## Diagnosis: First Stage, Active Phase ### Definition of Labor Stages and Phases Labor is divided into three stages, with the first stage subdivided into three phases based on cervical dilation and clinical progression. | Stage | Phase | Cervical Dilation | Duration (Primigravida) | Key Features | |-------|-------|-------------------|------------------------|---------------| | **First** | Latent | 0–3 cm | 8–12 hours | Mild contractions, patient ambulatory | | **First** | Active | 3–7 cm | 2–5 hours | Stronger contractions (every 2–3 min), increased pain, patient focused | | **First** | Transition | 7–10 cm | 30 min–2 hours | Intense contractions, nausea, urge to push (premature) | | **Second** | — | 10 cm (fully dilated) | 30 min–2 hours | Active pushing, descent to +2/+3 station | | **Third** | — | — | 5–30 minutes | Placental delivery | ### Clinical Analysis of This Case **Key Point:** The patient has cervical dilation of **4 cm** with 80% effacement and contractions every 3–4 minutes. This places her squarely in the **active phase** of the first stage. **Clinical Pearl:** In the active phase, the cervix dilates at approximately 1.2–1.5 cm/hour in primigravidas. Contractions are regular (every 2–3 minutes), moderately strong, and the patient becomes more focused and less communicative. **High-Yield:** The transition from latent to active phase is marked by: - Cervical dilation crossing 3 cm - Contractions becoming regular and stronger - Increased maternal discomfort and behavioral change - Acceleration of cervical dilation rate ### Why Not Other Options? - **Latent phase** would have dilation <3 cm; this patient is already at 4 cm. - **Transition phase** begins at 7 cm dilation; this patient is only at 4 cm. - **Second stage** begins only after full cervical dilation (10 cm); this patient is at 4 cm. [cite:Williams Obstetrics 26e Ch 21]
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