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MANAGEMENT OF LABOR and OBSTRUCTED LABOR

MANAGEMENT OF LABOR and
OBSTRUCTED LABOR

by: Yoshua Viventius
medical student@ 6th grade

Definitions

In order to assess progress in labor, we need to be confident in our definition of active labor and abnormal progress.

Labor Is:
Regular, Frequent Uterine Contractions
+
Cervical Change
(dilatation and effacement)

First stage:

• Latent Phase: is the presence of uterine activity resulting in progressive effacement and dilatation of the cervix preceding the active phase. Latent phase is complete when a primiparous woman reaches 3-4 cm dilatation and cervical length of 0-0.5 cm and a multiparous woman reaches 4-5 cm and cervical length 0.5-1.0 cm. The onset of the latent phase is often difficult to define. It can be difficult to separate from false labor and the true length of this stage is often assessed retrospectively.

• Active phase requires the presence of regular painful contractions leading to more rapid cervical dilatation after 3-4 cm dilatation in a primiparous woman, or 4-5 cm dilatation in a multiparous woman.

Second Stage: (divided into two components)

• Passive: Early descent occurs during the time from full dilatation until an urge to push is felt (about station+2).
• Active: The second component is usually associated with maternal expulsive effort and is the time from the onset of the urge to push until delivery.

Inadequate progress of labor is associated with increases in maternal stress, maternal infection, postpartum hemorrhage and the need for neonatal resuscitation. Tools such as partograms are essential to demonstrate and highlight inadequate progress in labor.

In evaluating the cause of dystocia, we can refer to the three Ps: Powers, Passenger, and Passage. The powers are the most likely to be responsible for dystocia, and are the most readily evaluated and influenced. Ineffective contractions, usually early in labor, are responsible for approximately 2/3 of dystocias in nulliparous women.

Use of the Partograph in Labor

Why the Partograph?

The delivery of a healthy baby and maintenance of a safe delivery for the mother are two goals of all maternity health care givers. A simple instrument called a partograph can aid this basic human right of safe passage. The partograph has been shown to reduce prolonged labor, the need for augmentation, emergency caesarian section and intrapartum stillbirth rates. It should be used in all labor wards and centers for maternity care. The following recommendations are adapted from the World Health Organization recommendations on the use of the partograph: (see Appendix 1A and 1B)

When should one use the partograph?

A partograph should be started on women in labor who have NO complications that require immediate action. Start ONLY when the woman is in labor—this means two contractions in ten minutes (lasting 20 seconds or more) in the latent phase (cervical dilatation of 0-2 cm). In the active phase (cervical dilatation of 3-10 cm), the contractions should be one per ten minutes (lasting 20 seconds or more).

What does the partograph involve?

The partograph demands the assessment of several observations—the first relate to progress of labor (cervical dilatation, descent of the fetal head and uterine contractions). The second set of observations focuses on the fetus: fetal heart rate, membranes and liquor and moulding of the fetal head.

The DILATATION is plotted with an ‘X’. After the first vaginal examination, repeat exams are every four hours (with a more frequent assessment if the woman is multiparous or in advanced labor).

Descent is assessed abdominally in fifths above the pelvic brim. An abdominal examination should be done before the pelvic assessment. Contractions are observed for frequency and duration. The number of contractions in ten minutes is recorded with three ways of shading on the partograph: a) less than 20 seconds b) 20-40 seconds and c) greater than 40 seconds.

Membranes are denoted as:

I=intact C=ruptured and clear M=meconium A=ruptured but absent liquor

Things to remember:

Satisfactory progress means the plot of cervical dilatation will remain ON or LEFT of the ALERT LINE.

The latent phase should not last beyond eight hours. If a mother is admitted in latent phase, start plotting at time zero hours. Once in the active phase, plotting of dilatation is transferred to the ALERT line. If a patient is admitted already in the active phase, dilatation is plotted immediately on the ALERT line.

Listen to fetal heart rate after peak of contractions with a woman on her left side. The fetal heart rate should be 120-160 beats per minute. Record the fetal heart rate every 30 minutes during the first stage of labor. Increasing moulding with a high fetal head is a sign of cephalopelvic disproportion.

