Maternal Physiology During Pregnancy

Questions

DIRECTIONS (Questions 1 through 27): For each of the multiple choice questions in this section, select the lettered answer that is the one best response in each case.

1. Most state-of-the-art serum pregnancy tests have a sensitivity for detection of β-human chorionic gonadotropin (β-hCG) of 25 mLU/ mL. Such tests would diagnose pregnancy as early as which of the following?

(A) 5 days after fertilization (B) 24 hours after implantation

(D) 5 weeks’ gestation age by menstrual dating (E) 6 weeks’ gestation age by menstrual dating

2. A 35-year-old G5P4004 patient is found to have ASCUS on her Pap smear done at her new obstetrics (OB) visit. In your counseling of the patient as to what this result means, you note that the hormonal changes of pregnancy will cause changes in the cervix. Which of the following cervical changes may be found more frequently in the pregnant state than in the nonpregnant state?

(A) atypical glandular hyperplasia (B) dysplasia

(E) vaginal adenosis

3. A 16-year-old G1P0 patient is brought for an examination due to a probable pregnancy. The patient says that she became sexually active approximately 5 months ago. To estimate her gestational age, you palpate the abdomen. At approximately 20 weeks’ estimated gestational age, which of the following best describes the uterus in a normal pregnancy?

(A) not palpable abdominally

(B) palpable at the level of the umbilicus (C) palpable at the level of the xiphoid (D) palpable just over the symphysis pubis

(E) palpable midway between the umbilicus and the sternum

4. A 21-year-old G1 now P1 just delivered after a prolonged induction of labor due to being postdates.

After the placental delivery she continues to bleed excessively. Your initial intervention to address this bleeding is to activate the normal physiologic mechanisms. Which of the following is the most

important hemostatic mechanism in combating postpartum hemorrhage?

(A) contraction of interlacing uterine muscle bundles (B) fibrinolysis inhibition

(D) intramyometrial vascular coagulation due to vasoconstriction (E) markedly decreased blood pressure in the uterine venules

5. The uterus must increase its volume over the course of a pregnancy from less than 20 cc to over 5 L.

This is accomplished while still maintaining the ability for the uterine muscles to contract with enough force to expel the infant during labor. The uterine muscle mass enlarges during pregnancy primarily because of which of the following?

(A) atypical hyperplasia (B) anaplasia

(E) production of new myocytes

6. During a pelvic examination on a patient that is approximately 8 weeks’ gestation by dates and pelvic examination, one adnexa is found to be slightly enlarged. This is most commonly due to which of the following?

(A) corpus luteum cyst (B) ectopic pregnancy (C) follicular cyst (D) ovarian neoplasm (E) parovarian cyst

7. A patient presents for her new obstetrical (OB) examination. She is 23 years of age and G1PO at 10 weeks without problems. Her prepregnant body mass index (BMI) was 22. As part of her pregnancy- based education, you inform her that she should follow a balanced diet with a recommended weight gain of approximately how many pounds?

(A) 5–10 (B) 10–15 (C) 15–20 (D) 25–35 (E) 30–40

8. A patient presents for her routine prenatal visit at 34 weeks’ estimated gestational age (EGA). She is complaining to the nurse of back pain. Her pulse and temperature are normal as well as her urine dip.

After the examination you determine that it is due to exaggerate posture caused by her weight (BMI 35) and her pregnancy. Which of the following is a characteristic posture of pregnancy?

(A) hyperextension (B) kyphosis

(E) scoliosis

9. A pregnant patient presents very concerned about some skin lesions/changes she is seeing that are just like her uncle’s who has liver cirrhosis from hepatitis C. What lesions or changes are she likely

referring to?

(A) hyperpigmentation and spider angiomata (B) linea nigra and chloasma

(E) striae and linea nigra

10. The physiologic changes of pregnancy can alter many of the common laboratory tests. During the evaluation of a patient with tachycardia, hypertension, and headache you are considering both

hyperthyroidism versus an atypical preeclampsia and draw the following laboratory tests. To correctly interpret the results, it is necessary to distinguish between normal versus abnormal changes during pregnancy. Which of the following would normally be expected to increase during pregnancy?

