DEAR DR. ROACH: My wife is Rh negative, and I am Rh positive. Our baby (fetus) is positive. I am worried about my wife and my baby. Is this dangerous? What can be done? This is her second pregnancy. — H.D.

ANSWER: Blood types are complicated. A simple version that’s familiar is the A, B and O types. An additional layer to that is the RhD factor. It’s the RhD factor that has the greatest potential to cause a dangerous condition called hemolytic disease of the fetus and newborn. Babies are at risk for HDFN when the mother is RhD-positive and the father is RhD-negative. Since we carry two genes for the RhD factor, not all babies will be RhD-positive, even if one parent is. When the developing fetus is also positive and the mother is negative, intervention is necessary to reduce the risk of HDFN.

In the first pregnancy, the risk of HDFN is low, since the mother does not usually have antibodies against the RhD factor. However, during birth, there is often exchange of fetal blood with maternal blood, which causes the mother to begin making antibodies against the RhD factor. It is also possible for the mother to begin making antibodies during the pregnancy due to small amounts of bleeding across the placenta, the organ that supplies the developing baby with all the nutrients it needs to develop and grow. Most cases of HDFN can be prevented by giving the mother anti-D immune globulin immediately after delivery. This prevents her from making antibodies to RhD factor. Your blood type and wife’s blood type should have been known and the medication given her during her first pregnancy.

Not all cases can be prevented, and so mothers in your wife’s situation are monitored for development of these anti-D antibodies. If the mother develops high amounts of antibodies (as measured by a blood test) during pregnancy, then the developing fetus is monitored carefully for signs that the maternal antibodies are destroying the developing fetus’ blood cells. Ultrasound measurement of blood flow is a noninvasive way that replaced the needle sampling we used to do. If there are signs of fetal distress, the fetus may need to be treated with transfusion of RhD-negative blood.

Less than half of all pregnancies where the mother has developed antibodies to RhD develop problems bad enough to be treated, so there is a very good chance she will have no problems.

DEAR DR. ROACH: I am an 88-year-old man in good health. Both my general doctor and my urologist prescribed CIPRO as a treatment for a suspected urinary tract infection. My pharmacist filled the prescription, despite a clear statement buried in the pharmacy information sheet that states “Do NOT prescribe for patients over 60.” Apparently, it potentially can adversely affect the Achilles’ tendons. Should I refuse to take CIPRO, and is there an alternative? Would there be some concern because of a previous cardiology issue? I have a pacemaker/defibrillator implant. — J.N.A.

ANSWER: Ciprofloxacin is a type of antibiotic called a quinolone, and these drugs were used a lot when they were first released. They are prescribed less frequently now because of worsening drug resistance as well as the possibility of toxicity. The risk to Achilles’ tendon is low. A rupture occurs in about three cases per 100,000. Neurological symptoms are much more common (3% to 4%) and can be serious, including hallucinations and delirium.

Because of this, ciprofloxacin and similar drugs should be used only when the benefit clearly outweighs the risk (and that does occasionally include patients over 60).

Dr. Roach regrets that he is unable to answer individual letters but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.

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