Differential Diagnosis for Severe Nausea and Vomiting in Pregnancy

Single Most Likely Diagnosis

• Hyperemesis Gravidarum: This condition is characterized by severe nausea and vomiting during pregnancy, often leading to dehydration and ketosis, as indicated by the presence of ketones in the urine. The symptoms presented, including severe nausea and vomiting, along with the urine test results (+1 protein and positive ketones), align closely with hyperemesis gravidarum, especially considering the patient is pregnant.

Other Likely Diagnoses

• Urinary Tract Infection (UTI): Although less directly related to the nausea and vomiting, a UTI could explain the +1 protein in the urine. However, the presence of ketones and the context of pregnancy make this less likely as the primary diagnosis.
• Gastroenteritis: This could cause severe nausea and vomiting but would not typically result in ketones in the urine unless the patient was significantly dehydrated and not consuming adequate calories, leading to a metabolic state that produces ketones.

Do Not Miss Diagnoses

• Diabetic Ketoacidosis (DKA): Although less common in early pregnancy, DKA is a life-threatening condition that can present with nausea, vomiting, and ketones in the urine. It's crucial to rule out DKA, especially if the patient has a history of diabetes or if there are other suggestive symptoms or lab findings.
• Preeclampsia: While preeclampsia typically presents with hypertension and proteinuria, severe cases can lead to nausea and vomiting. The presence of +1 protein in the urine warrants consideration of preeclampsia, especially if the patient has risk factors or other symptoms such as headaches or vision changes.
• Appendicitis: Although appendicitis is less likely to present with the combination of severe nausea, vomiting, and ketones in the urine, it is a surgical emergency that can occur during pregnancy and must be considered, especially if there is abdominal pain.

Rare Diagnoses

• Molar Pregnancy: A rare condition where a non-viable fertilized egg implants in the uterus, leading to severe nausea and vomiting among other symptoms. While rare, it's an important consideration in the differential diagnosis of severe nausea and vomiting in early pregnancy.
• Thyroid Storm: Although rare, thyroid storm can present with nausea, vomiting, and other systemic symptoms. The presence of ketones could be seen in the context of severe metabolic derangement. This diagnosis would be considered if there were other signs of thyroid dysfunction or a known history of thyroid disease.