Nm 602 Module 4 Study Guide/unit D

Front 1

What are the primary structural and functional changes in the renal system during pregnancy?

Back 1

(PG 375-376)Physiologic hydroureter and hydronephrosis with significant dilation of the renal calyces, pelvis, and urteters beginning as early as the seventh week. The mean kidney length increases by approximately 1 cm due to the increased renal blood flow (RBF) and vascular volume and renal hypertrophy. Renal volume increases by 30%. The diameter of the ureteral lumen increases with hypertonicity and hypermotility of the uretheral musculature. Hypomotility and reduced peristalic movements of the ureters may be mediated by prostoglandin E2 (PGE2).

Front 2

Discuss the effects of increased progesterone on the ureters, bladder, and periurethral connective tissue.

Back 2

(PG 376)Bladder tone decreases as a result of the effects of progesterone on smooth muscle.May induce hypertrophy of the longitudinal smooth muscle surrounding distal portions of the ureters and hyperplasia of the periurethral connective tissue. This may lead to a temporary stenosis and mild dilation of the upper portions of the ureters.

Front 3

Why is the right ureter more likely to be dilated?

Back 3

The right ureter makes a right-angle turn as it crosses the iliac and ovarian veins at the pelvic brim, the turn of the left ureter is less acute and it parallels rather than crosses the left ovarian vein. The illiac vessels are more rigid on the right than on the left, thus further compressing the ureters.

Front 4

What is the effect of estrogen on the trigone?

Back 4

Under the influence of estrogen, the trigone undergoes hyperplasia with hypertrophy of the bladder musculature. The bladder mucosa becomes hyperemic with increased size and tortuosity of the blood vessels. The mucosa becomes more edematous and vulnerable to trauma of infection after engagement of the presenting part.

Front 5

What are the causes of increased urinary output during pregnancy? (urodynamic and hemodynamic) (PG 376-377)

Back 5

●URODYNAMIC- urine output increases from a mean of 1475 to 1919ml per 24 hours primarily because of changes in sodium excretion. Mean flow rate decreases in the second and third trimester with and increase in flow time. Number of voids per day and mean daily urine output increase throughout gestation.
●HEMODYNAMIC- RBF increases up to 50%-80% by the end of the first trimester then slowly decreased to term. This change is accompanied by increased glomerular filtration rate (GFR), decreased renal vascular resistance (RVR), and activation of the renin-angiotensin-aldosterone system. Increased flow is enhanced by vasodilation of preglomerular and postglomerular capillaries.

Front 6

Renal blood flow is best when the mother is in what position?

Back 6

Left lateral position.

Front 7

Why are glucose and amino acids excreted in higher amounts?

Back 7

The basis for glycosuria is probably secondary to the increase in GFR. As the GFR increases during pregnancy, renal reabsorptive capacity for glucose also increases but not to the same extent

Front 8

What are the implications of higher urinary glucose for pregnant women?

Back 8

Women with greater than usual degree of glycosuria during pregnancy may have sustained renal tubular damage from earlier untreated UTIs. In some women, sites for glucose reabsorption may not be completely healed and thus unable to deal with the stresses imposted by the increases filtered load of glucose during pregnancy. In addition, random testing of urine samples is not useful in the diagnosis or control of diabetes during pregnancy and urine glucose may not be a reliable indicator of plasma glucose.

Front 9

Is proteinuria a common finding in pregnancy?

Back 9

(PG 379) Yes, protein excretion rises from less than 100mg per 24 hours to up to 250-300mg per 24 hours with marked day to day variation.

Front 10

When is proteinuria considered abnormal in pregnancy?

Back 10

When protein excretion values exceed 300 mg per 24 hours. And proteinuria associated with hypertension in the pregnant woman is associated with a greater risk of an adverse pregnancy outcome.

Front 11

Explain sodium filtration and reabsorption in pregnancy. What happens to the sodium that is retained?

Back 11

○The filtered load of Na+ increases up to 50% as a result of the increased GFR.
○Pregnant females filter 30,000 mg of Na+ compared to 20,000 mg that of the non-preg female.
○To prevent excessive urinary Na+ loss, tubluar reabsorption increases up to 99%.
○As a result there is a net retention of 950mg (2-6 Meq/day)
○Na+ increase in late pregnancy, much of Na+ is used by fetus/placenta. The rest in distributed in maternal blood and extracellular fluid. (See table 11-3 pg 380)
○Despite alteration, the pregnant femal remains in Na+ balance and responds normally to change both in Na+ and H20 balance.
○Table 11-3 pg 380: Storage of Sodium During pregnancy

Hint 11

Storage site/ Sodium (mEq)
Fetus 290
Edemal fluid 240
Plasma 140
Amniotic Fluid 100
Uterus 80
Placenta 57
Breasts 35
RBC’s 5
Total 947

Front 12

What is the physiologic explanation for the increases in renin, angiotensinogen, angiotensin-converting enzyme (ACE), angiotensin II, and aldosterone?

