Obstetrics | Abnormal Labor

Hi everyone, welcome back to the MedBullets Step 2 and 3 podcast. In today's episode, we cover the topic of abnormal labor found under the obstetrics section at MedBullets.com. Let's begin with a clinical snapshot. A 33-year-old G1P0 pregnant woman presents to the hospital at 41 weeks of gestation with contractions. She notes that she attended all of her prenatal appointments and had an uncomplicated pregnancy.

She requests spinal epidural anesthetics to alleviate her pain. After five hours of labor with adequate contractions, that being contractions with greater than 200 Montevideo units, her cervix is found to be dilated to eight centimeters. with ruptured membranes. Let's continue with an introduction to abnormal labor. As a general overview, remember that abnormal labor occurs when the milestones of normal labor

in which uterine contractions result in progressive dilation and effacement of the cervix, are not reached. In terms of epidemiology, remember that 8-11% of deliveries are complicated by an abnormal first stage of labor. And in terms of the pathophysiology, abnormal labor may be the result of problems with the three Ps. This stands for pelvis, passenger, and power. Pelvis may be too small or narrow to allow infants passage.

Passenger means that there may be a large fetal size also known as macrosomia or there may be an abnormal position, presentation, or lie of the fetus. Power means that the frequency or intensity of contractions may be inadequate.

Remember that this is the most common cause. Moving on to the presentation, the main symptom will be prolonged contractions. On exam, one may note delayed cervical dilation. Remember that prolonged or protracted labor is if there is cervical dilation less than 1.2 centimeters per hour for a primi para or 1.5 centimeters per hour for a multi para.

Also remember that labor arrest is if there is no cervical change in more than 4 hours with adequate contractions, that is, contractions that are greater than 200 Montevideo units, or greater than 6 hours with inadequate contractions. One may also note delayed cervical effacement. In terms of further studies, one can plot a labor curve. That means plotting the patient's labor progress, which is graphed as cervical dilation versus duration in hours.

One can also perform intrauterine pressure monitoring. This means that an intrauterine pressure catheter is used to measure the strength of uterine contractions. One can also perform fetal heart tracing. This means monitoring for reassuring fetal heart rate patterns throughout the labor course. And in terms of treatment, medical options include repositioning the patient,

This may be with the use of a quote-unquote peanut ball in order to decrease the length of the first and second stages of labor. One can also administer oxytocin. This is indicated for hypotonic contractions. and one should administer until contractions are deemed adequate by frequency, intensity, and duration measures. Surgical options include amniotomy. This is indicated when patients have reached the active phase of labor.

However, it is not recommended in the latent phase of labor as it may increase the risk of intrauterine infection or cord collapse. One can also perform operative vaginal delivery or cesarean delivery.

This is indicated if conservative measures fail or if the fetal heart pattern is non-reassuring. Complications related to abnormal labor include hyperstimulation of the uterus. This may result from prolonged medical induction of labor. and it can result in several complications such as uterine rupture, postpartum uterine atony, and postpartum hemorrhage. Another complication is chorioamnionitis.

Remember that there is an increased risk when rupture of membranes occurs for more than 18 hours, so one should administer antibiotics. And lastly, with regards to prognosis, Remember that the likelihood of abnormal labor in subsequent pregnancies depends on the cause for abnormal labor. For example, if abnormal labor was due to small contours of the pelvis that were inadequate for a normal or small-sized infant,

then the likelihood for recurrence is high. Now that we've discussed the major points relating to abnormal labor, let's walk through some questions to apply what we've learned and get a sense of how the topic might be tested. For the first question, consider the following clinical scenario. A 30-year-old woman, Gravita 2, Para 1, at 39 weeks gestation, presents to the hospital with painful contractions and rupture of membranes.

She reports that the contractions started a couple hours ago and are now occurring every four minutes. She is accompanied by her husband, who states her water broke an hour ago before we left for the hospital. The patient denies vaginal bleeding. and fetal movements are normal. The patient has attended all her prenatal visits without pregnancy complications. She has no chronic medical conditions and takes only prenatal vitamins. Her blood pressure is 110 over 75.

and pulse is 82 beats per minute. A fetal heart rate tracing shows a pulse of 140 beats per minute with moderate variability and no decelerations. Cervical exam reveals a cervix that is 7 centimeters dilated. and 100% effaced with the fetal head at the minus one station. The patient forgoes epidural anesthesia. During which of the following scenarios should a cesarean delivery be considered for this patient? And the answer choices are...

Choice one, cervix is seven centimeters dilated and fetal head is at the zero station after one hour with contractions every five minutes. Choice two, Cervix is 7 centimeters dilated and fetal head is at the minus one station after two hours with contractions every seven minutes. Choice three. Cervix is 7 centimeters dilated and the fetal head is at the zero station.

after four hours with contractions every two minutes. Choice four, cervix is nine centimeters dilated and fetal head is at the minus one station after three hours with contractions every three minutes. Our choice five, Cervix is 10 centimeters dilated and the fetal head is at the plus one station after two hours with contractions every two minutes.

