2010 OB/GYN Clinical Pearls

Physiology of Reproductive Cycle

When one encounters cycle abnormalities, the key is to identify the substance that is elevated or reduced. A systematic review of the HPO axis will frequently elucidate a cause.

Clinical studies of women with hypothalamic amenorrhea have demonstrated that it is possible to stimulate ovulation with primarily FSH, and that only passive amounts of LH are needed.

A key to remembering the menstrual cycle components and their relationships is to understand the goal of the cycle is to ovulate and establish a pregnancy.

The keys to success with IVF are stimulating the ovary appropriately, having a great lab, being patient and doing a great job on the embryo transfer.

The first IVF pregnancy was ectopic; the second was an IUP. The first successful cycle was about the 168th attempt and involved no stimulation medicines, and a laparotomy for egg retrieval. Her parents later conceived with IVF again.

Contraception

If someone will be immobilized (knee surgery, scoliosis surgery), stop pills.

Condom prescribing precautions. 2-3% of Americans have latex allergy. Non-latex condoms available (Durex-Avanti, Trojan Supra, Reality). Spermicide allergy: spermicide–free condoms available

First Trimester OB problems

There can be a physiologic suppression of TSH by hCG (same a-subunits). Also, total T4 increases in pregnancy because of estrogen-stimulated increase in thyroid binding globulin. Thus, need to check free T4 to rule out hyperthyroidism.

Vitamin B6 25 mg po BID and Unisom 1 tab at night (and if needed ½ tab in the morning) is a safe, easy, and relatively effective over-the-counter remedy for EG and mild HG.

If HG is refractory to other medical Rx, methylprednisolone 16 mg po TID x 3 days and then 2-week taper may provide improved control of symptoms.

In early losses, the most common chromosome anomaly is monosomy X (45,X), a.k.a. Turner Syndrome. The most conmon trisomy is trisomy 16, followed by trisomies 22 and 21. In general, the recurrence risk for future fetal aneuploidy is increased (usually 1-2%) except for monosomy X and triploidy which appear to maintain baseline risk.

The definition of abnormal fetal heart rate (FHR) varies with gestational age. FHR is abnormal if: < 100 bpm @ < 6 wks; < 120 bpm @ 6-8 wks

Most common dosing of Misoprostol in clinical practice is 400-800 mcg per vagina every 4-6 hours. Most patients have successful expulsion of the pregnancy loss within 24-48 hours.

If serum β-hCG is > 1500 mlU/ml and no pregnancy is seen in the uterus on transvaginal ultrasound, assume there is an ectopic until proven otherwise.

Medical therapy has an unacceptably higher failure rate for treatment of ectopic pregnancies that are large (> 4 cm) and with fetal heart motion.

Maternal-Fetal-Placental Physiology

Diastolic murmurs noted in pregnancy require evaluation, as they are never a normal part of pregnancy changes.

Multiparous pregnant women generally have iron deficiency anemia if not supplied with iron supplements previously. The patients’ blood count (CBC) will show microcytic (MCV < 80), hypochromic (MCH < 28) red blood cell indices.

The dyspnea of pregnancy experienced by many pregnant women in early gestation is due to a respiratory effect of progesterone. In later pregnancy, the mass effect of the gravid uterus commonly creates respiratory symptoms, especially when lying supine.

Patients with glucosuria have an increased risk for urinary track infections.

Skin nevi may darken and enlarge in pregnancy but removal of rapidly changing nevi in pregnancy is still recommended if clinically indicated.

Pregnant women in the first trimester with hyperemesis gravidarum, or uncontrolled vomiting in early pregnancy, (misnamed "morning sickness") may have abnormally low TSH levels that mimic hyperthyroid patients. The low TSH results from the feedback loop on the CNS by high HCG levels characteristic of early pregnancy in hyperemesis patients. In the absence of overt hyperthyroidism, the low TSH levels spontaneously resolve by mid-gestation without treatment with anti-thyroid medications.

Dental disease is associated with an increased risk for preterm delivery, although data are insufficient to assign cause and effect.

The fetus maintains adequate oxygen delivery to tissues because of a high cardiac output.

An increase in maternal blood oxygen content by increasing her inhaled oxygen level can raise delivery of oxygen to the fetus.

Life threatening bleeding can occur at any time, but with increased frequency as term is approached, in women with placenta previa or women with signs of abruption placentae.

Patients who present in the second half of pregnancy with unexplained vaginal bleeding should be assumed to have a placenta previa until proven otherwise. No vaginal exam should thus be conducted, since life-threatening bleeding may result from disruption of the placenta covering the cervical os.

Problem Pregnancies

A key component of the first prenatal care visit is to perform risk assessment for preterm birth.

The purpose of tocolysis is to allow time for the administration of corticosteroids, or to arrange transfer to a tertiary care facility.

Patients expectantly managed with PPROM are at increased risk of infection, and should be observed for maternal or fetal signs of intraamniotic infection.

In one randomized trial, weekly administration of 17-OHP was found to reduce the recurrence of spontaneous preterm birth.

Preeclampsia at term is generally an indication for delivery.

Watch for magnesium toxicity in patients with altered renal function. May need to adjust maintenance dose of MgSO4.