Back 12

○Changes in most components peak at 30-32 weeks. These changes are mediated by estrogens, progesterone, prostaglandins and alteration in the renal processing of sodium.
○Renin release is stimulated by estrogens (which also increase concentrations of angiotensinogen).
○Angiotensinogen is increased by estrogens. LOW angiontensinogen levels are associated with spontaneous abortion and may reflect reduced palcental estrogen production.
○Angiotensinogen-converting enzyme (ACE)- may be similar or slightly lower that nonpreganat values.
○Angiotensin II- Increases early in pregnancy and peaks at 2 to 3 times nonpregnant levels by 30 weeks. ATII levels may fall in 3rd trimester but are still above non-pregnant values.
○Aldosterone- Are significantly increased by 8 weeks and reach levels 4 to 6 times higher than those in nonpregnant women by the 3rd trimester. The increased aldosterone opposes the sodium-losing effects or progesterone and allows a progressive accumulation of sodium in maternal and fetal tissues. Increase aldosterone levels may be needed to help maintain new Na+/H20 balance.
○Preeclampsia is associated with a suppression of the renin-angiotensinogen-aldosterone system. (To read more Chapter 9 is recommended)

Front 13

How much water is a pregnant woman expected to accumulate?

Back 13

○6-8 L of water to meet their needs and those of the fetoplacental unit.

Front 14

What placental hormone may reset thirst receptors during pregnancy?

Back 14

○Human chorionic gonadotropin may also have a role in resetting the thirst and osmostat receptors during pregnancy.

Front 15

Water intoxication may occur when oxytocin infusion is used because

Back 15

○Oxytocin infusions have been associated with water intoxication and maternal and fetal hyponatremia. The risk of water intoxication in increased when oxytocin is administered with large volume of hypertonic dextrose solution. The hypertonic solution pulls fluid into the vascular compartment from the interstitial space, resulting in hemodilution. However, the additional fluid cannot be readily excreted due to the anitdiuretic effects of oxytocin.

Front 16

When do glomerular filtration rate, plasma creatinine, urinary glucose excretion, and blood urea nitrogen return to non-pregnant levels in postpartum?

Back 16

○RPF, GFR, plasma creatine, creatine clearance, and BUN return to nonpregnant levels by 2 to 3 months postpartum.
○Urinary glucose excretion returns to nonpregnant patterns by 1 week postpartum.

Front 17

Why is there natriuresis and diuresis on days 2-5 postpartum? What is the role of decreased oxytocin in this change?

Back 17

○The PP is characterized by rapid and sustained natriuresis and diuresis, especially on days 2 to 5, as the sodium and water retention of pregnancy is reversed. Fluid and electrolyte balance is generally restored to nonpregnant homeostatsis by 21 days postpartum and often earlier. Persistence of more than a trace of edema after this time is indicative of sodium retention or a protein-losing state. The decrease of oxytocin contributes to diuresis because oxytocin acts similarly to AVP in promoting reabsorption of free water. As oxytocin levels decrease, the diuresis becomes more pronounced, with up to 3000mL of urine excreted per 24 hours on the second through fifth days after delivery. A normal voiding for the postpartum woman may be 500mL to 1000mL, several times greater than nonpostpartum individual. Water may also be lost during via night sweats.

Front 18

Why is the pregnant woman at risk for urinary tract infection? Why are urinary tract infections more common during the postpartum period?

Back 18

○UTI occurs with increased frequency during pregnancy and is related to anatomic changes in the renal system
○Dilation of the urinary tract, along with partial obstruction of the ureters from ureteral compression at the pelvic brim, results in urinary stats.
○Large volumes of urine may be sequestered in the ureters and hypotonic bladder during pregnancy
○These static pools increase the risk of ASB (Asympotmatic Bacteriuria), especially because the urine may contain glucose, protein, amino acids, which promote additional substrates for bacterial growth.
○Edema and hyperemia of the bladder mucosa also increase susceptibility to infection.
○The static column of urine in the hypoactive ureters also facilitates ascending bacteria migration, increasing the risk of pyelonephritis.
○Women with sickle cell trait are at higher risk for UTI’s

Front 19

What are the maternal and fetal disadvantages of IV fluids to mother during labor?

Back 19

○There is little evidence to support routine use of IF infusions in otherwise healthy women not receiving anesthetics. O’Sullivan notes the following: “Intravenous therapy is seldom necessary during the first 12 hours of labor, irrespective of the finding of ketonuria; when it is prescribed, the indication for its use should be clearly documented and fluid balance charts should be meticulously maintained. In fact, the judicious use of oral fluids should mitigate the need for intravenous fluids in many patients.”
○Mothers receiving IV fluids are more likely to have hyponatremic newborns than women who receive only oral fluids. Administration of hypotonic fluid to the mother can, by increasing the maternal ECF volume, lead to decreases in fetal osmotic pressure and serum sodium and has resulted in maternal and neonatal hyponatremia and an increased risk of neonatal complications. If this therapy is used, the fluid and electrolyte status of both mother and infant must be carefully monitored.

Hint 19

Conditions associated with IV Fluid Administration during labor Table 11-7 pg 387