Source identification and control US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Source identification and control. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Source identification and control US Medical PG Question 1: A 72-year-old female presents to the emergency department complaining of severe abdominal pain and several days of bloody diarrhea. Her symptoms began with intermittent bloody diarrhea five days ago and have worsened steadily. For the last 24 hours, she has complained of fevers, chills, and abdominal pain. She has a history of ulcerative colitis, idiopathic hypertension, and hypothyroidism. Her medications include hydrochlorothiazide, levothyroxine, and sulfasalazine.
In the ED, her temperature is 39.1°C (102.4°F), pulse is 120/min, blood pressure is 90/60 mmHg, and respirations are 20/min. On exam, the patient is alert and oriented to person and place, but does not know the day. Her mucus membranes are dry. Heart and lung exam are not revealing. Her abdomen is distended with marked rebound tenderness. Bowel sounds are hyperactive.
Serum:
Na+: 142 mEq/L
Cl-: 107 mEq/L
K+: 3.3 mEq/L
HCO3-: 20 mEq/L
BUN: 15 mg/dL
Glucose: 92 mg/dL
Creatinine: 1.2 mg/dL
Calcium: 10.1 mg/dL
Hemoglobin: 11.2 g/dL
Hematocrit: 30%
Leukocyte count: 14,600/mm^3 with normal differential
Platelet count: 405,000/mm^3
What is the next best step in management?
- A. Emergent colonoscopy
- B. Contrast enema
- C. Colectomy
- D. Plain abdominal radiograph
- E. Abdominal CT with IV contrast (Correct Answer)
Source identification and control Explanation: ***Abdominal CT with IV contrast***
- The patient presents with **severe abdominal pain, bloody diarrhea, fever, hypotension, tachycardia, abdominal distension, rebound tenderness, and leukocytosis**, all suggestive of **toxic megacolon** complicating her ulcerative colitis.
- An **abdominal CT with IV contrast** is the most appropriate next step to confirm the diagnosis, assess the extent of colonic dilation and inflammation, and rule out complications like perforation.
*Emergent colonoscopy*
- **Colonoscopy** is generally **contraindicated** in suspected toxic megacolon due to the high risk of **perforation** of the severely inflamed and dilated colon.
- While it can diagnose ulcerative colitis, the current acute, severe presentation makes it too risky.
*Contrast enema*
- A **contrast enema** is also **contraindicated** in setting of potential **toxic megacolon** or suspected colonic perforation.
- The pressure from the contrast agent could worsen dilation or cause perforation in an already compromised colon.
*Colectomy*
- **Colectomy** is a surgical intervention reserved for cases of **toxic megacolon** that **fail medical management** or when there is evidence of **perforation** or **ischemia**.
- It is not the *immediate* next step in management without further imaging and attempts at medical stabilization.
*Plain abdominal radiograph*
- A plain abdominal radiograph can show colonic dilation and air-fluid levels, which are indicative of toxic megacolon; however, it has **limited ability to assess the extent of inflammation**, detect complications like **perforation**, or rule out other intra-abdominal pathologies.
- It might be a useful initial screen but is not as comprehensive as a CT scan, especially when a definitive diagnosis and management plan is needed.
Source identification and control US Medical PG Question 2: A 17-year-old woman presents to the emergency department with abdominal and pelvic pain. She states it started 3 days ago and it has been getting gradually worse. She states it is diffuse and is located over her abdomen, pelvis, and inside her vagina. She also endorses vaginal pruritus and a discharge from her vagina. The patient works in an ice cream parlor and is sexually active with multiple different partners. Her temperature is 98.0°F (36.7°C), blood pressure is 122/80 mmHg, pulse is 82/min, respirations are 15/min, and oxygen saturation is 98% on room air. Physical exam is notable for a foul smelling vagina with a thin, white discharge. Her abdomen is diffusely tender. The patient is noted to be itching her vagina during the exam. Which of the following is the most appropriate initial step in management?
- A. Wet mount (Correct Answer)
- B. KOH prep
- C. Urine hCG
- D. CT abdomen/pelvis
- E. Cervical swab and culture
Source identification and control Explanation: **Wet mount**
- A **wet mount** is crucial in this case as the patient presents with symptoms suggestive of a vaginal infection, including **vaginal pruritus**, foul-smelling discharge, and diffuse abdominal/pelvic pain.
