A 37-year-old woman presents with an inability to void in the hours after giving birth to her first child via vaginal delivery. Her delivery involved the use of epidural anesthesia as well as pelvic trauma from the use of forceps. She is currently experiencing urinary leakage and complains of increased lower abdominal pressure. Which of the following is the most appropriate treatment for this patient’s condition?

Pelvic floor muscle strengthening

A 65-year-old man is brought to the emergency department by ambulance after falling during a hiking trip. He was hiking with friends when he fell off a 3 story ledge and was not able to be rescued until 6 hours after the accident. On arrival, he is found to have multiple lacerations as well as a pelvic fracture. His past medical history is significant for diabetes and benign prostatic hyperplasia, for which he takes metformin and prazosin respectively. Furthermore, he has a family history of autoimmune diseases. Selected lab results are shown below: Serum: Na+: 135 mEq/L Creatinine: 1.5 mg/dL Blood urea nitrogen: 37 mg/dL Urine: Na+: 13.5 mEq/L Creatinine: 18 mg/dL Osmolality: 580 mOsm/kg Which of the following is the most likely cause of this patient's increased creatinine level?

Compression of urethra by prostate

A 65-year-old woman comes to the physician for the evaluation of several episodes of urinary incontinence over the past several months. She reports that she was not able to get to the bathroom in time. During the past 6 months, her husband has noticed that she is starting to forget important appointments and family meetings. She has type 2 diabetes mellitus treated with metformin. The patient had smoked a pack of cigarettes daily for 45 years. Her vital signs are within normal limits. On mental status examination, she is confused and has short-term memory deficits. She walks slowly taking short, wide steps. Muscle strength is normal. Deep tendon reflexes are 2+ bilaterally. Which of the following is the most likely underlying cause of this patient's urinary incontinence?

Bacterial infection of the urinary tract

Impaired detrusor contractility

A 72-year-old multiparous woman comes to the physician for the evaluation of episodes of involuntary urine leakage for the past 6 months. She loses small amounts of urine without warning after laughing or sneezing. She also sometimes forgets the names of her grandchildren and friends. She is retired and lives at an assisted-living facility. She has insulin-dependent diabetes mellitus type 2. Her mother received a ventriculoperitoneal shunt around her age. She walks without any problems. Sensation to pinprick and light touch is normal. Which of the following is the primary underlying etiology for this patient's urinary incontinence?

Decreased cerebrospinal fluid absorption

Impaired detrusor contractility

A 40-year-old woman was admitted to the surgical service after an uncomplicated appendectomy. She underwent surgery yesterday and had an uneventful postoperative course. However, she now complains that she is unable to completely void. She also complains of pain in the suprapubic area. You examine her and confirm the tenderness and fullness in the suprapubic region. You ask the nurse to perform a bladder scan, which reveals 450cc. What is the next appropriate step in management?

Neostigmine methylsulfate injection

Intravenous neostigmine methylsulfate

A 67-year-old man presents to the emergency department with trouble urinating. The patient states that in general he has had difficulty urinating but recently, it has taken significant effort for him to initiate a urinary stream. He finds himself unable to completely void and states he has suprapubic tenderness as a result. These symptoms started suddenly 3 days ago. The patient has a history of benign prostatic hyperplasia, constipation, and diabetes mellitus. His current medications include finasteride, sodium docusate, and hydrochlorothiazide. He recently started taking phenylephrine for seasonal allergies. The patient’s last bowel movement was 2 days ago. His temperature is 99.0°F (37.2°C), blood pressure is 167/98 mmHg, pulse is 90/min, respirations are 14/min, and oxygen saturation is 100% on room air. Physical exam is notable for suprapubic tenderness, and an ultrasound reveals 750 mL of fluid in the bladder. Which of the following is the most likely etiology of this patient’s symptoms?

Worsening benign prostatic hypertrophy

A 59-year-old man comes to the physician because of a 3-month history of frequent urination. He has to urinate every 1–2 hours during the day and wakes up at least 2–3 times at night to urinate. He also reports that over the last 2 months, he has difficulty initiating micturition and the urinary stream is weak, with prolonged terminal dribbling. His pulse is 72/min, and blood pressure is 158/105 mm Hg. Rectal exam shows a smooth, symmetrically enlarged prostate without any tenderness or irregularities. Prostate-specific antigen is within the reference range and urinalysis shows no abnormalities. A postvoid ultrasound shows a residual bladder volume of 110 mL. Which of the following is the most appropriate next step in management?

