This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Obs), Subject name: Gynaecology & Obstetrics
A nulliparous woman in spontaneous labor was examined by you at 2pm and was found to be 6 cm dilated, 80% effaced with absent membranes, clear liquor and fully effaced cervix and vertex at 0 station and oxytocin was started to augment the contractions. At 6pm, she is reassessed and found to have same findings, but now with a caput formation and grade 3 moulding. Her contractions were seen to have been adequate for the last 4 hrs. What is the next step? 
Select and explain. 
A. Wait and watch for another two hours, B. Oxytocin augmentation, C. Shift her to OT for caesarean, D. Vacuum delivery
C: Shift her to OT for caesarean
Answer: C: Shift her to OT for caesarean 
Explanation: Ans. C. Shift her to OT for caesareana. The woman is diagnosed with arrest of active stage of laborb. ACOG has updated the definition of arrest of 1st stage of labor in woman undergoing spontaneous labor to decrease the incidence of first caesarean section.c. Arrest in dilatation in active labor is defined at more than or equal to 6cm dilatation, with membrane rupture with no cervical change and one of the following:d. 4 hours or more of adequate uterine contractions (more than 200 Montevideo Units) ORe. 6 hours or more of inadequate uterine contractions