Reproductive Genetics/Prenatal Diagnosis

Sufficient hCG is secreted by second week after conception (by menstrual day 21-28) to produce a positive pregnancy test.

When a patient gives history of a family member with child with trisomy (such as Trisomy 21), this does not increase the risk for this pregnancy. 95% are non-disjunctional trisomies, 3% translocations, 2% mosaics.

There is no time in pregnancy when alcohol consumption can be considered “safe”.

Clinical Examples:

Pregnant patient has a sister born with a heart defect, with no other malformations or learning problems. Likelihood high for multifactorial inheritance, risk to fetus ~1%, which is not significantly different from general population risk for CHD. What should we offer this patient?

o Reassurance through targeted high-resolution prenatal ultrasound exam/fetal echo.

Patient has sibling with cystic fibrosis (autosomal recessive). Risk for unaffected patient to be CF carrier = 2/3. Risk for father to be carrier (Caucasian) ~1/25. Risk for affected child = 2/3 X 1/25 X ¼ = 1/150. Mutation analysis is possible but there are > 900 mutations identified. What are options for further evaluation?

o Best option: Identify mutations of affected relative & test patient for same mutations. Next best option: Test patient for as many mutations as possible & then if

negative, reduce her risk of being carrier.o Test father of fetuso If both parents are carriers, offer prenatal diagnosis for fetus.

Mrs. J. will be 36 years of age at delivery, her risk of having a child with any chromosome abnormality is 1/148, risk of trisomy 21 is 1/267. She is currently 8 weeks pregnant and is employed as a special education teacher. She and her husband would like to know with certainty whether or not they are expecting a child with a chromosome abnormality. What are her options?

o Must use diagnostic (not screening) tests: CVS in 2-4 weeks Genetic amniocentesis in 6-8 weeks

Mr. and Mrs. K are unrelated and of Chinese descent. Mrs. K. is pregnant with their second child and anemic. Her husband has not seen a doctor since childhood. You obtain a CBC which shows hemoglobin of 10.1 and a MCV of 63. Her hemoglobin electrophoresis and serum ferritin level are normal. What is the likely cause? She is now 21 weeks pregnant and an ultrasound shows that the baby is hydropic (swelling of the skin, ascites, pleural effusions). Why?

o Mrs. K has the alpha-thalassemia trait. o Mr. K probably also carries the alpha-thalassemia trait, and the baby has Hb Barts,

causing the hydrops fetalis.

Menopause, Osteoporosis, and HRT

Measurement of serum FSH is the most effective way to differentiate the etiology of low estrogen. Low estrogen from any cause can cause menopausal signs and symptoms. If it is associated with elevated FSH, it is menopause; i.e., ovarian failure.

Estrogen replacement definitely helps vasomotor symptoms and urogenital atrophy. Estrogen replacement can treat osteoporosis, but other therapies exist. Estrogen replacement improves sense of well being in some patients, but this is a complex issue with many other variables.

Many of the emotional signs and symptoms of menopause—fatigue, irritability, apprehension, decreased libido, headache, and feelings of inadequacy—are often due to lack of sleep, a common problem in menopause.

For elderly women, the most common impediment to regular sexual activity is the lack of a partner. Men have health problems and die earlier than women. This lack of a partner also makes women vulnerable to predatory men. HIV/AIDS is a health risk in this population.

Decrease in 1 SD in bone density is associated with 2-fold increase in fracture risk.

The best method to screen and monitor therapy for osteopenia and osteoporosis is DXA (dual-energy x-ray absorptiometry) of the lumbar spine and proximal femur.

Tamoxifen is used primarily to prevent recurrence of breast cancer. It has a maximum time limit of 5 years because it has weak estrogen activity on the uterine endometrium, increasing the risk of endometrial carcinoma after this time. Also, there is no further decrease in breast cancer risk of recurrence with greater than 5 years of Tamoxifen use. If a patient has uterine bleeding while on Tamoxifen, an endometrial biopsy should be performed to rule out this uterine cancer.

Treatment of hot flushes is a complex issue. Double blind studies demonstrate a consistent placebo success rate of 10-30%. Studies of the above prescription and non-prescription products sometimes show success for treatment of hot flushes greater than placebo, but most studies do not.

These products [botanicals] are neither drugs nor foods under present regulations, so manufacturers do not have to provide any evidence to support purported benefits before marketing their products. The FDA oversees the industry, but the FTC is responsible for identifying inappropriate or unsubstantiated claims.

Since the progestin component of HRT appears to contribute to an increased risk of breast cancer, ERT rather than HRT should be used in women without a uterus if estrogen is used for the treatment of menopausal signs and symptoms.

When counseling patients concerning this confusing and complex issue, it is important that she know that the overall death rate in women who use ERT, and those that do not, is the same. Newspaper headlines and talk shows suggest otherwise.

We must individualize our therapy for women in the menopause. Signs, symptoms, risk factors, and the wishes of the patient should guide our therapy recommendations. New data may well alter our current recommendations.

Data suggest that majority of benefits of HRT/ERT, particularly cardiovascular, accrue to patients treated early in menopause, and the reverse occurs if therapy is begun distant from onset of menopause.

These new data indicate once more that we must individualize our therapy for women in the menopause. Signs, symptoms, risk factors, and desire of patient will guide our therapy recommendations. New data will alter our current recommendations.