- This test can rapidly identify common causes of vaginitis such as **Trichomonas vaginalis** (motile trichomonads), **bacterial vaginosis** (clue cells), and **candidiasis** (yeast buds/hyphae), helping guide initial treatment.
*KOH prep*
- A **KOH prep** is specifically used to diagnose **candidiasis** by dissolving epithelial cells and highlighting fungal elements (hyphae and spores).
- While useful for yeast infections, it would not identify other potential causes of the patient's symptoms such as bacterial vaginosis or trichomoniasis, making a wet mount a more comprehensive initial diagnostic step.
*Urine hCG*
- A **urine hCG** test is used to detect pregnancy and is a standard part of evaluating women of reproductive age with acute abdominal/pelvic pain.
- While important to rule out ectopic pregnancy or other pregnancy-related complications, it does not directly address the likely infectious cause suggested by the vaginal discharge and pruritus.
*CT abdomen/pelvis*
- A **CT scan of the abdomen/pelvis** is an advanced imaging study typically reserved for cases where serious intra-abdominal or pelvic pathology (e.g., appendicitis, ovarian torsion, abscess) is suspected and cannot be ruled out by less invasive means.
- Given the strong indicators of a vaginal infection, less invasive and more targeted diagnostics are appropriate first.
*Cervical swab and culture*
- A **cervical swab and culture** is primarily used to detect sexually transmitted infections (STIs) such as **Chlamydia trachomatis** and **Neisseria gonorrhoeae**, which can cause cervicitis and pelvic inflammatory disease (PID).
- While STIs are a concern in a sexually active patient with pelvic pain, a wet mount provides a more immediate diagnosis for common vaginitis causes and helps prioritize treatment.
Source identification and control US Medical PG Question 3: A 49-year-old woman presents to her physician with a fever accompanied by chills and burning micturition since the past 5 days. She is an otherwise healthy woman with no significant past medical history and has an active sexual life. On physical examination, her temperature is 39.4°C (103.0°F), pulse rate is 90/min, blood pressure is 122/80 mm Hg, and respiratory rate is 14/min. Examination of the abdomen and genitourinary region do not reveal any specific positive findings. The physician orders a urinalysis of fresh unspun urine for this patient which shows 25 WBCs/mL of urine. The physician prescribes an empirical antibiotic and other medications for symptom relief. He also orders a bacteriological culture of her urine. After 48 hours of treatment, the woman returns to the physician to report that her symptoms have not improved. The bacteriological culture report indicates the growth of gram-negative bacilli which are lactose-negative and indole-negative, which produce a substance that hydrolyzes urea to produce ammonia. Which of the following bacteria is the most likely cause of infection in the woman?
- A. Enterobacter cloacae
- B. Klebsiella pneumoniae
- C. Escherichia coli
- D. Proteus mirabilis (Correct Answer)
- E. Citrobacter freundii
Source identification and control Explanation: ***Proteus mirabilis***
- The key indicators are **gram-negative bacilli**, **lactose-negative**, **indole-negative**, and the ability to **hydrolyze urea** to produce ammonia, which are classic characteristics of *Proteus mirabilis*.
- This bacterium is a common cause of **urinary tract infections (UTIs)**, especially those that may be resistant to initial empirical antibiotic therapy.
- The strong **urease activity** produces ammonia, which alkalinizes urine and can lead to **struvite stone formation**.
*Enterobacter cloacae*
- While *Enterobacter cloacae* is a **gram-negative bacillus** and can cause UTIs, it is typically **lactose-fermenting** and **indole-negative**.
- Its biochemical profile does not match the described **lactose-negative** result, though the indole test would match.
*Klebsiella pneumoniae*
- *Klebsiella pneumoniae* are **gram-negative bacilli** and common causes of UTIs, but they are typically **lactose-fermenting** and **indole-negative**.
- The given culture report explicitly states the organism is **lactose-negative**, ruling out *Klebsiella pneumoniae*.
*Escherichia coli*
- *Escherichia coli* is the most common cause of UTIs, and it is a **gram-negative bacillus** that is **lactose-fermenting** and typically **indole-positive**.
- The culture report indicates the organism is **lactose-negative** and **indole-negative**, which is inconsistent with *Escherichia coli*.
