Pregnancy and Kidney Disease — Advanced

Correct answer: Baseline maternal renal function (level of eGFR).

Rationale: The degree of maternal renal impairment is the strongest predictor of both maternal and fetal complications in pregnancy. Lower baseline eGFR (more advanced CKD) is associated with higher risks of pre-eclampsia, pregnancy loss, preterm birth and decline in maternal renal function. While duration of hypertension, choice of antihypertensive and maternal age influence risk, they are less predictive than the baseline level of kidney function. Low-dose aspirin reduces risk of pre-eclampsia in high-risk women but is preventive rather than a primary determinant of baseline risk.

Why the others are less appropriate:
- Duration of hypertension: Longer duration increases risk but is secondary to the presence and severity of end-organ damage (e.g. impaired renal function).
- Type of antihypertensive: Some drugs (ACE inhibitors/ARBs) must be stopped before conception, but drug class is not the dominant predictor of overall pregnancy outcome.
- Maternal age >35: Advanced maternal age increases obstetric risk but does not outweigh the impact of impaired renal function.
- Planned aspirin prophylaxis: Aspirin can reduce pre-eclampsia risk but does not change the baseline prognostic importance of maternal renal function.

Correct answer: Intravenous labetalol.

Rationale: For severe hypertension in pregnancy (commonly defined as systolic ≥160 mmHg or diastolic ≥110 mmHg), immediate BP lowering is recommended using agents with established safety and efficacy in pregnancy. Intravenous labetalol is a first-line option for acute control, along with intravenous hydralazine or oral immediate-release nifedipine depending on local availability and clinical context. ACE inhibitors (e.g. ramipril, enalaprilat), ARBs, atenolol and spironolactone are contraindicated or not recommended in pregnancy because of fetal toxicity or lack of evidence of safety.

Why the others are less appropriate:
- Oral ramipril and IV enalaprilat (ACE inhibitors): Contraindicated in pregnancy due to fetopathy (renal dysplasia, oligohydramnios, skull hypoplasia).
- Oral atenolol (beta-blocker): Some beta-blockers are used in pregnancy (e.g. labetalol), but atenolol is associated with fetal growth restriction and is not a first-line choice for acute severe hypertension.
- Oral spironolactone: Anti-androgenic effects and lack of safety data make it inappropriate in pregnancy.

Correct answer: Measurement of maternal angiogenic markers (sFlt-1/PlGF ratio).

Rationale: In late pregnancy, distinguishing superimposed pre-eclampsia from chronic kidney disease progression is challenging. Angiogenic biomarkers (sFlt‑1 and PlGF) and their ratio are useful adjuncts: an elevated sFlt‑1/PlGF ratio supports a diagnosis of pre-eclampsia, whereas a low ratio makes it unlikely. This has particular value when baseline proteinuria is present. Repeat urine protein quantification documents the degree of proteinuria but cannot reliably distinguish the aetiology. Serum uric acid is nonspecific. Renal biopsy in late third trimester carries increased maternal/fetal risk and is rarely the first-line diagnostic step. Empiric escalation of antihypertensives may be necessary for BP control but does not clarify the diagnosis.

Why the others are less appropriate:
- Repeat 24-hour urine: Confirms proteinuria magnitude but not the cause (CKD progression vs pre-eclampsia).
- Serum uric acid: Elevated in pre-eclampsia but lacks specificity and sensitivity in CKD.
- Percutaneous renal biopsy at 34 weeks: Higher procedural risk in third trimester and usually deferred unless results would change management and safer timing cannot be found.
- Empiric antihypertensive escalation: Important for maternal safety but not diagnostic; cannot reliably differentiate pre-eclampsia from CKD progression.

Correct answer: Ischaemic acute tubular necrosis (ATN) secondary to hypovolaemic/ischaemic injury.

Rationale: A large postpartum haemorrhage with hypotension and vasopressor requirement is a classic setting for ischaemic ATN due to renal hypoperfusion. Presentation over hours to days with oliguria and rising creatinine is typical. Obstructive uropathy from ureteric injury is uncommon and would usually present with pain and hydronephrosis; it does not explain hypotension and shock. Rapidly progressive glomerulonephritis is less likely to present acutely in the immediate post-PPH period without prior urinary abnormalities. Acute interstitial nephritis from antibiotics is possible but usually presents with eosinophilia, rash, and a less immediate severe creatinine rise. Atypical HUS can present postpartum with thrombocytopenia and microangiopathic haemolysis plus AKI, but the vignette lacks haemolysis/low platelets; ATN is the most likely immediate cause.

Why the others are less appropriate:
- Obstructive uropathy: Unlikely in the context of profound haemodynamic instability and immediate AKI.
- RPGN: Would usually have haematuria, RBC casts and subacute progression, not solely following hypotension.
- AIN: Typically drug-related with systemic features and not so immediate after hypovolaemia.
- aHUS: Consider if thrombocytopenia and MAHA are present; requires specific testing and therapies but is less likely here without those features.

Correct answer: Percutaneous renal biopsy is most safely performed in the second trimester when results will alter management.

Rationale: If the diagnostic result will change management, a percutaneous renal biopsy is generally safest in the second trimester (commonly quoted as 14–28 weeks) when the risks to mother and fetus are lower than in the first trimester and the technical difficulties/risks of third trimester (enlarged uterus, vascularity) are greater. Biopsy should not be deferred automatically if the diagnosis will influence therapy. First-trimester biopsy carries higher relative risk to the fetus; transjugular biopsy can be considered in selected high-bleeding-risk patients and is not universally contraindicated. Empiric immunosuppression without tissue diagnosis may be appropriate in selected severe cases but is not ‘always’ indicated.

