Acute urinary retention is the acute onset of bladder distention with inability to urinate, often accompanied by pain and anxiety due to significant urge to urinate, which severely affects the patient’s quality of life.
Acute urinary retention can be divided into induced AUR and spontaneous AUR. common triggers of AUR include: general or regional anesthesia, excessive fluid intake, overfilling of the bladder, urinary tract infection, prostate inflammation, excessive alcohol consumption, use of sympathomimetic or anticholinergic drugs, etc. Spontaneous AUR often has no obvious trigger.
Etiology
1, obstructive factors: increased resistance to urinary flow due to mechanical obstruction (e.g. urethral stricture, blood clot or stone blockage) or dynamic obstruction (e.g. increased alpha-adrenergic activity, prostatic inflammation).
2, neurogenic factors: bladder sensory or motor nerve damage (e.g. caused by pelvic surgery, multiple sclerosis, spinal cord injury, diabetes mellitus, etc.).
3, Myogenic factors: overfilling of the bladder (e.g., anesthesia, excessive alcohol consumption).
Diagnosis of acute urinary retention
The onset of acute urinary retention is sudden, and the patient’s bladder is distended with urine but cannot be discharged, which is very painful. The causes of acute urinary retention mainly include obstructive, neurogenic and myogenic. Through detailed history questioning and physical examination, together with corresponding laboratory tests and auxiliary examinations, the causes and diagnosis can be clarified and provide a basis for subsequent treatment.
(I) Basic examination
1.History inquiry (recommended)
(1) The presence of lower urinary tract symptoms and their characteristics, duration, and concomitant symptoms.
(2) History of surgery and trauma before the occurrence of acute urinary retention, especially history of trauma and surgery of lower abdomen, pelvis, perineum, rectum, urethra, spine, etc.; history of invasive examination and treatment such as transurethral catheterization, cystourethroscopy, urethral dilatation, etc.
(3) Past history should also pay attention to: past urinary retention, overflow incontinence, hematuria, lower urinary tract infection, urethral stricture, urinary stones, urethral excretion properties such as stones, celiac clots, tissue masses, recent sexual intercourse, abdominal pain or bloating, constipation, blood in stool, shock, diabetes mellitus, neurological diseases, systemic symptoms and other medical history. Male patients should also be asked about any history of prostate enlargement and its International Prostate Symptom Score (IPSS) and Quality of Life Score (QOL), acute prostatitis, and encopresis. Female patients should also pay attention to the history of postpartum urinary retention, presence of pelvic inflammatory disease, pelvic compression diseases such as uterine fibroids and ovarian cysts, pelvic organ prolapse such as uterine prolapse, anterior or posterior vaginal wall prolapse, dysmenorrhea, hymenal atresia, vaginal discharge properties, etc.
(4) Ask for medication history to find out whether the patient is currently or recently taking drugs that affect the function of the bladder and its outlet. The common ones are muscle relaxants such as drugs used for anesthesia during surgery and flavonoid permethrin, M-blockers such as atropine, scopolamine, tolterodine, etc., and alpha agonists such as ephedrine and midodrine hydrochloride. Other drugs such as antidepressants, antihistamines, antipyretics, antiarrhythmics, antihypertensives, opioid analgesics, mercurial diuretics, etc. can also cause urinary retention.
2.Physical examination (recommended)
(1) General examination: including body temperature, pulse, respiration, blood pressure and other vital signs, paying attention to the mental status, development, nutritional status, gait, posture, and the presence of anemia or swelling.
(2) Local and genitourinary system examination.
Visual examination: except for particularly obese patients, overinflated bladder can mostly be seen in the suprapubic area; some patients can see overflow incontinence and narrowing of the external urethra; some can also see eczema, bleeding, hematoma or bruising, swelling, and surgical scars in and around the perineum, external genitalia, or urethral orifice. In addition, male patients can be seen with prepuce or foreskin impaction, narrow circumcision, and female patients can have pelvic organ prolapse, hymenal atresia, etc.
Palpation: A distended bladder can be palpated in the suprapubic region of the lower abdomen, and there is pain and a sense of urinary urgency with pressure, except for some neurogenic bladders. Long-term chronic posterior renal obstruction may lead to severe hydronephrosis of the diseased kidney, and an enlarged kidney may be palpated under the rib cage. Urethral stones or scars in the body of the penis may also be palpable. Urethral or vaginal masses may also be palpable. Other abdominal masses should be noted. For example, the nature of the lower abdominal and pelvic masses and their possible origin should be screened, such as giant bladder tumors, intestinal tumors, uterine fibroids, ovarian cysts, etc., and double palpation should be performed if necessary. Note the fecal masses.
