A 28-year-old primigravida at 39 weeks gestation presents to the labor ward with regular uterine contractions (3 in 10 minutes, each lasting 40 seconds) and vaginal bleeding. On examination, the cervix is 3 cm dilated, 80% effaced, and the fetal heart rate is 140 bpm. She reports rupture of membranes 6 hours ago with clear fluid. To confirm entry into active phase of labor and assess fetal well-being, which is the investigation of choice?

Explanation

## Investigation of Choice: Partograph **Key Point:** The partograph is the gold standard investigation for monitoring progress of labor and identifying prolonged labor or arrest disorders. It graphically plots cervical dilatation, fetal descent, uterine contractions, and vital signs over time. ### Why Partograph Is Correct In this case, the patient is in early labor (3 cm dilatation, regular contractions). The partograph serves multiple functions: 1. **Cervical assessment every 2 hours** — allows detection of progress into active phase (typically 4 cm dilatation with strong, regular contractions) 2. **Fetal descent monitoring** — tracks station to rule out cephalopelvic disproportion 3. **Contraction pattern documentation** — ensures adequate labor progression 4. **Early identification of prolonged labor** — WHO-recommended tool to reduce maternal and fetal morbidity **Clinical Pearl:** The partograph is particularly valuable in primigravidas, where the risk of prolonged labor and obstructed labor is highest. Serial cervical examinations every 2 hours (not more frequently, to reduce infection risk post-ROM) guide clinical decision-making. **High-Yield:** The partograph has been shown to reduce operative delivery rates and maternal complications when used systematically in labor management. ### Why Other Options Are Incorrect | Investigation | Why Not Appropriate | |---|---| | **Transabdominal ultrasound** | Ultrasound is not used to assess labor progress; it does not provide real-time cervical dilatation data. AFI assessment is relevant only if polyhydramnios or oligohydramnios is suspected, not for routine labor monitoring. | | **Fetal scalp blood sampling** | This is a diagnostic test for fetal hypoxia when there is evidence of fetal distress on CTG (late decelerations, variable decelerations with slow recovery). It is not a routine investigation in early labor with normal FHR. | | **Maternal serum beta-hCG** | hCG estimation is used in early pregnancy to confirm viability or diagnose ectopic pregnancy, not to assess labor progress or fetal well-being in active labor. | [cite:Williams Obstetrics 26e Ch 17]