Transurethral resection of the prostate

A 65-year-old African American man presents for follow-up examination with a 6-month history of urinary hesitancy, weak stream, and terminal dribbling, which is refractory to a combination therapy of finasteride and tamsulosin. The patient’s past medical history is otherwise unremarkable. His father and brother were diagnosed with prostate cancer at the age of 55 years. His vital signs are within normal limits. The patient has a normal anal sphincter tone and a bulbocavernosus muscle reflex. Digital rectal exam (DRE) reveals a prostate size equivalent to 2 finger pads with a hard nodule and without fluctuance or tenderness. Serum prostate-specific antigen (PSA) level is 5 ng/mL. Which of the following investigations is most likely to establish a definitive diagnosis?

Magnetic resonance imaging (MRI)

Urinary retention management — USMLE Lesson

🧱 Core concept & Pathophysiology - The Blocked Dam

Inability to voluntarily void, leading to ↑ post-void residual (PVR).

Acute: Painful inability to void.
Chronic: Painless; may present with overflow incontinence.

Two Core Mechanisms:

Bladder Outlet Obstruction (BOO): A physical blockage.
- Most Common: Benign Prostatic Hyperplasia (BPH) in men.
- Others: Urethral strictures, stones, malignancy.
Detrusor Underactivity (DU): Impaired bladder contractility.
- Neurogenic: Spinal cord injury, MS, diabetic neuropathy.
- Pharmacologic: Anticholinergics, opioids.
- Myogenic: Chronic overdistension injury.

⭐ Post-Operative Urinary Retention (POUR) is common. Anesthesia and opioids impair detrusor contractility and bladder sensation.

Bladder outlet obstruction from benign prostatic hyperplasia

📌 Mnemonic (DAMN): Drugs, Anatomic, Myogenic, Neurogenic.

🩺 Diagnosis - Finding the Fault

Presentation: Patient reports acute inability to void, severe suprapubic pain, and restlessness, sometimes with overflow incontinence. Physical exam reveals a palpable, firm, suprapubic mass (the bladder) that is dull to percussion.
Diagnostic Flow:

Workup:
- Catheterization: Confirms diagnosis, measures PVR, and provides immediate relief.
- Labs: Check BUN/Cr for post-renal AKI. Urinalysis to rule out UTI.
- DRE: Essential to evaluate for BPH, prostate cancer, or fecal impaction.

⭐ A post-void residual (PVR) >200 mL is diagnostic. Acute retention often involves volumes >500 mL, risking post-obstructive diuresis after decompression.

🌊 Management - Releasing the Floodgates

Immediate Goal: Prompt bladder decompression to prevent renal damage and provide relief.

1st Line: Urethral (Foley) catheter.
- Use a coudé tip catheter for suspected BPH.
2nd Line: Suprapubic catheter if urethral access fails (e.g., stricture, false passage) or is contraindicated (urethral trauma).

Post-Decompression Monitoring:

⚠️ Post-Obstructive Diuresis (POD):
- Definition: Urine output > 200 mL/hr for ≥2 consecutive hours after catheterization.
- Pathophys: Physiologic diuresis of retained fluid/solutes; can become pathologic.
- Action: Monitor vitals, electrolytes (Na+, K+), and volume status. Replace fluids if hypotensive.

Long-Term Strategy:

Address the underlying cause (e.g., stop anticholinergics, treat BPH).
Plan for a Trial Without Catheter (TWOC).

⭐ High-Yield Pearl: For BPH-induced retention, start an alpha-1 blocker (e.g., tamsulosin) 1-3 days before attempting a TWOC to maximize success by relaxing the bladder neck and prostatic smooth muscle.

💥 Complications - The Aftermath

Post-Obstructive Diuresis (POD):
- Massive polyuria (>200 mL/hr) after decompression.
- Risks: Dehydration, hypotension, electrolyte loss (↓Na⁺, ↓K⁺).
Hydronephrosis & Renal Damage:
- ↑ back-pressure → renal pelvis dilation → AKI/CKD.
Infection & Sepsis:
- Urine stasis promotes bacterial growth (UTI, pyelonephritis).
Bladder Atony:
- Chronic overdistension damages detrusor muscle, causing poor contractility.

Hydronephrosis: Ultrasound & Diagrammatic Progression

⭐ Post-obstructive diuresis is a physiologic response to excrete retained fluid/solutes. Monitor urine output closely; pathologic diuresis may require IV fluid replacement.

⚡ Biggest Takeaways

Immediate management is bladder decompression via Foley or suprapubic catheter.

Always monitor for post-obstructive diuresis (POD) (>200 mL/hr); manage with IV fluids.

Benign Prostatic Hyperplasia (BPH) is the most common cause in men; initiate alpha-blockers (e.g., tamsulosin).

Acute retention is painful; chronic retention is often painless with overflow incontinence.

After stabilization, perform a Trial Without Catheter (TWOC), especially after starting BPH meds.

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