A 40-year-old pregnant patient, currently hospitalized for preterm labor at 34 weeks’ gestation, is discussing potential delivery options with her provider based on the results of a fetal lung maturity test.

 Which prenatal test would the provider likely order to check for fetal lung maturity? 

Choice A rationale:

Incorrect. This statement describes autosomal dominant inheritance, not autosomal recessive inheritance. In autosomal dominant inheritance, only one copy of the abnormal gene is needed to cause the disorder. However, in autosomal recessive inheritance, both copies of the gene must be abnormal for the disorder to be expressed.

Choice B rationale:

Incorrect. This statement describes X-linked recessive inheritance, not autosomal recessive inheritance. In X-linked recessive inheritance, the abnormal gene is located on the X chromosome. Males have only one X chromosome, so if they inherit the abnormal gene, they will have the disorder. Females have two X chromosomes, so they must inherit two copies of the abnormal gene (one from each parent) to have the disorder.

Choice C rationale:

Correct. This statement accurately describes autosomal recessive inheritance. In autosomal recessive inheritance, both copies of the gene must be abnormal for the disorder to be expressed. This means that both parents must be carriers of the abnormal gene in order for their child to have the disorder.

Choice D rationale:

Incorrect. This statement is partially correct, but it does not fully describe autosomal recessive inheritance. The disorder can occur in both males and females, but it is not limited to heterozygous females. Homozygous females (those who have two copies of the abnormal gene) will also have the disorder.

Choice A rationale:

Prostaglandins:

Mechanism of action: Prostaglandins are hormone-like substances that play a crucial role in labor initiation. They act by softening and ripening the cervix, stimulating uterine contractions, and rupturing the amniotic sac.

Types: Prostaglandins used for labor induction include:

Dinoprostone (Cervidil, Prepidil): Inserted into the vagina as a gel or pessary.

Misoprostol (Cytotec): Administered orally or vaginally.

Effectiveness: Generally effective in initiating labor within 24 hours, with success rates ranging from 60-85%.

Advantages:

Can be used when the cervix is unfavorable (not ripe).

Can be administered in a variety of ways to suit the patient's preferences.

May have a lower risk of uterine hyperstimulation compared to oxytocin.

Disadvantages:

Can cause side effects such as nausea, vomiting, diarrhea, and fever.

May increase the risk of uterine rupture, especially in women with a history of cesarean delivery.

Choice D rationale:

Amnioinfusion:

Procedure: Involves the infusion of sterile saline solution into the amniotic sac through a small catheter.

Mechanism of action: Not fully understood, but it's thought to work by:

Increasing amniotic fluid volume, which can help to stimulate contractions.

Stretching the uterine walls, which may trigger the release of prostaglandins.

Reducing pressure on the umbilical cord, which can improve fetal oxygenation.

Effectiveness: Usually used in conjunction with other induction methods, such as oxytocin or prostaglandins. Has a success rate of about 50-60% in initiating labor within 24 hours.

Advantages:

May be helpful in cases of low amniotic fluid (oligohydramnios).

Can decrease the risk of umbilical cord compression.

Disadvantages:

Requires the insertion of a catheter into the uterus, which carries a small risk of infection.

May cause discomfort for the mother.