(A) alanine aminotransferase (ALT) (B) aspartate aminotransferase (AST) (C) hematocrit

(D) plasma creatinine

(E) thyroxine-binding globulin (TBG)

11. A patient presents complaining of a friable painful local buildup of her gums around the base of a number of teeth. This is starting to interfere with eating due to pain and bleeding. She has not seen a dentist for some time due to finances. The remainder of the pregnancy has been uncomplicated. These changes are likely due to which of the following?

(A) abscessed tooth (B) decidualization (C) epulis of pregnancy (D) melasma

(E) spider hemangioma

Questions 12 through 14 apply to the following patient:

A patient at 19 weeks’ EGA is evaluated for vague gastrointestinal/abdominal complaints, and there is concern for possible appendicitis. She notes diffuse abdominal pain, some nausea, and temperature of 37.3°C. She is not particularly hungry but lacks anorexia. She does have new onset nausea. She has positive bowel sounds. There is a negative psoas sign and only diffuse periumbilical tenderness without rebound. Her white blood cell (WBC) count is 11,000 and remainder of liver functions and pancreatic laboratories are within normal limits.

12. Considerations in the evaluation are sensitive to the changes in the gastrointestinal (GI) tract during pregnancy include which of the following?

(A) compression and downward displacement of the appendix by the uterus (B) increased intestinal absorption helping to ensure weight gain

(E) physical elevation of the stomach

13. Given her presenting complaints and initial physical and laboratory testing, which one of the following represents an abnormal value?

(A) temperature 37.3°C

(B) only nausea without emesis (C) negative psoas sign

(D) white blood cell (WBC) count of 11,000 (E) bowel sounds

14. It is determined that imaging is needed to evaluate the pain further. What is the best imaging test to order?

(A) abdominal/pelvic ultrasound (B) KUB of the abdomen

Questions 15 and 16 apply to the following patient:

A patient presents to OB triage unit with complaints of back pain and fever. She is 30 weeks’ EGA. She had asymptomatic bacteria at her initial OB visit that was treated. Her temperature is 38.5°C and she has CVA tenderness. Because of changes in the urinary tract during pregnancy, patients are at greater risk for urinary tract infections.

15. Changes in the urinary tract during normal pregnancy include which of the following?

(A) decrease in renal plasma flow (RPF)

(B) increase in the amount of dead space in urinary tract (C) increase in blood urea nitrogen (BUN) and creatinine (D) increase in glomerular filtration rate (GFR)

(E) marked increase in both GFR and RPF when the patient is supine

16. On further questioning, a concern for renal stones possibly contributing to the infection is raised. It is decided to perform a one shot intravenous pyelogram (IVP) to evaluate for renal obstruction. If an IVP were performed in the third trimester, normal findings in pregnancy would include which of the

following?

(A) kidneys appearing smaller than normal because of diaphragmatic compression (B) obstruction of the right ureter secondary to the dextrorotation of the uterus (C) sediment in the renal collecting system due to the stasis effect of progesterone

(D) ureteral dilation, probably secondary to progesterone effect, and compression of the lower urinary tract by the uterus

(E) vesicoureteral reflux secondary to stretching of the trigone by the enlarging uterus 17. At the initial OB visit your patients receive nutritional information. Iron supplementation is

recommended in pregnancy in order to do which of the following?

(A) maintain the maternal hemoglobin concentration (B) prevent iron deficiency in the fetus

(E) raise the maternal hemoglobin concentration

18. A 22-year-old G3P2002 who had a hematocrit of 36% at her initial obstetrical examination at 12 weeks is found to have a hematocrit of 30% at 28 weeks when checked along with her 1 hour glucola.

