9) Maternal Medicine - Renal Flashcards
Incidence of AKI
1.4% of obstetric admissions
Fall in creatinine in pregnancy
35micromol/L (average creatinine 53)
What should be considered diagnostic of kidney injury?
New creatinine >90
Most common cause of AKI in pregnancy
Pre-eclampsia
Indications for renal replacement therapy
- Metabolic acidosis
- Hyperkalemia
- Fluid overload refractory to medical treatment
- Pregnancy specific: Urea >17 mmol/L*
What percentage of PET leads to AKI?
What percentage of HELLP leads to AKI?
PET: 1.5-2%
HELLP: 3-15%
Pathology finding in kidney in PET + HELLP
Glomerular endotheliosis (reduces glomerular capillary permeability therefore reducing filtration).
In HELLP, additional thrombotic microangiopathy.
How to adjust dose of MgSO4 in AKI?
If urine output <20ml/h or creatinine >90,
50% reduction in infusion rate of MgSO4 (still give bolus) and monitor Mg levels every 4-6h (aiming 2-3.5)
Incidence of thrombotic microangiopathy (TTP/HUS)
1 in 25,000
What is the pathology underlying TTP & HUS
TTP: ADAMTS13 (levels fall in pregnancy)
HUS: Abnormality in complement activation
What percentage of TTP in pregnancy leads to AKI?
30-80%
Incidence of ESRF in HUS
75%
When does TTP occur and when does HUS occur?
TTP in 2nd/3rd trimester.
HUS postpartum.
Factors distinguishing HELLP from TTP/HUS
- Profoundly low platelets more common TTP/HUS
- Liver function not usually affected TTP/HUS (except increased bilirubin)
- AKI more common TTP/HUS
- Coagulopathy more common HELLP (anti-thrombin and fibrinogen increased in TTP/HUS)
Incidence of AFLP
5 per 100,000
Incidence of AKI in AFLP (and percentage requiring renal replacement therapy)
14% develop AKI
3.5% require renal replacement
What happens in AFLP?
Fetal homozygosity of disorders of beta-fatty acid oxidation leading to excessive fatty acid load in mother.
Kidney biopsy in AFLP
Tubular free fatty acid deposition
Things to distinguish AFLP from HELLP
- Low serum glucose
- Raised serum ammonia
- Prodromal vomiting
What percentage of cases of SLE have renal involvement?
20-50%
What USS finding would suggest pathological renal obstruction?
If ureter dilated distal to pelvic brim, if obstruction does not decompress by positioning on all fours and if ureteric jets absent in contralateral position.
Most common cause of acute interstitial nephritis
NSAIDs
What percentage of people using NSAIDs develop significant effects or acute renal failure?
1-5% side effects
0.5-1% acute renal failure
Incidence of renal transplant
2-6 per 10,000 women of childbearing age
Number of pregnancies in women with renal transplants
30-40 annually
How long to wait after a renal transplant before conceiving?
1 year
Risk of acute rejection of renal transplant in first year?
10-15%
Effect of pregnancy on risk of renal graft rejection
If graft function normal then pregnancy doesn’t increase risk of rejection
What to switch mycophenolate to in transplant patients and when?
Switch to azathioprine and allow 3/12 washout period
Hypertension in patients with renal transplant
- 50% have hypertension predating and persisting pregnancy
- 15% new onset in pregnancy
GDM in patients with renal transplant
- 5-25%
- Calcineurin inhibitors are diabetogenic
What pre pregnancy renal parameter predicts increased rate of loss of maternal renal function?
> 1g/day
What proportion of people with a renal transplant see their creatinine increase and by what amount?
38% see creatinine increase >20%
Acute rejection rates for renal transplant during pregnancy
2-4%
Effect of renal transplant on delivery?
Vaginal delivery recommended with continuous CTG
Caesarean rates increased
Change in proteinuria in pregnancy in a patient with a transplant
Expect to double (and further double if ACEi/AR2 stopped)
When do renal transplant patients require VTE prophylaxis?
If PCR>300 or ACR>180
Effect of renal function on screening tools
Reduced urinary bhCG excretion therefore falsely elevated results.
How often to monitor renal function and pre-dose tac/ciclosporin levels?
At least monthly
Risk of injury to kidney at CS
1-2%
Risk of PET in kidney donors
2 x increased risk (should have aspirin prophylaxis!)
When does pancreatic transplant usually occur?
In conjunction with renal transplant.
Rate of adverse outcomes with liver transplant
Less than renal
Rejection rate with liver transplant
10%
Rate of adverse outcomes with cardiothoracic transplant
Comparable to renal
Overall incidence of urinary tract infection in pregnancy
8%
Definition of asymptomatic bacteriuria
> 10^5 bacteria in absence of symptoms
Incidence of asymptomatic bacteriuria
2-10%
What percentage of cases of asymptomatic bacteriuria progress to symptomatic urinary sepsis if untreated?
40% (30% cystitis, 50% pyelonephritis)
Incidence of symptomatic cystitis
2%
Incidence of pyelonephritis
2%
What percentage of cases of pyelonephritis are associated with bacteraemia?
15-20%
What is the recurrence rate of pyelonephritis?
20%
Most common organism for UTI
E. Coli (second: S. saprophytic)
Incidence of recurrent UTI in pregnancy
4-5%
What treatment for renal stones is contraindicated in pregnancy?
Lithotripsy
Three severities of CKD
Mild: Cr <125
Moderate: Cr 125-250
Severe: Cr >250
Effect of pregnancy on renal function in mild CKD
2% loss of function
0% permanent deterioration
Effect of pregnancy on renal function in moderate CKD
40% loss of function
20% permanent deterioration
2% ESRF
Effect of pregnancy on renal function in severe CKD
70% loss of function
50% permanent deterioration
35% ESRF
Pre-eclampsia in CKD
20% Mild CKD
40% Moderate CKD
60% Severe CKD
75% Dialysis
FGR in CKD
25% Mild CKD
40% Moderate CKD
65% Severe CKD
>90% Dialysis
PTB in CKD
30% Mild CKD
60% Moderate CKD
90% Severe CKD
>90% Dialysis
Perinatal mortality with CKD
1% Mild CKD
5% Moderate CKD
10% Severe CKD
50% Dialysis
