a plastic spacer on the needle that limits its depth of penetration to 5 mm beyond the Iowa Trumpet. Removal of the spacer allows for a full 10 mm depth of penetration (too deep for a paracervical block, but just right for a pudendal block).

Open the kit and put on sterile gloves. The injection is done by feel, not by visualization. Use your right hand to examine the patient, determine the cervical dilatation, and location of the fetal presenting part. Keeping two fingers of the right hand in the vaginal, slide the Iowa Trumpet (without the needle) down the length of your vaginal fingers and direct it into the right lateral vaginal fornix. It should go in as far as it can go so the tip is resting against the vaginal mucosa of the later fornix. Adjust the Trumpet so that it is at the 8 o'clock position.

Once the trumpet is in place, slide the long needle through the Iowa Trumpet until it is fully seated within the trumpet. At this point, the tip of the needle will be extending 5 mm beyond the Iowa Trumpet and just into the paracervical tissues.

Aspirate to make sure you haven't perforated a blood vessel, then slowly inject 5 cc. Repeat the procedure at the 10 o'clock position.

Move to the opposite side. Switch vaginal examining hands so that the left hand is in the vagina when injecting on the left side of the patient. Repeat the procedure, injecting 5 cc at 2 and 4 o'clock.




 

Complications
The only common complication from this procedure is a post-paracervical block bradycardia. This usually develops 10 to 20 minutes following injection, lasts less than 10 minutes, and resolves spontaneously. It is seen in about 10% (or less) of patients receiving paracervical blocks.

The reason for the bradycardia is probably a direct fetal myocardial depressive effect of relatively high levels of fetal serum lidocaine. The base of the broad ligament is very vascular and injection of lidocaine into this area causes a relatively high, but short-lived surge in maternal lidocaine levels (below toxic levels). However, because of the acid-base gradient across the placenta (fetuses are always a little more "acidy" than their mothers) and the base nature of lidocaine, the drug is driven across the placenta, concentrating and resulting in even higher levels of lidocaine in the fetus than in the mother. Depending on the rate of absorption and the degree of acid-base gradient, the fetal lidocaine levels can reach toxic levels and have a pharmacologic effect on the fetal heart. As the lidocaine levels then rapidly fall in the mother's blood, the fetal levels also fall and the fetal heartbeat returns to baseline rates. In studies of fetal effects of this bradycardia, no change in scalp pH was measurable before, during or after the fetal bradycardia, so long as the bradycardia lasted less than 10 minutes.

Rare complications, such as direct fetal injection and broad ligament hematoma have been reported.


 

Patient Selection
Because of the problem of potential fetal bradycardia, the paracervical block is best reserved for those patients without any significant abnormality in their fetal monitor tracing. Fetuses who already have significant variable decelerations or late decelerations will have a greater than average difference in acidity between the placenta and the mother and will be expected to be even more likely to concentrate lidocaine in their bloodstreams. Normal patients, however, have very little risk of developing a significant bradycardia that seriously threatens the fetus.



Local infiltration




Local infiltration of 1% lidocaine provides excellent anesthesia for the skin of the perinuem.

The injection is best made just below the skin, raising just a small weal to visualize the extent of the infiltration.

There is no need to infiltrate deep into the perineal tissues as there are very few nerves there. The skin, however, is very sensitive.

Watch your total dose of lidocaine. The maximum safe limit for 1% lidocaine (without risking toxicity) is 50 cc.





Pudendal block



Bilateral blockage of the pudendal nerve will result in complete anesthesia over the perineum (shown here), and lower third of the vagina.



The ischial spines are boney landmarks found on deep pelvic examination of the lateral and posterior vaginal walls.



Palpate the ischial spine with your fingertip.



Place the Iowa Trumpet along the length of the sacrospinous ligament, about one cm from it's insertion onto the ischial spine.



Using the Iowa Trumpet as a guide, insert the needle so that it perforates the sacrospinous ligament. Slowly infiltrating 10 cc of 1% lidocaine will effectively block the pudendal nerve as it courses (with the pudendal artery and vein) just beneath the sacrospinous ligament at this point.


A pudendal block provides excellent anesthesia to an area about the size of a dinner plate, centered on the vagina.

This block will allow for numbing the vaginal opening to allow for a less painful delivery, some introital relaxation, and satisfactory anesthesia for repair of lacerations or episiotomies.

The perineum is innervated by the pudendal nerves that originate from S3-S4, and pass close to the ischial spine as it traverses the pelvic sidewall.