*Citrobacter freundii*
- *Citrobacter freundii* is a **gram-negative bacillus** that can cause UTIs and is generally **lactose-fermenting** (though often delayed) and **indole-negative**.
- The reported **lactose-negative** characteristic does not align with the typical biochemical profile of *Citrobacter freundii*, though it shares the indole-negative trait with the cultured organism.
Source identification and control US Medical PG Question 4: A 42-year-old man presents to the emergency department with abdominal pain. The patient was at home watching television when he experienced sudden and severe abdominal pain that prompted him to instantly call emergency medical services. The patient has a past medical history of obesity, smoking, alcoholism, hypertension, and osteoarthritis. His current medications include lisinopril and ibuprofen. His temperature is 98.5°F (36.9°C), blood pressure is 120/97 mmHg, pulse is 130/min, respirations are 22/min, and oxygen saturation is 97% on room air. The patient is in an antalgic position on the stretcher. His abdomen is rigid and demonstrates rebound tenderness and hypoactive bowel sounds. What is the next best step in management?
- A. CT of the abdomen
- B. Urgent laparoscopy
- C. NPO, IV fluids, and analgesics
- D. Urgent laparotomy (Correct Answer)
- E. Abdominal radiograph
Source identification and control Explanation: ***Urgent laparotomy***
- The patient's presentation with **sudden, severe abdominal pain**, a **rigid abdomen**, **rebound tenderness**, and **hypoactive bowel sounds** indicates **acute peritonitis**, most likely from a **perforated viscus**.
- In a patient with **frank peritonitis** and clinical signs of perforation, the diagnosis is **made clinically** based on physical examination findings.
- **Urgent laparotomy** (exploratory surgery) is the definitive management and should not be delayed for imaging when peritonitis is obvious.
- The patient's risk factors (NSAID use, alcoholism) further support peptic ulcer perforation as the likely etiology.
*CT of the abdomen*
- While CT scan is highly sensitive for identifying perforation and can provide anatomic detail, it is **not necessary when the diagnosis of peritonitis is clinically evident**.
- In a patient with **obvious peritonitis**, obtaining a CT scan would **delay definitive surgical treatment** without changing management.
- CT is more appropriate for stable patients with **uncertain diagnosis** or equivocal physical findings, not for those with frank peritonitis.
*Urgent laparoscopy*
- **Laparoscopy** can be used diagnostically and therapeutically in selected cases of abdominal emergencies.
- However, in a patient with diffuse peritonitis and suspected perforation, **laparotomy** is generally preferred over laparoscopy as it provides better exposure, faster source control, and easier peritoneal lavage.
- Laparoscopy may be considered in stable patients with localized findings, but this patient has signs of diffuse peritonitis.
*NPO, IV fluids, and analgesics*
- These are **essential supportive measures** and should be initiated immediately as part of resuscitation.
- However, they are **adjunctive** to definitive surgical management and do not constitute the "next best step" in a patient requiring emergency surgery.
- These measures should be initiated concurrently while preparing for urgent laparotomy.
*Abdominal radiograph*
- An **upright chest X-ray** or **abdominal radiograph** can show **free air under the diaphragm** (pneumoperitoneum) in cases of perforation.
- However, it is **only 50-70% sensitive**, meaning it misses many perforations.
- In a patient with **clinical peritonitis**, the absence of free air on X-ray does **not rule out perforation** and should not delay surgery.
- Imaging should not delay surgical intervention when peritonitis is clinically evident.
Source identification and control US Medical PG Question 5: A 62-year-old man is brought to the emergency department with fatigue, dry cough, and shortness of breath for 3 days. He reports a slight fever and has also had 3 episodes of watery diarrhea earlier that morning. Last week, he attended a business meeting at a hotel and notes some of his coworkers have also become sick. He has a history of hypertension and hyperlipidemia. He takes atorvastatin, hydrochlorothiazide, and lisinopril. He appears in mild distress. His temperature is 102.1°F (38.9°C), pulse is 56/min, respirations are 16/min, and blood pressure is 150/85 mm Hg. Diffuse crackles are heard in the thorax. Examination shows a soft and nontender abdomen. Laboratory studies show:
Hemoglobin 13.5 g/dL
Leukocyte count 15,000/mm3
Platelet count 130,000/mm3
Serum
Na+ 129 mEq/L
Cl- 100 mEq/L
K+ 4.6 mEq/L
HCO3- 22 mEq/L
Urea nitrogen 14 mg/dL
Creatinine 1.3 mg/dL
An x-ray of the chest shows infiltrates in both lungs. Which of the following is the most appropriate next step in diagnosis?
