Approach
The diagnosis of NVP is largely clinical. Typically, NVP begins between the fourth and eighth week after the last menstrual period and resolves in the second trimester. For a patient between 7 and 20 weeks' estimated gestational age, no evaluation is necessary if the patient has the typical symptoms of nausea and vomiting but without signs of volume depletion or electrolyte imbalances. However, any patient demonstrating volume depletion or electrolyte imbalances should be evaluated for the presence of hyperemesis gravidarum (characterized by persistent vomiting, volume depletion and electrolyte imbalance, ketosis, and >5% weight loss) and to exclude alternative potentially serious etiologies for their symptoms.
History and clinical examination
A full medical history should be taken to include recognized risk factors for NVP (e.g., previous episodes of NVP and any family history). The sex of the fetus should be ascertained (female sex may confer weak risk), and whether the pregnancy is single or multiple.[10] As fetal abnormalities (e.g., gestational trophoblastic disease, fetal trisomy, hydrops fetalis) also increase the risk, available information regarding the presence of such should be obtained from either the patient or her obstetric provider.[1]
Patients may report mild epigastric discomfort after retching. More significant abdominal pain, abdominal tenderness, fever, and headache are not present in NVP; seek an alternative diagnosis if these symptoms and signs are present.[2] Patients presenting with NVP should have their vital signs checked and reviewed with each visit. Care should be taken to identify orthostatic vital signs of volume depletion such as tachycardia and hypotension. Additionally, a weight loss of >5% should be considered supportive of hyperemesis gravidarum.[12]
On physical examination, mucous membranes should be evaluated for hydration. Additionally, as thyroid function tests may be abnormal in NVP, the neck should be palpated for the presence of thyroid enlargement or thyroid nodules.[2] Neurologic examination should focus on signs and symptoms of pseudotumor cerebri (headache, papilledema), vestibular disturbances (vertigo, nystagmus), and tumors (headache, focal neurology) to exclude central nervous system pathology as a cause of nausea and vomiting. Postural dizziness or ketotic breath is suggestive of significant volume depletion due to hyperemesis gravidarum.
Laboratory investigations
Any patient demonstrating signs of volume depletion or having >5% weight loss should be investigated to assess the extent of systemic upset in NVP and to exclude alternative etiologies of nausea and vomiting. Workup should include a complete blood count, basic metabolic panel, thyroid function tests, liver function tests, serum blood urea nitrogen and creatinine, and urinalysis. If vomiting is severe, urine/serum ketones should be ordered. Assessment of any Helicobacter pylori infection may be of value. Assessments for nuchal translucency, serum analytes, and screening for trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and fetal triploidy is encouraged.
Additional investigations may include serum amylase and lipase to exclude acute pancreatitis and, if urinalysis shows pyuria, urine culture to exclude pyelonephritis.
Radiology
Any patient demonstrating signs of volume depletion or having >5% weight loss should have a pelvic ultrasound to evaluate for the presence of multiple gestation, gestational trophoblastic disease, and hydrops fetalis.
If liver function tests are consistent with an obstructive pattern, an abdominal ultrasound should be performed to rule out biliary tract disease and pancreatitis. If urinalysis demonstrates hematuria and history or physical exam suggests kidney stones, a renal ultrasound should be obtained.
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