Why the others are less appropriate:
- Deferring until after delivery: May delay necessary treatment and worsen maternal/fetal outcomes when biopsy would alter management.
- First trimester biopsy: Higher miscarriage risk and often avoided unless absolutely necessary.
- Transjugular biopsy contraindicated: Incorrect—transjugular approach can be used when percutaneous biopsy is high risk (e.g. coagulopathy), though it carries its own risks.
- Empiric immunosuppression always: Inappropriate—decision should be individualised and informed by the likelihood of specific diagnoses and risks of therapy.

Correct answer: Increase dialysis intensity and frequency (e.g. daily or extended sessions).

Rationale: Pregnant women on dialysis have better fetal outcomes when dialysis is intensified—more frequent and/or longer sessions to lower predialysis blood urea, optimise volume status and reduce uraemia-related fetal risks. Many centres aim for increased weekly dialysis dose and more frequent sessions. Maintaining conventional thrice-weekly dialysis is generally associated with worse outcomes (higher rates of polyhydramnios, preterm birth). Switching to peritoneal dialysis is an option in some patients but is not universally superior and may be complicated by increased intra-abdominal pressure and infections. Reducing ultrafiltration to avoid hypotension is sensible, but not at the cost of inadequate solute clearance; careful fluid and dialysis prescription adjustments are needed. Ceasing dialysis is unsafe.

Why the others are less appropriate:
- Conventional thrice-weekly: Often insufficient to optimise metabolic milieu for pregnancy.
- Switch to peritoneal dialysis: Not routinely recommended solely for pregnancy; selection depends on patient factors.
- Reduce ultrafiltration at expense of uraemic control: Avoid intradialytic hypotension but maintain adequate dialysis dose; balance is needed.
- Cease dialysis: Dangerous for mother and fetus.

Correct answer: Mycophenolate mofetil (MMF).

Rationale: Mycophenolate is teratogenic and associated with pregnancy loss and congenital malformations. Women of reproductive potential should be switched to alternative agents (commonly azathioprine) prior to conception and must use effective contraception until an appropriate washout period and substitution are completed. Azathioprine, prednisolone and calcineurin inhibitors (tacrolimus, cyclosporine) are generally considered compatible with pregnancy when clinically indicated, with careful monitoring.

Why the others are less appropriate:
- Azathioprine: Considered acceptable in pregnancy and often used as a safer alternative to MMF.
- Prednisolone: Used in pregnancy when needed; crosses placenta in limited amounts relative to maternal dose.
- Tacrolimus and cyclosporine: Calcineurin inhibitors can be used in pregnancy with monitoring; they are not teratogenic like MMF.

Correct answer: Atypical haemolytic uraemic syndrome (aHUS) with complement-mediated thrombotic microangiopathy.

Rationale: While HELLP and TTP commonly present in late pregnancy, a hallmark that points towards complement-mediated aHUS is persistence or worsening of microangiopathic haemolysis, thrombocytopenia and particularly renal failure after delivery. HELLP typically improves after delivery. TTP is characterised by severe ADAMTS13 deficiency (<10%) and often responds to plasma exchange. Atypical HUS often presents or worsens postpartum and is associated with predominant and progressive renal injury; it may require complement inhibition (eculizumab) when diagnosed. Acute fatty liver of pregnancy has prominent liver dysfunction and hypoglycaemia and usually improves after delivery. DIC would usually have broader coagulation abnormalities and a clear trigger. Why the others are less appropriate: - HELLP: Usually improves within days after delivery; persistence of worsening renal failure argues against isolated HELLP. - TTP: ADAMTS13 testing is required; severe deficiency supports TTP, but normal/near-normal ADAMTS13 plus persistent renal failure favours aHUS. - Acute fatty liver: Distinguished by profound liver failure and metabolic derangements rather than isolated renal deterioration. - DIC from retained products: Usually associated with consumptive coagulopathy and clinical signs of bleeding; does not classically cause isolated progressive renal failure.

Correct answer: Wait at least 12 months after transplant with stable graft function and no recent rejection episodes.

Rationale: The usual recommendation is to delay conception until graft function is stable and there have been no recent rejection episodes—commonly for at least 12 months post-transplant. This allows optimisation of immunosuppression, stabilisation of graft function and minimises maternal and fetal risk. Calcineurin inhibitors are not absolute contraindications to pregnancy. Delaying 5 years is unnecessarily long for most patients. Mycophenolate is contraindicated in pregnancy and should be stopped well before conception and switched to a pregnancy-compatible agent; it should not be started immediately before conception.

Why the others are less appropriate:
- No minimum interval: Early pregnancy risks are higher and a period of stability is generally advised.
- Avoid calcineurin inhibitors: These are used in pregnancy with monitoring if needed; they are not absolute contraindications.
- Delay 5 years: Unnecessary except in exceptional clinical scenarios.
- Switch to mycophenolate immediately before conception: MMF is teratogenic and should be stopped well before conception, not started.

Women with CKD are at increased risk of pre-eclampsia and are generally offered low-dose aspirin prophylaxis from around 12 weeks of pregnancy until birth, unless contraindicated, according to guideline-based practice. Low-dose aspirin is not contraindicated solely because of CKD. It is not restricted to women with nephrotic-range proteinuria, starting after 28 weeks is too late for optimal prophylaxis, and high-dose aspirin is not recommended for this purpose.