Doc I Can’t Pee, What Could It Be? Evaluation and Management of Acute Urinary Retention in the Emergency Department
- Mar 1st, 2017
- Candace Johnson
Author: Candace Johnson, MD (EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) and Brit Long, MD (@long_brit)
There are few more welcome sights on a busy ED shift than an apparent “slam dunk” chief complaint. The 65 y/o male with inability to urinate, lower abdominal pain, and a palpable bladder on exam may seem like such a case. If the patient’s retention is a result of the most common cause of acute urinary retention (AUR), an enlarged prostate, the work-up and disposition are simple. Assess for infection, place Foley catheter, initiate alpha blocking therapy, and discharge with follow-up to Urology. However, the picture becomes more complex when the patient is young, female, febrile, or post-prostatectomy. Even the classic 65 y/o male may be hiding additional pathology behind his larger than average prostate gland. To ensure appropriate management, it is important that a detailed history and a thorough physical exam are conducted to develop a differential that includes some of the less common causes of acute urinary retention. This post will evaluate what you cannot miss in the patient who presents with urinary retention.
There are numerous causes that lead to acute urinary retention. Its pathophysiology typically falls under the category of obstructive, inflammatory, infectious, neurologic, or pharmacologic related causes1. The follow-up and treatment plan varies depending upon the underlying cause. In all cases, prompt and complete decompression of the bladder, commonly with a Foley catheter, is critical to reducing discomfort and long term morbidity for the patient. Now, let’s get started with the evaluation and management of acute urinary obstruction.
The process of micturition requires the coordinated efforts of sympathetic, parasympathetic, and somatic nervous systems. The two functions of the bladder, storage and voiding, are regulated by norepinephrine and acetylcholine, respectively. The sympathetic nervous system stemming from T10-L2 facilitates storage of urine by release of norepinephrine onto beta receptors on the bladder wall (detrusor muscle) and onto alpha receptors that act to constrict the internal sphincter of the bladder. The parasympathetic nervous system conversely releases acetylcholine which acts to relax the bladders internal sphincter and contract the detrusor muscle of the bladder for the purpose of voiding.2 Somatic innervation along the pudendal nerves in S2-S4 provide sensory information of bladder distention to cortical centers in the brain, that regulate the processes. Any disruption of the signaling in the somatic, sympathetic or parasympathetic pathways can inhibit synchronized actions necessary for voiding.3 Over time decreased ability to void despite a full bladder, whether from a physical obstruction or chemical or neural inhibitor, leads to deconditioning of the detrusor muscle of the bladder and decreased ability to perform voiding functions, despite appropriate signaling.3
Essential H&P for AUR
A thorough history is helpful in identifying the underlying cause of urinary retention. Some necessary questions include a detailed medication history, both prescribed and over the counter. Use of recreational drugs should be discussed. The presence of pain as well as the duration and location of the pain is telling in cases of obstruction. Weight loss or presence of fever is helpful in determining underlying malignancy or infection. History of gynecologic or urologic procedures in the past should be elicited. The presence of incontinence, nocturia, and urinary frequency should be discussed as well. The information discussed will assist in narrowing down the broad differential that should be considered in a patient with urinary retention.
Physical exam should include a rectal exam and genital exam in both men and women. Saddle anesthesia or decreased rectal tone may point to a neurologic cause of retention. A tender prostate on DRE may suggest prostatitis, and phimosis is a less common but important obstructive pathology in men. The most common cause of urinary retention in women is uterine prolapse which may go unnoticed without a bimanual exam. The bladder should be palpated for masses. Tenderness in the flanks may suggest obstructive lesions proximal to the bladder in both sexes, while lesions distal to the bladder may cause tenderness to palpation of the scrotum in men.
Below are some of the common causes of AUR that should be considered while eliciting a history and performing a physical exam to evaluate acute urinary retention:
Common Causes of Acute Urinary Retention3
-Benign prostatic hypertrophy
-Neoplasm of the bladder
-Urethral foreign body
Now that a good exam has been completed and a differential formed, lab studies and imaging can help further characterize the origin and severity of retention. Urine should be examined for infectious cells, hematuria or gross blood with clots, large amounts of glucose that may point to poorly controlled diabetes, and more. Renal ultrasound is important in determining if an obstructive process has led to hydronephrosis, and CT of the renal collecting system may also be necessary to assess for tumor, metastasis, stranding to indicate infection, presence of prolapse, or other gynecologic pathology. Labs should include Basic Metabolic panel to evaluate renal function through BUN: Creatinine ratio and electrolyte abnormalities that may be associated with drug use or cancers. CBC can be helpful in evaluation for infection and in cases where hemorrhagic cystitis or other causes of bleeding are discovered.
