Definition:
Mild to moderate nausea and vomiting are seen commonly
until approximately 16 weeks in most pregnant ladies. Although nausea and
vomiting tend to be worse in the morning, thus erroneously termed morning
sickness, they frequently continue throughout the day. In some cases, however,
it is severe and unresponsive to simple dietary modification and antiemetics.
Hyperemesis gravidarum is defined as vomiting
sufficiently severe to produce weight loss, dehydration, alkalosis from loss of
hydrochloric acid and hypokalemia. Rarely, acidosis from partial starvation and
transient hepatic dysfunction develop.
Modified PUQE scoring index (Pregnancy-Unique
Quantification of Emesis and Nausea) can be used to quantify the severity of
nausea and vomiting.
Epidemiology:
There appears to be an ethnic or familial predilection. The
hospitalization rate for hyperemesis is around 0.5 to 0.8%. Hospitalization is
less common in obese women. In women hospitalized in a previous pregnancy for
hyperemesis, up to 20 percent require hospitalization in a subsequent pregnancy.
Pathophysiology:
Hyperemesis appears to be related to high or rapidly
rising serum levels of pregnancy-related hormones. The presumed culprits
include human chorionic gonadotropin (hCG), estrogens, progesterone, leptin, placental
growth hormone, prolactin, thyroxine and adreno-cortical hormones. Some studies
have implicated the vestibular system while others have showed some involvement
of psychological components.
Other factors that increase the risk for admission
include
1) hyperthyroidism,
2) previous molar pregnancy,
3) diabetes,
4) gastrointestinal illnesses and
5) asthma.
For unknown reasons, a female fetus
increases the risk by 1.5-fold.
Complications:
Vomiting may be prolonged, frequent and severe.
1) Various degrees of acute renal failure from dehydration
are encountered.
2) Life-threatening complications of continuous retching
include Mallory-Weiss tears shown in the figure below. Others are esophageal rupture, pneumothorax and
pneumomediastinum.
3) At least two serious vitamin deficiencies have been
reported with hyperemesis in pregnancy. Wernicke encephalopathy from thiamine (vitamin
B1) deficiency is not uncommon. Vitamin K deficiency has been reported causing
maternal coagulopathy and fetal intracranial hemorrhage.
The photo shows a Mallory Weiss tear with the endoscope in retroflexion.
Management:
1) Eating small meals at more frequent intervals but
stopping short of satiation is valuable. The herbal remedy, ginger, was effective as showed by this meta-analysis published in 2014. Ginger capsules 250 mg 4 times daily.
2) A number of antiemetics given orally or by rectal
suppository as first-line agents. When simple measures fail, intravenous crystalloid
solutions are given to correct dehydration, ketonemia, electrolyte deficits,
and acid-base imbalances. Thiamine, 100 mg, is given to prevent Wernicke encephalopathy. Diclegis (Doxylamine and Pyridoxine (Vitamin B6) ) is the only FDA approved medication for nausea and vomiting in pregnancy.
3) If vomiting persists after rehydration and failed
outpatient management, hospitalization is recommended. Antiemetics such as
- Promethazine 12.5-25 mg 4 hourly,
- Prochlorperazine 5-10 mg 6 hourly,
- Metoclopramide 5-10 mg 8 hourly are given
parenterally.
With persistent vomiting after hospitalization,
appropriate steps should be taken to exclude possible underlying diseases as a
cause of hyperemesis (gastroenteritis, cholecystitis, pancreatitis, hepatitis,
peptic ulcer and pyelonephritis).
Further readings:
Nice article
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