Abnormal Labor in Obstetrics: Recognition and Management

Excerpt

Normal labor is defined as regular and painful uterine contractions resulting in progressive cervical effacement and dilation. Abnormal labor refers to labor patterns that deviate from established normal standards. A clear understanding of normal labor progression is crucial for recognizing dysfunctional labor.

Labor consists of 3 stages: the first stage begins with painful contractions, causing progressive cervical change, and concludes with full cervical dilation. The first stage is further divided into latent and active phases. The second stage of labor begins with complete cervical dilation and concludes with the delivery of the fetus. This stage is characterized by active maternal expulsive efforts to facilitate birthing. The third stage of labor begins with the delivery of the fetus and ends with placental delivery. Abnormal labor occurs across all stages and is described as a prolonged, protracted, or arrested progression of labor.

The stages and phases of labor have specific time intervals used in labor evaluation and interpretation. Ideally, patients are evaluated with or without pelvic examinations every 2–4 or more hours to assess labor progress. The American College of Obstetricians & Gynecologists (ACOG) defines the stages and phases of labor as follows:

1. First Stage: 0 to 10 cm cervical dilation

   1. Latent phase: 0 to 5 cm dilation

   2. Active phase: 6 cm dilation to complete cervical dilation

2. Second Stage: begins at 10 cm dilation; uterine contractions, along with maternal expulsive efforts, lead to the descent of the presenting fetal part and delivery of the fetus

3. Third Stage: time between delivery of the fetus and placental delivery

In 2020, the World Health Organization (WHO) launched a new Labor Care Guide, comprising 7 sections. This care guide defines the start of the active phase of labor as 5 cm. The International Federation of Gynecology and Obstetrics (FIGO) supports this care guide and recommends implementation in all obstetrical settings. Notably, a discrepancy among international guidelines regarding the onset of active labor. As stated above, ACOG defines active labor as beginning at 6 cm of cervical dilation. The following parameters apply to full-term singleton pregnancies and represent the time 95% of patients will complete a given stage or phase of labor. These parameters should be considered when classifying labor as abnormal:

First Stage Prolongation, Protraction, and Arrest

1. Latent Phase Prolongation

   1. Nulliparous: The latent phase duration is longer than 20 hours

   2. Multiparous: The latent phase duration is longer than 14 hours

   3. Due to its variable and slow progression, latent phase prolongation alone does not indicate cesarean delivery.

1. Active Phase Protraction and Arrest (once 6 cm cervical dilation is achieved)

   1. No cervical dilation after 4 hours of adequate contractions, with ruptured membranes.

   2. No cervical dilation after 6 hours of inadequate contractions, with ruptured membranes, and despite oxytocin administration.

Second Stage Protraction and Arrest

1. Nulliparous: The second stage duration is longer than 3 hours without an epidural or 4 hours with an epidural.

2. Multiparous: The second stage duration is longer than 2 hours without an epidural or 3 hours with an epidural.

3. Longer durations may be appropriate when maternal and fetal statuses are reassuring and the fetal presenting part continues to descend.

4. ACOG recommends that second-stage labor arrest be diagnosed earlier with a lack of fetal descent and rotation despite adequate expulsive efforts, contractions, and time.

Third Stage Abnormality

1. Placental retention duration is longer than 30 minutes following fetal delivery.

2. The risk of adverse maternal outcomes increases after a third stage of 15 minutes.