Actions on the Partogram:

The Alert Line:

A laboring mother should be referred from a health center to a hospital when the cervical dilatation moves to the RIGHT of the ALERT line. Amniotomy may be performed if the membranes are still intact—she may be observed for a short time prior to transfer. In hospital, movement to the RIGHT of the ALERT line should signal the need for an amniotomy and close observation.

The Action Line:

If the patient’s partograph crosses the ACTION line in a central hospital, active intervention is required. Initially this would include: the start of an intravenous line, bladder catheterization, analgesia and augmentation using oxytocin. These measures would be carried out as long as there was no evidence of fetal distress or obstructed labour.

A vaginal examination should be carried out in three hours, then in two more hours (and every two hours thereafter). The dilatation rate should be 1cm/hour minimum. CHECK the FETAL HEART rate every half hour at minimum when oxytocin is being infused. If these measures are not successful, a cesarian section would be carried out.

Prolonged Latent Phase:

In the case of a woman with a prolonged latent phase (>8 hours), a full assessment must be carried out. Is she truly in labor—if not, abandon the partograph. One may consider an amniotomy plus oxytocin infusion if there is no evidence of fetal distress and the contraction pattern is not satisfactory. A final option is cesarian section—especially if evidence of obstruction or need for imminent delivery.

Antibiotics should be given if the membranes have been ruptured for more than 12 hours.

Fetal distress should be managed aggressively: if the woman is in a health centre, transfer to hospital (for operative delivery) immediately. If the woman is in hospital, stop oxytocin, turn on left side, examine for cord prolapse and hydrate. If the fetal distress does not resolve, an immediate cesarian section is needed.

Etiology of Dystocia

POWERS ineffective contractions
maternal expulsive efforts (second stage)
fetal position

PASSENGER
fetal attitude
fetal size
fetal abnormalities e.g. hydrocephalus

PASSAGE
bony pelvis abnormality

soft tissue causes:
tumours
full bladder/full rectum
vaginal septum

The diagnosis of true or absolute cephalopelvic disproportion (CPD) should be limited to the uncommon instances of real disproportion i.e. inability of the well flexed head (sub-occipito bregmatic presentation) to pass through the bony pelvis. Other presentations may lead to relative cephalopelvic disproportion.

If the woman is making satisfactory progress in labor then the interaction of the three P’s must be adequate. These three variables act together and should generally not be assessed in isolation.

If progress is inadequate, attention should be directed to:

1. Adequate Powers:
Contractions that are…
1) Regular
2) Progressive, which lead to cervical dilatation
3) Frequent ( 2-3 minutes)

2. The Passenger should be assessed for size and malposition. Inadequate powers in active labor may be responsible for malposition. A normal sized infant may present an excessively large diameter to the pelvis because the head is not flexed.

3. The Passage: Clinical examination of the passage may reveal prominent spines or sacrum, a narrow pubic arch or a space-occupying mass in the pelvis. A trial of labor is the only real assessment of the pelvic adequacy.

Prevention and Management of Dystocia

1) Prevention

Accurate Diagnosis of Labor

Some cesarean sections performed for dystocia in nulliparous patients are done in the latent phase of labor. It is likely that at least a portion of these women were not in true labor at the time of labour management interventions or at the time of cesarean section. Appropriate management, of suspected early labor, could result in a decrease in the cesarean section rate.

Management of Prolonged Latent Phase

Different definitions of prolonged latent phase exist including greater than 20 hours in a primip, or a time limit of six hours from admission to health center to 3 cm dilatation. If women are not admitted until they are in active labor, this latter definition becomes irrelevant. Regardless, it is important to separate this entity from false labor.

Management is controversial due to the limited number of published studies.
• The patient should preferably not be admitted to the labor and delivery area.
• Observation, rest and analgesia are favoured over a more active approach of amniotomy and oxytocin induction.

Labor Preparation

For nulliparous women who have attended prenatal education, there may be more rapid progress in labor. Some studies have shown a benefit and others show no difference, but all studies show that women who were prepared for labor had a more positive experience. Trials also show that prenatal education decreases the amount of analgesia used during labor.

Birth Companion

There is now strong evidence that the presence of a supportive companion results in faster progress and less dystocia. This companion should have experience with labouring women, but is not necessarily trained in a health discipline.

