Clinical Medicine - Nephrology & Genitourinary

Kidneys

regulate blood volume/composition, reguate pH, and produce hormones, excrete waste

Renal corpuscle

glomerulus - filters water and dissolved substances from plasma

glomerulus capsule - receives glomerular filtrate

Renal tubule - proximal convoluted tubule

reabsorbs glucose, amino acids, creatine, acids, and ions by active transport

reabsorbs water by osmosis

reabsorbs chloride and other negative ions by electrochemical attraction

actively secretes penicillin, histamine, creatine, and hydrogen ions

Renal tubule - descending limb of nephron loop

reabsorbs water by osmosis

reabsorbs sodium, potassium, and chloride ions by active transport

Renal tubule - ascending limb of nephron loop

reabsorbs sodium ions by active transport

reabsorbs water by osmosis

secretes hydrogen and potassium ions by electrochemical attraction

Renal tubule - distal convoluted tubule

reabsorbs water by osmosis

Process of urination

visceral sensory fibers relay to the spinal cord (S2-S4) that the bladder wall is stretched

stimulation of parasympathetic nerves causes detrusor muscle to contract and internal urethral sphincter to relax

somatic motor neurons in pudendal nerve causes relaxation of external urethral sphincter and contraction of bulbospongiosus muscles - expels last drops of urine from urethra

What prevents incontinence

mental status

ambulation

physical/muscle issues

outflow issues

Incontinence

involuntary loss of urine or stool in a sufficient amount or frequency which constitutes a social and/or health problem

Is incontinence more common in men/women?

women

Incontinence is related to decreases in

detrusor muscle contractility

maximum bladder capacity

maximum flow rate

ability to withhold voiding with an increase in postvoid residual (PVR)

Complications of urinary incontinence

increased fall risk

nocturia and sleep disruption

hydronephrosis and renal dysfunction from urinary retention

embarrassment/social withdrawal

reduced fluid intake

compromised skin integrity

Types of incontinence

stress - MC

urge

overflow

functional

mixed

Stress incontinence

impaired urethral support from pelvic floor muscle weakness - intrinsic sphincter deficiency

increased intra-abdominal pressure

Urge incontinence

uninhibited bladder contractor due to detrusor hyperactivity

leakage of urine after abrupt urge to void

inability to delay voiding after sensation of bladder fullness is noticed - large or small volume

Overflow incontinence

incomplete emptying due to impaired detrusor contractility, bladder outlet obstruction (BPH or prolapse), or neuropathy

frequent small-volume leakage, weak stream, dribbling, hesitancy, frequency, and nocturia

Functional incontinence

urine loss caused by the inability to reach the toilet because of environmental barriers, physical limitations, loss of memory, or disorientation

urine loss is large/complete

Exacerbating conditions of incontinence

constipation

dehydration or UTI

pulmonary edema, peripheral edema, hypercalcemia, hyperglycemia

COPD/cough

delirium, dementia, depression

spinal cord injury, neurologic issue

urogenital atrophy

Reversible causes of incontinence

DRIPSS

Delirium

Restricted mobility

Infection, inflammation, impaction

Pharmaceuticals, psychological, polyuria

Stones

DDx for incontinence and OAB

DRIPSS

GU malignancy

prolapse

post-surgical

neurologic

3 incontinence questions

during the last 3 months:

-have you leaked urine?

-did you leak with activity, urge, or neither?

-did you leak most often with activity, urge, neither, or both?

Common meds that can cause urinary incontinence

antihypertensives

pain relievers

psychotherapeutics

others

Incontinence physical exam

visual inspection with standing

distended bladder on abdominal exam

rectal exam for hard stool in vault

prostate exam

genital exam for skin integrity, adequacy of pelvic floor, and prolapse

mental status

Incontinence lab workup

exclude metabolic, infectious, and malignant conditions:

urinalysis

urine cytology

renal function (BUN, creatine, EGFR)

serum electrolytes

blood glucose and calcium

Incontinence testing/procedures

bladder US

renal US and/or CT

urodynamic testing

Assessment of post-void residual (PVR)

bladder US

less than 50mL should be present after voiding

more than 200mL indicates dysfunction

Urodynamic testing

probes into urethra and bladder testing muscular contractions

more invasive - last resort done by urology

Incontinence general management

treat underlying or reversible etiologies and prevent constipation

smoking cessation

fluid intake timing and amount (don't restrict fluid)

reduce caffeine, alcohol, and carbonation

prompted voiding

weight loss

pelvic floor exercises

Stress incontinence treatment

general/lifestyle measures

pelvic floor therapy

topical vaginal estrogen

trans or periurethral injection of bulking agents

Urge incontinence treatment

general lifestyle/measures

pelvic floor exercises

1st line: antimuscarinic/anticholinergic - oxybutynin, tolterodine, solifenacin, darifenacin