Auscultation: A distended bladder sounds turbid on percussion in the suprapubic area and can sometimes distend to the level of the umbilicus. Mobile turbid sounds can determine the presence or absence of ascites and should be performed after emptying the bladder of urine.
(3) Rectal palpation: It is best performed after the bladder is emptied. Rectal palpation can understand the condition of anal sphincter tone, anal canal sensation, random contraction of pelvic muscles, etc., and the presence of tumors or fecal masses in the rectum. For male patients, it can also find out whether there is prostate hyperplasia, prostate cancer, prostate abscess, etc.
(4) Neurological examination.
Urinary activity is regulated by the nervous system, involving central nerves above the brainstem, spinal cord centers, peripheral vegetative and trunk nerves, bladder and urethral nerve receptors and transmitters, etc. Therefore, a thorough neurological examination can help to distinguish the presence or absence of combined neurogenic bladder. Clinical examination of the plantar reflex, ankle reflex, testicular reflex, bulbocavernosus reflex, anal reflex, abdominal wall reflex, saddle area and lower extremity sensation, and lower extremity movement are often performed, with the assistance of a neurologist if necessary.
3.Urinary routine (recommended)
Routine urinalysis can find out whether the patient has hematuria, pusuria, proteinuria and urine sugar, etc.
4.Ultrasound examination (recommended)
Transabdominal ultrasonography can find out whether there is fluid or dilatation in the urinary system, stones, occupying lesions, etc. In male patients, the shape and size of the prostate gland, the presence of abnormal echogenicity, and the degree of protrusion into the bladder can be found. It is also possible to understand other lesions outside the urinary system such as uterine fibroids and ovarian cysts. In addition, ultrasound residual urine volume determination is feasible after the patient’s acute urinary retention is relieved and he/she can urinate on his/her own.
(B) Depending on the results of the initial evaluation, some patients need further tests
1. Renal function (optional)
Because bladder outlet obstruction can cause hydronephrosis, ureteral dilatation reflux, etc., which eventually leads to renal function impairment and elevated blood creatinine, it is recommended to choose this test when renal insufficiency is suspected.
2.Glucose (optional)
Diabetic peripheral neuropathy can lead to diabetic bladder. Blood glucose, especially fasting blood glucose test, can help to clarify the diagnosis of diabetes.
3.Blood electrolytes (optional)
Hypokalemia and hyponatremia can also lead to urinary retention, so this test is recommended for those suspected of having electrolyte disorders.
4. Serum PSA (optional)
Prostate cancer, prostate enlargement, and prostatitis may all increase serum PSA. Acute urinary retention, indwelling catheterization, urinary tract infection, prostate puncture, rectal palpation and prostate massage can also affect the determination of serum PSA value.
5. Urinary diary (optional)
After the acute urinary retention is relieved and the patient can urinate on his own, if the patient’s lower urinary tract symptoms are the main clinical manifestation, recording the urinary diary for 3 consecutive days can help to understand the patient’s urinary situation and is also helpful for the identification of nocturia.
6.Urinary flow rate examination (optional)
The maximum urinary flow rate (Qmax) is the most important, but Qmax reduction cannot distinguish between obstruction and reduced contraction of the detrusor muscle, so it should be combined with other examinations and urodynamic examination if necessary; Qmax is more accurate when the urine volume is 150-200ml, and the examination can be repeated if necessary.
7.Urodynamic examination (optional)
This test is recommended when there is doubt about the cause of bladder outlet obstruction or when bladder function needs to be evaluated, combined with other relevant tests to exclude the possibility of neurological pathology or neurogenic bladder due to diabetes mellitus.
8.Urethral cystoscopy (optional)
This test is recommended for suspected urethral strictures, bladder urethral calculi, and intravesical occupational lesions.
9.Urethrography (optional)
This test is recommended when urethral stricture is suspected.
10.Computerized tomography (CT) and magnetic resonance imaging (MRI) (optional)
CT or MRI is an important addition when the nature of the lower abdominal or pelvic mass is not clear on ultrasound. When neurogenic bladder is suspected
CT or MRI is helpful to clarify central nervous system such as brain or spinal cord lesions.