CES: Genitourinary System

Tom HeapsConsultant Acute Physician

Outline Basic anatomy

Functional physiology

Symptoms

Examination

Nephrolithiasis

Obstruction

BREAK

Acute Kidney Injury (AKI)

Basic anatomy

Kidneys

Ureters

Urethra

Bladder

Functional anatomyOuter cortex

Inner medulla

Nephron

Ureter

Renal Pelvis

Calyces

Nephron: the functional unit of the kidney

Glomerular filtrationNet filtration pressure at the glomerulus

= blood hydrostatic pressure – colloid oncotic pressure – capsular hydrostatic pressure

= 55mmHg – 30mmHg – 15mmHg

= 10mmHg

Large surface area and porous membrane

glomerular filtration rate (GFR) of 125 mL/min in normal health

fluid volume of ~180L/day enters glomerular capsule

GFR is regulated by the body depending on circulating volume and [Na+]

Efferent

arteriole

Afferent arteriole

Filtration

Vasodilatation mediated by

prostaglandins

Vasoconstriction mediated by angiotensin II

ACE-inhibitors reduce production of angiotensin II

from angiotensin I by ACE

NSAIDs reduce prostaglandin

synthesis

Glomerula

r hydrostatic pressure

and filtration

Glomerula

r hydrostatic pressure

and filtration

Role of the kidneys

Production and excretion of urine

- Removal of waste e.g. creatinine, urea, uric acid

- Maintenance of homeostasis

Regulation of ECF volume and composition:

- Control of ion balance and pH

- Control blood volume / blood pressure

- Control osmolality (excretion / resorption of Na+)

Production of hormones / vitamins

- Renin and erythropoietin (EPO)

- Vitamin D3

GU Symptoms 1

Polyuria Too much urine DM, DI, hypercalcaemia, post-obstruction

Oliguria / Anuria Not enough / no urine Dehydration , AKI,

obstruction

Frequency Going too often Infection, stones, detrusor instability

Urgency Having to go quickly! Infection, detrusor instability

Dysuria Painful / burning micturition Infection

Nocturia Going >2x per night

Outflow obstruction, infection, stones,

detrusor instability, causes of polyuria

Hesitancy Difficulty starting Outflow obstruction

Terminal Dribbling Weak stream Outflow obstruction

Incontinence Loss of control Urge, stress, neurological problems, dementia

GU Symptoms 2

Haematuria Microscopic or Macroscopic

Infection, stones, tumours, trauma,

glomerulonephritis, coagulopathy / anticoagulants

Renal Angle Pain

Renal: pyelonephritis, abscess, stones (renal colic), hydronephrosis,

cysts, tumours, infarction

Non-renal: cholecystitis, hepatitis, pancreatitis,

splenic infarction, gynaecological, shingles, basal pneumonia, MSK

Urethralgia Pain along the urethra +/- discharge

Infection / urethritis, STI, stone, foreign body,

tumour

Orchalgia Testicular pain Epididymo-orchitis, tumour, trauma, torsion

Prostatitis

Perineal pain, dysuria, obstructive

symptoms, tenderness on DRE

Urogenital infection or instrumentation

Additional GU History

Hypertension, diabetes

Family and congenital history

Drug History

Sexual and travel history

Systems review

GU Examination

Full systems examination focusing on abdomen

- Inspection

GU Examination

Full systems examination focusing on abdomen

- Inspection

- Palpation

- Percussion

- Auscultation

Costovertebral angle between lower border of 12th rib and lateral border of erector spinae

Pain / tenderness, Murphy’s punch +ve

Kidneys usually not palpable unless hydronephrosis, tumour, cystic disease

Palpate specifically for bladder distension in the elderly

GU Examination

Full systems examination focusing on abdomen

- Inspection

- Palpation

- Percussion

- Auscultation

Perineum / Scrotum / Testicles

Vagina / Penis

Digital rectal examination (DRE)

- Prostatic enlargement and / or tenderness

- Constipation

- Masses

Nephrolithiasis (urinary tract stones)

>80% are calcium stones, majority of these are calcium oxalate

Usually asymptomatic until they pass into ureter

- Pain (may be excruciating) and nausea

- Waxing and waning (renal / ureteric colic)

- Abdomen / flank testicle / penis / labia (‘loin to groin’)

- Haematuria, frequency, urgency, dysuria, strangury

Non-contrast CT urogram is Ix of choice (sensitivity 88%, specificity 100%)

USS if radiation an issue (sensitivity 57%)

Plain AXR no longer has a role (if CT available)

Conservative Rx with hydration, NSAIDs / opioids, tamsulosin / nifedipine

Urgent urological referral if AKI, sepsis, stone >10mm

Urinary retention / obstruction

Acute vs. chronic, unilateral vs bilateral

Kidney / ureter – stones, TCC, extrinsic tumour, retroperitoneal fibrosis

Bladder – stones, tumour, blood clots, neurological, drugs, constipation

Urethra – prostate cancer, BPH, stricture, stone

Pain (may be absent in chronic retention and dementia)

Oligo-anuria and AKI, haematuria, hypertension,

DRE is mandatory, bladder scan then USS abdomen / pelvis

IV fluids, urinary catheter, fluid balance, -blockers and antispasmodics

Treat precipitant (pain, infection, constipation, drugs etc.)