- A. Urine antigen assay (Correct Answer)
- B. CT Chest
- C. Direct immunofluorescent antibody test
- D. Stool culture
- E. Polymerase chain reaction
Source identification and control Explanation: ***Urine antigen assay***
- This patient presents with **pneumonia symptoms** (low-grade fever, dry cough, dyspnea, bilateral infiltrates) along with **gastrointestinal symptoms** (watery diarrhea) and **hyponatremia**, after attending a hotel meeting with other sick attendees. These are classic features of **Legionnaires' disease**.
- A **urine antigen assay** is a rapid and highly specific test for **Legionella pneumophila serogroup 1**, which causes the majority of Legionnaires' disease cases.
*CT Chest*
- A CT scan of the chest would provide more detailed imaging of the lung infiltrates but is typically used to characterize findings once pneumonia is diagnosed or to rule out other lung pathologies, not as an initial diagnostic test for the specific pathogen.
- While it can reveal characteristic patterns, it doesn't identify the causative organism and is not the most appropriate *next step in diagnosis* for a presumed Legionella infection.
*Direct immunofluorescent antibody test*
- A **direct immunofluorescent antibody (DFA) test** is used to identify legionella in respiratory secretions. However, collecting a sufficiently good sputum sample can be difficult, especially with a **dry cough**.
- Its sensitivity is lower than urine antigen testing for serogroup 1 and requires a respiratory sample, making it less convenient for initial diagnosis.
*Stool culture*
- While the patient has diarrhea, a **stool culture** would primarily detect typical bacterial enteric pathogens (e.g., Salmonella, Shigella, Campylobacter) and would not identify **Legionella**.
- The diarrhea, in this context, is likely an extrapulmonary manifestation of Legionnaires' disease caused by Legionella, not a separate primary enteric infection.
*Polymerase chain reaction*
- **PCR testing** can detect Legionella DNA in respiratory samples, offering high sensitivity and specificity.
- However, it is generally less rapid and widely available than the urine antigen test for initial diagnosis of Legionella pneumophila serogroup 1, which is the most common cause of Legionnaires' disease.
Source identification and control US Medical PG Question 6: A 68-year-old man presents to the emergency department with left lower quadrant abdominal pain and fever for 1 day. He states during this time frame he has had weight loss and a decreased appetite. The patient had surgery for a ruptured Achilles tendon 1 month ago and is still recovering but is otherwise generally healthy. His temperature is 102°F (38.9°C), blood pressure is 154/94 mmHg, pulse is 90/min, respirations are 15/min, and oxygen saturation is 98% on room air. Physical exam is remarkable for an uncomfortable and thin man with left lower quadrant abdominal tenderness without rebound findings. Fecal occult test for blood is positive. Laboratory studies are ordered as seen below.
Hemoglobin: 10 g/dL
Hematocrit: 30%
Leukocyte count: 3,500/mm^3 with normal differential
Platelet count: 157,000/mm^3
Which of the following is the most appropriate next step in management?
- A. Ceftriaxone and metronidazole
- B. Ciprofloxacin and metronidazole
- C. Colonoscopy
- D. CT abdomen (Correct Answer)
- E. MRI abdomen
Source identification and control Explanation: ***CT abdomen***
- A **CT scan of the abdomen and pelvis** is the most appropriate initial diagnostic step for acute left lower quadrant pain with fever, leukopenia, and a positive fecal occult blood test, as it can efficiently evaluate for **diverticulitis**, bowel perforation, or **colonic malignancy**.
- The patient's presentation with constitutional symptoms like **weight loss and decreased appetite** in an older male, along with signs of anemia and occult blood, raises concern for **colorectal cancer**, making imaging a critical next step to differentiate potential etiologies.
*Ceftriaxone and metronidazole*
- While this is a common antibiotic regimen for suspected **diverticulitis**, it should not be initiated without definitive imaging, especially given the patient's concerning systemic symptoms and signs of **anemia and occult bleeding**, which could indicate a more serious underlying condition.