Based on the indices of the red blood cells on the CBC, you diagnose iron deficiency. She asks why that occurred since she has been taking her prenatal vitamins. As part of the explanation, you note that which of the following maternal measurements or findings is first decreased by the iron requirements of pregnancy?

(A) bone marrow iron (B) hemoglobin

(E) serum iron-binding capacity

19. During pregnancy the blood volume increases by 40%. The increase in blood volume in normal pregnancy is made up of which of the following?

(A) erythrocytes

(B) more erythrocytes than plasma (C) more plasma than erythrocytes (D) neither plasma nor erythrocytes (E) plasma only

20. In response to the increased vascular volume, the maternal cardiovascular system undergoes great change during pregnancy. During prenatal care, which of the following findings is part of the

cardiovascular response to this increase in preload?

(A) apical systolic murmurs are heard in approximately half of pregnant patients (B) arrhythmias are common

(D) the heart enlarges greatly, as can be demonstrated by standard chest X-rays (E) the stroke volume decreases

21. During pregnancy, the hormonal system of a woman is markedly altered since the fetus and placenta add their production to the maternal hormone production. This impacts maternal physiology and some of the findings of pregnancy. Estrogen is such a hormone that increases markedly. Most of this estrogen is produced by which of the following?

(A) adrenals (B) fetus (C) ovaries (D) placenta (E) uterus

Questions 22 and 23 apply to the following patient:

A patient presents for preconceptive counseling. Her history is complicated by significant mitral stenosis.

You tell her that this may be problematic at times of high cardiac output in pregnancy. Because of the fixed outflow, she could experience heart failure.

22. The time at which cardiac output is highest is during which phase of pregnancy?

(A) in the first trimester

(B) in the second trimester (C) in the third trimester (D) during labor

(E) immediately postpartum (10–30 minutes)

23. Which of the following factors contribute to the increase in cardiac output in pregnancy?

(A) decrease in blood volume (B) increase in ejection fraction (C) increase in heart rate

(D) increase in left ventricular stroke work index (E) increase in systemic vascular resistance Questions 24 and 25 apply to the following patient:

A 24-year-old nurse at 32 weeks’ gestation complains of shortness of breath during her pregnancy, especially with physical exertion. She has no prior medical history. Her respiratory rate is 16; her lungs are clear to auscultation; and your office oxygen saturation monitor reveals her oxygen saturation to be 98% on room air.

24. You reassure her that this sensation is normal and explain which of the following?

(A) Airway conductance is decreased during pregnancy.

(B) Because of enlarging uterus pushing up on the diaphragm, her vital capacity is decreased by 20%.

(D) Pulmonary resistance increases during pregnancy.

(E) Small amniotic fluid emboli are shed throughout pregnancy.

25. She urges you to perform pulmonary function tests. Assuming that your medical judgment is correct, these tests should show which of the following?

(A) diminished vital capacity

(B) increased functional residual capacity (FRC) (C) increased reserve volume (RV)

(D) increased tidal volume

(E) unchanged expiratory reserve volume (ERV)

26. A 25-year-old G3P2 in her sixth week of pregnancy, by last menstrual period (LMP) calculation, has an endovaginal ultrasound examination because of vaginal bleeding. The ultrasound confirms an

intrauterine pregnancy with fetal cardiac activity present and fetal pole length consistent with 6 weeks’

gestation. Scan of the adnexae reveals a 5-cm simple cyst on the left ovary. Which of the following statements is true?

(A) This patient likely has both an intrauterine pregnancy and an ectopic pregnancy.

(B) This patient should be told that she will probably miscarry.

(D) First-trimester vaginal bleeding is uncommon and implies a poor pregnancy outcome.

(E) This patient has a blighted ovum.

27. Most obstetrical providers screen pregnant women for gestational diabetes around 28 weeks’

gestation. The increased risk of developing diabetes in pregnancy is due to which of the following?

