A term multigravida is in labour since 12 hours. O/E PR: 116/min, BP is 90/60, tongue is dry, uterine contractions of 45 sec felt every 3 mins, cervix is thick, 6-7 cm dilated, membranes are absent, fetal head is at station -2 with a caput till +3 station. Urine is blood stained. The most likely diagnosis is:-