- Empirical antibiotic therapy without a clear diagnosis could delay the identification of conditions like **colorectal cancer** or abscess, which require different management strategies.
*Ciprofloxacin and metronidazole*
- This is also a typical antibiotic combination for uncomplicated **diverticulitis**; however, giving antibiotics without confirmation of the diagnosis via imaging is inappropriate in this case due to the patient's **systemic symptoms** and signs of **GI bleeding**.
- Without imaging to rule out intestinal perforation or malignancy, starting antibiotics could mask symptoms or delay crucial diagnostic and therapeutic interventions.
*Colonoscopy*
- A **colonoscopy** is indicated to investigate the **positive fecal occult blood** and rule out colorectal malignancy, but it is generally *contraindicated* in the acute setting of suspected diverticulitis due to the risk of **perforation**.
- Imaging (like CT) should always precede colonoscopy when acute abdominal pain and inflammation are present to assess for safety and guide the timing of endoscopy.
*MRI abdomen*
- While **MRI provides excellent soft tissue delineation**, it is typically not the first-line imaging modality for acute abdominal pain presentations in the emergency department.
- **CT scans are faster, more readily available**, and provide comprehensive imaging of the bowel, mesentery, and surrounding structures, making them superior for initial evaluation of acute abdominal conditions like diverticulitis or perforation.
Source identification and control US Medical PG Question 7: A 55-year-old man, who underwent a kidney transplant 2 years ago, presents in septic shock. He is compliant with his immunosuppressive therapy. He does not use any drugs and is sexually active with one male partner. His complete blood count returns as follows: Hemoglobin: 13.7 g/dL, white blood cell count: 4000 cells/microliter, platelets 250,000 cells/microliter. Of note, from his differential: neutrophils: 10%, lymphocytes: 45%, and monocytes: 7%. His basic metabolic profile is notable for a creatinine remaining at his baseline of 0.9 mg/dL. The patient is started on broad spectrum antibiotics, but his condition does not improve. Fungal blood cultures are obtained and grow Candida species. Which of the following was the most-likely predisposing factor?
- A. Defective IL-2 receptor
- B. HIV infection
- C. Decreased phagocytic cell count (Correct Answer)
- D. Renal failure
- E. Failure to take suppressive trimethoprim/sulfamethoxazole therapy
Source identification and control Explanation: **Decreased phagocytic cell count**
- The patient's **neutrophil count is 10%** of 4000 WBCs, which is 400 cells/microliter. This profound **neutropenia** is a major risk factor for fungal infections like *Candida*.
- Immunosuppressive therapy post-transplant often suppresses **myeloid cell lines**, leading to a decreased phagocytic cell count and increased susceptibility to opportunistic infections.
*Defective IL-2 receptor*
- A defective **IL-2 receptor** would impair T-cell proliferation and function, predisposing to disseminated viral infections (e.g., CMV, EBV) or specific intracellular bacterial infections, rather than typically *Candida* fungemia.
- While broad immunosuppression occurs, the direct link to *Candida* septic shock with severe neutropenia is less direct than a primary phagocytic defect.
*HIV infection*
- HIV infection causes **CD4+ T-cell depletion**, leading to susceptibility to various opportunistic infections, including *Candida* (especially oral/esophageal). However, the patient's lymphocyte count (45%) is not critically low, and the primary issue here is severe neutropenia, which HIV does not directly cause to this extent.
- The patient also reports being sexually active with one male partner but does not use drugs and the complete blood count (CBC) does not show direct signs of HIV-related immune deficiency such as extremely low lymphocyte counts.
*Renal failure*
- The patient's **creatinine is at baseline (0.9 mg/dL)**, indicating that his transplanted kidney is functioning well and he is not in renal failure.
- While chronic kidney disease can cause some immune dysfunction, acute renal failure is not present and cannot be the predisposing factor here.
*Failure to take suppressive trimethoprim/sulfamethoxazole therapy*
- **Trimethoprim/sulfamethoxazole (TMP/SMX)** is primarily prophylactic against *Pneumocystis jirovecii* pneumonia and certain bacterial infections, not typically systemic fungal infections like *Candida* septicemia.
- Although broad-spectrum, its main role is not preventing disseminated candidemia, especially in a severely neutropenic patient.