The ischial spines are boney landmarks palpable to the examining finger, and located deep, lateral and a little posterior to the vagina. The spine can be felt as a distinct boney "bump" quite separate from the rest of the pelvic sidewall.

Running from the ischial spine to the sacrum is the sacrospinous ligament, a tough band of tissue that can be felt with the examining fingers. This ligament is important because the pudendal nerve runs just underneath it and next to the ischial spine.

How to give a pudendal block
The essential equipment includes and "Iowa Trumpet," a long, hollow, blunt tube for placing at the injection site, and a matching needle, slightly longer. Pre-packaged kits typically will include both the Iowa Trumpet and the needle. Most kits will also have a plastic spacer on the needle that limits its depth of penetration to 5 mm beyond the Iowa Trumpet. This 5 mm depth of penetration is just right for a paracervical block, but is too shallow for a pudendal block. Remove the spacer  to allow for a full 10 mm depth of penetration.

Open the kit and put on sterile gloves. The injection is done by feel, not by visualization. Use your right hand to examine the patient, determine the cervical dilatation, location of the fetal presenting part, and the ischial spine on the patient's right side. Keeping two fingers of the right hand in the vagina, slide the Iowa Trumpet (without the needle) down the length of your vaginal fingers and direct it onto the sacrospinous ligament, about 1 cm from the ischial spine.

Once the trumpet is in place, slide the long needle through the Iowa Trumpet until it is fully seated within the trumpet. At this point, the tip of the needle will be extending 10 mm beyond the Iowa Trumpet and will have perforated through the sacrospinous ligament.

Aspirate to make sure you haven't perforated a blood vessel, then slowly inject 10 cc of 1% lidocaine.

Move to the opposite side. Switch vaginal examining hands so that the left hand is in the vagina when injecting on the left side of the patient. Repeat the procedure, injecting another 10 cc.

It will take 10-20 minutes to achieve maximum anesthesia effect after the injections are complete. One-sided blocks are common and can be treated with an additional 5 cc of lidocaine to the poorly-anesthetized side.

 



Inhalation Analgesia


Inhalation of 50% nitrous oxide with 50% oxygen, can give very effective pain relief during labor and is safe for the mother and baby. It is safest when self-administered by the mother, under the guidance of her birth attendant. If she feels dizzy or starts to achieve anesthetic levels of the nitrous, she will naturally release the mask, reversing the effects of the nitrous oxide.

Less commonly used is a self-administered volatilized gas of methoxyflurane. It is capable of achieving anesthetic levels and so must be very closely monitored.


Second Stage Labor


On reaching complete cervical dilatation, the woman has entered the second stage of labor. The second stage lasts until the delivery of the baby. During the second stage, try to measure the fetal heart rate every 5 minutes.

During the second stage of labor, the woman will feel the uncontrollable urge to bear down. This Valsalva has the effect of increasing the expulsive forces and speeding the delivery process.

For most women, the most effective way to push is in the semi-recumbent position. With the onset of a contraction, she takes several, rapid, deep breaths. Then she holds her breath and tightens her stomach muscles, as though she were trying to move her bowels. She pushes for 10 seconds, relaxes, takes another breath, and pushes for another 10 seconds. Most women can get three or four pushes into a single contraction. She will usually push more effectively if her knees are pulled back towards her shoulders.


  • Some women find they are not comfortable in the semi-reclining position and they may push while tilted toward one side or the other.

  • Some women prefer to deliver on their side, with one knee drawn up and the other leg straightened (the Sims position).

  • Some women prefer to deliver in the sitting or squatting position.

Duration of the second stage is typically an hour or two for a woman having her first baby. For a woman having a subsequent baby, the second stage is usually shorter, less than an hour.

Episiotomy


Sometimes, a small incision is made in the perineum to widen the vaginal opening, reduce the risk of laceration, and speed the delivery. This is called an episiotomy.

There are two forms, midline and mediolateral.

A midline episiotomy is safe, and avoids major blood vessels and nerves. It heals well and quickly and is reasonably comfortable after delivery.

If the fetal head is still too big to allow for delivery without tearing, the lacerations will likely extend along the line of the episiotomy. Lacerations through the rectal sphincter and into the rectum are relatively common with this type of episiotomy.

A mediolateral episiotomy avoids the problems of tearing into the rectum by directing the forces laterally. However, these episiotomies bleed more, take longer to heal, and are generally more uncomfortable after delivery.


  • If you don't perform an episiotomy, you are increasing the risk of vulvar lacerations, but these are usually (not always) small, non-threatening lacerations that will heal well without further complications. There may not be a laceration at all.