Ambulation

It is important to recognize the women’s choice of labor position. Ambulation and upright posture reduces the amount of pain perceived by women in labor. The use of a birth stool often helps if the woman does not want to walk. Upright posture in labor may be useful in reducing backpain and the need for epidural anesthesia. Static supine position may result in aorto-caval compression, hypotension and non-reassuring fetal monitoring.

Analgesia

Some patients in labor reach the limit of their pain tolerance. Furthermore, patients experiencing excessive pain or anxiety have high endogenous catecholamines. This produces a direct inhibitory effect on uterine contractility and establishes a vicious circle of poor uterine progress leading to increased anxiety, leading to increased catecholamines, leading to further impairment of progress. The relief of pain by effective analgesia may allow release of the uterus from the constraints of the endogenous catecholamines and enhance progress in labor. High endogenous catecholamine levels may also adversely affect uterine blood flow and therefore fetal oxygenation.

Amniotomy (ARM*)

Routine early use of amniotomy after 3 cm dilatation shortens the average length of labor, but does not in itself reduce the incidence of dystocia or cesarean section. Early amniotomy at less than 3 cm dilatation may increase the incidence of dystocia.
• ARM: Artificial Rupture of the Membranes

Fetal Size

Fetal size does not significantly affect the progress of labor in first and second stage.

Management

If an arrest disorder is diagnosed, management is as follows:
• Arrest without CPD
– amniotomy
– consider oxytocin augmentation if contractions are inadequate
• Arrest with true CPD
– cesarean section

Oxytocin

In the event of unsatisfactory progress (<0.5cm/hr x 4 hours or arrest of descent for over 1 hour) in the active phase of labor, oxytocin is indicated. Before the use of oxytocin, consideration should be given to the appropriate use of analgesia, hydration, rest and amniotomy.Oxytocin should be used to achieve adequate contractions before operative delivery is considered.Concern is sometimes raised about the use of oxytocin. The principal complications that cause apprehension are fetal compromise and uterine rupture due to uterine hyperstimulation. Judicious use of oxytocin should not result in complications.Fetal hypoxia may occur accompanying spontaneous contractions. Judicious use of oxytocin produces contractions with intrauterine pressures equivalent to spontaneous labor. If the fetus develops signs of fetal hypoxia with these contractions, this is due to pre-existing uteroplacental insufficiency and not to the oxytocin. Inappropriate use of oxytocin may produce hyperstimulation and decrease transplacental oxygen transport to the fetus. In the primigravida rupture of the uterus in association with oxytocin is almost unknown. However care must be taken in the multipara and those with previous uterine surgery.All labor and delivery units must be prepared to manage uterine hyperstimulation whether it is associated with oxytocin use or not. Management of uterine hyperstimulation is outlined in the section on induction of labor. The following are possible complications, their mechanism of occurrence and preventative management, with the use of oxytocin.Adverse Effects of Oxytocin and Their PreventionAdverse Effects Mechanism PreventionFetal compromise Hyperstimulation Correct doseUterine rupture Hyperstimulation Correct doseEach woman’s uterus varies in its sensitivity to oxytocin. Even in the same uterus, the sensitivity may change during the course of labor. The dose must be sufficient to achieve adequate contractions. Protocols or guidelines for the administration of oxytocin vary but suggest starting with a low dose and small increments at intervals of 30 minutes. Starting incremental dosages for augmentation may be less than those for induction.Augmentation of LaborInitial dose of oxytocin 1-2mU/minIncrease interval Every 30 minutesDosage increment 1-2mUUsual dose for good labor 2-12mU/minIt is important to allow adequate time for oxytocin to work. This is especially true if it is started when the cervix is less than 5 cm dilated. Do not expect to see immediate progress.For the conversion to the equivalent to drops per minute (20 drops=1ml):Oxytocin Normal Saline Drops10 unites 500 ml 1mu = 1 drop5 unites 1 lt 1mu = 4 drops10 unites in 1 lt 1mu = 2 dropsActive Management of LaborActive management of labor encompasses the following principles:• Rigorous diagnosis of labor• Close surveillance of progress of labor by partogram• Continuous support in labor• Early intervention to correct inadequate progress of labor:• ARM• OxytocinThis has been shown to reduce the incidence of dystocia and cesarean sections. Management of the Prolonged Second Stage Setting an arbitrary time limit for the second stage in the absence of suspected fetal compromise, is not well founded. Women should not be encouraged to push until the head has descended to the pelvic floor and they feel the urge to do so. If no urge to push occurs after one hour of second stage, reassess the contractions and consider the use of oxytocin if contractions are inadequate. A lack of descent in the absence of moulding or caput is likely due to inadequate contractions.Summary