Be vigilant for post-obstructive diuresis and decompression haematuria

Other Rx e.g. ureteric stent, nephrostomy

Acute Kidney InjuryTom Heaps

Consultant Acute Physician

Clinical Case

82-year-old male presenting with confusion and vomiting

PMHX: T2DM, hypertension, heart failure, BPH

DHX: Aspirin, metformin, ramipril, bendroflumethiazide, bisoprolol

RR 24, SpO2 94% (air), T 38.5C, BP 101/50mmHg, HR 119/min

Urine dip: leuc +++, nit +ve, blood +, protein ++

Na+ 144mmol/L

K+ 5.9mmol/L

urea 15.4mmol/L

creatinine 142μmol/L

With reference to this case…

GROUP 1: Is this AKI? What are the definitions of AKI?

GROUP 2: What are the risk factors for AKI? Which apply to this case?

GROUP 3: What are the common causes of AKI? Which apply to this case?

GROUP 4: What are the 6 most important steps in management of AKI?

GROUP 5: What are the complications of AKI and how are they treated?

AKI 1: definitions

calculated GFR is usually more accurate than serum creatinine in estimating renal function but most definitions of AKI rely on creatinine measurement

KDIGO (Kidney Disease Improving Global Outcomes) definition of AKI:

Stage of AKI

Serum Creatinine (SCr) criteria

Urine output criteria

1

increase ≥ 26 μmol/L within 48h or 

increase ≥1.5x to 1.9x reference SCr

<0.5 mL/kg/h for >6 consecutive hrs

2 increase ≥ 2x to 2.9x reference SCr

<0.5 mL/kg/h for >12 hrs

3

increase ≥3x reference SCr or 

increase ≥354 μmol/L or commenced on renal

replacement therapy (RRT) irrespective of stage

creatinine rise by ≥ 26µmol/L within 48 hours or;

creatinine rise ≥ 1.5-fold from the reference value* which is known or presumed to have occurred within one week or

urine output < 0.5mL/kg/h for >6 consecutive hours

*reference serum creatinine is the lowest creatinine value recorded within 3m of the event

AKI 2; risk factors

CKD (especially if eGFR <60mL/minute) heart failure liver disease diabetes history of AKI neurological / cognitive impairment or disability hypovolaemia use of drugs with nephrotoxic potential (NSAIDs, ACE-i,

diuretics etc.) use of iodinated contrast agents within the past week symptoms / history of or conditions predisposing to

urological obstruction sepsis deteriorating early warning scores (MEWS) age ≥ 65

AKI 3: causes

Pre-Renal (75%)

•hypotension•hypovolaemia•redistribution•decreased cardiac output•renal artery stenosis or thrombosis

Renal (20%)

•nephrotoxic medications•glomerulonephritis•interstitial nephritis•vasculitis•ischaemia•rhabdomyolysis

Post-Renal (Obstructive)

(5%)•urethral e.g. BPH•bladder e.g. stones, blood clots, tumours•ureteric e.g. stones, fibrosis, malignancy•PUJ obstruction•intra-tubular e.g. crystals•renal vein thrombosis•abdominal compartment syndrome

AKI 4: management principles

1. Treat underlying cause

2. IV fluids- restore and maintain renal perfusion (may require

vasopressors)- balanced crystalloids e.g. Hartmann’s + / - sodium

bicarbonate

3. Stop nephrotoxics and adjust doses of other medications if necessary

4. Monitoring - strict fluid input / output monitoring- consider urinary catheter- monitor for and treat complications of AKI

5. USS urinary tract

6. Renal referral + / - RRT

selected cases only

Myths regarding balanced crystalloids…

‘you can’t give Hartmann’s to patients with hyperkalaemia because it contains potassium’

‘you can’t give Hartmann’s to patients with lactic acidosis because it contains lactate’

Haemodialysis (HD) vs Continuous Veno-Venous Haemofiltration (CVVH)

Indications for Renal Replacement Therapy (RRT) in AKI persistent hyperkalaemia (K+ >7.0mmol/l) severe refractory metabolic acidosis (pH <7.1, HCO3

- <12 or BE < -10 )

refractory pulmonary oedema uraemic complications (urea usually >45mmol/L)

Prevention is better than cure…55% of AKI is avoidable (including 30% of deaths due to AKI)

AKI 5: complications

hyperkalaemia (K+ >5.5mmol/L)

other electrolyte abnormalities e.g. hyperphosphataemia, hyponatraemia

metabolic acidosis- IV fluids, IV bicarbonate (especially if hyperkalaemia),

RRT

fluid overload / pulmonary oedema- diuretic / GTN (often ineffective), RRT

uraemia: encephalopathy, pericarditis, bleeding

mortality- overall mortality 26% (severity of illness and / or frailty

of patient) - 16% in Stage 1, 33% in Stage 2, 36% in Stage 3, 58% if

RRT required

?QUESTIONS?