  • If you perform a midline episiotomy, you will have fewer vulvar lacerations, but the few you have are more likely to be the trickier 3rd and 4th degree lacerations involving the anal sphincter and rectum.

  • If you perform a mediolateral episiotomy, you will avoid the 3rd and 4th degree lacerations, but you may open the ischio-rectal fossa to contamination and infection and increase the intrapartum blood loss.

As with any large vaginal or vulvar lacerations, an episiotomy should be surgically repaired following delivery.

Delivery of the baby


Delivery is also known as the second stage of labor, or part of the second stage of labor. It begins with complete dilatation and ends when the baby is completely out of the mother. The exact time of delivery is normally taken at the moment the baby's anterior shoulder (the shoulder delivering closest to the mother's pubic bone) is out.

As the fetal head passes through the birth canal, it normally demonstrates, in sequence, the "cardinal movements of labor." These include:



  • Engagement (fetal head reaches 0 station.)

  • Descent (fetal head descends past 0 station.)

  • Flexion (head is flexed with the chin to its' chest.)

  • Internal Rotation (head rotates from occiput transverse to occiput anterior.)

  • Extension (head extends with crowning, passing through the vulva.)

  • External Rotation (head returns to its' occiput transverse orientation)

  • Expulsion (shoulders and torso of the baby are delivered.)

As the fetal head descends below 0 station, the mother will perceive a sensation of pressure in the rectal area, similar to the sensation of an imminent bowel movement. At this time she will feel the urge to bear down, holding her breath and performing a Valsalva, to try to expel the baby. This is called "pushing." The maternal pushing efforts assist in speeding the delivery.

For women having their first baby, the second stage will typically take an hour or two.


Delivery of the baby



During the delivery, the fetal head emerges through the vaginal opening, usually facing toward the woman's rectum.

As the fetal head delivers, support the perineum to reduce the risk of perineal laceration from uncontrolled, rapid delivery.

After the fetal head delivers, allow time for the fetal shoulders to rotate and descend through the birth canal. This pause also allows the birth canal to squeeze the fetal chest, forcing amniotic fluid out of the baby's nose and mouth.

After a reasonable pause (15-30 seconds), have the woman bear down again, delivering the shoulders and torso of the baby.





Clamp the umbilical cord


Cut between the clamps

Clamp and Cut the Umbilical Cord



After the baby is born, leave the umbilical cord alone until the baby is dried, breathing well and starts to pink up. During this time, keep the baby more or less level with the placenta still inside the mother.

Once the baby is breathing, put two clamps on the umbilical cord, about an inch (3 cm) from the baby's abdomen. Use scissors to cut between the clamps.



  • During the transition from intrauterine to extrauterine life, the umbilical cord will continue, for a short time, to provide oxygenated blood to the fetus. Once the baby is breathing, then blood is shunted to its lungs where it receives much better oxygenated blood than it was getting from the placenta.

  • While the cord remains intact, elevation of the fetus above the level of the placenta (for example, resting on the mother's abdomen) results in some pooling of newborn blood within the placenta and can make the baby somewhat anemic. Holding the baby below the level of the placenta results in pooling of placental blood within the newborn. This isn't good either, as the rapid homolysis of the fetal hemoglobin can lead to increased problems with neonatal jaundice. It is better to keep the baby more or less level with the placenta until the cord is clamped.

  • If the baby is not breathing well after delivery and needs resuscitation, immediately clamp and cut the cord so you can move the baby to the resuscitation area.

Delivery the Placenta



Immediately after delivery of the baby, the placenta is still attached inside the uterus. Some time later, the placenta will detach from the uterus and then be expelled. This process is called the "3rd stage of labor" and may take just a few minutes or as long as an hour.

Signs that the placenta is beginning to separate include:



  • A sudden gush of blood

  • Lengthening of the visible portion of the umbilical cord.

  • The uterus, which is usually soft and flat immediately after delivery,  becomes round and firm.

  • The uterus, the top of which is usually about half-way between the pubic bone and the umbilicus, seems to enlarge and approach the umbilicus.

Immediately after the delivery of the baby, uterine contractions stop and labor pains go away. As the placenta separates, the woman will again feel painful uterine cramps. As the placenta descends through the birth canal, she will again feel the urge to bear down and will push out the placenta.

If the placenta is not promptly expelled, or if the patient hemorrhages while awaiting delivery of the placenta, this is called a "retained placenta" and it should be manually removed.

After delivery of the placenta, the uterus normally contracts firmly, closing off the open blood vessels which previously supplied the placenta. Without this contraction, rapid blood loss would likely prove very problematic or worse.