Prevention of Dystocia
• Avoid unnecessary induction
• Admit only women in active labor
• Encourage ambulation and upright posture
• Encourage the use of prenatal education
• Continuous support of laboring women
• Use appropriate analgesia

Management of Dystocia
• Appropriate assessment of adequate progress in labor
• Appropriate intervention when necessary
 Amniotomy
 Analgesia
 Rest
 Ambulation
 Augmentation
 Cesarean sections

OBSTRUCTED LABOR

Definitions

“Failure of descent of the fetus in the birth canal for mechanical reasons in spite of good uterine contractions”. (Philpott, 1982)

Incidence
1 – 3%

Risks Associated with Neglected Obstructed Labor

Fetal:
• Asphyxia
• Sepsis
• Death

Maternal:
• Sepsis
• Uterine rupture
• Hemorrhage
• Fistula (Vesico-vaginal, recto-vaginal)
• Death

Etiology of Obstructed Labor

Fetal – Pelvic Disproportion:

Malpresentations
– Face
– Brow
– Shoulder/arm presentation – Transverse lie
– Breech
– Compound presentation

Malposition- Persistent occipito posterior
– Persistent occipito transverse

Malformations
– Hydrocephalus
– Abdominal tumors (eg. Wilms Tumor)
– Cystic Hygroma
-Conjoined twins

Maternal

•Small pelvis
– Childhood malnutrition
– Contracted or deformed bony pelvis

•Soft tissue tumors of the pelvis
– Uterine fibroids
– Ovarian tumors
– Rectal tumors

Clinical Features of Obstructed Labor

In most cases, prolonged labor preceeds obstruction. However, in the grand multiparous patient labor may be quick and relatively silent, and in the presence of a malpresentation, such as a transverse lie, obstructed labor may rapidly occur.

Clinical Presentation of a Patient with Obstructed Labor:

Dehydration

Dehydration is due to muscular activity in the absence of adequate fluid intake. Signs and symptoms will include hot and dry skin with loss of tissue turgor.

• Oliguria

Decreased urinary output occurs in association with the patient’s state of dehydration.

• Keto-acidosis

Metabolic acidosis develops, from accumulation of lactic acid produced by the prolonged contractions of uterine and skeletal muscles. With inadequate caloric intake, endogenous tissue breakdown occurs, and the catabolism of fat in the absence of carbohydrates leads to the production of ketones which further increases the acidosis. Dehydration exaggerates the acidaemia because anions accumulate due to the diminished urinary output. In a response to restore the acid base equilibrium, potassium is mobilized from the cells, which diminishes the activity of the involuntary muscles.

The clinical signs of keto-acidosis are: a rapid pulse in association with deep and rapid respiration and pyrexia. Acetone is present in the urine, and the bowel is frequently distended and atonic due to hypokalemia.

• Sepsis

Infection that is frequently established by the time-prolonged labor has reached the stage of obstruction, particularly if the membranes have been ruptured for a long time. The introduction of pathogens often occurs with un-sterile vaginal examinations or manipulations. Even in the absence of vaginal interventions, infection will develop in the birth canal in association with prolonged obstructed labor.

The clinical signs of infection are purulent vaginal discharge, pyrexia and tachycardia. In advanced cases, infections due to gas-forming organisms may produce a crackling sensation when the uterus is palpated.

When the fetus has been dead for several days, significant gas may be produced from putrefaction and the uterus becomes distended and tympanitic. The terminal signs of severe intrapartum infection are septic shock with circulatory collapse, hypotension, a rapid thready pulse with subnormal temperature.