2nd line: beta 3 agonists: mirabegron and vibegron

botox into detrusor muscle

neuromodulation

surgery - last resort

Anticholinergic/antimuscarinic MOA

inhibiting involuntary detrusor muscle contractions at efferent pathway

Beta 3 receptor agonist MOA

inhibits afferent nerve firing independent of the relaxing effects on the bladder smooth muscle

Overflow incontinence treatment

relief of obstruction (constipation or BPH)

catheterization

alpha-adrenergic antagonists for BPH

micturition maneuvers - suprapubic pressure, Valsalva, double voiding

Pessaries

adds support to vagina and increases tightness of the tissues and muscles of the pelvis

Overactive bladder (OAB)

chronic syndrome of urinary urgency which may be accompanied by frequency, nocturia, +/- small volume of incontinence without UTI or pathology

dx of exclusion

Overactive bladder pathophysiology

multifactorial - true cause unknown

Overactive bladder diagnosis

same as incontinence - rule everything else out

Overactive bladder treatment

general/lifestyle measures

antimuscarinic/anticholinergic agents - oxybutynin

beta 3 receptor agonists - mirabegron and vibegron

Incontinence and OAB - elderly patient considerations

side-effects

drug interactions

renal and hepatic impairment

cost

Cystocele

bladder prolapse

vaginal hernia where bladder drops down into vagina causing soft anterior fullness

may be accompanied by urethrocele due to detachment from pubic symphysis during childbirth

Cystocele diagnostics

pelvic exam

US to help further evaluate

Cystocele treatment

improve constipation, weight loss, limit straining

pelvic muscle training

pessaries

only curative treatment: surgery

Clinically significant ejaculation disorders

failure of emission

retrograde ejaculation

premature ejaculation

hematospermia

anorgasmia

Retrograde ejaculation or failure of emission may result from

anatomic abnormalities

functional abnormalities

DM

surgery

urethral strictures

meds - alpha blocker therapy, antipsychotics

MS

peripheral neuropathy

Painful ejaculation etiology

infectious

obstructive

psychological

Hematospermia etiology

idiopathic

secondary to prolonged abstinence

infection or inflammation of the GU tract

self-limiting and typically resolves with 10-15 ejaculations

Anorgasmia etiology

spinal cord injury

psychological factors

dysfunctional sexual techniques

medications (SSRIs)

Ejaculation and orgasm disorders

labs: UA, CBC, BMP, PT, PTT, STD testing

US, CT, +/- MRI

Ejaculation and orgasm disorders treatment

retrograde and failure of emission - reassurance unless trying to conceive

premature - psychotherapy, behavioral interventions (coronal squeeze or start/stop), communication, SSRIs, topical lidocaine, TCAs

painful - NSAIDs, muscle relaxants, abx

Erectile dysfunction

consistent inability to maintain an erect penis with sufficient rigidity to allow sexual intercourse due to arterial, venous, neurogenic, psychogenic causes, or anti HTN or antidepressant medications

Loss of libido may indicate

androgen deficiency

Loss of orgasm if libido and erections are intact

psychological origin

Erectile dysfunction - questions to ask

timing and frequency

normal erections in morning or sleep

hx of dyslipidemia, HTN, neuro, DM, CKD, endocrine, depression, or vascular disease

drugs, alcohol, tobacco

Erectile dysfunction labs

urinalysis

fasting lipids

serum glucose

testosterone

prolactin

free testosterone and LH if testosterone and prolactin abnormal

Erectile dysfunction imaging

duplex US

pudendal arteriography

Erectile dysfunction diagnostic procedures

nocturnal penile tumescence testing for frequency and rigidity

direct injection of vasoactive substances

Erectile dysfunction treatment

PDE-5 inhibitors: sildenafil, vardenafil, tadalafil, avanafil

prostaglandin urethral suppository - alprostadil

injection of prostaglandins into base of penis

testosterone replacement

behavioral therapy

vacuum erection device

penile prosthesis

surgery for venous/arterial disorders

Which PDE-5 inhibitor can be taken daily?

tadalafil - also helps with BPH

Contraindication for PDE-5 inhibitors

nitrates!

Priapism

persistent and painful erection +/- sexual stimulation

may be due to low-flow (veno-occlusive) or high-flow (increased arterial flow without increased venous flow)

Priapism epidemiology

peak ages: 5-10 (consider malignancy or sickle cell) and 20-50 (consider drug use)

Low-flow priapism

more common than high flow

edema of cavernosal trabeculae resulting in stasis, thrombosis, venous occlusion, fibrosis, and scarring

similar to compartment syndrome

High-flow priapism

cavernosal artery rupture leading to arteriocavernous fistula

Priapism etiology

idiopathic: prolonged sexual arousal

secondary: sickle cell, DM, leukemia, solid tumor, spinal cord injury, trauma, ED treatments, cocaine

Priapism treatment

non ischemic: ice packs and analgesia

ischemic: aspiration of corpora, penile injection of phenylephrine/epinephrine, urgent urology consult

If priapism is lasting longer than ____ hours, 90% of men will no longer be able to become erect.

