Tests
1st tests to order
clinical diagnosis
Test
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.
Result
clinical features of NVP
Tests to consider
CBC
Test
Order to exclude alternative etiologies of nausea and vomiting.
Abnormalities are unusual in NVP and hyperemesis.
Result
normal
basic metabolic panel
Test
Usually normal in uncomplicated NVP, but hyponatremia and hypochloremia common in hyperemesis.
Consistent with persistent vomiting and volume depletion.
Result
variable; hyponatremia and hypochloremia
serum LFTs
Test
Order to exclude alternative etiologies of nausea and vomiting.
Typically normal in hyperemesis.
Elevated in pancreatitis, hepatitis, biliary tract disease.
Result
normal
serum BUN and creatinine
Test
Commonly elevated in hyperemesis.
Consistent with persistent vomiting and volume depletion.
Result
variable; elevated in hyperemesis
serum thyroid-stimulating hormone (TSH) and free thyroxine (T4)
Test
Decreased TSH is common in women with hyperemesis; elevated human chorionic gonadotropin may be the cause.[1]
If TSH is low then serum-free T4 should be ordered to exclude hyperthyroidism.
T4 is elevated in hyperthyroidism and normal in hyperemesis.
Result
variable; decreased TSH, normal T4
urinalysis
Test
Presence of ketonuria and elevated specific gravity is consistent with volume depletion and hyperemesis.
Presence of pyuria should prompt consideration of pyelonephritis as an alternative diagnosis.
Result
ketonuria and elevated specific gravity
urine or serum ketones
Test
Consistent with hyperemesis.
Result
positive
fetal ultrasound with nuchal translucency
Test
Nuchal translucency should be measured as part of first-trimester screening.
Presence of trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), fetal triploidy, multiple gestation, gestational trophoblastic disease, or hydrops fetalis increases the risk of hyperemesis.
Result
variable; may show multiple gestation, gestational trophoblastic disease, hydrops fetalis; may show increased nuchal translucency
serum analytes
Test
Order as part of first-trimester screening.
Presence of trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), or fetal triploidy increases the risk of hyperemesis.
Abnormal levels of human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein-A (PAPP-A) have predictive value for screening in conjunction with nuchal translucency.
Result
variable; abnormally high or low hCG and PAPP-A
Helicobacter pylori breath test
Test
In one study, 61.8% of women with hyperemesis were positive for H pylori, compared with 27.6% without hyperemesis.[7]
Result
variable; positive result if Helicobacter pylori present
urine culture
Test
Order to exclude pyelonephritis as an alternative diagnosis for nausea and vomiting.
Result
normal
serum amylase and lipase
Test
Order to exclude pancreatitis as an alternative diagnosis for nausea and vomiting.
If abnormal, follow-up should include right upper quadrant ultrasound.
Result
normal
abdominal ultrasound
Test
Order to exclude alternative etiologies of nausea and vomiting (e.g., gallstones, pancreatitis, and hepatitis).
Result
normal
renal ultrasound
Test
Order to exclude kidney stones as an alternative diagnosis for nausea and vomiting.
Result
normal
cranial CT or MRI
Test
Order to exclude alternative etiologies of nausea and vomiting (e.g., pseudotumor cerebri, central nervous system tumors).
Result
normal
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