Now we will discuss a few cases to examine the various causes of acute urinary retention and its management.
A 70 y/o male with history of hypertension and benign prostatic hypertrophy (BPH) presents with inability to void x 6hrs. Bedside ultrasound shows 500 cc of urine in the distended bladder.
Obstructive causes of AUR are either intrinsic (prostatic hypertrophy, bladder mass, cystolith) or extrinsic (uterine prolapse, pelvic mass, severe constipation). Age is the greatest risk factor for retention in males. 1 in 10 men in their 70’s will have an episode of AUR, and incidence continues to increase with age.4 Emergency physicians must be careful to avoid anchoring bias when treating patients with known BPH. The affected population are at increased risk for missed diagnosis because of their likelihood to have co-morbid chronic conditions or undiagnosed malignancy in addition to BPH. Despite BPH being the most common cause for AUR, comorbidities and alternatives should be considered in the differential diagnosis.
In cases of BPH obstruction, attempts should be made to decompress the bladder with a transurethral Foley or coude catheter. In uncircumcised men it is important to retract the foreskin after placement of the foley catheter. If foreskin is not retracted, paraphimosis may develop. After Foley catheter placement, most patients without other issues may be discharged with Urology follow-up in 3 days. For a prior post on Foley catheter issues, see http:// www.emdocs.net/foley-catheter-patients-common-ed-presentations-management-pearls-pitfalls/.
Studies show that initiation of an alpha reductase inhibitor like Finasteride or alpha receptor antagonist like tamsulosin at the time of the catheter placement increases the chance of a successful trial of voiding when the catheter is removed at follow-up.5 Finasteride is typically given in doses of 5 mg daily, with tamsulosin given in doses of 0.4-0.8 mg daily. Urinalysis should be obtained and antibiotics given only if acute cystitis is suspected.
In women, obstructive causes are typically from an intrauterine source. Vaginal prolapse in an elderly woman, uterine entrapment in a pregnant woman, and gynecologic tumor in women of various ages are potential sources. Pelvic exam is helpful in identifying these diagnoses and should be included in the work-up of any woman with AUR. Chronically ill patients and both men and women with severe constipation may also develop AUR due to compression of the bladder neck against hardened stool in the colon.
A 62 y/o woman with poorly controlled Type II diabetes, morbid obesity, and history of total hysterectomy presents with abdominal pain. She is markedly tender to palpation bilaterally below the umbilicus. Labs reveal acute kidney injury. CT-abdomen/pelvis reveals large distended bladder, but is otherwise normal. Foley catheter is placed, and 740cc of cloudy urine is immediately evacuated resulting in relief for the patient.
Neurologic causes of acute urinary retention include diabetic cystopathy, multiple sclerosis, Parkinson’s disease, stroke, cord compression due to lesion, and cord disruption due to trauma. Given the prevalence of diabetes in the population, neurogenic bladder in the diabetic is likely to be encountered in the ED. Studies show up to 25% of patients with diabetes greater than 10 years and greater than 75% of patients with diabetic neuropathy will develop diabetic cystopathy.6 Gradual decrease in sensation, increase in bladder capacity, and weakened contractility lead to retention. Morbidity related to this includes recurrent urinary tract infections that may precipitate DKA, uremia, and chronic kidney disease. In the case of diabetic cystopathy and other non-reversible causes of retention that are secondary to chronic disease, treatment options include: scheduled voiding, cholinergic receptor agonist therapy, and intermittent self-catheterization.7 The cholinergic agonist, Bethanechol improves contractility of bladder smooth muscle and is prescribed in doses of 10-50mg TID or QID. Treatment of the underlying disease process is prudent but unlikely to prevent urologic dysfunction.
A 42 y/o male with a history of depression, stable on Amitriptyline, presents with acute urinary retention. He denies drugs of abuse, but history is significant for recent daily usage of OTC “night time cold and flu med” for recent URI symptoms.
