An 18-month-old girl is brought to her pediatrician's office by her parents with a 6-hour history of intermittent, severe abdominal pain, accompanied by drawing her knees to her chest. Initially, these episodes were followed by periods of normal playfulness, but over the last 2 hours, she has become increasingly lethargic. She has had three episodes of non-bloody vomiting, which recently became bilious. Her parents also report a single bowel movement described as 'currant jelly' stool about an hour ago. On examination, she appears pale and somewhat irritable but arouses easily. Her temperature is 37.5 C, heart rate is 165 beats/min, blood pressure is 88/40 mm Hg, and respiratory rate is 30 breaths/min. Abdominal palpation reveals mild diffuse tenderness, but no guarding or rigidity. No obvious masses are initially palpable. A peripheral intravenous line is established, and a bolus of 20 mL/kg of isotonic saline is administered. Given the progression of symptoms and findings, what is the most appropriate diagnostic approach and subsequent initial therapeutic management for this patient?

A 62-year-old man presents to his primary care physician's office complaining of progressive abdominal discomfort over the past 24 hours. He reports intermittent, crampy abdominal pain, accompanied by significant bloating, obstipation, and bilious vomiting that started approximately 18 hours ago. He has a remote history of an open appendectomy performed 30 years prior. His current medications include lisinopril and atorvastatin. On examination, he appears distressed. His temperature is 37.5°C, blood pressure 130/80 mmHg, heart rate 102 beats/min, respiratory rate 16 breaths/min, and oxygen saturation 97% on room air. Abdominal inspection reveals marked distension with visible peristaltic waves. Palpation elicits diffuse tenderness, more pronounced in the periumbilical region, with no rebound or guarding. Bowel sounds are diminished and high-pitched. Cardiopulmonary examination is unremarkable. Given these findings, what is the most likely diagnosis, and what should be the immediate course of action upon transfer to the emergency department?

A 45-year-old man with a long-standing history of Crohn disease, complicated by multiple previous abdominal surgeries for strictures, presents to the outpatient clinic complaining of progressive abdominal pain, distension, and recurrent bilious vomiting over the past 24 hours. He reports no bowel movements or flatus since the onset of symptoms. Initially, his pain was crampy and intermittent, but it has now become constant and severe, localized to the periumbilical region, and exacerbated by movement. He denies fever or chills. On examination, he appears acutely distressed. His initial vital signs are: temperature 37.0°C, blood pressure 130/80 mmHg, heart rate 92 bpm, respiratory rate 16 breaths/min. Abdominal examination reveals significant distension, diffuse tympany, and hyperactive bowel sounds. Palpation elicits moderate diffuse tenderness, but no guarding or rebound. Due to the worsening nature of his symptoms, he is immediately transferred to the emergency department. Upon arrival an hour later, his condition has deteriorated. His temperature is now 38.5°C, blood pressure 90/50 mmHg, pulse 135 bpm, respirations 22 breaths/min, and oxygen saturation 96% on 2L nasal cannula. Abdominal examination now reveals marked generalized rigidity, exquisite tenderness to light palpation, and significant rebound tenderness throughout the abdomen. Bowel sounds are absent. Laboratory studies are drawn. Given his clinical presentation and rapid deterioration, what is the most likely diagnosis and the critical immediate management strategy?

A 55-year-old male presents to the emergency department complaining of progressive, colicky abdominal pain for the past 24 hours, associated with nausea, intermittent vomiting of bilious material, and inability to pass flatus or stool for nearly 36 hours. He has a past surgical history significant for an open appendectomy performed 15 years ago. On arrival, his vital signs are: Temperature 37.5 °C, Heart Rate 110 bpm, Blood Pressure 100/60 mmHg, Respiratory Rate 18 breaths/min, SpO2 97% on room air. Physical examination reveals a dehydrated appearing male with a distended, tympanitic abdomen. There is diffuse tenderness to palpation, particularly in the periumbilical region, but no palpable masses, rebound tenderness, or guarding. Bowel sounds are hyperactive and high-pitched. Given this patient's presentation, what is the most appropriate initial management strategy, and what is the likely underlying diagnosis?

