At what day post-ovulation (dpo) are prostaglandins released in a typical menstrual cycle, particularly in a patient trying to conceive with a history of gastrointestinal issues and abdominal pain?

Prostaglandin Release During the Menstrual Cycle

Prostaglandins are released primarily during the luteal phase of the menstrual cycle, with peak levels occurring just before and during menstruation (approximately days 21-28 of a typical 28-day cycle, or roughly 7-14 days post-ovulation). 1

Timing of Prostaglandin Release Across the Cycle

Luteal Phase Dominance

• Prostaglandin secretion is significantly higher during the secretory/luteal phase compared to the proliferative phase, driven by cyclical effects of ovarian estrogen and progesterone 1
• The luteal phase begins shortly after ovulation and continues until either luteolysis (just before menstruation) or pregnancy establishment 2
• During the late luteal phase, when progesterone levels are highest, prostaglandin synthesis increases substantially 3

Peak Release at Menstruation

• Maximum prostaglandin levels occur with the onset of menses, when endometrial tissue breakdown triggers massive prostaglandin release into menstrual fluid 4
• In primary dysmenorrhea, this increased prostaglandin release causes incoordinate uterine hyperactivity, resulting in ischemia and pain 4
• Approximately 50% of menstruating individuals experience dysmenorrhea related to elevated prostaglandin levels, with 10% incapacitated for 1-3 days monthly 4

Hormonal Regulation of Prostaglandin Production

Progesterone's Role

• Progesterone levels peak during the luteal phase and directly influence prostaglandin synthesis 1
• Women with cyclic attacks of certain conditions (like acute hepatic porphyrias) typically experience symptoms during the luteal phase when progesterone levels are highest, resolving with menses onset 3

Estrogen Effects

• COX-2 enzyme expression in the myometrium increases with estradiol exposure, enhancing prostaglandin production capacity 3
• The balance between estrogen and progesterone throughout the cycle modulates overall prostaglandin synthesis 1

Clinical Implications for Patients with GI Issues

Prostaglandin Effects on the GI Tract

• Prostaglandins maintain gastrointestinal mucosal integrity and microcirculation 5
• PGE series prostaglandins inhibit gastric acid secretion and stimulate alkaline secretion while increasing mucosal blood flow 5
• The cyclical increase in prostaglandins during the luteal phase and menstruation may exacerbate pre-existing GI symptoms through effects on smooth muscle contractility 5

Abdominal Pain Considerations

• Elevated prostaglandins cause uterine muscle hyperactivity and cramping, which can be difficult to distinguish from other sources of abdominal pain 4
• In pregnancy, abdominal attacks occur more frequently and may complicate differential diagnosis 3
• NSAIDs work by inhibiting prostaglandin synthesis and should be restricted to the first and second trimester only (discontinued after gestational week 28) if pregnancy is achieved, as they can cause oligohydramnios and ductus arteriosus complications 3

Impact on Fertility

• Continuous periovulatory NSAID exposure can induce luteinized unruptured follicle (LUF) syndrome, reducing fertility 3
• Women trying to conceive with difficulty should consider discontinuing NSAIDs to avoid interference with ovulation, which is prostaglandin-dependent 3, 6

Key Pitfalls to Avoid

• Do not assume prostaglandin levels remain constant throughout the cycle—they fluctuate dramatically with hormonal changes 1
• Avoid using NSAIDs continuously in women trying to conceive, as prostaglandins are essential for follicular rupture and ovulation 6
• Be aware that prostaglandin-related symptoms (cramping, GI disturbance) peak in the late luteal phase and during menses, not immediately post-ovulation 1, 4