A 24-year-old female presents to the emergency department (ED) with a history of intractable vomiting for 4 weeks. She is 13 weeks pregnant. On examination she appears dehydrated with evidence of recent weight loss. The rest of her examination is normal. Her urine shows ketones 1+ and her blood sugar level is 5.8 mmol/L.
Regarding hyperemesis gravidarum in this case, which ONE of the following statements is FALSE?
Answer: B: Various definitions for hyperemesis gravidarum (HG) exist but the important features are unexplained intractable vomiting associated with weight loss of more than 5% of pre-pregnancy weight, dehydration, electrolyte imbalances (especially hyponatraemia and hypokalaemia), ketosis and vitamin deficiencies. By far the most important serious complication of HG is Wernicke’s encephalopathy as a result of thiamine (vitamin B1) deficiency. In some cases, Wernicke’s encephalopathy has been precipitated by infusion of dextrose-containing solutions before administration of thiamine. In order to prevent this serious complication, it is recommended that when a patient’s vomiting is sufficient to require intravenous hydration, thiamine (100 mg) should be administered parenterally on the assumption there is thiamine deficiency.
Rehydration with 0.9% normal saline or Hartmann’s solution is the first-line initial treatment. Although it is often thought that infusions of dextrose-containing fluids (5% dextrose, 10% dextrose or dextrose saline) are useful to provide the patient with energy, this assumption is erroneous as Wernicke’s encephalopathy may be precipitated by intravenous dextrose, especially in cases of severe or prolonged vomiting. Fluid and electrolyte balance must be reassessed frequently and management adjusted according to clinical assessment and fluid balance.
In cases of ongoing vomiting, antiemetics should be prescribed. Combinations of several parenteral antiemetics may be needed. There is no evidence that any one antiemetic is superior to another and most antiemetics are safe in pregnancy. The TGA risk categorisation of commonly used antiemetics is metoclopromide (A), ondansteron (B1) and promethazine (C).
Vitamin supplementation is essential. Thiamine supplements should be given routinely to all women admitted to hospital for prolonged vomiting. Pyridoxine (vitamin B6) (10–25 mg, three times daily) has been shown to reduce nausea and vomiting of pregnancy, although the effect on vomiting is not clear. In many countries, including Australia, pyridoxine is used first line in combination with an antiemetic. Ginger (in doses equivalent to 1 to 2 g of powdered ginger daily) may also be helpful. If vomiting continues, it is appropriate to consult an obstetrician and consider treatment with corticosteroids and/or hospital admission for rehydration/nutrition.
References:
Regarding ultrasound findings in early pregnancy, which ONE of the following is TRUE?
Answer: C: The first sonographic sign of early pregnancy is the intradecidual sign – a small sac seen at 4–5 weeks, only a few millimeters in diameter, which is completely embedded within the endometrium on one side of the uterine midline, not deforming the midline stripe. The gestational sac is seen shortly thereafter, at about 5 weeks. It is characterized by a sonolucent center, surrounded by a thick symmetric echogenic ring. If a clear double decidual sign is seen with the gestational sac, an IUP is likely. The double decidual sign consists of two concentric echogenic rings surrounding a gestational sac. A gestational sac with a vague or an absent double decidual sign is not diagnostic of an IUP and may be a pseudo-gestational sac associated with an ectopic pregnancy. For this reason, many authors consider the yolk sac as the first definitive evidence of an IUP, rather than the gestational sac.
The yolk sac is the first structure visualized inside the gestational sac and is seen by transvaginal (TV) sonography at about 5–6 weeks. When a higher solution transvaginal probe (≥6.5 MHz) is used, a yolk sac is usually seen within the gestational sac when the mean sac diameter (MSD) ≥10 mm. However, in the ED, trans-abdomial scanning or TV scanning with a lower frequency probe is usually performed, where a yolk sac may not be seen until the MSD ≥20mm. Therefore, for the ED purpose, an empty gestational sac ≥20 mm is a good predictor of fetal demise and is referred to as a blighted ovum.
An indeterminate ultrasound examination in early pregnancy demonstrates no signs of intrauterine or ectopic pregnancy and could still indicate an early pregnancy, embryonic demise or ectopic pregnancy. Serial βHCG and ultrasounds are useful in such cases but for ED purposes, all patients without a confirmed IUP (gestational sac plus yolk sac) should be regarded as an ectopic pregnancy until proven otherwise and the obstetricians should urgently be informed.
Reference:
Regarding the clinical features of ectopic pregnancies, which ONE of the following is TRUE?
Answer: C: Major risk factors for ectopic pregnancy include PID, history of tubal surgery, use of an intrauterine device (IUD), assisted reproduction techniques and a previous ectopic pregnancy. However, more than 50% of cases of ectopic pregnancy occur in patients without recognized risk factors.
