25.4 Pregnancy/Post-Partum, Post-Transplant, and Pediatric Patients (03.T–U)
Key Takeaways
- Eclamptic seizures are treated with magnesium sulfate (typical load 4–6 g IV then 1–2 g/h), not a phenytoin-first status pathway; definitive therapy of severe preeclampsia, eclampsia, and HELLP is delivery after maternal stabilization.
- Postpartum thunderclap headache, seizures, or visual change should trigger a differential of PRES, RCVS, and cerebral venous thrombosis, not only migraine; treat severe blood pressure (generally ≥160/110 mm Hg) with labetalol, hydralazine, or nifedipine.
- Calcineurin inhibitors (tacrolimus, cyclosporine) cause PRES after organ transplant; opportunistic CNS infection and EBV-associated lymphoma or PTLD enter the same time window as immunosuppression intensity.
- The 2023 AAN/AAP/CNS/SCCM BD/DNC guideline uses age-based rules: two independent examinations about 12 hours apart in children under 18 years, a minimum of one examination in adults, and no BD/DNC determination before 37 weeks postmenstrual age.
- Internists sitting this shared exam still see pediatric items: weight-based dosing, abusive head trauma recognition, and neurologic injury on congenital-heart and ECMO circuits. ABIM and ABPN do not publish a separate pediatric percent-correct cut score for this 270-item examination.
Why special populations are written as one section
The content specifications group pregnancy and post-partum (03.T.1), post-organ transplant (03.T.2), and pediatric patients (03.U). Intensivists whose primary training is internal medicine still encounter these stems on the shared computer-based examination that ABPN administers. Treat the physiology in front of you. Do not invent a unpublished pediatric passing percentage or a separate ABIM pediatric cut score—none is published for this 270-item exam.
Preeclampsia, eclampsia, and HELLP
Preeclampsia is new hypertension after 20 weeks of gestation plus proteinuria or end-organ involvement (platelets, creatinine, liver enzymes, pulmonary edema, or cerebral or visual symptoms). Severe-range blood pressure is commonly systolic ≥160 mm Hg or diastolic ≥110 mm Hg. Eclampsia is a seizure in that setting, including postpartum. HELLP is hemolysis, elevated liver enzymes, and low platelets; it can occur with or without massive proteinuria and is a delivery indication after stabilization.
Magnesium sulfate is first-line for eclamptic seizures and for seizure prophylaxis in preeclampsia with severe features. A typical intravenous regimen is a 4–6 g load over 15–20 minutes, then 1–2 g/h. If intravenous access is impossible, an intramuscular load of 10 g (5 g in each buttock) is the historic alternative. Recurrent seizures may receive an additional 2 g bolus. Watch for magnesium toxicity: loss of deep-tendon reflexes, then respiratory depression; calcium gluconate is the reversal. Adjust maintenance in renal failure.
This is not the ESETT pathway. Benzodiazepines may be used if the airway is lost or seizures continue despite magnesium, but the examination error is reaching for phenytoin or levetiracetam instead of magnesium in a clearly eclamptic patient. Magnesium is a poor antihypertensive; treat severe hypertension separately with intravenous labetalol, intravenous hydralazine, or oral nifedipine. Avoid ACE inhibitors in pregnancy.
Delivery planning is definitive therapy for eclampsia, HELLP, and preeclampsia with severe features once the mother is oxygenating, seizing less, and coagulopathy is addressed. Mode and timing are obstetric decisions; the neurointensivist’s job is airway protection during convulsions, left-uterine-displacement positioning, blood-pressure control without placental hypoperfusion, magnesium continuation typically 24 hours postpartum, and a plan for where the patient will seize if she seizes again. Fetal monitoring does not override maternal CPR mechanics.
PRES, RCVS, and cerebral venous thrombosis
The same puerperal week produces three overlapping cerebrovascular syndromes:
| Syndrome | Clue | Imaging | ICU treatment idea |
|---|---|---|---|
| PRES (posterior reversible encephalopathy syndrome) | Seizures, visual change, hypertension; overlaps eclampsia | Vasogenic edema, often posterior but can be atypical and hemorrhagic | Blood-pressure control, magnesium if eclamptic, delivery as indicated |
| RCVS (reversible cerebral vasoconstriction syndrome) | Recurrent thunderclap headache, postpartum, vasoconstrictive drugs | Beading on angiography; convexity SAH possible | Blood-pressure and trigger control; calcium-channel blockers are used; distinguish from vasculitis |
| CVT (cerebral venous thrombosis) | Headache, seizures, hemorrhagic infarcts that cross arterial territories, postpartum hypercoagulability | MR or CT venography | Anticoagulation even with hemorrhage; treat seizures and intracranial hypertension |
Do not send a postpartum thunderclap home as migraine. Do not start dual antiplatelet therapy for RCVS as if it were atherosclerotic stenting. CVT anticoagulation despite hemorrhage is the classic counterintuitive move already taught in the venous-stroke chapter; here the trigger is the puerperium.
Blood-pressure targets in eclampsia/PRES are treat severe-range hypertension while avoiding a sudden plunge that wipes out cerebral and placental perfusion. There is no single secret number that replaces treating ≥160/110 mm Hg and watching the neurologic exam.
Post-organ transplant
Three neurologic disaster clusters dominate the transplant ICU.