The best answer to this question is choice three. Cervix is seven centimeters dilated and the fetal head is at the zero station after four hours with contractions every two minutes. The patient initially presents with a cervix that is 7 cm dilated and 100% effaced. Cesarean delivery is indicated for stage 1 arrest of labor, which is defined as no cervical change.

that is, the cervix remaining 7 centimeters dilated, after 4 hours with adequate contractions, that is, contractions of greater than 200 Montevideo units every 2-3 minutes. Women with a cervical dilation of greater than 6 centimeters who have not reached complete cervical dilation are considered to be in the active phase of the first stage of labor. Normal progress is on average of at least 1 centimeter of cervical dilation per hour.

for spontaneous delivery. An active phase arrest of labor is defined as either no cervical change for four or more hours despite adequate contractions or no cervical change for six or more hours with inadequate contractions. Adequate contractions are usually considered to be greater than 200 Montevideo units and occurring every 2-3 minutes. While intravenous oxytocin can be used for labor protraction, cesarean delivery is indicated.

once the mother reaches criteria for arrest of labor. Let's also discuss why the other choices are incorrect. Choice one, cervix is seven centimeters dilated and the fetal head is at the zero station after one hour. with contractions every five minutes, describes a patient with no cervical change and inadequate contractions. However, only one hour has passed, which is not enough time to adequately assess labor progression. Choice two.

Cervix is 7 cm dilated and the fetal head is at the minus 1 station after 2 hours, with contractions every 7 minutes, describes a patient with no cervical change and inadequate contractions. This patient most likely has labor protraction due to inadequate contractions and would benefit from oxytocin. She does not yet meet the criteria for arrest of labor. Choice four.

Cervix is 9 cm dilated and the fetal head is at the minus 1 station after 3 hours with contractions every 3 minutes. Describes a patient who has had cervical change of 2 cm in 3 hours with adequate contractions. cesarean delivery is not indicated. Choice five, cervix is 10 centimeters dilated and the fetal head is at the plus one station after two hours with contractions every two minutes, describes a patient who has had a cervical change.

of three centimeters in two hours with adequate contractions. No augmentation of labor is indicated. Finally, a bullet summary. Arrest of labor is defined as no cervical change in four or more hours with adequate contractions.

or six or more hours with inadequate contractions. For the second question, consider the following clinical scenario. A 31-year-old G1P0 woman presents to labor and delivery at 39 weeks gestation, in active labor, and is admitted. On admission, she is 6 centimeters dilated and 90% effaced. After 2 hours, her cervix is 7 centimeters dilated and 100% effaced.

The fetal station is minus two and the fetal lie is vertex. Leopold maneuvers are performed and the estimated fetal weight is 3.2 kilograms. Her membranes have not ruptured. She has received regular prenatal care and has had no complications during her pregnancy. She has no medical or surgical history. Temperature is 98.4 degrees Fahrenheit or 36.9 degrees Celsius.

Blood pressure is 122 over 82. Pulse is 80 beats per minute. And respirations are 16 breaths per minute. The fetal heart tracing is category one. What is the next best step in management for this patient? And the answer choices are... Choice one, amniotomy. Choice two, cesarean delivery. Choice three, observe for two more hours. Choice four, vacuum-assisted delivery. Or choice five, tocolysis.

The best answer to this question is choice one, amniotomy. This patient presents in the active phase of stage one labor and proceeds to dilate 0.5 centimeters per hour, suggesting protraction of labor. amniotomy should be performed to promote progression of labor. Active stage of labor is defined by rapid cervical change occurring after 6 cm dilation in noliparous women

and 5 cm dilation in multiparous women. Noliparous women should dilate at 1.2 cm per hour and multiparous women should dilate at 1.5 cm per hour. Protracted labor is defined as less than 1 cm cervical dilation over 2 hours of active labor. For patients whose membranes have not ruptured, amniotomy performed in conjunction with oxytocin administration

may help with the progression of labor. Afterward, the patient should be maintained on oxytocin titrated to achieve adequate contractions. An intrauterine monitor may be placed to monitor contraction strength. If cervical dilation does not increase or is very slow for 4 hours with adequate contractions or 6 hours with inadequate contractions, cesarean delivery may be considered. Let's also discuss why the other choices are incorrect.

Choice two, cesarean delivery is indicated for the arrest of labor, defined as no cervical change for four or more hours with adequate contractions or no cervical change for six or more hours with inadequate contractions. After the membranes are ruptured, an intrauterine monitor can be placed to assess the adequacy of contractions. Choice 3. Observing for two or more hours is incorrect.

because protraction of labor can be diagnosed if dilation is less than 1 cm over 2 hours during active phase of labor. Once it is diagnosed, the patient should be treated to prevent complications related to protracted labor. Choice 4. Vacuum-assisted delivery is indicated for prolonged second stage of labor, maternal exhaustion from pushing, a maternal medical need to avoid pushing, or suspicion of severe fetal distress during the second stage of labor.

This patient has not reached the second stage of labor. Choice 5. Tocolysis or the administration of tocolytic drugs reduces the frequency and intensity of uterine contractions to prolong pregnancy. This patient is in the active phase of labor at term and prolonging the pregnancy is an unnecessary risk. Finally, a bullet summary. Protracted labor is defined as less than 1 cm cervical dilation over 2 hours.

during active phase of labor, that is when dilation is 6 centimeters or greater in noliparous women and 5 centimeters in multiparous women, and should be treated with amniotomy if the rupture of membranes has not occurred. in conjunction with oxytocin. That's all for this review about abnormal labor. We hope that was helpful. This is the MedBullets Step 2 in 3 podcast, a daily audio review session for MedBullets, the free learning and collaboration community.

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