To encourage the uterus to firmly contract, oxytocin 10 mIU IM can be given after delivery. Alternatively, oxytocin 10 or 20 units in a liter of IV fluids can be run briskly (150 cc/hour) into a vein. Breast feeding the baby or providing nipple stimulation (rolling the nipple between thumb and forefinger) will cause the mother's pituitary gland to release oxytocin internally, causing similar, but usually milder effects.

A simple way to encourage firm uterine contraction is with uterine massage. The fundus of the uterus (top portion) is vigorously massaged to keep it the consistency of a tightened thigh muscle. If it is flabby, the patient will likely continue to bleed.

Post Partum Care


Lochia is the name for vaginal discharge following delivery. For several days, vaginal bleeding will persist, similar to a heavy menstrual period (lochia rubra). Then, it will thin and become more pale in color (lochia serosa). By the 10th day, it will take on a white or yellow appearance due to the admixture of white blood cells (lochia alba). If it has a foul smell at any time, the odor suggests the presence of infection.

Maternal temperature should be periodically assessed. Any persistent fever (>100.4 twice over at least 6 hours) indicates the possibility of infection and should be investigated.

Blood pressure should also be checked several times during the first day and periodically thereafter. Abnormally high blood pressure can indicate late-onset pre-eclampsia. Low blood pressure may indicate hypovolemia.

For the first several days after delivery, the breasts produce a clear, yellow liquid known as colostrum. For nursing mothers, colostrum provides some nutrition and significant antibodies to their babies. Then, the breasts will swell (engorge) with milk, white in color, and containing more calories (fat) and volume. The initial engorgement can be uncomfortable. Nursing relieves this discomfort. For women not breast-feeding, firm support of the breasts and ice packs will help relieve the discomfort, which will disappear within a few days in any event. Nipples should be kept clean and dry.

It is important to establish bladder function early in the post partum phase. Because bladder distention due to post partum bladder atony or urethral obstruction is common, encourage the woman to void early and often. Any evidence of significant urinary retention should be treated with catheterization and prompt resolution is expected. When cleansing the vulva, avoid rectal contamination of the vagina or urethra.

Aftercramps are common, crampy pains originating in the uterus. They are less common among first-time mothers, and more common when nursing. They are annoying but not dangerous and will usually disappear within a few days.

Oral analgesics, such as acetaminophen with codeine, or ibuprofen are appropriate and will ease the pain of vulvar lacerations, aftercramps, and the various muscle aches related to a physically demanding labor and delivery. Rarely will these medications need to be continued beyond the first few days.

Swelling of the hands, ankles and face in the first few days following delivery is common, particularly if IV fluid have been given. In the absence of other indicators of pre-eclampsia (elevated blood pressure and proteinuria), it is of no clinical significance, but may be distressing to the patient. Reassure the patient that this is a normal, expected event and will resolve spontaneously.

Rh negative women who deliver Rh positive babies should receive an injection of Rh immune globulin (Rhogam) to prevent Rh sensitization in later pregnancies. This is best done within 3 days of delivery. In operational settings where the Rh type of the infant is not known, it is safe to give Rhogam to all Rh negative women following delivery. Those with Rh positive babies will benefit and those with Rh negative babies will not be harmed.

After delivery, the mother needs time to rest, sleep, and regain her strength. She may eat whatever appeals to her and can get up and move around whenever she would like. Prolonged bedrest is neither necessary nor desirable. There are a few cautionary notes:



  • While she may be up walking, strenuous physical activity will increase her bleeding and is not a good idea.

  • The first time she gets up, someone should be with her to assist in getting her back down if she feels light-headed.

  • She may shower or bathe freely, but prolonged standing in a hot shower may lead to dizziness, in this setting of borderline hypovolemia and vasodilatation.

After 3 weeks, the uterine lining is normally completely healed and a new endometrium regenerated. At this point, most normal activities can be resumed, although strenuous physical activity is usually restricted until after 6 weeks.

In normal circumstances, women can resume sexual activities whenever they feel like it. Most women won't feel like it for a while, and perineal lacerations generally take 4-6 weeks to completely heal. Even then, intercourse may be uncomfortable, due to residual irritation around any laceration sites, vaginal dryness due to the natural estrogen suppression after delivery, or psychological factors surrounding resumption of intercourse. Patients can be reassured that this is common, temporary, and very much improved with the use of water-soluble lubricants, such as KY Jelly or Surgilube.



Oral contraceptive pills, if desired, can be started any time during the first few days post partum and are compatible with breast feeding. Alternatively, their use may be postponed until the 6-week examination, a common time for follow-up care.
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