State of the Uterus

In multigravid, the uterus reacts to obstruction by frequent and stronger contractions of the upper segment. Meanwhile, the lower segment continues to retract and already thinned by circumferential dilatation in the first stage of labor, elongates and becomes progressively thinner. As the contractions continue, progressive retraction and thinning of the lower segment continues and the junction ring between the lower and upper segment rises progressively, often up to the level of the umbilicus. This is called a pathological ring or Bandl’s Ring.

In the primigravid patient, obstruction will usually occur before full dilatation. If the obstruction is neglected the following sequence of events will occur:

• Prolonged uterine activity may lead to reduced intervillous blood flow and fetal asphyxia
• Fetal trauma associated with operative vaginal delivery
• Avascular pressure necrosis from the fetal presenting part. This develops in a ring formation at the obstruction site leading to sloughing of the lower uterine segment and cervix.

Palpation of the uterus and observation of contractions provides important information. In the early stages of obstruction the uterus may contract vigorously and frequently, with little relaxation between contractions. This is followed by a continuous spasm when the uterus is hard, uniformly convex, and tender to pressure – particularly over the distended lower uterine segment. The patient is usually not in constant pain but feels continuous discomfort.

In obstructed labor, asphyxia is likely to have caused intra-uterine fetal death by the time the patient presents for treatment. The asphyxia results from interference with placental exchange of gas between fetus and mother through the mechanism of strong repetitive uterine contractions over a long period of time or the development of a contracted uterus.

Ruptured Uterus

The clinical findings may vary from mild and non-specific to an obvious clinical crisis and abdominal catastrophe. The following signs and symptoms of impending, or early, uterine rupture are not consistent but can aid early detection:

- Persistent lower uterine segment pain and tenderness between contractions
– Swelling and crepitus of lower uterine segment
– Vaginal bleeding
– Maternal tachycardia, hypotension and syncope
– Haematuria
– Fetal heart rate abnormalities: tachycardia, variable and late deceleration. This is the most reliable
warning sign.

The classic signs and symptoms of complete uterine rupture are:

- Sudden onset of tearing abdominal pain
– Cessation of uterine contractions
– Vaginal bleeding
– Recession of the presenting part
– Absent fetal heart
– Signs of intra-abdominal hemorrhage associated with hypovolaemic shock.

The lower uterine segment may rupture with few dramatic signs and symptoms. The thin avascular scar of a previous lower uterine segment cesarean section may rupture with little bleeding and labor continue uneventfully- rupture of the uterus becoming apparent in the post partum period.

State of the Bladder

During labour, the bladder is normally displaced out of the pelvis and becomes palpable above the symphysis pubis. Compression between the back of the symphysis and the presenting part may prevent the patient from emptying her bladder and make catheterisation impossible. The bladder forms a tender swelling above the symphysis. This overlies the stretched lower uterine segment, and the transverse depression at the junction of the superior border of the bladder and the lower segment of the uterus may be confused with a pathological retraction ring.

Prolonged compression traumatizes the bladder, so blood stained urine is a fairly constant feature of obstructed labor but does not necessarily mean the uterus has ruptured.

Vaginal Findings

Obstructed labor often produces oedema of the lower vagina and vulva. Associated sepsis often leads to a thick offensive vaginal discharge. Bleeding is of significant concern, as it usually indicates the uterus has ruptured.

Cervical Findings

In cephalic presentations full cervical dilation will usually occur as the moulded fetal head is driven down through the cervix. With shoulder or compound presentations, a rim of cervix usually persists because the presenting part is arrested at a higher level.

By the time obstruction has occurred, the caput succedaneum makes identification of the presentation and position very difficult. In vertex presentations, a large caput on the apex of an extremely molded head may reach the outlet when the greatest diameter is still above the brim. Therefore, more reliance should be placed on the abdominal findings when deciding the level or station of the head.