(A) decreased fetal glucose requirements

(B) decreased free fatty acids in maternal circulation (C) increased maternal glucose requirements

(D) peripheral insulin resistance (E) shorter insulin half life

Answers and Explanations

1. (C) Circulating β-hCG in early pregnancy at a level of 25 mLU/mL is detected in most women by 12 to 13 days after the luteinizing hormone (LH) peak. Therefore, the test should be positive by the date of the expected menses.

2. (C) Metaplasia from hormonally induced changes in the squamocolumnar junction is common in pregnancy. Dysplasia or atypia is not common and needs to be evaluated. The cervix can be

histologically evaluated for malignant change during pregnancy as well as during the nonpregnant state.

Pap smears and colposcopy are both reliable. Dysplasia is probably best not treated until the

postpartum period. However, CIS or microinvasive cervical cancer may be treated depending on the gestational age.

3. (B) This measurement is only a rough guide to the duration of gestation. It may be increased by twins, myomas, and hydramnios and decreased by oligohydramnios, intrauterine growth retardation, fetal death, and so on. Considerable individual variation is also common. One study found up to 3-cm difference, depending on whether the fundal height was measured with the gravida’s bladder full or empty (see Figure 6–1).

Figure 6–1. Fundal height in pregnancy. (Reproduced, with permission, from DeCherney AH, Nathan L. Current Obstetric and Gynecologic Diagnosis and Treatment, 9th ed. New York:

McGraw-Hill, 2003.)

4. (A) If uterine atony exists, the muscles do not provide the pressure on the endometrial vessels needed to occlude them. Methods such as massage and oxytocin administration will usually cause sufficient uterine contraction to inhibit such bleeding. Methergine, misoprostol, and prostaglandins (PGs) are also used as ther apeutic agents. Although pregnancy is a time of increased coagulation factors, those are not key to placental site hemostasis.

5. (C) During pregnancy, the enlargement of preexisting myocyte cells is the primary source of growth.

This is done by stretching and marked hypertrophy of the muscle cells. Also there is an accumulation of fibrous tissue in the muscle layers and a considerable increase in elastic tissues. These add strength to the uterus despite a thinning of the wall thickness. Involution occurs postpartum, when the uterus

decreases from about 1,000 g to about 60 g. There are few new myocytes created during pregnancy.

This increase is in a normal controlled fashion so there is no anaplasia or atypical.

6. (A) The corpus luteum normally decreases in its function after 8 weeks into the gestation. In

midgestation, it is no longer needed to maintain the hormonal milieu of pregnancy (the placenta does that). Thus a slightly enlarged ovary and a positive pregnancy test signal normal pregnancy typically. If the uterus was not 8-week size and there was adnexal enlargement and tenderness the differential needs to include an ectopic pregnancy as well. Once the uterus is 8-week size this implies an intrauterine pregnancy since in a pregnancy not just hormonal change is necessary for uterine enlargement. A follicular cyst is uncommon after ovulation. An ovarian neoplasm is possible but less common unless markedly enlarged ovary (i.e., >6 cm). Ultrasound can be very helpful in differentiating between these.

7. (D) In 2009, the Institute of Medicine summarized studies and published guidelines for weight gain during pregnancy, which the American College of Obstetrics and Gynecology supports. It

recommended a weight gain of 25 to 35 lb for normal-weight women to minimize low-birth-weight infants. The weight gain is accounted for by adding up the components that contribute to it, such as the fetus, placenta, increased blood volume, and increased maternal fat stores. More and more evidence is accumulating to show that low-weight gain when associated with inadequate diet is detrimental to the pregnancy. Women who are morbidly obese can gain less weight, but dieting to lose weight during pregnancy is never recommended. There continues to be controversy about the role of maternal weight gain to maternal obesity after pregnancy.

8. (D) The change in center of gravity caused by the enlarging uterus predisposes to a lordotic position and puts strain on paraspinal muscles and pelvic joints. Backache is a common complaint during

pregnancy. Less commonly, the neck flexion and depressed shoulder girdle may cause median and ulnar nerve traction. Treatment is generally not effective and those complaints regress only after delivery.