Abdominal discomfort or pain is the most common presenting symptom of ectopic pregnancy and occurs in 90% of patients. Pain is due to tubal distention or rupture. Vaginal bleeding occurs in 50–80% of cases and is often scant. However, heavy bleeding does not exclude ectopic pregnancy. Although heavy bleeding and the passage of clots are more common with failed IUP, the history of passage of products of conception should not be used as the basis for diagnosis as blood clots or a decidual cast in an ectopic pregnancy may be misinterpreted as products of conception. The menstrual history is often, but not always, abnormal. No missed menses are reported in 15% of ectopic pregnancies.
Ectopic pregnancy cannot reliably be diagnosed or excluded on physical examination. The cervix may have a blue discoloration, as in normal pregnancy. Furthermore, the uterine size for estimated gestational age is most often normal. The adnexae may be enlarged, particularly unilaterally, due to a cystic corpus luteum or ectopic pregnancy. Interestingly, when an adnexal mass is palpated, one-third of patients will have a contralateral ectopic pregnancy.
Regarding threatened miscarriage in the first trimester of pregnancy, which ONE of the following is TRUE?
Answer: A: Vaginal bleeding is the most common presentation of a threatened miscarriage. However, the severity of bleeding does not correlate with the risk of the patient proceeding to a complete miscarriage. About 50% of pregnant patients with vaginal bleeding will proceed to have a viable pregnancy. However, the presence of cardiac activity on ultrasound significantly reduces this risk, as at least 90% will continue with a normal pregnancy. At the same time, embryonic bradycardia predicts a poor prognosis. A heart rate <100 bpm prior to 6 weeks and <120 bpm between 7 and 8 weeks is associated with a poor outcome. Advice such as bed rest is commonly given to patients to ‘prevent’ miscarriage. This advice is not useful because there is no evidence that any therapy influences outcome. Furthermore, most fetuses can be shown to be nonviable 1 to 2 weeks before actual symptoms occur. In the vast majority of cases, spontaneous miscarriage is the body’s natural method of expelling an abnormal or undeveloped (blighted) pregnancy. Patients should be advised that modern daily activities would not affect pregnancy. Tampons, intercourse and other activities that might induce uterine infection should be avoided as long as the patient is bleeding.
Regarding serial βHCG testing in early pregnancy, which ONE of the following is MOST CORRECT?
Answer: A: A common misconception is that a very low βHCG rules out an ectopic pregnancy. However, studies show that about 40% of ectopic pregnancies present with a βHCG <1000 mIU/mL and about 20% with a βHCG <500 mIU/mL. 62,63 Furthermore, the risk of tubal rupture has been found to be similar across a wide range of βHCG levels and a low level does not predict a benign course. Approximately 30–40% of ectopic pregnancies with a βHCG level <1000 mIU/mL will be ruptured at the time of diagnosis. In another review study, a very low level <100 mIU/mL, 30% were found to be ruptured on laparoscopy.
The discriminatory zone is the lowest concentration of βHCG at which a viable pregnancy should be visible on an ultrasound scan. An intrauterine gestation is usually visible on a transvaginal scan at a βHCG concentration of ≥1500 mIU/mL, and on transabdominal ultrasound if ≥6500 mIU/mL. Diagnostic accuracy is subsequently better if the transvaginal route is used for ultrasound examination but ultrasound is still inconclusive regarding the exact location of a pregnancy in 8–31% of women. In such cases, measurement of serial βHCG concentrations is used to guide management and is best used in conjunction with ultrasound findings. Serial measures of βHCG are used to either heighten or lower the suspicion of ectopic pregnancy, but are not diagnostic.
The pattern of rise or fall in βHCG after 48 hours is useful in distinguishing between pregnancy of unknown locations (PUL) that will develop into failing PUL from intrauterine and ectopic pregnancy, particularly whenever the βHCG levels are lower than the discriminatory zone or when an ultrasound diagnosis cannot be made despite the βHCG being above the discriminatory zone. A doubling of βHCG concentrations over 48 hours is often used to predict viability but an increase of at least 66% is generally regarded as suggestive of a viable pregnancy. However, a large study published in 2004 suggests that the slowest increase associated with viability is 53% after 2 days and many authors now use a minimum rise of >50% as suggestive of viable pregnancy.65 However, an increase in of βHCG >50% does not rule out an ectopic pregnancy. If βHCG levels fall by at least 15%, the most likely outcome is a failing PUL. When the rise or fall in βHCG is suboptimal, the most likely outcome is ectopic pregnancy. However, failing PUL may and 15% of normal pregnancies will have an abnormal doubling time.
Click to expand