A 32-year-old G3P2 at 36 weeks gestation presents to the emergency department with the sudden onset of excruciating, diffuse, and constant abdominal pain, which began approximately two hours ago. She reports a history of intermittent recreational drug use, though the specific substance used most recently is unknown. She denies any vaginal bleeding or fluid leakage but describes very frequent, painful uterine contractions that do not subside. Her obstetric history includes two prior spontaneous vaginal deliveries. On examination, her temperature is 37.20C, blood pressure is 100/55 mmHg, pulse is 110/min, and respirations are 18/min. Abdominal palpation reveals a tense, rigid, and woody uterus. Fetal heart rate monitoring shows frequent, low-amplitude contractions, fetal tachycardia (baseline 170 bpm), minimal variability, and recurrent late decelerations. Cervical examination reveals fingertip dilation, an effaced but high cervix, and no active bleeding. Considering these findings, what is the most likely diagnosis, and what immediate management strategy should be implemented to prevent further complications?

A 33-year-old G2P1 woman with a history of chronic hypertension is admitted to the labor and delivery unit after experiencing a fall at home. She is at 37 weeks and 5 days gestation. Upon admission, she reports sudden onset of constant, severe lower abdominal pain and dark red vaginal bleeding that began shortly after the fall. She denies a gush of fluid but describes her uterus as feeling "rock hard." Her vital signs include: temperature 36.80C, blood pressure 188/102 mmHg, pulse 115/min, respirations 22/min, and oxygen saturation 97% on room air. Physical examination reveals a tender, rigid, and hypertonic uterus. Moderate dark red blood is noted in the vaginal vault. Fetal heart tones are initially concerning, showing late decelerations, which then progress to prolonged bradycardia. An immediate bedside ultrasound is inconclusive for placental location but shows an intrauterine pregnancy with no gross fetal anomalies. What is the most appropriate immediate management strategy and the most critical potential maternal complication to anticipate?

A 38-year-old G2P1 woman at 31 weeks gestation presents to the obstetrical triage with sudden onset of dark red vaginal bleeding and constant, severe abdominal pain that started about an hour ago. She reports a history of chronic hypertension, which was well-controlled with medication prior to this pregnancy, but notes her blood pressure has been trending higher recently. She denies trauma, recent falls, or drug use. On examination, her abdomen is rigid and exquisitely tender, and the fundal height appears inconsistent with gestational age, possibly larger than expected due to concealed hemorrhage. Fetal heart rate monitoring shows repetitive late decelerations with minimal variability. Given the clinical presentation and initial findings, what is the most likely diagnosis and the immediate management strategy?

A 28-year-old G1P0 woman at 30 weeks gestation presents to the emergency department complaining of sudden onset, severe abdominal pain and dark red vaginal bleeding that started an hour ago. She reports feeling lightheaded and her baby's movements have significantly decreased. Her medical history includes chronic fatigue and a low body mass index of 17.5 prior to pregnancy. Earlier prenatal labs showed a hemoglobin of 10.2 g/dL with an MCV of 102 fL, and a serum homocysteine level was noted to be significantly elevated. On examination, her abdomen is rigid and exquisitely tender, with a fundal height consistent with gestation. Fetal heart rate monitoring shows repetitive late decelerations. What is the most likely diagnosis and the most appropriate immediate management for this patient?

A 32-year-old primigravida at 37 weeks gestation presents to the emergency department, accompanied by her partner, reporting the sudden onset of dark red vaginal bleeding that soaked through her clothes, accompanied by severe, constant abdominal pain radiating to her back. She denies recent trauma but mentions feeling generally unwell and lightheaded for the past few hours. Her past medical history includes chronic hypertension managed with medication and a history of smoking. On examination, she appears pale and anxious. Her temperature is 37.6°C, blood pressure is 90/50 mmHg, pulse is 115/min, respirations are 22/min, and oxygen saturation is 96% on room air. Abdominal palpation reveals a tense, rigid uterus that is exquisitely tender. Fetal heart tones are difficult to ascertain with an external monitor, but intermittent late decelerations are noted. Given this patient's presentation and initial findings, what is the most likely diagnosis and the immediate critical management step?