Use of heat, muscle relaxant, and exercise may help temporize these complaints.

9. (C) Hyperpigmentation in pregnancy includes the transformation of the linea alba to the linea nigra and the development of the “mask of pregnancy” or chloasma. Striae result from stretching of the skin under hormonal influences. The vascular changes occurring during states of high estrogen levels are common to both liver disease and normal pregnancy. These include the development of spider angiomata and

palmar erythema.

10. (E) The mother and a rapidly growing infant use an increased amount of oxygen, resulting in an increased basal metabolic rate (BMR). When combined with elevated binding protein secondary to estrogen effect, one can be misled to diagnose hyperthyroidism when, in fact, these are normal pregnancy changes. For this reason, a thyroid evaluation in pregnancy will often use a free T4 level rather than total T4. Even mild hyperthyroidism probably does not merit treatment during pregnancy.

AST and ALT are not elevated in normal pregnancy but may be elevated in patients with severe preeclampsia. Hematocrit will tend to drop because of plasma volume expansion. Creatinine also decreases because of increased glomerular filtration.

11. (C) This rather uncommon lesion tends to regress spontaneously with delivery. This is an extreme form of gingival hyperplasia that is common in pregnancy. There is no link to dental caries or

permanent changes. It is often associated with poor dental hygiene and irritation of the gum line. Gums may bleed more easily in pregnancy. Melasma is the darkening of the skin over the cheeks and

forehead. An abscess would be deeper in the gum line and not necessarily friable. Decidualization is glandular hyperplasia. A spider angioma is on the skin and is a vascular abnormality created by high estrogen levels.

12. (E) With prolonged gastric emptying time and an elevated stomach and progesterone acting to relax the sphincter mechanism of the stomach, the reflux of gastric contents into the esophagus becomes more frequent. These physiologic events are translated into the physical symptom of heartburn and/or

gastroesophageal reflux disease (GERD), about which many patients complain. Appendicitis can be more difficult to diagnose because of the abnormal position of the appendix. It is elevated toward the right upper quadrant of the abdomen. The stomach is elevated and also somewhat compressed.

Intestinal tone and mobility are slowed by progesterone effect. Intestinal absorbency remains the same, and for weight gain to take place, the gravida must increase caloric intake.

13. (E) The presentation of an acute abdomen in pregnancy is very difficult due to the anatomic and physiologic changes in pregnancy. Pregnant women often do not muster the inflammatory response due to an infectious process during pregnancy that a nonpregnant woman does. During pregnancy, C

reactive protein and sedimentation rates are elevated as a baseline. WBC counts vary greatly during pregnancy from 5,000 to 12,000. Pregnant women also have a slightly elevated basal temperature. The elevation of the abdominal wall away from the intestines by the uterus may also decrease the findings of rebound, lack of bowel sounds, and anorexia. The positioning of the appendix in pregnancy appears to make the psoas sign less helpful. Given all these confounders, none of the findings in this woman make the diagnosis of appendicitis unlikely. The only abnormal value is the new onset of nausea even though there is no emesis. Given the serious ramifications of a ruptured appendicitis in pregnancy, one must be vigilant for this occurrence.

14. (E) Often imaging is needed to make diagnosis. Although an ultrasound has the least ionizing radiation impact and may identify other causes of pain such as ovarian mass or gallstones, by 20 weeks’ EGA it is very hard to find little less compress the appendix. A KUB will be helpful only if there is free air under the diaphragm due to rupture. If a CT scan is to be done, oral contrast is safe and allows much better imaging for the diagnosis. The problem with CT scans is the ionizing radiation. MRI avoids the radiation and in expert hands has an excellent performance regarding sensitivity for appendicitis

diagnosis. The problem is that it is very expensive, not always available 24/7 and expert readings may

Placental, Fetal, and Newborn Physiology

Pelvic Floor Dysfunction: Genital Prolapse and Urogynecology