Source identification and control US Medical PG Question 8: A 27-year-old man presents to the emergency department with weakness and a fever for the past week. The patient is homeless and has a past medical history of alcohol and IV drug abuse. His temperature is 102°F (38.9°C), blood pressure is 107/68 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for a tremulous patient with antecubital scars and a murmur over the left lower sternal border. Blood cultures are drawn and the patient is started on vancomycin and ceftriaxone and is admitted to the ICU. The patient's fever and symptoms do not improve despite antibiotic therapy for which the initial identified organism is susceptible. Cultures currently reveal MRSA as one of the infective organisms. Which of the following is the best next step in management?
- A. Transesophageal echocardiography (Correct Answer)
- B. Obtain new blood cultures
- C. CT scan of the chest
- D. Nafcillin and piperacillin-tazobactam
- E. Vancomycin and gentamicin
Source identification and control Explanation: ***Transesophageal echocardiography***
- The patient's history of **IV drug abuse**, **fever**, **new murmur**, and identification of **MRSA** strongly suggest **infective endocarditis**.
- A Transesophageal echocardiography (TEE) is the **most sensitive and specific imaging modality** to detect vegetations, abscesses, or valvular damage, which is crucial for guiding further management.
*Obtain new blood cultures*
- While repeating blood cultures can be useful to confirm eradication or identify new pathogens, the initial blood cultures already revealed MRSA, which is a common cause of **endocarditis in IV drug users**.
- The immediate priority given the lack of improvement and high suspicion of endocarditis is to visualize the heart valves for vegetations.
*CT scan of the chest*
- A CT scan of the chest would be useful to look for complications such as **septic emboli in the lungs** or other pulmonary pathologies.
- However, it would not provide the detailed visualization of heart valves necessary to diagnose or rule out valvular vegetations characteristic of endocarditis.
*Nafcillin and piperacillin-tazobactam*
- **Nafcillin** is active against **methicillin-susceptible Staphylococcus aureus (MSSA)**, but the patient's cultures already identified **MRSA**.
- **Piperacillin-tazobactam** is a broad-spectrum antibiotic but not a first-line treatment for MRSA infections and would not be appropriate given the identified pathogen.
*Vancomycin and gentamicin*
- The patient is already on **Vancomycin**, which is appropriate for MRSA, but adding **gentamicin** without clear indication would not be the best next step.
- While gentamicin is sometimes used as an adjunct in specific endocarditis regimens (e.g., enterococcal), the primary concern here is the lack of clinical improvement despite appropriate MRSA coverage, pointing towards a structural cardiac issue.
Source identification and control US Medical PG Question 9: A 38-year-old previously healthy woman develops septic shock from necrotizing fasciitis of the lower extremity. Despite three debridements, broad-spectrum antibiotics (vancomycin, meropenem, clindamycin), IVIG, and aggressive critical care support, she develops refractory shock requiring norepinephrine 1.2 mcg/kg/min, vasopressin 0.04 units/min, and epinephrine 0.1 mcg/kg/min. Lactate is 15 mmol/L. Surgical team recommends hemipelvectomy as last option for source control. Family is devastated. ICU team notes SOFA score of 18. Synthesize an approach to management and decision-making.
- A. Transfer to ECMO center for consideration of VA-ECMO as bridge to hemipelvectomy
- B. Multidisciplinary meeting with surgery, ICU, palliative care, and family to discuss realistic outcomes, quality of life, and patient values before decision (Correct Answer)
- C. Continue medical management for 24 hours and proceed with hemipelvectomy only if shock improves
- D. Decline surgery based on futility given SOFA score >15 and initiate comfort care
- E. Proceed with hemipelvectomy immediately as only chance for survival with informed consent from family
Source identification and control Explanation: ***Multidisciplinary meeting with surgery, ICU, palliative care, and family to discuss realistic outcomes, quality of life, and patient values before decision***
- In high-acuity cases with refractory shock and high **SOFA scores (>15)**, shared decision-making is essential to align surgical intervention with the patient’s **goals of care**.
- This approach ensures that the **prognosis**, which carries a high risk of mortality and morbidity from **hemipelvectomy**, is transparently communicated by the entire medical team.
*Transfer to ECMO center for consideration of VA-ECMO as bridge to hemipelvectomy*
- **VA-ECMO** is generally not indicated in septic shock with refractory vasoplegia and severe multi-organ failure as it doesn't solve the **source control** issue.