Calcineurin-inhibitor PRES. Tacrolimus and cyclosporine cause PRES, tremor, seizures, and sometimes atypical edema that is not strictly posterior. Check a drug level, but toxicity can occur in the “therapeutic” range. Reduce or switch the calcineurin inhibitor, control blood pressure, and treat seizures. Do not double the tacrolimus because the patient is “rejecting” when the MRI is PRES.
Opportunistic CNS infection. Timing follows immunosuppression: early bacterial surgical infection, then months of Aspergillus (stroke plus hemorrhage, ring lesions), Cryptococcus (high-pressure meningitis), Toxoplasma (ring-enhancing, especially after heart transplant or in patients off prophylaxis), Nocardia, Listeria, JC-virus PML, HHV-6 limbic encephalitis after hematopoietic transplant, and CMV. Steroids and more calcineurin inhibitor without an infection search is how these patients die. Send CSF, antigen tests, and MRI before you call every lesion PTLD.
Lymphoma and PTLD. Epstein–Barr virus–associated post-transplant lymphoproliferative disorder and primary CNS lymphoma present with mass lesions, leptomeningeal disease, or encephalitis. Treatment conceptually includes reducing immunosuppression, rituximab-based therapy, and high-dose methotrexate regimens in selected patients. Biopsy when safe; empiric steroids can again vanish lymphoma.
Graft-versus-host disease, PRES from other drugs (including VEGF blockade), and calcineurin-inhibitor thrombotic microangiopathy round out the differential. The stem’s timeline and drug list matter more than a rare eponym.
Pediatric patients on a predominantly adult exam
You will see pediatric stems. The shared examination covers pediatric patients (03.U) even when your diploma says internal medicine. What you will not see is a published, pediatric-only percent-correct cut score for ABIM candidates. Scoring is a criterion-referenced total standard score on the 270-item test; do not memorize a fake pediatric passing percentage.
Age-based brain death / death by neurologic criteria (BD/DNC). The 2023 AAN/AAP/CNS/SCCM consensus guideline unifies pediatric and adult determination with age-specific rules:
- Do not determine BD/DNC before 37 weeks postmenstrual age.
- In children younger than 18 years, two attending clinicians perform independent examinations, with an observation interval of 12 hours for all pediatric ages in the 2023 document (replacing the older 24-hour/12-hour age split).
- In adults, a minimum of one examination is required; a second examiner may be added.
- Pediatric blood-pressure prerequisites use SBP and MAP at least the 5th percentile for age, not the adult 100/75 mm Hg pair alone.
- Two apnea tests are described for children versus one in adults in summaries of the 2023 pathway; ancillary testing is used when the examination or apnea test cannot be completed.
Full prerequisites, the apnea carbon dioxide rule (PaCO2 ≥60 mm Hg and ≥20 mm Hg above baseline), and ancillary-test details live in the brain-death chapter. Here the point is: children are not small adults on the observation clock.
Different dosing. Pediatric infusions, osmotic agents, antiseizure loads, and sedation are weight-based, with age-specific hemodynamics and a smaller margin for propofol-infusion syndrome in children. Do not copy an adult 4 mg lorazepam cap onto a 12 kg toddler, and do not invent an official exam “pediatric dose table” that ABPN did not publish. Use known pediatric emergency doses when a stem gives a weight.
Abusive head trauma (AHT). Recognize the mismatch: a trivial history, an infant with subdural hemorrhage, retinal hemorrhages, and encephalopathy, plus additional injuries (posterior rib fractures, metaphyseal lesions, bruising). The triad is not pathognomonic—glutaric aciduria, coagulopathy, and accidental trauma remain on the list—but the ICU obligation is to protect the child, document, involve child protection, obtain a skeletal survey and dilated retinal exam, and avoid contaminating the history with leading questions. Hypoxic-ischemic injury on MRI is common in severe AHT and does not by itself equal a natural SIDS death.
Congenital heart disease and ECMO. Neonatal and infant heart surgery and extracorporeal membrane oxygenation (ECMO) produce stroke, intracranial hemorrhage on anticoagulation, seizures, white-matter injury, and cannulation-related carotid complications on VA ECMO. Deep hypothermic circulatory arrest historically associated with choreoathetosis. The internist-neurointensivist may be asked to manage anticoagulation-related ICH, EEG monitoring, or BD/DNC on ECMO (specialized apnea and ancillary rules). Anticipate neurologic injury rather than assuming a perfect circuit means a perfect brain.
Examination traps
- Phenytoin-first for a 32-week eclamptic seizure.
- Ignoring postpartum thunderclap because delivery is over.
- Raising tacrolimus in PRES.
- Declaring pediatric brain death with a single adult-style examination at 36 weeks postmenstrual age.
- Inventing a pediatric passing score.
- Dismissing AHT because the caregiver’s story is confident.
A 28-year-old at 34 weeks has a 3-minute generalized seizure, blood pressure 182/114 mm Hg, and proteinuria. Which first antiseizure plan is correct?
Ten days after kidney transplant, a patient on tacrolimus has seizures and posterior-predominant vasogenic edema. Which statement is most accurate?
Which 2023 BD/DNC statement about children is correct on this shared exam?
A 4-month-old arrives unresponsive. The caregiver describes a short fall from a couch. There are bilateral subdural collections, multilayered retinal hemorrhages, and a posterior rib fracture. Which ICU statement is most accurate?