Differential Diagnosis for Postpartum Change
Single Most Likely Diagnosis
- Postpartum Psychosis: This condition is characterized by the sudden onset of psychotic symptoms, such as delusions and hallucinations, within the first few weeks after childbirth. The patient's history of mood changes, rapid speech, agitation, flight of ideas, and delusional thoughts, especially the conviction of harming her son, are highly suggestive of postpartum psychosis. The history of previous psychiatric admission for mania and the rejection of a diagnosis of bipolar disorder could indicate a predisposition to mood disorders, which are risk factors for postpartum psychosis.
Other Likely Diagnoses
- Bipolar Disorder with Postpartum Onset: Despite the patient's previous rejection of this diagnosis, the symptoms of rapid speech, agitation, flight of ideas, and mood swings (euphoric and tearful, irritable) are consistent with a manic or hypomanic episode. The postpartum period can trigger the onset of bipolar disorder in susceptible individuals.
- Postpartum Depression with Psychotic Features: While the patient exhibits more manic-like symptoms, postpartum depression can sometimes present with psychotic features, including delusions and hallucinations. The tearfulness and irritability could also be part of a depressive presentation.
Do Not Miss Diagnoses
- Puerperal Thyroiditis: Although lab abnormalities are mentioned as absent, thyroid function tests might not have been conducted or could be pending. Puerperal thyroiditis can cause mood changes, anxiety, and irritability due to transient hyperthyroidism or hypothyroidism following childbirth.
- Postpartum Preeclampsia: This condition can present with severe headaches, visual disturbances, and right upper quadrant abdominal pain, but in rare cases, it might also cause alterations in mental status, including confusion, agitation, or even psychosis due to cerebral edema or stroke.
Rare Diagnoses
- Organic Psychotic Disorder: Although rare, conditions such as cerebral venous thrombosis or other postpartum vascular events could lead to psychotic symptoms. The absence of other neurological deficits or specific risk factors makes this less likely but not impossible.
- Autoimmune Encephalitis: This is a rare condition that can present with psychosis, mood changes, and sometimes delusions, among other neurological symptoms. It would be an unusual cause of postpartum psychosis but could be considered if other diagnoses are ruled out and there are additional neurological findings.