A nurse is caring for a client who is at 16 weeks of gestation and reports a sudden gush of vaginal fluid.
Which of the following findings indicates premature rupture of membranes?

Choice A rationale

Nalbuphine hydrochloride is a synthetic opioid agonist-antagonist analgesic often used for pain relief during labor. Its agonist effects on kappa (κ) opioid receptors in the central nervous system lead to analgesia and common side effects, including central nervous system depression. Sedation is a frequent manifestation of this effect, caused by the drug's action on brain centers controlling arousal.

Choice B rationale

Nalbuphine primarily acts as an opioid, and its μ-receptor antagonist activity counteracts some opioid effects, but typical opioid-related gastrointestinal effects include decreased peristalsis, often leading to constipation. Diarrhea is not a common or expected adverse effect of nalbuphine; instead, it tends to slow gut motility due to its opioid effects on the enteric nervous system.

Choice C rationale

Opioid use, including nalbuphine, can sometimes lead to the adverse effect of urinary retention, due to increased detrusor muscle tone and internal sphincter spasm, which is a suppression of the micturition reflex. Diuresis, which is an increased or excessive production of urine, is not a recognized adverse effect of this medication.

Choice D rationale

Opioids, such as nalbuphine, typically interact with the thermoregulatory centers in the hypothalamus, often resulting in hypothermia due to vasodilation and decreased metabolic rate, not fever. Fever (pyrexia) is not a common or characteristic adverse effect associated with the administration of nalbuphine hydrochloride during labor.

Choice A rationale

While heroin use, an opioid, is associated with various adverse pregnancy outcomes, its direct causation of placenta previa is not a primary, established link. Placenta previa, the implantation of the placenta over the cervical os, is more commonly linked to risk factors such as previous Cesarean birth, advanced maternal age, and multiparity, rather than a direct pharmacological effect of heroin on uterine implantation sites.

Choice B rationale

Increased amniotic fluid (polyhydramnios) is often associated with conditions like maternal diabetes, fetal gastrointestinal or central nervous system anomalies, or twin to twin transfusion syndrome. Heroin use is primarily associated with decreased amniotic fluid (oligohydramnios) and Intrauterine Growth Restriction (IUGR), a consequence of vasoconstriction and compromised uteroplacental perfusion.

Choice C rationale

Opioid use, including heroin, is a significant risk factor for preterm labor (PTL). The vasoconstrictive effects of heroin on the uteroplacental circulation can lead to ischemia and placental abruption, both of which are strong triggers for uterine irritability and the initiation of PTL (delivery before 37 weeks gestation), posing a high risk for the fetus.

Choice D rationale

Heroin use is a teratogen and is associated with multiple adverse effects, including IUGR and Neonatal Abstinence Syndrome (NAS). However, heroin itself is not typically classified as a primary cause of chromosomal abnormalities, which are structural or numerical errors in the genetic material, usually arising from meiotic nondisjunction or inherited genetic defects, rather than an opioid's pharmacologic action.