24

Phimosis

fibrous constriction of foreskin preventing retraction

often associated with balanitis and may cause urinary retention

normal in first few years of life

may require elective circumcision

Paraphimosis

retracted foreskin develops a fixed constriction proximal to the glans

penis distal to the constricting foreskin may become swollen and painful or even gangrenous and may result in urinary retention

Paraphimosis management

manual reduction: squeeze glans for 5-10 min to reduce size

ice

urgent or elective circumcision

Balanitis

inflammation of penile head

if foreskin is involved - balanoposthitis

Balanitis S&S

itching, tenderness, pain, dysuria, local edema, erythema

ulceration and lymph node enlargement

superimposed bacterial infections

inability to void

Balanitis etiology

poor hygiene

infectious: MC candida, Neisseria gonorrhea, HPV, herpes, syphillis, HIV, trich, staph aureus, anaerobic bacteria

Balanitis diagnostics

KOH

STD testing

wet mount for trich

Balanitis treatment

topical and/or systemic - antifungals, steroid, abx

hygiene education - retraction and bathing

warm Sitz baths

circumcision consideration

Hypospadias

urethral folds fail to mature in utero - urethral meatus is ventrally displaced on glans on shaft of penis or more proximal at scrotum or perineum

may interfere with urination, ejaculation, and cosmetic appearance

Hypospadias management

do not circumcise because foreskin may be used in repair

IF associated with cryptorchidism or scrotal/perineal locations then workup with US, karyotype, and electrolytes

referral and early repair depending on severity

Epispadias

rare congenital anomaly associated with bladder exstrophy

urethra opens on dorsum of penis with deficient corpus spongiosum and loosely attached corpora cavernosa

Male infertility

inability to conceive after 1 year of unprotected intercourse

Male infertility etiology

testicular defects in spermatogenesis

idiopathic

sperm transport disorders

endocrine - hypogonadism

FSH and LH in men

FSH stimulates Sertoi cells for spermatogenesis

LH stimulates Leydig cells to produce testosterone

Male infertility diagnostics

semen analysis

endocrine testing

imaging of accessory glands/ducts

genetic testing

Semen analysis

sample collected after 3-7 days of abstinence and second sample taken at least 1 week apart

looks at volume, pH, concentration, count, motility, morphology, debris, agglutination, leukocyte count, immature germ cells

Male infertility imaging

scrotal US

transrectal US - prostate and seminal vesicles

MRI of head, penis, and scrotum

Low testosterone, high FSH, high LH

primary (hypergonadotropic) hypogonadism

order karyotype

Normal testosterone and LH, high FSH

primary (hypergonadotropic) hypogonadism

seminiferous tubule damage without Leydig cell dysfunction

Low testosterone, but FSH and LH low-normal

secondary (hypogonadotrophic) hypogonadism

High testosterone and LH but normal FSH

partial androgen resistance

Normal testosterone, LH and FSH

further eval

Low sperm count and very low LH in a man who is very muscular

suspicious for androgen abuse

Horseshoe Kidney

MC renal fusion abnormality occurring in 5th-9th week

most fuse at lower poles

2 separate excretory renal units and ureters remain

isthmus can be of renal parenchyma or a fibrous band

asymptomatic or complications later in life

Horseshoe kidney results from

normal embryologic migration of the kidneys

Normal embryogenesis of kidneys

pronephros

mesonephros

metanephros - where permanent kidney is formed

Horseshoe kidney epidemiology

male > females

Horseshoe kidney associated conditions

vesicoureteral reflux

ureteropelvic junction obstruction

nephrolithiasis

cryptorchidism

Turnery syndrome or trisomy 13, 18, and 21

Horseshoe kidney eval

PE often normal

often detected on 20 week anatomy scan

postnatal renal US

voiding cystourethrogram to detect vesicoureteral reflux

creatinine

Horseshoe kidney management

monitor for renal function

US every 2 years

creatinine

blood pressure

urinalysis

Nephrolithiasis

kidney stones

hard crystalline formations in the urinary tract causing pain, NV, urinary symptoms

Nephrolithiasis epidemiology

men > women

Ureteral stones

kidney stones migrate to ureters

Ureteral stones are common at narrow areas like

ureteropelvic junction

ureterovesical junction

crossing at iliac vessels