- The logistics and physiological stress of a transfer in the setting of **1.2 mcg/kg/min norepinephrine** would be highly unstable and likely fatal.
*Continue medical management for 24 hours and proceed with hemipelvectomy only if shock improves*
- Delaying source control in **necrotizing fasciitis** while shock is worsening usually leads to death, as medical management alone cannot overcome the focus of infection.
- Waiting for improvement in the setting of a **lactate of 15 mmol/L** and triple vasopressors is unrealistic without definitive surgical intervention.
*Decline surgery based on futility given SOFA score >15 and initiate comfort care*
- While the **SOFA score** indicates a very high mortality risk, unilateral physician declaration of **medical futility** is ethically complex and can damage family trust.
- Comfort care should remain a possibility, but first requires a thorough **interdisciplinary discussion** to ensure legal and ethical standards are met.
*Proceed with hemipelvectomy immediately as only chance for survival with informed consent from family*
- Performing such a **mutilating surgery** without a detailed discussion of the expected **quality of life** and long-term functional loss is poor surgical practice.
- Immediate surgery without addressing the massive **operative mortality** risk ignores the patient's potential preference for a dignified death over a futile procedure.
Source identification and control US Medical PG Question 10: A 52-year-old woman with septic shock from intra-abdominal infection undergoes emergency exploratory laparotomy for perforated diverticulitis with fecal peritonitis. Surgery reveals extensive contamination requiring damage control approach. Postoperatively, she requires norepinephrine 0.8 mcg/kg/min plus vasopressin 0.04 units/min, has lactate of 8.5 mmol/L, temperature 35.2°C, INR 2.8, pH 7.18, and base deficit -12. Planned return to OR is in 48 hours. Evaluate the priority interventions to optimize outcome.
- A. Immediate return to OR for definitive repair and anastomosis
- B. Start therapeutic hypothermia and delay reoperation until hemodynamically stable off vasopressors
- C. Initiate high-dose vasopressors to maintain MAP >75 mmHg and early enteral nutrition
- D. Administer massive transfusion protocol and emergency re-exploration within 6 hours
- E. Aggressive rewarming, correction of coagulopathy, ongoing resuscitation, and source control at planned reoperation (Correct Answer)
Source identification and control Explanation: ***Aggressive rewarming, correction of coagulopathy, ongoing resuscitation, and source control at planned reoperation***
- This patient presents with the **lethal triad** (coagulopathy, acidosis, and hypothermia) in the setting of **septic shock**, necessitating physiologic stabilization before definitive surgery.
- The gold standard for **damage control** is to stabilize the patient in the ICU by correcting **base deficit**, improving **lactate clearance**, and restoring normal temperature and coagulation parameters.
*Immediate return to OR for definitive repair and anastomosis*
- Attempting **definitive repair** or anastomosis in an unstable patient with fecal peritonitis and high-dose **vasopressor requirements** carries a prohibited risk of dehiscence and death.
- Surgery should be limited to **staged re-intervention** only after the metabolic and physiologic insults have been partially reversed.
*Start therapeutic hypothermia and delay reoperation until hemodynamically stable off vasopressors*
- **Hypothermia** is a component of the lethal triad that worsens **coagulopathy** by inhibiting the clotting cascade; metabolic rewarming is required, not cooling.
- While stability is the goal, waiting to be completely off vasopressors might dangerously delay **source control** if the infection is driving the shock.
*Initiate high-dose vasopressors to maintain MAP >75 mmHg and early enteral nutrition*
- Focus should be on **volume resuscitation** and reversing tissue hypoxia (lactate) rather than solely escalating vasopressors, which can cause **mesenteric ischemia**.
- **Early enteral nutrition** is contraindicated in the immediate postoperative phase of an open abdomen with significant **hemodynamic instability** and high pressor requirements.
*Administer massive transfusion protocol and emergency re-exploration within 6 hours*
- **Massive transfusion protocol** is typically reserved for active, uncontrolled hemorrhage, whereas this patient primarily requires reversal of **septic shock** and metabolic derangements.
- **Re-exploration within 6 hours** is too early for a damage control patient who has not yet been adequately rewarmed or had their **acidosis** corrected.
More Source identification and control US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
