HDCN Ask the Professor: Pregnancy in a CAPD patient

Question: I am an obstetrician-gynecologist, and I have a patient with CAPD who is 19 weeks pregnant. She is 23 years old and this is her second pregnancy. Last April, she had a spontaneous abortion of twins at 16 weeks gestation. Her blood pressure is well controlled by Aldomet (alpha methyldopa) and she is receiving erythropoietin. I am looking for case histories, articles or for any personal experience you might have with CAPD in pregnancy.

Nicole Racette, MD (Vancouver, Canada)

Response by Dr. Susan Hou, Associate Professor of Medicine, Rush-Presbyterian St. Luke's Medical Center, Chicago, IL:
Pregnancy is infrequent in women receiving chronic dialysis and the outcome is generally felt to be poor. There have been case reports of women receiving peritoneal dialysis which suggest that pregnancy may have a better outcome with this ESRD treatment modality. It is postulated that peritoneal dialysis may allow for a more constant intrauterine metabolic environment and fewer rapid changes in volume, with a beneficial effect for the fetus. Many questions about peritoneal dialysis during pregnancy remain:

Should a woman who starts dialysis during pregnancy be started on peritoneal dialysis?

Should a pregnant hemodialysis patient be switched to peritoneal dialysis?

Should changes be made in the dialysis regimen?

Will the catheter function normally?

What effect will peritonitis have on the baby and how should it be treated?

Isn't the abdomen going to get a little crowded with the catheter, the dialysate and the baby?

Frequency of conception in peritoneal dialysis patients
There are approximately 13,000 women under the age of 44 receiving chronic dialysis in the United States. Twenty-five percent of these are treated with peritoneal dialysis. A survey of 35% of women of childbearing age over a three year period revealed 9 pregnancies, or 0.25 % per year. In contrast, hemodialysis patients become pregnant more than twice as often. The reasons for the differences in the frequency of conception are not understood.

CAPD regimen during pregnancy
A widely practiced although unproven practice in the care of the pregnant dialysis patients is to increase the total amount of dialysis delivered. There is no commonly accepted target KT/V for a pregnant woman, but the goal is to achieve a higher KT/V than is accepted as adequate dialysis in a non pregnant patient. With hemodialysis, this goal is achieved by increasing the frequency of dialysis to as often as six days a week. With peritoneal dialysis, the achievement of a higher than usual KT/V requires an increased number of exchanges. It is sometimes necessary to combine several daytime exchanges with the use of a cycler at night. Increasing the amount of dialysis delivered is made more difficult in late pregnancy because exchange volumes have to be decreased because of abdominal discomfort.

Catheter placement during pregnancy
A recently established American Registry for Pregnancy in Dialysis Patients has recorded 13 instances where peritoneal dialysis catheters were placed during pregnancy between 4 and 29 weeks gestation. Only one instance of a leak and two instances of failure to drain were noted. Two patients were switched from peritoneal to hemodialysis during pregnancy for catheter problems. One was because of failure to drain. In a second instance a woman who conceived after starting CAPD had serious bleeding resulting from laceration of a uterine vein by a peritoneal dialysis catheter.

One concern about the use of peritoneal dialysis during pregnancy is what effect peritonitis might have on the pregnancy. The information on peritonitis is limited. There are three published reports of peritonitis reported in CAPD patients. Two were followed by premature labor with one premature birth and one stillbirth. Because of the connection between fallopian tubes and the peritoneum, there is a risk that any pregnancy associated infections may lead to peritonitis. If peritonitis becomes a common problem in pregnant CAPD patients, its contribution to premature labor may be substantial.

When peritoneal dialysis was first used in pregnant women, it was hoped that obstetric bleeding problems might be reduced with a modality which did not require the use of heparin. However, bleeding problems continue to occur. Bloody dialysate, which is rarely a sign of a serious problem in a non pregnant patient, may indicate abruptio placentae or impending abortion. A pregnant woman with bloody dialysate should be hospitalized for observation and should have an ultrasound to look for placental separation.

The most common life threatening problem encountered in pregnant CAPD patients is hypertension. Eighty percent of pregnant women treated with CAPD develop hypertension during pregnancy and 40% suffer diastolic blood pressures greater than 110 mm/hg.

During normal pregnancy, red cell production is increased as is plasma volume. In dialysis patients, intravascular volume increases but hematocrit usually drops. Erythropoietin appears to be safe during pregnancy. It does not cross the placenta and does not appear to make hypertension more difficult to control. However, the dose must be increased some times more than twofold to maintain the prepregnancy hematocrit. The tendency toward iron deficiency is aggravated by pregnancy.

Fifty percent of pregnancies in CAPD patients reported to the American Registry resulted in surviving infants. The success rate for pregnancy is 43% in hemodialysis patients but the difference between the two modalities is not statistically significant. There is not enough evidence of better outcome in CAPD patients to warrant changing dialysis modalities during pregnancy. Most infants are born prematurely.

In summary, peritoneal dialysis patients become pregnant less frequently than hemodialysis patients, but when pregnancy occurs, the outcome is as good or better than in hemodialysis patients. The use of peritoneal dialysis does not avoid the problems of hypertension, bleeding, and premature birth that plague pregnancies in hemodialysis patients. Peritonitis and catheter problems are unique to peritoneal dialysis. Pregnancy in any dialysis patient is a high risk situation and the specific role of peritoneal dialysis in management of such pregnancies is a subject of ongoing investigation.
(January, 1996)