A 32-year-old primigravida at 39 weeks of gestation presents to the labor ward with spontaneous rupture of membranes. On examination, the cervix is 2 cm dilated, 80% effaced, and the fetal head is at −2 station. Fetal heart rate is 140 bpm with normal variability. After 18 hours of expectant management, there is no progress in cervical dilation. The patient is afebrile with normal white blood cell count. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient is a primigravida at 39 weeks with spontaneous rupture of membranes (SROM), cervix 2 cm dilated, 80% effaced, fetal head at −2 station, and no progress after 18 hours of expectant management. She is afebrile with a normal WBC count, and the fetal heart rate is reassuring. ## Key Point: **Augmentation with oxytocin** is the most appropriate next step in a patient with SROM and prolonged latent phase (no active labor after 18 hours), provided there are no signs of infection and the fetal status is reassuring. This is consistent with ACOG, Williams Obstetrics, and FOGSI guidelines. ## High-Yield: - **Prolonged latent phase after SROM** is an indication to augment labor with oxytocin, NOT to proceed directly to cesarean section. - Cesarean section for "arrest of dilation" requires the patient to be in **active labor** (cervix ≥6 cm per contemporary ACOG criteria) with no progress despite adequate contractions — this patient is still in the **latent phase** (2 cm dilation). - The absence of infection signs (afebrile, normal WBC) means there is no urgency to deliver by cesarean; a trial of oxytocin augmentation is both safe and appropriate. ## Clinical Pearl: **Arrest disorders** are defined only in **active labor**: - Active phase begins at ≥6 cm (ACOG 2014 / Williams Obstetrics 26e). - Arrest of active phase = no cervical change for ≥4 hours with adequate contractions, or ≥6 hours with inadequate contractions. - This patient at 2 cm is in the **latent phase**; cesarean section at this stage would be premature and not evidence-based. ## Why Other Options Are Incorrect: - **A (Continue expectant management):** After 18 hours of SROM with no labor progress, continued expectant management increases chorioamnionitis risk without benefit; active intervention is warranted. - **B (Artificial rupture of membranes):** Membranes are already ruptured (SROM stated in stem); this option is not applicable. - **C (Cesarean section for arrest of dilation):** Incorrect because arrest of dilation is an active-phase diagnosis (cervix ≥6 cm). Performing cesarean for a latent-phase patient at 2 cm is not guideline-supported and exposes the patient to unnecessary surgical risk. ## Rationale for Oxytocin Augmentation: 1. SROM with no spontaneous labor onset after 18 hours = indication to augment per ACOG Practice Bulletin 107 and Williams Obstetrics 26e Ch 21. 2. Oxytocin stimulates uterine contractions, promotes cervical dilation, and reduces the duration of membrane rupture, thereby lowering chorioamnionitis risk. 3. Fetal status is reassuring (FHR 140 bpm, normal variability), making augmentation safe. 4. Only if augmentation fails to achieve active labor progress should operative delivery be considered. [cite: ACOG Practice Bulletin 107; Williams Obstetrics 26e Ch 21; FOGSI Good Clinical Practice Recommendations on Labor Augmentation]