Complications of Obstructed Labor

Maternal
– Ruptured Uterus
– Vesico-Vaginal Fistulae (VVF)
– Recto-Vaginal Fistulae (RVF)
– Pueperal sepsis

• Extensive sloughing heals by fibrosis leading to almost complete stenosis of the vagina and dyspareunia/ apareunia
• Osteitis pubis – infection of pubic bone after damage to the periosteum and superficial cortex by pressure necrosis

Fetal
– Asphyxia / cerebral palsy
– Neonatal sepsis
– Death

Treatment

• Prevention – In most cases, obstructed labor can be prevented by:

- Good nutrition in childhood
– Promotion of appropriate and accessible antenatal care with health care providers trained in history and
physical examination skills
– Use of a partogram in the health unit when the patient is in labor
– The development of appropriate and timely referral systems.

•The standard procedure for obstructed labor is cesarean section when the diagnosis has been made.

•Prolonged or neglected obstructed labor (uterus intact)

1. If the fetus is still alive – The patient should be prepared for delivery with simultaneously attention to the sequelae of prolonged labor.

- Fluid electolyte imbalance
– Control of infections with broad spectrum antibiotics and tetanus prophylaxis

Method of delivery:
– Vacuum in cases of mild disproportion
– Forceps: which will require special skills for mid cavity operations
– Symphysiotomy (see Appendix 2)

2. With a dead fetus – If the fetus is dead, destructive operations may be considered, particularly if the mother’s condition is morbid. Resuscitation of the mother is essential before proceeding with a destructive procedure. This resuscitation should include:

- Correction of fluid and electrolyte imbalance
– Control infection
– Be prepared to prevent/treat post partum hemorrhage

• Ruptured Uterus

1. Prompt management of hypovolaemia

2. Laparotomy:
– Remove fetus and placenta

3. Secure hemostasis :
– Deliver the uterus out of the abdominal incision. Assistant’s hands may hold the uterus and with fingers and thumbs occlude the uterine vessels.
– Control the bleeding edges of the uterine laceration with ring forceps.
– Manual compression of the aorta will often enable the surgeon to identify the extent of the lacerations in the uterus.
– Uterine artery ligation should be considered to reduce blood loss before proceeding to definitive surgery.
– Internal iliac artery ligation may be necessary to control bleeding in the base of the broad ligament.

Before carrying out any surgical procedures on major vessels, identification of the course of the uretery should be undertaken in order to avoid ureteric injury. The integrity of the bladder should always be carefully reviewed, as the bladder wall may frequently be involved in a lower uterine segment rupture.

Surgical Options:

The choice of operative procedure is dependant on a number of factors including the patient’s condition, type of rupture, facilities available, and experience of the surgeon. 5
– Total hysterectomy
– Subtotal hysterectomy
– -Laceration repair and tubal ligation
– Laceration repair alone

Destructive Procedures

- Craniotomy
– Decapitation
– Evisceration
– Cleidotomy

In a series reported by Raksha Anura on 33 patients who underwent destructive operations, craniotomy was the most common destructive procedure and the main indication was hydrocephalus.5

The performance of destructive fetal operation will depend on local facilities and experience.

Before performing any destructive procedure, it is important to ensure the bladder is empty. The aim of the treatment is to deliver the mother by the safest possible method. The operative vaginal delivery and destructive procedures must be performed in an operating theatre where a set of laporatomy instruments are available for immediate use.

References:
1. Kwast B et al., World Health Organization partograph in management of labour. Lancet, 1994, 343:1399-1404.
2. WHO. “Preventing Prolonged Labour: A Practical Guide.” The Partograph. Geneva: Maternal Health and Safe Motherhood Programme, Division of Family Health, 1994.
3. SOGC “DYSTOCIA”. SOGC Policy Statement No. 40, October 1995
4. Keirse MJNC, Chalmers I. In: Chalmers, Enkin, Keirse (Eds). Effective Care in Pregnancy and Childbirth. Oxford University Press, Oxford, England, 1989.
5. Friedman EA. Labour: Clinical evaluation and management. Second edition (New York). Appleton Century Crofs. 1976. Studd JWW (Ed). The Management of Labour. Oxford: Blackwell Scientific Publications, 1985.
6. O’Driscoll K, Foley M, MacDonald D. Active management of labor as an alternative to caesarean section for dystocia. Obstet Gynecol 1984; 63: 485-90
7. Akoury HA, BrodieG, Caddick R, McLaughlin VD, Pugh PA. Active Management of Labor and Operative Delivery in Nulliparous Women. AM J Obstet Gynecol 1988;255

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