A 52-year-old woman presents to the emergency department, transferred from an urgent care clinic, with a 6-hour history of rapidly worsening diffuse abdominal pain, persistent nausea, and bilious vomiting. She reports having not passed flatus or had a bowel movement for the past 5 days, initially experiencing intermittent crampy pain that has now become constant and excruciating. Her medical history is significant for a laparoscopic cholecystectomy performed 10 years prior. She denies taking any regular medications. Upon arrival, her vital signs are: temperature 38.9°C, blood pressure 88/55 mmHg, pulse 145/min, and respirations 28/min. Her pulse oximetry is 98% on room air. Cardiac and pulmonary auscultation reveal clear sounds. Abdominal examination reveals marked distension, diffuse tenderness with prominent rebound and voluntary guarding, and high-pitched, tinkling bowel sounds with areas of decreased activity. Capillary refill is sluggish at 4 seconds. Given these rapidly deteriorating findings, what is the most likely diagnosis and the critical next step in her definitive management?

A 68-year-old woman is admitted to the general surgery ward from the emergency department with a 3-day history of worsening diffuse abdominal pain, nausea, and persistent bilious vomiting. She reports no flatus or bowel movements since the onset of symptoms. Her medical history includes well-controlled hypertension, type 2 diabetes managed with oral agents, chronic constipation, and a remote history of an open appendectomy performed 25 years ago. On admission, her temperature is 37.8°C (100.0°F), blood pressure is 155/90 mmHg, pulse is 105/min, respirations are 18/min, and oxygen saturation is 96% on room air. Physical examination reveals a moderately distended, tympanitic abdomen with diffuse tenderness, but no rebound or guarding. Bowel sounds are diminished, and a 5 cm right lower quadrant surgical scar is noted. Rectal examination reveals an empty vault. Given this patient's presentation, what is the most likely diagnosis, and what immediate therapeutic intervention is indicated?

An 82-year-old male patient with a history of severe Parkinson's disease, atrial fibrillation, and a recent hip fracture repair, is transferred to the hospital from a rehabilitation facility due to progressive abdominal distension, obstipation, and persistent nausea over the past 48 hours. He is afebrile at 37.0°C (98.6°F), blood pressure is 128/76 mmHg, pulse 92/min, and respirations 16/min. His medications include carbidopa/levodopa, rivaroxaban, metoprolol, and oxycodone for post-operative pain. On physical examination, his abdomen is markedly distended with diffuse tympany to percussion and sluggish bowel sounds; no peritoneal signs are elicited. A nasogastric tube has been placed, draining minimal bilious fluid. Initial abdominal radiographs reveal marked dilation of the cecum, right hemicolon, and transverse colon, with a maximal colonic diameter of 11.3 cm. An abdominal CT scan with oral contrast confirms significant colonic dilation with no evidence of mechanical obstruction, intussusception, or bowel wall thickening. Intravenous fluids have been initiated, along with preliminary potassium and magnesium supplementation. Considering his clinical presentation and initial findings, what is the most likely diagnosis and the subsequent immediate therapeutic approach?

A 68-year-old man presents to the emergency department accompanied by his family, complaining of severe, colicky abdominal pain for the past 24 hours, associated with progressive abdominal distension, nausea, and bilious vomiting. He reports no passage of flatus or stool since the onset of pain. His past medical history includes hypertension, type 2 diabetes, and a laparoscopic appendectomy 15 years ago, followed by an open incisional hernia repair 5 years ago. On initial assessment, he is lethargic and grimacing in pain. His vital signs are T 39.4°C, HR 130 bpm, BP 85/50 mmHg, RR 28/min, and SpO2 94% on room air, necessitating oxygen supplementation via nasal cannula. Physical examination reveals a markedly distended abdomen, diffusely tender to palpation with rebound tenderness and guarding in the right lower quadrant. Bowel sounds are absent. A nasogastric tube is placed, yielding a large volume of dark green, foul-smelling fluid. Laboratory studies, an upright abdominal radiograph (Figure A), and a CT abdomen/pelvis with intravenous contrast (Figure B) are obtained. Given his acute presentation and clinical deterioration, what is the most likely diagnosis and the immediate definitive management strategy?