A 32-year-old woman presents with primary infertility of 3 years duration. She has regular menstrual cycles (28 days), normal BMI, and no hirsutism. Semen analysis of her husband is normal. Basal body temperature charting suggests ovulation. What is the most appropriate next investigation to evaluate tubal and peritoneal factors?

## Investigation of Tubal and Peritoneal Factors in Infertility **Key Point:** Hysterosalpingography (HSG) is the first-line imaging investigation for assessing tubal patency and uterine cavity abnormalities in the evaluation of female infertility. ### Why HSG is the Investigation of Choice In this case, ovulatory status has been confirmed (regular cycles, normal BBT), and male factor has been excluded (normal semen analysis). The next logical step is to evaluate structural and tubal factors. **High-Yield:** HSG is: - Non-invasive, outpatient procedure - Cost-effective and widely available - Provides information about tubal patency (spillage into peritoneal cavity) - Detects intrauterine pathology (polyps, fibroids, septate uterus, synechiae) - Performed in follicular phase (days 7–12) to avoid disrupting early pregnancy ### Diagnostic Algorithm for Female Infertility ```mermaid flowchart TD A[Primary infertility 3 years]:::outcome --> B{Ovulation confirmed?}:::decision B -->|Yes| C{Male factor excluded?}:::decision B -->|No| D[Ovulation induction]:::action C -->|Yes| E[Evaluate tubal/peritoneal factors]:::action C -->|No| F[Treat male factor]:::action E --> G[HSG - first-line imaging]:::action G --> H{Tubes patent?}:::decision H -->|Yes, normal cavity| I[Laparoscopy if needed for endometriosis]:::action H -->|No/abnormal| J[Diagnostic laparoscopy ± hysteroscopy]:::action ``` **Clinical Pearl:** HSG can have both diagnostic and therapeutic value — flushing of tubes with contrast may improve fertility in the following 3 cycles (oil-based contrast may be superior to water-soluble for this effect). ### Timing and Technique | Aspect | Details | |--------|----------| | **Timing** | Follicular phase (days 7–12 of cycle) | | **Contrast** | Water-soluble or oil-based (oil may improve fertility) | | **Findings** | Tubal patency, spillage, filling defects, uterine shape | | **Limitations** | Does not assess ovarian reserve, endometrial quality, or peritoneal surface disease | **Tip:** HSG is preferred over diagnostic laparoscopy as the initial investigation because it is less invasive, requires no general anesthesia, and provides adequate information for most cases. Laparoscopy is reserved for cases where HSG is abnormal or when endometriosis is suspected.