The list of drugs associated with AUR is extensive. Emergency physicians should suspect medication involvement when a patient is taking one or more drugs with anti-cholinergic properties, sympathomimetic, or NSAIDS.3 The medications have direct effect on the tone of the detrusor muscle of the bladder or the sphincter tone. The treatment is to identify and then remove the offending agent. Foley catheter may be placed temporarily until normal bladder function resumes. There is no demonstrated benefit to beginning alpha reductase inhibitor in these patients as the removal of the offending agent will reverse the cause of the retention. Below are a list of medications that are known to be associated with urinary retention:
-Calcium Channel Blockers
A 20 y/o male presents with acute inability to urinate x 8 hrs. Vitals are significant for fever of 101.8 F. He recently traveled to Cancun for spring break. Noted on physical exam is yellow discharge from the urethra.
The most common cause of infectious urinary retention is acute prostatitis.3 In younger men, or men of any age who report unprotected sexual activity, therapy should be targeted toward gonorrhea and chlamydia. Older men who report monogamous or no sexual activity can be treated with routine medications targeting cystitis. If the inflammation is too extensive or patient cannot tolerate passage of foley catheter due to pain, a suprapubic catheter should be placed. Admission for monitoring and IV antibiotics may be considered in these cases.
Not all patients with acute urinary retention are appropriate for discharge. Patients with acute kidney injury as evidenced by serum creatinine increase by 0.5 in a 2 week period or 20% increase in serum creatinine in patients with chronic kidney disease should be considered for admission. Retained urine is at risk for becoming infected. Patients who are stable with cystitis and normal renal function may reasonably discharged after decompression, but patients with pyelonephritis or SIRS criteria should be considered for admission for administration of IV antibiotics.
Patient with a fixed obstruction such as enlarged prostate or pelvic mass should be discharged with a foley catheter and urology follow-up. Patients with drug related, infectious, or other causes may attempt trial of voiding in the ED after decompression and rehydration. If able to void in the ED, they do not require a catheter at discharge but should still be given close follow-up. Evidence for successfully voiding after trial with foley and alpha reductase inhibitors is strong for patients with BPH. Evidence does not support its use in neurologic, diabetic, infectious, or toxicologic retention. Targeting the root cause such as tight blood sugar control, antibiotics targeting infection, or removing the offending medication is the recommended method for successful voiding at follow-up both with and without a catheter trial period.
Take Home Points
– Consider all of the possible causes of acute urinary retention, and avoid prematurely anchoring on BPH, even in men with known BPH.
– If the cause is determined to be BPH, start alpha reductase inhibitor immediately and attempt to arrange 3 day follow up to improve outcomes and reduce complications.
– In addition to trauma, chronic diseases such as diabetes may cause neurogenic bladder. Patients with peripheral neuropathy are at high risk of developing neurogenic bladder.
– Antidepressants, over-the-counter cold medicines, and NSAIDS are common pharmacologic causes of urinary retention.
– Fever and urinary retention in a male should lead to a high suspicion for prostatitis. Treatment should be directed based on risk factors.
1. Marshall, J., Haber, J. An Evidence Based Approach to Emergency Department Management of Acute Urinary Retention. Emergency Medicine Practice. 2014; 16(1):1-24
2. Fowler CJ, Griffiths D, de Groat WC. The neural control of micturition. Nat Rev Neurosci. 2008;9(6):453-46
3. Vilke GM, Ufberg JW, Harrigan RA, et al. Evaluation and treatment of acute urinary retention. J Emerg Med. 2008;35(2):193-198.
4. Selius, B, Subedi, R. Urinary Retention in Adults: Diagnosis and Initial Management. Am Fam Physician. 2008 Mar 1;77(5):643-650.
5. Taube M, Gajraj H. Trial without catheter following acute retention of urine. British Journal of Urology. 1989;63(2):180-182.
6. Sasaki K, Yoshimura N, Chancellor MB. Implications of diabetes mellitus in urology. Urology Clinicians of North America. 2003;30(1):1- 12.
7. Ellenburg M. Development of urinary bladder dysfunction in diabetes mellitus. Annals of Internal Medicine 1980;92(2):321–3.