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Clinically, it is condition in which the kidneys are unable to perform their excretory and regulatory functions.
Defined as urine output < 400ml in 24 hours or < 30mls in 1 hour
It causes disturbance of
- Water
- Electrolytes
- Acid-base balance
- Nitrogenous waste products
- Blood pressure
It occurs infrequently in pregnancy but carries a high mortality rate.
It must be prevented where possible and treated aggressively.
GFR increases by about 50% in second trimester and decreases to 20% in the last trimester.significant hyperfiltration
Renal plasma flow is increased due to increase cardiac output and renal vasodilatation
- Normal BUN value falls
- Normal Cr level falls
These changes are particularly important, as a normal serum creatinine level or BUN level in a pregnant woman may represent kidney disease.
Increase heart rate due to activation of RENIN-ANGIOTENSIN ALDOSTERON SYSTEM
Sodium retention— osmotic threshold for arginine vasopresin resets downward leading to lower sodium values
Increased urate clearance leading to lower serum uric acid values
Filter load of glucose increase causing renal glycosuria
Increased ventilation
- Chronic respiratory alkalosis
- Fall in serum bicarbonate value
Classified broadly as
- Pre-renal
- Renal
- Post renal
Pre-renal
Usually due to renal hypoperfusion
- Obstetrics haemorrhage
- APH
- Placenta Abruptio
- Placenta Praevia
- PPH
- Sepsis
- Dehydration e.g. from hyperemesis gravidarum
- Circulating nephrotoxin
- Mismatched blood transfusion
- Pre-eclampsia/eclampsia
- DIC
- Heart failure
- Chronic lung disease
Renal
Usually due to intrinsic renal disease
- Acute glomerulonephritis
- Acute pyelonephritis
- Amyloidosis
Post Renal
Urinary obstruction
- Ureteric stone
- Retroperitoneal tumor
History and Examination
History
- Depends on cause— APH, PPH, etc.
- Nephrotoxic drug ingestions e.g. NSAIDs, aminoglycosides
- Blood loss or transfusions
- Urine output
- Flank pain
- Hematuria
Examination
- Tailored toward the cause as well
Clinical course
- Oliguric
- Diuretic
- Recovery
Oliguric phase
- BUN elevated
- Urine < 30mls/hr
- Hyperkalemia
- Px is acidotic with hydrogen ion accumulation and loss of bicarbonate
Diuretic phase
- Large volume of urine is passed
- Loss of electrolytes due to absent renal tubular fxn
Recovery phase
- Volume and composition normalise as tubular fxn returns
- Oliguria
- Anuria
- Acidotic breath
- Anorexia
- Vomiting
- Lethargy
- Cardiac arythmias due electrolyte disturbance
- Anemia
- Extra renal infection
Investigations
Patient should be catheterized to monitor urine output
Related to clinical findings and causes
- FBC and differentials
- EUCr- electrolyte abnormalities
- Blood culture to rule out sepsis
- Urinalysis
- ECG- electrolyte abnormalities can cause arrhythmia
- Urine MCS- renal system infection
- ABG- acid-base disorder
- RBS, FBS can be used to rule out acute fatty liver in pregnancy
Results may show
- Hyponatremia, hypomagnesemia, hyperphosphatemia, hypermagnesimia, hypocalcemia, hyperkaelemia
- Thrombocytopenia
- Low pcv
- Metabolic acidosis
- Arrhythmias
Treatment
Prevention should be the aim in obstetrics
- Adequate volume replacement. Must be done with caution, especially in patients at risk of fluid overload and pulmonary edema e.g. patient with pre-eclampsia/eclampsia.
- Proper management of high risk obstetrics condition
- Ready blood availability
- Avoid nephrotoxic antibiotics
Co-manage with the nephrologist
Emergency treatment of underlying causes e.g. PPH, APH
Surgical treatment of obstructive uropathy
Evacuation of infected product of conception causing sepsis
Fluid and electrolyte correction
- Input/output monitoring
- Daily weighing
- Hyperkalemia correction
- Dietary intake (150 calories, protein free, carbohydrate diet)
Parenteral feeding
Antibiotics
Diuretics
Manitol
Dopamine
Dialysis Indication
- Serum potassium 7mEq/l or more
- Sodium level of 130mEq/l or less
- Serum bicarbonate 13mEq/Lor less
- BUN more than 120mg/dl or daily increment of 30mg/dl in px with sepsis, dialyzable poison or toxins
Delivery
- Indicated by worsening renal condition
- Obstetric condition of the patient
- The fetus
- Abortion
- Low birth weight
- Premature labor
- Still birth
- ACN- acute cortical necrosis
- ATN- acute tubular necrosis
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